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Jun Hirai,1,2 Hiroyuki Suzuki,3 Daisuke Sakanashi,2 Yuji Kuge,4 Takaaki Kishino,4 Nobuhiro Asai,1,2 Mao Hagihara,5 Hiroshige Mikamo1,2 1Department of Clinical Infectious Diseases, Aichi Medical University Hospital, Nagakute, Aichi, Japan; 2Department of Infection Control and Prevention, Aichi Medical University Hospital, Nagakute, Aichi, Japan; 3Department of Neurology, Aichi Medical University, Nagakute, Aichi, Japan; 4Department of Emergency and Critical Care Medicine, Aichi Medical University Hospital, Nagakute, Aichi, Japan; 5Department of Molecular Epidemiology and Biomedical Sciences, Aichi Medical University, Nagakute, Aichi, JapanCorrespondence: Jun Hirai, Department of Clinical Infectious Diseases, Aichi Medical University Hospital, 1-1, Yazako-karimata, Nagakute, Aichi, 480-1195, Japan, Tel +81-561-62-3311, Fax +81-561-76-2673, Email hiraichimed@gmail.comAbstract: Staphylococcus argenteus is a new species classified as part of the Staphylococcus aureus-related complex in 2015 and has been recognized to be as pathogenic as S. aureus. We describe the first case of endocarditis caused by S. argenteus. A 51-year-old man presented with chief complaints of fever and headaches. On admission, he showed a slight decrease in consciousness level (Glasgow Coma Scale, E4V4M6). Careful physical examination and imaging revealed a systolic heart murmur, Janeway lesions, and complicating convexity subarachnoid hemorrhage (cSAH) of the left frontal lobe. Ceftriaxone 4 g/day was administered immediately after blood cultures were obtained. The next day, all blood cultures grew Gram-positive cocci, identified as Staphylococcus aureus or Staphylococcus argenteus by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). However, the version of MALDI-TOF MS used could not distinguish these bacteria. Although we could not find valvular vegetation, he was clinically diagnosed with infective endocarditis according to the modified Duke’s criteria. Meropenem 6 g/day and linezolid 1.2 g/day were started to cover S. aureus and methicillin-resistant S. aureus. Finally, ampicillin was selected based on drug susceptibility, and the patient was treated for 8 weeks and recovered without permanent damage. The isolated strain formed white colonies on blood agar plates, characteristic of S. argenteus, and differs from golden colony-forming S. aureus. Genetic analysis revealed the isolated strain as S. argenteus (sequence type 1223). Although distinguishing S. argenteus from S. aureus using routine conventional laboratory tests is difficult, the updated library version of MALDI-TOF MS is useful in identifying S. argenteus. Interestingly, all published cases of infection caused by ST1223 have been reported in Japan. Therefore, the trend of infections from the ST1223 strain should be carefully monitored, particularly in Japan. Further investigation is needed to clarify the epidemiology and clinical characteristics of S. argenteus infection, as there are few studies regarding this pathogen.Keywords: Staphylococcus argenteus, sequence type 1223, infective endocarditis, convexity subarachnoid hemorrhage, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, Japan

Jun Hirai,1,2 Tessei Kuruma,3 Daisuke Sakanashi,2 Yuji Kuge,4 Takaaki Kishino,4 Yuuichi Shibata,5 Nobuhiro Asai,1,2 Mao Hagihara,6 Hiroshige Mikamo1,2 1Department of Clinical Infectious Diseases, Aichi Medical University Hospital, Nagakute, Aichi, 480-1195, Japan; 2Department of Infection Control and Prevention, Aichi Medical University Hospital, Nagakute, Aichi, 480-1195, Japan; 3Department of Otolaryngology, Aichi Medical University Hospital, Nagakute, Aichi, 480-1195, Japan; 4Department of Emergency and Critical Care Medicine, Aichi Medical University Hospital, Nagakute, Aichi, 480-1195, Japan; 5Department of Pharmacy, Aichi Medical University Hospital, Nagakute, Aichi, 480-1195, Japan; 6Department of Molecular Epidemiology and Biomedical Sciences, Aichi Medical University, Nagakute, Aichi, 480-1195, JapanCorrespondence: Jun Hirai, Department of Clinical Infectious Diseases, Aichi Medical University Hospital, Nagakute, Aichi, 480-1195, Japan, Tel +81-561-62-3311, Fax +81-561-76-2673, Email hiraichimed@gmail.comAbstract: Although Dialister pneumosintes is a commensal microorganism of the oral cavity, it may sometimes cause severe systemic infections. We report a case of Lemierre syndrome (LS), which developed after D. pneumosintes infection, in a 73-year-old Japanese woman who was admitted to the hospital for throat pain, neck swelling, and fever for 3 days. She had a 3-month history of neglected dental caries, gingivitis, and periodontitis. Physical examination revealed right tonsillar erythema and swelling, and computed tomography (CT) showed peritonsillar and retropharyngeal abscesses. Ampicillin/sulbactam was promptly administered after collecting two sets of blood cultures. Surgical drainage for peritonsillar and retropharyngeal abscesses was also conducted on the second hospital day. Although only commensal oral microflora grew in the culture from the drained pus, Gram-negative bacilli were confirmed in the anaerobic blood cultures. Metronidazole was administered intravenously; however, the fever and neck swelling persisted. Repeat CT performed on the fifth hospital day revealed right internal jugular vein thrombosis, a known complication of tonsillitis and pharyngitis once the infection extends beyond the oropharynx. We diagnosed she had coexisting LS, and anticoagulant therapy was added to her treatment regimen. Her condition improved, and she was discharged after completing 3 weeks of antibiotics. Conventional methods failed to identify the isolated bacterium, and 16S rRNA sequencing ultimately identified it as D. pneumosintes. In a literature review of bacteremia due to D. pneumosintes, poor oral hygiene was considered a probable risk factor for invasive D. pneumosintes infection. We consider this to be the case in our patient who presented with dental caries, gingivitis, and periodontitis. In addition, all cases revealed that the 16S rRNA gene sequencing is useful for identifying this species. Although the diagnosis of LS by physical examination is difficult, physicians should always consider it as a potential complication of infections in the pharyngeal area.Keywords: Dialister pneumosintes, Lemierre syndrome, tonsillar abscess, retropharyngeal abscess, oral hygiene, anticoagulation

BACKGROUND - Recent studies have indicated that bone marrow stromal cells (BMSC) have the potential to improve neurological function when transplanted into animal model of central nervous system (CNS) disorders. However, there still exist several questions to solved prior to clinical application. In this study, therefore, we aimed to clarify the optimal delivery route of BMSC transplantation over a reasonable time window.MATERIALS AND METHODS - The rats were subjected to permanent middle cerebral artery occlusion. The BMSC were labeled with quantum dot (QD) 800. The labeled BMSC were transplanted into the infarct brain directly or intravenously at 7 days after the insult. Motor function was serially assessed. The BMSC were also tracked using near infrared (NIR) fluorescence imaging technique every week. The fate of the transplanted BMSC was examined at 5 weeks after transplantation, using Immunohistochemistry. RESULTS - Direct, but not intravenous, transplantation of BMSC significantly enhanced functional recovery. NIR fluorescence imaging could visualize their migration towards cerebral infarct in directly, but not intravenously, injected animals. The findings were supported on histological analysis. Thus, the BMSC were widely engrafted in the infarct brain in the directly injected animals, but few BMSC were observed in the intravenously injected ones. CONCLUSION - This study strongly suggests that direct transplantation of BMSC may be more beneficial in treating patients with ischemic stroke than their intravenous transplantation. Therapeutic time window must be called into account when considering the route of BMSC transplantation.

