Development of Low Molecular Weight Ligands for Integrin αvß3.

We designed and synthesized non-peptide organic molecular ligands for integrin αvß3. Candidate ligands featured amidino analog and carboxy groups as binding sites on either side of a spacer, which consisted of benzophenone or an analog, such as diphenyl sulfide, diphenyl sulfoxide, diphenyl sulfone, or diphenyl ether. Competitive binding assays to integrin αvß3 with respect to [125I]echistatin were used to determine inhibitory activity of the synthetic ligands. Ligands bearing 2-aminobenzimidazoyl and glycyl groups separated by a benzophenone spacer demonstrated more potent binding than did a linear Arg-Gly-Asp (RGD) tripeptide that represents the native integrin αvß3 binding motif. Ligands possessing 2-aminobenzimidazoyl and carboxy groups and diphenyl sulfoxide or diphenyl ether spacers inhibited binding of [125I]echistatin with IC50 values similar to that of the linear RGD tripeptide.

Paradoxical changes in mood-related behaviors on continuous social isolation after weaning.

Continuous social isolation (SI) from an early developmental stage may have different effects in youth and adulthood. Moreover, SI is reported to impair neuronal plasticity. In this study, we used post-weaning rats to compare the impact of continuous SI on depressive-like, anxiety-related, and fear-related behaviors and neuronal plasticity in puberty and adulthood. Furthermore, we assessed the effect of lithium on behavioral changes and neuronal plasticity. Continuous SI after weaning induced depressive-like behaviors in puberty; however, in adulthood, depressive-like and anxiety-related behaviors did not increase, but-paradoxically-decreased in comparison with the controls. The decreased expression of neuronal plasticity-related proteins in the hippocampus in puberty was more prominent in the prefrontal cortex and hippocampus in adulthood. In contrast, SI after weaning tended to decrease fear-related behaviors in puberty, a decrease which was more prominent in adulthood with increased neuronal plasticity-related protein expression in the amygdala. Lithium administration over the last 14 days of the SI-induced period removed the behavioral and expression changes of neuronal plasticity-related proteins observed in puberty and adulthood. Our findings suggest that the extension of the duration of SI from an early developmental stage does not simply worsen depressive-like behaviors; rather, it induces a behavior linked to neuronal plasticity damage. Lithium may improve behavioral changes in puberty and adulthood by reversing damage to neuronal plasticity. The mechanisms underlying the depressive-like and anxiety-related behaviors may differ from those underlying fear-related behaviors.

The vertebral 3'-deoxy-3'-18F-fluorothymidine uptake predicts the hematological toxicity after systemic chemotherapy in patients with lung cancer.

OBJECTIVES: Although hematological toxicities (HT) are the leading adverse events of systemic chemotherapy, the estimation of severe HT is challenging. Recently, 3'-deoxy-3'-[18F]-fluorothymidine (18F-FLT) accumulation with PET has been considered a biomarker of the cell proliferation. This study aims to elucidate whether the vertebral accumulation of 18F-FLT could estimate severe HT during platinum-doublet chemotherapy. METHODS: In this Institutional Review Board-approved retrospective study, 50 patients with primary lung cancer underwent 18F-FLT PET scan before platinum-doublet chemotherapy. We evaluated the standardized uptake value, total vertebral proliferation (TVP), and TVP/body surface area (TVP/BSA) of the vertebral body (Th4, Th8, Th12, and L4), and then the associations between those parameters and frequency of severe HT during platinum-doublet chemotherapy were assessed. RESULTS: Severe HT (grade 3/4) was observed in 40.0% of patients during the first cycle. The ROC curve analyses revealed that the TVP/BSA of L4 was the most discriminative parameter among PET parameters for the prediction of severe HT. The multivariate logistic regression analysis revealed the TVP/BSA of L4 (odds ratio [OR], 0.94; p = 0.0036) and the frequency of the grade 3/4 hematological toxicity in previous clinical trials (OR, 1.03; p = 0.023) were independent predictors. Furthermore, the sensitivity, specificity, and accuracy of the TVP/BSA of L4 cut-off of 68.7 to predict grade 3/4 HT were 80.0%, 86.7%, and 84.0%, respectively. A low TVP/BSA of L4 (< 68.7) as a binary variable was a significant indicator of severe HT (OR, 26.0; p = 0.000026). CONCLUSIONS: The low 18F-FLT uptake in the lower vertebral body is a predictor of severe HT in patients with lung cancer who receive platinum-doublet chemotherapy. TRIAL REGISTRATION: Trial registration: UMIN000027540 KEY POINTS: • The vertebral 18 F-FLT uptake with PET is an independent predictor of the severe hematological toxicity during the first cycle of platinum-doublet chemotherapy. • The 18 F-FLT uptake in L4 vertebral body estimated hematological toxicities better than that in the upper vertebra (Th4, Th8, and Th12). • The evaluation of the amount and activity of hematopoietic cells in the bone marrow cavity using 18 F-FLT PET imaging could provide predictive data of severe hematological toxicities and help determine an appropriate drug combination or dose intensity in patients with advanced malignant diseases.