In the synthesis of 18F-FDG by the nucleophilic substitution method, 18O-H2O is usually used as target water. The target water should be recovered after synthesis and reused, because it is expensive, but recovered water contains impurities such as organic substances, and it must be purified before reuse. For this reason Sumitomo Heavy Industries, Ltd. developed an O-18 water purifier for elimination of organic substances in recovered water. This instrument consists of a UV irradiation unit and low-temperature distillation unit. Our institution had an opportunity to test use this instrument and evaluated its performance. The concentrations of organic substances after UV irradiation was greatly reduced, and recovery efficiency after distillation by the low-temperature distillation unit was very satisfactory at 99.3 +/- 0.5%. Furthermore, the yield of 18F-FDG from 18O-H20 purified with this instrument was sufficient for the clinical use. [ABSTRACT FROM AUTHOR]

Octanoate is taken up into the brain and is converted in astrocytes to glutamine through the TCA cycle after beta-oxidation. We speculate that [1-11C]octanoate may be used as a tracer for astroglial functions and/or fatty acid metabolism in the brain and may be useful for studying cerebral ischemia. In the present study we investigated brain distribution of [1-11C]octanoate and compared it with cerebral blood flow (CBF) by using rat and canine models of middle cerebral artery (MCA) occlusion and a high resolution PET. In rats brain distribution of [15O]H2O measured 1-2 h and 5-6 h after insult was compared with that of [1-11C]octanoate measured 3-4 h after insult. Radioactivity ratios of lesioned to normal hemispheres determined with [15O]H2O were lower than those determined with [1-11C]octanoate. These results were confirmed by a study on a canine model of MCA-occlusion. Twenty-four hours after insult, CBF decreased in the MCA-territory of the occluded hemisphere, whereas normal or higher accumulation of [1-11C]octanoate was observed in the ischemic regions. The uptake of [1-11C]octanoate-derived radioactivity therefore increased relative to CBF in the ischemic regions, indicating that [1-11C]octanoate provides functional information different from CBF. In conclusion, we found that [1-11C]octanoate is a potential radiopharmaceutical for studying the pathophysiology of cerebral ischemia. [ABSTRACT FROM AUTHOR]

Spinal cord injury (SCI) leads to devastating sequelae, demanding effective treatments. Recent advancements have unveiled the role of neutrophil extracellular traps (NETs) produced by infiltrated neutrophils in exacerbating secondary inflammation after SCI, making it a potential target for treatment intervention. Previous research has established that intravenous administration of stem cell-derived exosomes can mitigate injuries. While stem cell-derived exosomes have demonstrated the ability to modulate microglial reactions and enhance blood-brain barrier integrity, their impact on neutrophil deactivation, especially in the context of NETs, remains poorly understood. This study aims to investigate the effects of intravenous administration of MSC-derived exosomes, with a specific focus on NET formation, and to elucidate the associated molecular mechanisms. Exosomes were isolated from the cell supernatants of amnion-derived mesenchymal stem cells using the ultracentrifugation method. Spinal cord injuries were induced in Sprague-Dawley rats (9 weeks old) using a clip injury model, and 100 μg of exosomes in 1 mL of PBS or PBS alone were intravenously administered 24 h post-injury. Motor function was assessed serially for up to 28 days following the injury. On Day 3 and Day 28, spinal cord specimens were analyzed to evaluate the extent of injury and the formation of NETs. Flow cytometry was employed to examine the formation of circulating neutrophil NETs. Exogenous miRNA was electroporated into neutrophil to evaluate the effect of inflammatory NET formation. Finally, the biodistribution of exosomes was assessed using 64 Cu-labeled exosomes in animal positron emission tomography (PET). Rats treated with exosomes exhibited a substantial improvement in motor function recovery and a reduction in injury size. Notably, there was a significant decrease in neutrophil infiltration and NET formation within the spinal cord, as well as a reduction in neutrophils forming NETs in the circulation. In vitro investigations indicated that exosomes accumulated in the vicinity of the nuclei of activated neutrophils, and neutrophils electroporated with the miR-125a-3p mimic exhibited a significantly diminished NET formation, while miR-125a-3p inhibitor reversed the effect. PET studies revealed that, although the majority of the transplanted exosomes were sequestered in the liver and spleen, a notably high quantity of exosomes was detected in the damaged spinal cord when compared to normal rats. MSC-derived exosomes play a pivotal role in alleviating spinal cord injury, in part through the deactivation of NET formation via miR-125a-3p.

Objective: We previously reported that alterations of the tumor microenvironment (TME) by programmed death receptor-1 (PD1) blockade affected tumor glucose metabolism and tumor 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) uptake. In cancer cells, high glycolysis allows cells to sustain rapid proliferation since glycolysis is closely related to the proliferation of cancer cells. Therefore, imaging of cellular proliferation may provide more detail of TME alterations. In this study, we investigated how TME alterations by PD1 blockade affects the uptake of 3'-deoxy-3'-[ 18 F]fluorothymidine ([ 18 F]FLT), which is a 18 F-radiolabeled thymidine derivative and is taken up by proliferating cells., Methods: Mice inoculated with murine colon carcinoma CT26 cells were intraperitoneally administered an anti-PD1 antibody on Day 0, when the tumor volume exceeded 50 mm 3 , and Day 5. [ 18 F]FLT-PET imaging was performed pre-treatment (Day 0) and post treatment (Day 7). Tumor infiltrating lymphocytes (TILs) were identified by flow cytometry. [ 18 F]FLT accumulation and localization in tumor tissue was evaluated by autoradiography and immunohistochemistry. The cell-cycle distribution of tumors and CT26 cells exposed to cytokines (interleukin-2, interferon [INF]-γ, and tumor necrosis factor [TNF]-α) was analyzed by flow cytometry., Results: PD1 blockade increased CD8 + and CD4 + T cells in tumor tissue and significantly suppressed tumor proliferation; however, tumor [ 18 F]FLT uptake remained unchanged. Autoradiography and immunohistochemistry showed that [ 18 F]FLT was mainly taken up by cancer cells, but not TILs. Flow cytometric analysis demonstrated that the population of cells in G2/M phase increased after PD1 blockade. Moreover, INF-γ and TNF-α significantly increased cells in G2/M phase in vitro., Conclusion: PD1 blockade-induced alteration of the TME increased CT26 tumor cells in the G2/M phase, which have high thymidine kinase 1 activity. Therefore, [ 18 F]FLT is taken up by tumor cells even if tumor proliferation is suppressed. This observation may be useful for evaluating the response to immunotherapy., (© 2022. The Author(s) under exclusive licence to The Japanese Society of Nuclear Medicine.)

Introduction: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is used as an intra-aortic balloon occlusion in Japan; however, protocols for its effective use in different conditions have not been established. This study aimed to summarize the strategies of REBOA use in severe torso trauma., Methods: Twenty-nine cases of REBOA for torso trauma treated at our hospital over 5 years were divided into hemodynamically unstable (HU) ( n  = 12), cardiac arrest (CA) ( n  = 13), and hemodynamically stable (HS) ( n  = 4) groups. We retrospectively examined patient characteristics, trauma mechanism, injury site, severity score, intervention type, and survival rates at 24 h in each group., Results: In the HU group, 9 and 3 patients survived and died within 24 h, respectively; time to intervention (56.6 versus 130.7 min, P  = 0.346) tended to be shorter and total occlusion time (40.2 versus 337.7 min, P  = 0.009) was significantly shorter in survivors than in nonsurvivors. In the CA group, 10 patients were converted from resuscitative thoracotomy with aortic cross-clamp (RTACC); one patient survived. All four patients in the HS group survived, having received prophylactic REBOA., Conclusion: The efficacy of REBOA for severe torso trauma depends on the patient's condition. If the patients are hemodynamically unstable, time to intervention and total occlusion time could correlate with survival. The combined use of REBOA with definitive hemostasis could improve outcomes. Conversion from RTACC in the cardiac arrest patients and prophylactic use in the hemodynamically stable patients can be one of the potentially effective options, although further studies are needed., (© 2022 The Authors. Acute Medicine & Surgery published by John Wiley & Sons Australia, Ltd on behalf of Japanese Association for Acute Medicine.)

Background: Due to the lack of effective therapies, stem cell transplantation is an anticipated treatment for chronic intracerebral hemorrhage (ICH), and higher cell survival and engraftment are considered to be the key for recovery. Mesenchymal stromal cells (MSCs) compounded with recombinant human collagen type I scaffolds (CellSaics) have a higher potential for cell survival and engraftment compared with solo-MSCs, and we investigated the validity of intracerebral transplantation of CellSaic in a chronic ICH model., Methods: Rat CellSaics (rCellSaics) were produced by rat bone marrow-derived MSC (rBMSCs). The secretion potential of neurotrophic factors and the cell proliferation rate were compared under oxygen-glucose deprivation (OGD) conditions. rCellSaics, rBMSCs, or saline were transplanted into the hollow cavity of a rat chronic ICH model. Functional and histological analyses were evaluated, and single-photon emission computed tomography for benzodiazepine receptors was performed to monitor sequential changes in neuronal integrity. Furthermore, human CellSaics (hCellSaics) were transplanted into a chronic ICH model in immunodeficient rats. Antibodies neutralizing brain-derived neurotrophic factor (BDNF) were used to elucidate its mode of action., Results: rCellSaics demonstrated a higher secretion potential of trophic factors and showed better cell proliferation in the OGD condition. Animals receiving rCellSaics displayed better neurological recovery, higher intracerebral BDNF, and better cell engraftment; they also showed a tendency for less brain atrophy and higher benzodiazepine receptor preservation. hCellSaics also promoted significant functional recovery, which was reversed by BDNF neutralization., Conclusion: Intracerebral transplantation of CellSaics enabled neurological recovery in a chronic ICH model and may be a good option for clinical application., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2022 Soichiro Takamiya et al.)