PET probe detecting non-small cell lung cancer susceptible to epidermal growth factor receptor tyrosine kinase inhibitor therapy.

Tyrosine kinase inhibitors for epidermal growth factor receptor (EGFR-TKIs) are used as molecular targeted therapy for non-small cell lung cancer (NSCLC) patients. The therapy is applied to the patients having EGFR-primary L858R mutation, but drug tolerance caused by EGFR-secondary mutation is occurred within one and half years. For the non-invasive detection of the EGFR-TKIs treatment positive patients by positron emission tomograpy (PET) imagaing, fluorine-18 labeled thienopyrimidine derivative, [18F]FTP2 was newly synthesized. EGFR inhibition assay, cell uptake study, and blocking study indicated [18F]FTP2 binds with high and selective affinity for EGFR with L858R mutation, and not with L858R/T790M dual mutations. On animal PET study using tumor bearing mice, H3255 cells expressing L858R mutated EGFR was more clearly visualized than H1975 cells expressing L858R/T790M dual mutated EGFR. [18F]FTP2 has potential for detecting NSCLC which is susceptible to EGFR-TKI treatment.

Comparison of Radioiodine- or Radiobromine-Labeled RGD Peptides between Direct and Indirect Labeling Methods.

Radiolabeled cyclic peptides containing the (Arg-Gly-Asp) RGD sequence for use in positron emission tomography (PET) imaging, single-photon emission computed tomography (SPECT) imaging, and targeted radionuclide therapy of cancer have been reported. In this study, RGD was used as a model carrier peptide for diagnosis and therapy of cancer. To evaluate the characteristics of radiohalogen-labeled peptides, several kinds of labeled RGD peptides [125I-c(RGDyK), 77Br-c(RGDyK), [125I]SIB-c(RGDfK), [77Br]SBrB-c(RGDfK), [125I]SIB-EG2-c(RGDfK), and [77Br]SBrB-EG2-c(RGDfK)] were designed, prepared, and evaluated. In these initial studies, 77Br (t1/2=57.0 h) and 125I (t1/2=59.4 d) were used because of their longer half-lives. Precursor peptides were synthesized using a standard 9-fluorenylmethyloxycarbonyl (Fmoc)-based solid-phase methodology. Radiolabeled peptides were prepared by chloramine-T method or conjugation of RGD peptides with [125I]N-succinimidyl 3-iodobenzoate ([125I]SIB) or [77Br]N-succinimidyl 3-bromobenzoate ([77Br]SBrB). Measurement of the partition coefficients, integrin binding assay, and biodistribution experiments in tumor-bearing mice were performed. 125I and 77Br labeling were successfully performed using similar methods, and in vitro characteristics and biodistributions were similar between the 125I-labeled and corresponding 77Br-labeled peptides. [125I]SIB- and [77Br]SBrB-conjugated RGD peptides showed higher partition coefficients, lower tumor uptakes, and higher intestinal uptake than 125I-c(RGDyK) and 77Br-c(RGDyK). [125I]SIB-EG2-c(RGDfK) and [77Br]SBrB-EG2-c(RGDfK), which possess an ethylene glycol linker, decreased lipophilicity and uptake in intestine compared with [125I]SIB-c(RGDfK) and [77Br]SBrB-c(RGDfK), which possess no linker. However, the improvement in biodistribution of [125I]SIB-EG2-c(RGDfK) and [77Br]SBrB-EG2-c(RGDfK)] was insufficient. In conclusion, directly radiohalogenated c(RGDyK) peptides are potentially more useful for tumor imaging and therapy than indirectly radiohalogenated ones.