We conducted a prospective multicenter trial to compare the usefulness of 11 C-methionine (MET) and 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for identifying tumor recurrence. Patients with clinically suspected tumor recurrence after radiotherapy underwent both 11 C-MET and 18 F-FDG PET. When a lesion showed a visually detected uptake of either tracer, it was surgically resected for histopathological analysis. Patients with a lesion negative to both tracers were revaluated by magnetic resonance imaging (MRI) at 3 months after the PET studies. The primary outcome measure was the sensitivity of each tracer in cases with histopathologically confirmed recurrence, as determined by the McNemar test. Sixty-one cases were enrolled, and 56 cases could be evaluated. The 38 cases where the lesions showed uptake of either 11 C-MET or 18 F-FDG underwent surgery; 32 of these cases were confirmed to be subject to recurrence. Eighteen cases where the lesions showed uptake of neither tracer received follow-up MRI; the lesion size increased in one of these cases. Among the cases with histologically confirmed recurrence, the sensitivities of 11 C-MET PET and 18 F-FDG PET were 0.97 (32/33, 95% confidence interval [CI]: 0.85-0.99) and 0.48 (16/33, 95% CI: 0.33-0.65), respectively, and the difference was statistically significant (P < .0001). The diagnostic accuracy of 11 C-MET PET was significantly better than that of 18 F-FDG PET (87.5% vs. 69.6%, P = .033). No examination-related adverse events were observed. The results of the study demonstrated that 11 C-MET PET was superior to 18 F-FDG PET for discriminating between tumor recurrence and radiation-induced necrosis., (© 2021 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Breast positron emission tomography (PET) has had insurance coverage when performed with conventional whole-body PET in Japan since 2013. Together with whole-body PET, accurate examination of breast cancer and diagnosis of metastatic disease are possible, and are expected to contribute significantly to its treatment planning. To facilitate a safer, smoother, and more appropriate examination, the Japanese Society of Nuclear Medicine published the first edition of practice guidelines for high-resolution breast PET in 2013. Subsequently, new types of breast PET have been developed and their clinical usefulness clarified. Therefore, the guidelines for breast PET were revised in 2019. This article updates readers as to what is new in the second edition. This edition supports two different types of breast PET depending on the placement of the detector: the opposite-type (positron emission mammography; PEM) and the ring-shaped type (dedicated breast PET; dbPET), providing an overview of these scanners and appropriate imaging methods, their clinical applications, and future prospects. The name "dedicated breast PET" from the first edition is widely used to refer to ring-shaped type breast PET. In this edition, "breast PET" has been defined as a term that refers to both opposite- and ring-shaped devices. Up-to-date breast PET practice guidelines would help provide useful information for evidence-based breast imaging.

Ferroptosis induction has been recognized as a novel cancer therapeutic strategy. To effectively apply ferroptosis-targeting cancer therapy to individual patients, a diagnostic indicator for selecting this therapeutic strategy from a number of molecular targeting drugs is needed. However, to date, methods that can predict the efficacy of ferroptosis-targeting treatment have not been established yet. In this study, we focused on the iron metabolic pathway to develop a nuclear imaging technique for diagnosing the susceptibility of cancer cells to ferroptosis. As a nuclear probe, human transferrin (Tf) was labeled with Gallium-68 ( 68 Ga) using 2-(p-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) as a chelator ( 68 Ga-NOTA-Tf). Western blot assay and clonogenic survival assay with human renal cancer cell lines A498 and 786-O revealed that the protein expression level of transferrin receptor1 (TfR1) and sensitivity to a ferroptosis inducer, erastin, were correlated. A cellular uptake assay with 68 Ga-NOTA-Tf revealed that the cancer cells sensitive to erastin highly internalized the 68 Ga-NOTA-Tf. Furthermore, treatment with the TfR1 inhibitor ferristatin II reduced the cellular uptake of 68 Ga-NOTA-Tf, indicating that the intracellular uptake of the probe was mediated by TfR1. These results suggest that 68 Ga-NOTA-Tf can be useful in predicting the sensitivity of cancer cells to ferroptosis inducers., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 Published by Elsevier B.V.)

Aims: Exercise intolerance in patients with heart failure (HF) is partly attributed to skeletal muscle abnormalities. We have shown that reactive oxygen species (ROS) play a crucial role in skeletal muscle abnormalities, but the pathogenic mechanism remains unclear. Xanthine oxidase (XO) is reported to be an important mediator of ROS overproduction in ischaemic tissue. Here, we tested the hypothesis that skeletal muscle abnormalities in HF are initially caused by XO-derived ROS and are prevented by the inhibition of their production., Methods and Results: Myocardial infarction (MI) was induced in male C57BL/6J mice, which eventually led to HF, and a sham operation was performed in control mice. The time course of XO-derived ROS production in mouse skeletal muscle post-MI was first analysed. XO-derived ROS production was significantly increased in MI mice from Days 1 to 3 post-surgery (acute phase), whereas it did not differ between the MI and sham groups from 7 to 28 days (chronic phase). Second, mice were divided into three groups: sham + vehicle (Sham + Veh), MI + vehicle (MI + Veh), and MI + febuxostat (an XO inhibitor, 5 mg/kg body weight/day; MI + Feb). Febuxostat or vehicle was administered at 1 and 24 h before surgery, and once-daily on Days 1-7 post-surgery. On Day 28 post-surgery, exercise capacity and mitochondrial respiration in skeletal muscle fibres were significantly decreased in MI + Veh compared with Sham + Veh mice. An increase in damaged mitochondria in MI + Veh compared with Sham + Veh mice was also observed. The wet weight and cross-sectional area of slow muscle fibres (higher XO-derived ROS) was reduced via the down-regulation of protein synthesis-associated mTOR-p70S6K signalling in MI + Veh compared with Sham + Veh mice. These impairments were ameliorated in MI + Feb mice, in association with a reduction of XO-derived ROS production, without affecting cardiac function., Conclusion: XO inhibition during the acute phase post-MI can prevent skeletal muscle abnormalities and exercise intolerance in mice with HF., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: journals.permissions@oup.com.)

Background: Positron emission tomography with 11 C-methionine (MET) is well established in the diagnostic work-up of malignant brain tumors. Texture analysis is a novel technique for extracting information regarding relationships among surrounding voxels, in order to quantify their inhomogeneity. This study evaluated whether the texture analysis of MET uptake has prognostic value for patients with glioma., Methods: We retrospectively analyzed adults with glioma who had undergone preoperative metabolic imaging at a single center. Tumors were delineated using a threshold of 1.3-fold of the mean standardized uptake value for the contralateral cortex, and then processed to calculate the texture features in glioma., Results: The study included 42 patients (median age: 56 years). The World Health Organization classifications were grade II (7 patients), grade III (17 patients), and grade IV (18 patients). Sixteen (16.1%) all-cause deaths were recorded during the median follow-up of 18.8 months. The univariate analyses revealed that overall survival (OS) was associated with age (hazard ratio (HR) 1.04, 95% confidence interval (CI) 1.01-1.08, p = 0.0093), tumor grade (HR 3.64, 95% CI 1.63-9.63, p = 0.0010), genetic status ( p < 0.0001), low gray-level run emphasis (LGRE, calculated from the gray-level run-length matrix) (HR 2.30 × 10 11 , 95% CI 737.11-4.23 × 10 19 , p = 0.0096), and correlation (calculated from the gray-level co-occurrence matrix) (HR 5.17, 95% CI 1.07-20.93, p = 0.041). The multivariate analyses revealed OS was independently associated with LGRE and correlation. The survival curves were also significantly different (both log-rank p < 0.05)., Conclusion: Textural features obtained using preoperative MET positron emission tomography may compliment the semi-quantitative assessment for prognostication in glioma cases.