Highly Sensitive Telomerase Assay Insusceptible to Telomerase and Polymerase Chain Reaction Inhibitors for Cervical Cancer Screening Using Scraped Cells.

A sensitive telomerase assay based on asymmetric-polymerase chain reaction (A-PCR) on magnetic beads and subsequent application of cycling probe technology, STAMC, which is insusceptible to DNase and PCR inhibitors, was for the first time applied to clinical specimens in addition to a conventional telomeric repetitive amplification protocol (TRAP). The electrophoresis results showed that an increase in scraped cervical cancer cells not only reduced TRAP products but also increased smaller products, suggesting the unreliability of TRAP for clinical samples. To achieve the required sensitivity of STAMC for clinical application, the sequence and concentration conditions were explored for the forward and reverse primers for A-PCR, which resulted in a detection limit of only two HeLa cells with 1 µM TS primer (5'-AATCCGTCGAGCAGAGTT-3') and 0.04 µM ACX primer (5'-GCGCGGCTTACCCTTACCCTTACCCTAACC-3'). Under the same primer conditions, the fluorescence signal of STAMC increased as scraped cervical cancer cells increased despite showing a negligible intensity for benign tumors. Furthermore, STAMC showed no signal for a cervical cancer patient treated with irradiation therapy. These results indicate that STAMC is useful for not only cervical cancer screening but also investigating the effect of cancer treatments such as radiation therapy and drug administration.

Metabolic tumor burden predicts prognosis of ovarian cancer patients who receive platinum-based adjuvant chemotherapy.

Volumetric parameters of positron emission tomography-computed tomography using 18F-fludeoxyglucose ((18) F-FDG PET/CT) that comprehensively reflect both metabolic activity and tumor burden are capable of predicting survival in several cancers. The aim of this study was to investigate the predictive performance of metabolic tumor burden measured by (18) F-FDG PET/CT in ovarian cancer patients who received platinum-based adjuvant chemotherapy after cytoreductive surgery. Included in this study were 37 epithelial ovarian cancer patients. Metabolic tumor burden in terms of metabolic tumor volume (MTV) and total lesion glycolysis (TLG), clinical stage, histological type, residual tumor after primary cytoreductive surgery, baseline serum carbohydrate antigen 125 (CA125) level, and the maximum standardized uptake value (SUVmax ) were determined, and compared for their performance in predicting progression-free survival (PFS). Metabolic tumor volume correlated with CA125 (r = 0.547, P < 0.001), and TLG correlated with SUVmax and CA125 (SUVmax , r = 0.437, P = 0.007; CA125, r = 0.593, P < 0.001). Kaplan-Meier analysis showed a significant difference in PFS between the groups categorized by TLG (P = 0.043; log-rank test). Univariate analysis indicated that TLG was a statistically significant risk factor for poor PFS. Multivariate analysis adjusted according to the clinicopathological features was carried out for MTV, TLG, SUVmax , tumor size, and CA125. Only TLG showed a significant difference (P = 0.038), and a 3.915-fold increase in the hazard ratio of PFS. Both MTV and TLG (especially TLG) could serve as potential surrogate biomarkers for recurrence in patients who undergo primary cytoreductive surgery followed by platinum-based chemotherapy, and could identify patients at high risk of recurrence who need more aggressive treatment.

Comparison of image quality with 62Cu and 64Cu-labeled radiotracers in positron emission tomography whole-body phantom imaging.