Background: [ 18 F]Fluoromisonidazole ([ 18 F]FMISO) is a PET imaging probe widely used for the detection of hypoxia. We previously reported that [ 18 F]FMISO is metabolized to the glutathione conjugate of the reduced form in hypoxic cells. In addition, we found that the [ 18 F]FMISO uptake level varied depending on the cellular glutathione conjugation and excretion ability such as enzyme activity of glutathione-S-transferase and expression levels of multidrug resistance-associated protein 1 (MRP1, an efflux transporter), in addition to the cellular hypoxic state. In this study, we evaluated whether MRP1 activity affected [ 18 F]FMISO PET imaging., Methods: FaDu human pharyngeal squamous cell carcinoma cells were pretreated with MRP1 inhibitors (cyclosporine A, lapatinib, or MK-571) for 1 h, incubated with [ 18 F]FMISO for 4 h under hypoxia, and their radioactivity was then measured. FaDu tumor-bearing mice were intravenously injected with [ 18 F]FMISO, and PET/CT images were acquired at 4 h post-injection (1st PET scan). Two days later, the same mice were pretreated with MRP1 inhibitors (cyclosporine A, lapatinib, or MK-571) for 1 h, and PET/CT images were acquired (2nd PET scan)., Results: FaDu cells pretreated with MRP1 inhibitors exhibited significantly higher radioactivity than those without inhibitor treatment (cyclosporine A: 6.91 ± 0.27, lapatinib: 10.03 ± 0.47, MK-571: 10.15 ± 0.44%dose/mg protein, p < 0.01). In the in vivo PET study, the SUV mean ratio in tumors [calculated as after treatment (2nd PET scan)/before treatment of MRP1 inhibitors (1st PET scan)] of the mice treated with MRP1 inhibitors was significantly higher than those of control mice (cyclosporine A: 2.6 ± 0.7, lapatinib: 2.2 ± 0.7, MK-571: 2.2 ± 0.7, control: 1.2 ± 0.2, p < 0.05)., Conclusion: In this study, we revealed that MRP1 inhibitors increase [ 18 F]FMISO accumulation in hypoxic cells. This suggests that [ 18 F]FMISO-PET imaging is affected by MRP1 inhibitors independent of the hypoxic state.

Alzheimer disease (AD) is a progressive neurodegenerative disorder and the most common type of dementia worldwide. There is considerable evidence of age-related disruption of proteostasis being responsible for the development of AD. The proteasome is a multicatalytic enzyme complex that degrades both normal and damaged proteins, and an age-related decline in its activity has been implicated in age-related pathologies. Although proteasomal dysfunction is assumed to be a key AD hallmark, it remains unclear whether its role in disease onset is causative or secondary. In this study, we demonstrate that mice with proteasomal dysfunction exhibited memory impairment with associated neuronal loss, accumulation of phosphorylated tau, and activation of endoplasmic reticulum (ER) stress-related apoptosis pathways. Impaired proteasomal activity also activated ER stress-related apoptosis pathways in HT-22, a murine hippocampal neuronal cell line. HT-22 cell death, caused by proteasomal inhibition, was prevented by an inhibitor of c-Jun N-terminal kinase, an ER stress-related molecule. Collective evidence suggests that impaired proteasomal activity alters proteostasis, and subsequent ER stress-mediated pathways play pivotal roles in neuronal loss. Because aging decreases proteasomal function, age-related impairment of proteasomes may be involved in the development and progression of AD in elderly patients., (Copyright © 2021 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Objective: 123 I-15-(p-iodophenyl)-3(R,S)-methylpentadecanoic acid ([ 123 I]BMIPP), a fatty acid analog, is widely used for the diagnosis of cardiac diseases. Feeding condition is one of the important factors in the myocardial fatty acid uptake, which may also affect myocardial accumulation of [ 123 I]BMIPP and image quality of [ 123 I]BMIPP scintigraphy. However, the relationship between the myocardial accumulation of [ 123 I]BMIPP and the feeding condition is not entirely clear. Therefore, we determined the myocardial accumulation of [ 125 I]BMIPP in mice at various metabolic statuses induced by fasting in comparison with the hepatic accumulation., Methods: Fed or fasted (6-, 12-, and 24-h fasted) mice were intravenously injected with [ 125 I]BMIPP (35.2-75.0 kBq, 4 nmol). Radioactivities in the heart and liver were measured at 1, 5, 10, 30, 60, and 120 min after the injection (n = 5-15/time point for each group), and then, the heart-to-liver (H/L) ratios were calculated., Results: The myocardial accumulation level of [ 125 I]BMIPP in the fed group was almost the same as that in the 6-h-fasted group at each time point, although it was decreased by 12- and 24-h fasting. The H/L ratios of [ 125 I]BMIPP accumulation level were significantly decreased by fasting (1.92 ± 0.22, 1.45 ± 0.13, 1.12 ± 0.13, and 0.91 ± 0.15 at 10 min, and 3.30 ± 0.62, 2.09 ± 0.35, 1.79 ± 0.34, and 1.27 ± 0.06 at 30 min after the injection, respectively, for the fed group and the 6-, 12-, and 24-h-fasted groups; p < 0.0001), largely owing to the increase in the hepatic accumulation level in the fasting groups., Conclusion: Although short-period (6 h) fasting did not affect the myocardial accumulation level of [ 125 I]BMIPP, the hepatic accumulation level was increased. The present results indicate that the fed condition may provide higher-contrast images in myocardial [ 123 I]BMIPP scintigraphy.

The naked mole-rat (NMR) is a heterothermic mammal that forms eusocial colonies consisting of one reproductive female (queen), several reproductive males, and subordinates. Despite their heterothermy, NMRs possess brown adipose tissue (BAT), which generally induces thermogenesis in cold and some non-cold environments. Previous studies suggest that NMR-BAT induces thermogenesis by cold exposure. However, detailed NMR-BAT characteristics and whether NMR-BAT thermogenesis occurs in non-cold environments are unknown. Here, we show beta-3 adrenergic receptor (ADRB3)-dependent thermogenic potential of NMR-BAT, which contributes to thermogenesis in the isolated queen in non-cold environments (30 °C). NMR-BAT expressed several brown adipocyte marker genes and showed noradrenaline-dependent thermogenic activity in vitro and in vivo. Although our ADRB3 inhibition experiments revealed that NMR-BAT thermogenesis slightly delays the decrease in body temperature in a cold environment (20 °C), it was insufficient to prevent the decrease in the body temperatures. Even at 30 °C, NMRs are known to prevent the decrease of and maintain their body temperature by heat-sharing behaviors within the colony. However, isolated NMRs maintained their body temperature at the same level as when they are in the colony. Interestingly, we found that queens, but not subordinates, induce BAT thermogenesis in this condition. Our research provides novel insights into NMR thermoregulation.

Objective: We evaluated the radiation dosage, biodistribution, human safety, and tolerability of the injection of a single dose of [ 123 I] 5-iodo-6-[(2-iminoimidazolidinyl)methyl]uracil (IIMU), a new radiotracer targeting thymidine phosphorylase (TP), in healthy volunteers., Methods: Potential participants were tested at our hospital to confirm their eligibility. Two healthy male adults passed the screening tests. They were injected with 56 and 111 MBq of [ 123 I]IIMU, respectively. Safety assessments were performed before and at 1, 3, 6, 9, 24, 48 h, and 1-week post-injection. Whole-body emission scans were conducted at 1, 3, 6, 24, and 48 h post-injection. Regions of interest were manually drawn to enclose the entire body at each time point, identifying high-uptake organs to obtain the time-activity curves. Urine and blood samples were collected at 1, 2, 3, 4, 5, 6, 9, 24, and 48 h post-injection. The radiation dose for each organ and the effective doses were estimated using OLINDA/EXM 1.1 software., Results: No adverse events were observed as of the follow-up visit > 1-week post-injection. In both subjects, the highest uptake of [ 123 I]IIMU occurred in the liver, with peak injected activity (%IA) values of 17.7% and 15.1%, respectively. The second highest uptake was in the thyroid (0.35% and 0.66% IA). The %IA decreased gradually toward the end of the study (48 h) in all organs except the liver and thyroid. By the end of the study, 52.5% and 51.5% of the injected activity of [ 123 I]IIMU had been excreted via the subjects' renal systems. The estimated mean effective doses of [ 123 I]IIMU were 9.19 μSv/MBq and 10.1 μSv/MBq, respectively., Conclusion: In this preliminary study, [ 123 I]IIMU was safely administered to healthy adults, and its potential clinical use in TP imaging was revealed.