OBJECTIVE: PET imaging is possible with copper (Cu) isotopes, (60)Cu, (61)Cu, (62)Cu and (64)Cu. Although (62)Cu- and (64)Cu-labeled radiotracers are often used for preclinical and clinical PET studies, we do not know which radiotracers have better image quality for tumor imaging. In this study, we compare image quality between (62)Cu and (64)Cu imaging with a different acquisition mode and reconstruction algorithm using a whole-body phantom for tumor imaging. METHODS: In a National Electrical Manufacturers Association (NEMA) 2001 whole-body phantom, the concentration of (62)Cu-ATSM and (64)Cu-ATSM was, respectively, approximately 2.7 and 1.8MBq/mL in all the spheres and approximately 0.9 and 0.6MBq/mL in the background. After adjustment for true coincidence events between (62)Cu and (64)Cu, two-dimensional (2D) and three-dimensional (3D) PET scan data were acquired for 10min. The data were reconstructed using filtered back projection (FBP) and the ordered subset expectation maximization (OSEM) algorithm. Image quality of (62)Cu and (64)Cu was compared using recovery coefficient (RC), sphere-to-background ratio (SBR) and coefficient of variation (%COV). RESULTS: There were little significant differences between (62)Cu and (64)Cu imaging, visually. Recovery coefficients of (64)Cu images were higher than those of (62)Cu images. The RC of (64)Cu images with 3D acquisition mode and OSEM was the highest in all experiments. No SBR values were significantly different from the true value of 3.0 in 37mm sphere diameters, but 3D acquisition and OSEM yielded slight overestimations compared with 2D acquisition and FBP, the gold standard for quantification in PET studies. Percentage COV values of (64)Cu with OSEM were significantly lower than those of (62)Cu. CONCLUSIONS: Copper-64 radiotracers provide higher image quality than (62)Cu-radiotracers in whole-body tumor imaging only when the 3D acquisition mode and OSEM algorithm are applied. However, the quantitative values for smaller tumors may be slightly overestimated.

The potential of o-bromo-trans-decalinvesamicol as a new PET ligand for vesicular acetylcholine transporter imaging.

We investigated the characteristics of the regional rat brain distribution of radio-brominated o-bromo-decalinvesamicol (OBDV) in vivo to evaluate its potential as a PET ligand for vesicular acetylcholine transporter (VAChT). In in vivo biodistribution study, the specific brain regional accumulation of [(77) Br]OBDV was revealed 30 min after intravenous injection. The specific brain regional accumulation of [(77) Br]OBDV was significantly inhibited by co-injection of (+/-)-vesamicol. In contrast, no significant inhibition of the uptake of [(77) Br]OBDV in all brain regions was observed with co-injection of (+)-pentazocine (selective σ-1 receptor agonist) and (+)-3-(3-hydroxyphenyl)-N-propylpiperidine, [(+)-3-PPP] (σ-1 and σ-2 receptor agonist) with [(77) Br]OBDV. [(77) Br]OBDV accumulation in VAChT-rich brain regions was observed in ex vivo autoradiography. These results showed that [(77) Br]OBDV selectively bound to VAChT with high affinity in rat brain in vivo. Hence, OVBDV radiolabelled with more suitable (76) Br was suggested to be a potent VAChT ligand for PET.

[Assessment of validity of the archived standard curve in endotoxin assay, produced in other facilities].

We have reported the possibility of the use of the archived standard curve of endotoxin assay, which is prepared in the same facility from the viewpoint of the accuracy and precision. In this study, the possibility of the use of the archived standard curves prepared in the different facilities was investigated with the same data set in the previous paper. The evaluation was performed with the recovery rate of the concentrations of the standard solutions, as the same method as the previous study. The clotting times of the standard solutions were substituted into the standard curves prepared in the different facilities from those, in which standard solutions were prepared. The recovery rates were 86.1-125.0%, and the range was almost the same as that when the facility preparing standard solutions were the same as that preparing the standard curve. From this data, if the protocols of the preparation of standard solutions, such as mixing and the interval timing until set to the apparatus and so on, can be set the same between the endotoxin test and the preparation of the archived standard curves, the endotoxin concentration calculated with the archived standard curves prepared in other facilities were not varied very much, compared to the true values and the values obtained from the use of the archived standard curves prepared in the same facility.

High efficacy of particle beam therapies against tumors under hypoxia and prediction of the early stage treatment effect using 3'-deoxy-3'-[18F]fluorothymidine positron emission tomography.