Delivery systems to lymph node-resident T cells around tumor tissues are essential for cancer immunotherapy, in order to boost the immune responses. We previously reported that anionic dendrimers, such as carboxyl-, sulfonyl-, and phosphate-terminal dendrimers, were efficiently accumulated in lymph nodes via the intradermal injection. Depending on the terminal structure, their cell association properties were different, and the carboxyl-terminal dendrimers did not associate with any immune cells majorly. In this study, we investigated the delivery of carboxyl-terminal dendrimers with different hydrophobicity to lymph node-resident lymphocytes. Four types of carboxyl-terminal dendrimers-succinylated (C) and 2-carboxy-cyclohexanoylated (Chex) dendrimers with and without phenylalanine (Phe)-were synthesized and named C-den, C-Phe-den, Chex-den, and Chex-Phe-den, respectively. Chex-Phe-den was well associated with lymphocytes, but others were not. Chex-Phe-den, intradermally injected at the footpads of mice, was accumulated in the lymph node, and was highly associated with the lymphocytes, including T cells. Our results suggest that Chex-Phe-den has the potential for delivery to the lymph node-resident T cells, without any specific T cell-targeted ligands.

Background: Anti-programmed cell death 1 (PD-1) antibody is an immune checkpoint inhibitor, and anti-PD-1 therapy improves the anti-tumor functions of T cells and affects tumor microenvironment. We previously reported that anti-PD-1 treatment affected tumor glycolysis by using 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) positron emission tomography (PET). That study showed that anti-PD-1 therapy in a mouse B16F10 melanoma model increased glucose metabolism in cancer cells at the point where anti-PD-1 therapy did not cause a significant inhibition of tumor growth. However, the B16F10 melanoma model is poorly immunogenic, so it is not clear how anti-PD-1 treatment affects glucose metabolism in highly immunogenic cancer models. In this study, we used a cyclic dinucleotide GMP-AMP (cGAMP)-injected B16F10 melanoma model to investigate the effect of anti-PD-1 therapy on [ 18 F]FDG uptake in a highly immune activated tumor in mice., Results: To compare the cGAMP-injected B16F10 model with the B16F10 model, experiments were performed as described in our previous manuscript. [ 18 F]FDG-PET was measured before treatment and 7 days after the start of treatment. In this study, [ 18 F]FDG uptake in tumors in the cGAMP/anti-PD-1 combination group was lower than that in the anti-PD-1 treatment group tumors on day 7, as shown by PET and ex vivo validation. Flow-cytometry was performed to assess immune cell populations and glucose metabolism. Anti-PD-1 and/or cGAMP treatment increased the infiltration level of immune cells into tumors. The cGAMP/anti-PD-1 combination group had significantly lower levels of GLUT1 high cells/hexokinase II high cells in CD45 - cancer cells compared with tumors in the anti-PD-1 treated group. These results suggested that if immune responses in tumors are higher than a certain level, glucose uptake in cancer cells is reduced depending on that level. Such a change of glucose uptake might be caused by the difference in infiltration or activation level of immune cells between the anti-PD-1 treated group and the cGAMP/anti-PD-1 combination group., Conclusions: [ 18 F]FDG uptake in cancer cells after anti-PD-1 treatment might be affected by the tumor immune microenvironment including immune cell infiltration, composition, and activation status.

Background: We investigated the prognostic predictive value of the combination of fluorodeoxyglucose (FDG)- and fluoromisonidazole (FMISO)-PET in patients with non-small cell lung carcinoma (NSCLC) treated with stereotactic body radiation therapy (SBRT)., Patients and Methods: We prospectively examined patients with pathologically proven NSCLC; all underwent FDG and FMISO PET/CT scans before SBRT. PET images were acquired using a whole-body time-of-flight PET-CT scanner with respiratory gating. We classified them into recurrent and non-recurrent groups based on their clinical follow-ups and compared the groups' tumor diameters and PET parameters (i.e., maximum of the standardized uptake value (SUVmax), metabolic tumor volume, tumor-to-muscle ratio, and tumor-to-blood ratio). We performed univariate analysis to evaluate the impact of the PET variables on the patients' progression-free survival (PFS). We divided the patients by thresholds of FDG SUVmax and FMISO SUVmax obtained from receiver operating characteristic analysis for assessment of recurrence rate and PFS., Results: Thirty-two NSCLC patients (19 male and 13 females; median age, 83 years) were enrolled. All received SBRT. At the study endpoint, 23 patients (71.9%) were non-recurrent and nine patients (28.1%) had recurrent disease. Significant between-group differences were observed in tumor diameter and all the PET parameters, demonstrating that those were significant predictors of the recurrence in all patients. In the 22 patients with tumors > 2 cm, tumor diameter and FDG SUVmax were not significant predictors. Thirty-two patients were divided into three patterns from the thresholds of FDG SUVmax (6.81) and FMISO SUVmax (1.89); A, low FDG and low FMISO (n = 14); B, high FDG and low FMISO (n = 8); C, high FDG and high FMISO (n = 10). No pattern A patient experienced tumor recurrence, whereas two pattern B patients (25%) and seven pattern C patients (70%) exhibited recurrence. A Kaplan-Meier analysis of all patients revealed a significant difference in PFS between patterns A and B (p = 0.013) and between patterns A and C (p < 0.001). In the tumors > 2 cm patients, significant differences in PFS were demonstrated between pattern A and C patients (p = 0.002)., Conclusion: The combination of FDG- and FMISO-PET can identify patients with a baseline risk of recurrence and indicate whether additional therapy might be performed to improve survival.

High concentrations of antioxidants in cancer cells are huge obstacle in cancer radiotherapy. Erastin was first discovered as an inducer of iron-dependent cell death called ferroptosis accompanied by antioxidant depletion caused by cystine glutamate antiporter inhibition. Therefore, treatment with erastin is expected to potentially enhance cellular radiosensitivity. In this study, we investigated the influence of treatment with erastin on the radiation efficiency against cancers. The clonogenic ability, glutathione peroxidase 4 (GPX4) expression, and glutathione concentration were evaluated using HeLa and NCI-H1975 adenocarcinoma cell lines treated with erastin and/or X-ray irradiation. For in vivo studies, NCI-H1975 cells were transplanted in the left shoulder of nude mice, and then radiosensitizing effect of erastin and glutathione concentration in the cancer were evaluated. Treatment with erastin induced ferroptosis and decreased the concentration of glutathione and GPX4 protein expression levels in the two tumor cell lines. Moreover, erastin enhanced X-ray irradiation-induced cell death in both human tumor cell lines. Furthermore, erastin treatment of a tumor-transplanted mouse model similarly demonstrated the radiosensitizing effect and decrease in intratumoral glutathione concentration in the in vitro study. In conclusion, our study demonstrated the radiosensitizing effect of erastin on two adenocarcinoma cell lines and the tumor xenograft model accompanied by glutathione depletion, indicating that ferroptosis inducers that reduce glutathione concentration could be applied as a novel cancer therapy in combination with radiotherapy., Competing Interests: The authors have declared that no competing interests exist.

Medication-related osteonecrosis of jaws (MRONJ) is one of the most complicated inflammatory conditions in oral and maxillofacial region. It is very difficult to correctly evaluate the degree and extent of necrosis and infection. This refractory osteonecrosis often needs extended surgery, leading to impaired quality-of-life. We have performed hyperbaric oxygen therapy (HBO) combined with conservative surgery for advanced cases. We have appraised the value of FDG-PET and 3-phase bone scintigraphy in the diagnosis and management of this condition. MRONJ showed significantly higher SUV max on FDG-PET than the others. Although the 3 phase pool bone images did not change significantly, perfusion and static bone image as well as PET showed remarkable response to HBO for MRONJ. SUV max after HBO was significantly lower than those of before HBO. These preliminary results indicate that FDG-PET is useful for monitoring the effect of HBO for MRONJ.

Glioma is the most common malignant brain tumor. Hypoxia is closely related to the malignancy of gliomas, and positron emission tomography (PET) can noninvasively visualize the degree and the expansion of hypoxia. Currently, 18 F-fluoromisonidazole (FMISO) is the most common radiotracer for hypoxia imaging. The clinical usefulness of FMISO PET has been established; it can distinguish glioblastomas from lower-grade gliomas and can predict the microenvironment of a tumor, including necrosis, vascularization, and permeability. FMISO PET provides prognostic information, including survival and treatment response information. Because hypoxia decreases a tumor's sensitivity to radiation therapy, dose escalation to an FMISO-positive volume is an attractive strategy. Although this idea is not new, an insufficient amount of evidence has been obtained regarding this concept. New tracers for hypoxia imaging such as 18 F-DiFA are being tested. In the future, hypoxia imaging will play an important role in glioma management.

Background: To facilitate hypoxia imaging in a clinical setting, we developed 1-(2,2-dihydroxymethyl-3-[ 18 F]-fluoropropyl)-2-nitroimidazole ([ 18 F]DiFA) as a new tracer that targets tumor hypoxia with its lower lipophilicity and efficient radiosynthesis. Here, we evaluated the radiation dosage, biodistribution, human safety, tolerability, and early elimination after the injection of [ 18 F]DiFA in healthy subjects, and we performed a preliminary clinical study of patients with malignant tumors in a comparison with [ 18 F]fluoromisonidazole ([ 18 F]FMISO)., Results: The single administration of [ 18 F]DiFA in 8 healthy male adults caused neither adverse events nor abnormal clinical findings. Dynamic and sequential whole-body scans showed that [ 18 F]DiFA was rapidly cleared from all of the organs via the hepatobiliary and urinary systems. The whole-body mean effective dose of [ 18 F]DiFA estimated by using the medical internal radiation dose (MIRD) schema with organ level internal dose assessment/exponential modeling (OLINDA/EXM) computer software 1.1 was 14.4 ± 0.7 μSv/MBq. Among the organs, the urinary bladder received the largest absorbed dose (94.7 ± 13.6 μSv/MBq). The mean absorbed doses of the other organs were equal to or less than those from other hypoxia tracers. The excretion of radioactivity via the urinary system was very rapid, reaching 86.4 ± 7.1% of the administered dose. For the preliminary clinical study, seven patients were subjected to [ 18 F]FMISO and [ 18 F]DiFA positron emission tomography (PET) at 48-h intervals to compare the two tracers' diagnostic ability for tumor hypoxia. The results of the tumor hypoxia evaluation by [ 18 F]DiFA PET at 1 h and 2 h were not significantly different from those obtained with [ 18 F]FMISO PET at 4 h ([ 18 F]DiFA at 1 h, p = 0.32; [ 18 F]DiFA at 2 h, p = 0.08). Moreover, [ 18 F]DiFA PET at both 1 h (k = 0.68) and 2 h (k = 1.00) showed better inter-observer reproducibility than [ 18 F]FMISO PET at 4 h (k = 0.59)., Conclusion: [ 18 F]DiFA is well tolerated, and its radiation dose is comparable to those of other hypoxia tracers. [ 18 F]DiFA is very rapidly cleared via the urinary system. [ 18 F]DiFA PET generated comparable images to [ 18 F]FMISO PET in hypoxia imaging with shorter waiting time, demonstrating the promising potential of [ 18 F]DiFA PET for hypoxia imaging and for a multicenter trial.

Background: Eribulin, an inhibitor of microtubule dynamics, shows antitumor potency against a variety of solid cancers through its antivascular activity and remodeling of tumor vasculature. 18 F-Fluoromisonidazole ( 18 F-FMISO) is the most widely used PET probe for imaging tumor hypoxia. In this study, we utilized 18 F-FMISO to clarify the effects of eribulin on the tumor hypoxic condition in comparison with histological findings., Material and Methods: Mice bearing a human cancer cell xenograft were intraperitoneally administered a single dose of eribulin (0.3 or 1.0 mg/kg) or saline. Three days after the treatment, mice were injected with 18 F-FMISO and pimonidazole (hypoxia marker for immunohistochemistry), and intertumoral 18 F-FMISO accumulation levels and histological characteristics were determined. PET/CT was performed pre- and post-treatment with eribulin (0.3 mg/kg, i.p.)., Results: The 18 F-FMISO accumulation levels and percent pimonidazole-positive hypoxic area were significantly lower, whereas the number of microvessels was higher in the tumors treated with eribulin. The PET/CT confirmed that 18 F-FMISO distribution in the tumor was decreased after the eribulin treatment., Conclusions: Using 18 F-FMISO, we demonstrated the elimination of the tumor hypoxic condition by eribulin treatment, concomitantly with the increase in microvessel density. These findings indicate that PET imaging using 18 F-FMISO may provide the possibility to detect the early treatment response in clinical patients undergoing eribulin treatment.

Objective: Macrophages play an essential role in immune response, and are closely related to the progression of diseases such as cancer and atherosclerosis. Macrophages polarize to M1 or M2 type, which is related to the environmental hypoxic state. Previously, we found that 18 F-FMISO uptake varied according to expression levels of biomolecules such as glutathione S-transferase P1 (GST-P1), which catalyzes the conjugation of glutathione to 18 F-FMISO metabolites, and multidrug resistance-associated protein 1 (MRP1), which exports glutathione- 18 F-FMISO metabolite conjugates out of cells. However, the relationship between macrophage polarization and 18 F-FMISO accumulation remains unclear., Methods: Mouse peritoneal macrophages were polarized to either the M1 or M2 type, and were treated with 18 F-FMISO. Then, their radioactivity after a 4 h incubation period under normoxic (21% O 2 ) or hypoxic (1% O 2 ) condition was measured. GST-P1 and MRP1 expression levels were measured by qRT-PCR., Results: M2 macrophages exhibited a significantly higher uptake of 18 F-FMISO than non-polarized (M0) macrophages, whereas M1 macrophages had a significantly lower uptake than M0 macrophages (M0: 1.05 ± 0.22, M1: 0.34 ± 0.02, M2: 4.17 ± 0.36 %dose/mg protein). The GST-P1 expression level in M1 macrophages was higher than that in M2 and M0 macrophages [GST-P1/β-actin normalized by M0: 9.0 ± 3.7 (M1), 1.2 ± 0.2 (M2)]. The MRP1 expression level in M1 macrophages was significantly higher than that in M2 and M0 macrophages [MRP1/β-actin normalized by M0 macrophages: 5.1 ± 2.1 (M1), 2.8 ± 1.0 (M2)]., Conclusions: 18 F-FMISO accumulation in macrophages may depend on the polarization state in addition to hypoxic condition.

Background: Hypoxia can induce radiation resistance and is an independent prognostic marker for outcome in head and neck cancer. As 18F-FMISO (FMISO), a hypoxia tracer for PET, is far less common than 18F-FDG (FDG) and two separate PET scans result in doubled cost and radiation exposure to the patient, we aimed to predict hypoxia from FDG PET with new techniques of voxel based analysis and texture analysis., Methods: Thirty-eight patients with head-and-neck cancer underwent consecutive FDG and FMISO PET scans before any treatment. ROIs enclosing the primary cancer were compared in a voxel-by-voxel manner between FDG and FMISO PET. Tumour hypoxia was defined as the volume with a tumour-to-muscle ratio (TMR) > 1.25 in the FMISO PET and hypermetabolic volume was defined as >50% SUVmax in the FDG PET. The concordance rate was defined as percentage of voxels within the tumour which were both hypermetabolic and hypoxic. 38 different texture analysis (TA) parameters were computed based on the ROIs and correlated with presence of hypoxia., Results: Within the hypoxic tumour regions, the FDG uptake was twice as high as in the non-hypoxic tumour regions (SUVmean 10.9 vs. 5.4; p<0.001). A moderate correlation between FDG and FMISO uptake was found by a voxel-by-voxel comparison (r = 0.664 p<0.001). The average concordance rate was 25% (± 22%). Entropy was the TA parameter showing the highest correlation with hypoxia (r = 0.524 p<0.001)., Conclusion: FDG uptake was higher in hypoxic tumour regions than in non-hypoxic regions as expected by tumour biology. A moderate correlation between FDG and FMISO PET was found by voxel-based analysis. TA yielded similar results in FDG and FMISO PET. However, it may not be possible to predict tumour hypoxia even with the help of texture analysis., Competing Interests: The authors have declared that no competing interests exist.

Background: Programmed cell death 1 (PD-1) inhibitors act as immune checkpoint inhibitors and are more effective for improving survival time with less toxicity as compared with conventional chemotherapies. In anti PD-1 therapy, it is important to evaluate metabolism in the cancer microenvironment, as this helps to clarify the pathological conditions. Herein, we investigate the early effects of PD-1 therapy on 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) uptake in vivo, focusing on cell distribution and glycolysis in both cancer and immune cells., Results: In a B16F10 melanoma model, [ 18 F]FDG-positron emission tomography (PET) was performed before treatment and 7 days after the start of treatment. Values were calculated as the percentage-injected activity per gram of tissue (%IA/g). Flow-cytometry was then performed to assess immune cell populations and glucose metabolism. There was a negligible difference in [ 18 F]FDG uptake between tumors in the treatment group and non-treatment group before the treatment. In contrast, mean [ 18 F]FDG uptake in the treatment group tumors was significantly higher (8.06 ± 0.48 %IA/g; P = 0.0074) than that in the non-treatment group (4.02 ± 1.03 %IA/g) after anti PD-1 treatment. Assessment of tumor immune cell populations showed that treatment slightly enriched CD8 + T cells and CD4 + T cells; however, infiltration of immune cells was negligible, and thus, immune cells were not responsible for the increase in [ 18 F]FDG uptake. On the other hand, anti PD-1 treatment significantly increased glucose transporter 1 (GLUT1) and hexokinase II expression in CD45 - cancer cells, indicating that anti PD-1 treatment increased glucose metabolism in cancer cells., Conclusion: The present study shows that anti PD-1 therapy increases glucose metabolism in cancer cells.

Background: The potential application of bone marrow stromal cell (BMSC) therapy in stroke has been anticipated due to its immunomodulatory effects. Recently, positron emission tomography (PET) with [ 18 F]DPA-714, a translocator protein (TSPO) ligand, has become available for use as a neural inflammatory indicator. We aimed to evaluate the effects of BMSC administration after transient middle cerebral artery occlusion (MCAO) using [ 18 F]DPA-714 PET. The BMSCs or vehicle were administered intravenously to rat MCAO models at 3 h after the insult. Neurological deficits, body weight, infarct volume, and histology were analyzed. [ 18 F]DPA-714 PET was performed 3 and 10 days after MCAO., Results: Rats had severe neurological deficits and body weight loss after MCAO. Cell administration ameliorated these effects as well as the infarct volume. Although weight loss occurred in the spleen and thymus, cell administration suppressed it. In both vehicle and BMSC groups, [ 18 F]DPA-714 PET showed a high standardized uptake value (SUV) around the ischemic area 3 days after MCAO. Although SUV was increased further 10 days after MCAO in both groups, the increase was inhibited in the BMSC group, significantly. Histological analysis showed that an inflammatory reaction occurred in the lymphoid organs and brain after MCAO, which was suppressed in the BMSC group., Conclusions: The present results suggest that BMSC therapy could be effective in ischemic stroke due to modulation of systemic inflammatory responses. The [ 18 F]DPA-714 PET/CT system can accurately demonstrate brain inflammation and evaluate the BMSC therapeutic effect in an imaging context. It has great potential for clinical application.

Background: Traumatic brain injury (TBI) causes brain dysfunction in many patients. Using C-11 flumazenil (FMZ) positron emission tomography (PET), we have detected and reported the loss of neuronal integrity, leading to brain dysfunction in TBI patients. Similarly to FMZ PET, I-123 iomazenil (IMZ) single photon emission computed tomography (SPECT) is widely used to determine the distribution of the benzodiazepine receptor (BZR) in the brain cortex. The purpose of this study is to examine whether IMZ SPECT is as useful as FMZ PET for evaluating the loss of neuronal integrity in TBI patients. The subjects of this study were seven patients who suffered from neurobehavioral disability. They underwent IMZ SPECT and FMZ PET. Nondisplaceable binding potential (BP ND ) was calculated from FMZ PET images. The uptake of IMZ was evaluated on the basis of lesion-to-pons ratio (LPR). The locations of low uptake levels were visually evaluated both in IMZ SPECT and FMZ PET images. We compared FMZ BP ND and (LPR-1) of IMZ SPECT., Results: In the visual assessment, FMZ BP ND decreased in 11 regions. In IMZ SPECT, low uptake levels were observed in eight of the 11 regions. The rate of concordance between FMZ PET and IMZ SPECT was 72.7%. The mean values IMZ (LPR-1) (1.95 ± 1.01) was significantly lower than that of FMZ BP ND (2.95 ± 0.80 mL/mL). There was good correlation between FMZ BP ND and IMZ (LPR-1) (r = 0.80)., Conclusions: IMZ SPECT findings were almost the same as FMZ PET findings in TBI patients. The results indicated that IMZ SPECT is useful for evaluating the loss of neuronal integrity. Because IMZ SPECT can be performed in various facilities, IMZ SPECT may become widely adopted for evaluating the loss of neuronal integrity.

Objective: 18 F-fluoromisonidazole (FMISO), a well-known PET imaging probe for diagnosis of hypoxia, is believed to accumulate in hypoxic cells via covalent binding with macromolecules after reduction of the nitro group. Previously, we showed the majority of 18 F-FMISO was incorporated into low-molecular-weight metabolites in hypoxic tumors, and the glutathione conjugate of reduced FMISO (amino-FMISO-GS) distributed in the tumor hypoxic regions as revealed by imaging mass spectrometry (IMS). The present study was conducted to clarify whether FMISO is metabolized to amino-FMISO-GS within tumor cells and how amino-FMISO-GS contributes to FMISO accumulation in hypoxic cells. We also evaluated the relationship between FMISO accumulation and the glutathione conjugation-related factors in the cells., Methods: Tumor cells (FaDu, LOVO, and T24) were treated with 18 F-FMISO and incubated under normoxic or hypoxic conditions for 4 h. The FMISO metabolites were analyzed with LC-ESI-MS. Several glutathione conjugation-related factors of tumor cells were evaluated in vitro. FaDu tumor-bearing mice were intravenously injected with 18 F-FMISO and the tumors were excised at 4 h post-injection. Autoradiography, IMS and histologic studies were performed., Results: Amino-FMISO-GS was the main contributor to FMISO incorporated in hypoxic FaDu cells in vitro and in vivo. Total FMISO uptake levels and amino-FMISO-GS levels were highest in FaDu, followed by LOVO, and then T24 (total uptake: 0.851 ± 0.009 (FaDu), 0.617 ± 0.021 (LOVO) and 0.167 ± 0.006 (T24) % dose/mg protein; amino-FMISO-GS: 0.502 ± 0.035 (FaDu), 0.158 ± 0.013 (LOVO), and 0.007 ± 0.001 (T24) % dose/mg protein). The glutathione level of FaDu was significantly higher than those of LOVO and T24. The enzyme activity of glutathione-S-transferase catalyzing the glutathione conjugation reaction in FaDu was similar levels to that in LOVO, and was higher than that in T24. Quantitative RT-PCR analysis revealed that the expression levels of efflux transporters of the glutathione conjugate (multidrug resistance-associated protein 1) were lowest in FaDu, followed by LOVO, and then T24., Conclusions: FMISO accumulates in hypoxic cells through reductive metabolism followed by glutathione conjugation. We illustrated the possibility that increased production and decreased excretion of amino-FMISO-GS contribute to FMISO accumulation in tumor cells under hypoxic conditions.

Background: Hypoxic cancer cells are thought to be radioresistant and could impact local recurrence after radiotherapy (RT). One of the major hypoxic imaging modalities is [ 18 F]fluoromisonidazole positron emission tomography (FMISO-PET). High FMISO uptake before RT could indicate radioresistant sites and might be associated with future local recurrence. The predictive value of FMISO-PET for intra-tumoral recurrence regions was evaluated using high-resolution semiconductor detectors in patients with nasopharyngeal carcinoma after intensity-modulated radiotherapy (IMRT)., Methods: Nine patients with local recurrence and 12 patients without local recurrence for more than 3 years were included in this study. These patients received homogeneous and standard doses of radiation to the primary tumor irrespective of FMISO uptake. The FMISO-PET image before RT was examined via a voxel-based analysis, which focused on the relationship between the degree of FMISO uptake and recurrence region., Results: In the pretreatment FMISO-PET images, the tumor-to-muscle ratio (TMR) of FMISO in the voxels of the tumor recurrence region was significantly higher than that of the non-recurrence region (p < 0.0001). In the recurrent patient group, a TMR value of 1.37 (95% CI: 1.36-1.39) corresponded to a recurrence rate of 30%, the odds ratio was 5.18 (4.87-5.51), and the area under the curve (AUC) of the receiver operating characteristic curve was 0.613. In all 21 patients, a TMR value of 2.42 (2.36-2.49) corresponded to an estimated recurrence rate of 30%, and the AUC was only 0.591., Conclusions: The uptake of FMISO in the recurrent region was significantly higher than that in the non-recurrent region. However, the predictive value of FMISO-PET before IMRT is not sufficient for up-front dose escalation for the intra-tumoral high-uptake region of FMISO. Because of the higher mean TMR of the recurrence region, a new hypoxic imaging method is needed to improve the sensitivity and specificity for hypoxia.

A mechanistic dissociation exists between tumor starvation and vascular normalization after antiangiogenic therapy. Thus, improved understanding of tumor responses (tumor starvation or vascular normalization) is important for optimizing treatment strategies. 18 F-fluoromisonidazole ( 18 F-FMISO) is widely used for imaging tumor hypoxia. To clarify the tumor response to the antiangiogenic drug sorafenib, the present study evaluated the changes in the tumor oxygen state using 18 F-FMISO in mice bearing a renal cell carcinoma xenograft (A498). Mice bearing A498 xenografts were assigned to the control and three sorafenib-treatment groups and administered sorafenib (0, 10, 20 or 40 mg/kg/day, per os ) once daily for 3 days. Following one day after the final administration, the mice were injected with 18 F-FMISO and pimonidazole (a hypoxia marker). 18 F-FMISO accumulation in the tumor was determined by autoradiography. Immunohistochemistry of pimonidazole and cluster of differentiation (CD)31 (a vascular marker) was also performed. 18 F-FMISO accumulation levels in the tumor significantly increased by 4.3-, 8.4- and 8.6-fold compared with in the control group following 10, 20 and 40 mg/kg sorafenib treatments, respectively [0.07±0.04, 0.32±0.11, 0.62±0.15 and 0.63±0.23 (%ID/m 2 ) × kg for the control, and 10, 20 and 40 mg treatments, respectively; all P<0.0083 vs. the control]. The number of pimonidazole-positive cells also significantly increased by 6.8-, 12.3- and 20.2-fold compared with in the control group following 10, 20 and 40 mg/kg sorafenib treatments, respectively (0.78±0.79, 5.36±2.29, 9.66±1.58 and 15.85±4.59% pimonidazole-positive cells; all P<0.0083 vs. the control). The number of microvessels in tumors markedly decreased to 33.5, 17.6, and 14.0% of the control following 10, 20 and 40 mg/kg sorafenib treatments, respectively (17.1±2.5, 5.7±1.0, 3.0±1.0 and 2.4±0.3 vessels/mm 2 ; P<0.0083 vs. the control). The 18 F-FMISO expression level in the tumor increased sorafenib-dose-dependently, which is consistent with the increase in the number of pimonidazole-positive cells and decrease in the number of microvessels. These findings indicated that the present sorafenib treatment protocol induces 'tumor hypoxia/starvation' in the renal cell carcinoma xenograft (A498) due to its antiangiogenic properties.

Diabetes mellitus accelerates atherosclerosis that causes most cardiovascular events. Several metabolic pathways are considered to contribute to the development of atherosclerosis, but comprehensive metabolic alterations to atherosclerotic arterial cells remain unknown. The present study investigated metabolic changes and their relationship to vascular histopathological changes in the atherosclerotic arteries of rabbits with alloxan-induced diabetes. Diabetic atherosclerosis was induced in rabbit ilio-femoral arteries by injecting alloxan (100 mg/kg), injuring the arteries using a balloon, and feeding with a 0.5% cholesterol diet. We histologically assessed the atherosclerotic lesion development, cellular content, pimonidazole positive-hypoxic area, the nuclear localization of hypoxia-inducible factor-1α, and apoptosis. We evaluated comprehensive arterial metabolism by performing metabolomic analyses using capillary electrophoresis-time of flight mass spectrometry. We evaluated glucose uptake and its relationship to vascular hypoxia using 18F-fluorodeoxyglucose and pimonidazole. Plaque burden, macrophage content, and hypoxic areas were more prevalent in arteries with diabetic, than non-diabetic atherosclerosis. Metabolomic analyses highlighted 12 metabolites that were significantly altered between diabetic and non-diabetic atherosclerosis. A half of them were associated with glycolysis metabolites, and their levels were decreased in diabetic atherosclerosis. The uptake of glucose evaluated as 18F-fluorodeoxyglucose in atherosclerotic lesions increased according to increased macrophage content or hypoxic areas in non-diabetic, but not diabetic rabbits. Despite profound hypoxic areas, the nuclear localization of hypoxia-inducible factor-1α decreased and the number of apoptotic cells increased in diabetic atherosclerotic lesions. Altered glycolysis metabolism and an impaired response to hypoxia in atherosclerotic lesions under conditions of insulin-dependent diabetes might be involved in the development of diabetic atherosclerosis.

The rupture of vulnerable atherosclerotic plaques and subsequent thrombus formation are the major causes of myocardial and cerebral infarction. Accordingly, the detection of vulnerable plaques is important for risk stratification and to provide appropriate treatment. Inflammation imaging using 2-deoxy-2-[ 18 F]fluoro-D-glucose ( 18 F-FDG) has been most extensively studied for detecting vulnerable atherosclerotic plaques. It is of great importance to develop PET/SPECT probes capable of specifically visualizing the biological molecules involved in atherosclerotic plaque formation and/or progression. In this article, we review recent advances in the development of PET/SPECT probes for visualizing atherosclerotic plaques and their application to therapy monitoring, mainly focusing on experimental studies., Competing Interests: Yoichi Simizu and Yuji Kuge declare that they have no conflict of interest. Ethical Statement This review article does not contain any studies with human participants or animals performed by any of the authors.

Background: Sorafenib, an oral multikinase inhibitor, has anti-proliferative and anti-angiogenic activities and is therapeutically effective against renal cell carcinoma (RCC). Recently, we have evaluated the tumor responses to sorafenib treatment in a RCC xenograft using [Methyl- 3 H(N)]-3'-fluoro-3'-deoxythythymidine ([ 3 H]FLT). Contrary to our expectation, the FLT level in the tumor significantly increased after the treatment. In this study, to clarify the reason for the elevated FLT level, dynamic 3'-[ 18 F]fluoro-3'-deoxythymidine ([ 18 F]FLT) positron emission tomography (PET) and kinetic studies were performed in mice bearing a RCC xenograft (A498). The A498 xenograft was established in nude mice, and the mice were assigned to the control (n = 5) and treatment (n = 5) groups. The mice in the treatment group were orally given sorafenib (20 mg/kg/day p.o.) once daily for 3 days. Twenty-four hours after the treatment, dynamic [ 18 F]FLT PET was performed by small-animal PET. Three-dimensional regions of interest (ROIs) were manually defined for the tumors. A three-compartment model fitting was carried out to estimate four rate constants using the time activity curve (TAC) in the tumor and the blood clearance rate of [ 18 F]FLT., Results: The dynamic pattern of [ 18 F]FLT levels in the tumor significantly changed after the treatment. The rate constant of [ 18 F]FLT phosphorylation (k 3 ) was significantly higher in the treatment group (0.111 ± 0.027 [1/min]) than in the control group (0.082 ± 0.009 [1/min]). No significant changes were observed in the distribution volume, the ratio of [ 18 F]FLT forward transport (K 1 ) to reverse transport (k 2 ), between the two groups (0.556 ± 0.073 and 0.641 ± 0.052 [mL/g] in the control group)., Conclusions: Our dynamic PET studies indicated that the increase in FLT level may be caused by the phosphorylation of FLT in the tumor after the sorafenib treatment in the mice bearing a RCC xenograft. Dynamic PET studies with kinetic modeling could provide improved understanding of the biochemical processes involved in tumor responses to therapy.

Hypoxia, or low oxygen concentration, is a key factor promoting tumor progression and angiogenesis and resistance of cancer to radiotherapy and chemotherapy. 2-Nitroimidazole-based agents have been widely used in pathological and nuclear medicine examinations to detect hypoxic regions in tumors; in particular, pimonidazole is used for histochemical staining of hypoxic regions. It is considered to accumulate in hypoxic cells via covalent binding with macromolecules or by forming reductive metabolites after reduction of its nitro group. However, the detailed mechanism of its accumulation remains unknown. In this study, we investigated the accumulation mechanism of pimonidazole in hypoxic tumor tissues in a mouse model by mass spectrometric analyses including imaging mass spectrometry (IMS). Pimonidazole and its reductive metabolites were observed in the tumor tissues. However, their locations in the tumor sections were not similar to the positively stained areas in pimonidazole-immunohistochemistry, an area considered hypoxic. The glutathione conjugate of reduced pimonidazole, a low-molecular-weight metabolite of pimonidazole, was found in tumor tissues by LC-MS analysis, and our IMS study determined that the intratumor localization of the glutathione conjugate was consistent with the area positively immunostained for pimonidazole. We also found complementary localization of the glutathione conjugate and reduced glutathione (GSH), implying that formation of the glutathione conjugate occurred in the tumor tissue. These results suggest that in hypoxic tumor cells, pimonidazole is reduced at its nitro group, followed by conjugation with GSH., Competing Interests: Yuji Kuge has received a research grant from Shionogi & Co., Ltd. Yukiko Masaki, Takeshi Yoshioka, Kenichi Higashino and Yoshito Numata are employees of Shionogi & Co., Ltd. All the other authors have no relationships relevant to the contents of this paper to disclose. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.