OBJECTIVE: Compared with radiation therapy using photon beams, particle therapies, especially those using carbons, show a high relative biological effectiveness and low oxygen enhancement ratio. Using cells cultured under normoxic conditions, our group reported a greater suppressive effect on cell growth by carbon beams than X-rays, and the subsequent therapeutic effect can be predicted by the cell uptake amount of 3'-deoxy-3'-[18F]fluorothymidine (18F-FLT) the day after treatment. On the other hand, a hypoxic environment forms locally around solid tumors, influencing the therapeutic effect of radiotherapy. In this study, the influence of tumor hypoxia on particle therapies and the ability to predict the therapeutic effect using 18F-FLT were evaluated. METHODS: Using a murine colon carcinoma cell line (colon 26) cultured under hypoxic conditions (1.0% O2 and 5.0% CO2), the suppressive effect on cell growth by X-ray, proton, and carbon irradiation was evaluated. In addition, the correlation between decreased 18F-FLT uptake after irradiation and subsequent suppression of cell proliferation was investigated. RESULTS: Tumor cell growth was suppressed most efficiently by carbon-beam irradiation. 18F-FLT uptake temporarily increased the day after irradiation, especially in the low-dose irradiation groups, but then decreased from 50 h after irradiation, which is well correlated with the subsequent suppression on tumor cell growth. CONCLUSIONS: Carbon beam treatment shows a strong therapeutic effect against cells under hypoxia. Unlike normoxic tumors, it is desirable to perform 18F-FLT positron emission tomography 2-3 days after irradiation for early prediction of the treatment effect.

PET/MRI multimodality imaging to evaluate changes in glymphatic system function and biomarkers of Alzheimer's disease.

The glymphatic system is considered to play a pivotal role in the clearance of disease-causing proteins in neurodegenerative diseases. This study employed MR diffusion tensor imaging (DTI) to evaluate glymphatic system function and its correlation with brain amyloid accumulation levels measured using [11C]Pittsburgh compound-B (PiB) PET/MRI. Fifty-six patients with mild cognitive impairment and early Alzheimer's disease (AD: 70 ± 11 y) underwent [11C]PiB PET/MRI to assess amyloid deposition and were compared with 27 age-matched cognitively normal volunteers (CN: 69 ± 10y). All participants were evaluated for cognitive function using the Mini Mental State Examination (MMSE) before [11C]PiB PET/MRI. DTI images were acquired during the PET/MRI scan with several other MR sequences. The DTI analysis along the perivascular space index (DTI-ALPS index) was calculated to estimate the functional activity of the glymphatic system. Centiloid scale was applied to quantify amyloid deposition levels from [11C]PiB PET images. All patients in the AD group showed positive [11C]PiB accumulation, whereas all CN participants were negative. ALPS-index for all subjects linearly correlated with PiB centiloid, MMSE scores, and hippocampal volume. The correlation between the ALPS-index and PiB accumulation was more pronounced than with any other biomarkers. These findings suggest that glymphatic system dysfunction is a significant factor in the early stages of Alzheimer's disease.

Region-specific causal mechanism in the effects of ammonia on cerebral glucose metabolism in the rat brain.

Ammonia, which is considered to be the main agent responsible for hepatic encephalopathy, inhibits oxidative glucose metabolism in the brain. However, the effects of ammonia on cerebral glucose metabolism in different brain regions remains unclear. To clarify this issue, we added ammonia directly to fresh rat brain slices and measured its effects on glucose metabolism. Dynamic positron autoradiography with [(18)F]2-fluoro-2-deoxy-D-glucose and 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium (WST-1) colorimetric assay revealed that ammonia significantly increased the cerebral glucose metabolic rate and depressed mitochondrial function, as compared to the unloaded control in each of the brain regions examined (cerebral cortex, striatum, and cerebellum), reflecting increased glycolysis that compensates for the decrease in aerobic metabolism. Pre-treatment with (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801), a N-methyl-D-aspartate (NMDA) receptor antagonist, significantly attenuated these changes induced by ammonia in cerebellum, but not in cerebral cortex or striatum. The addition of ammonia induced an increase in cyclic guanosine monophosphate (cGMP) levels in cerebellum, but not in cerebral cortex or striatum, reflecting the activation of the NMDA receptor-nitric oxide-cGMP pathway. These results suggested that NMDA receptor activation is responsible for the impairment of glucose metabolism induced by ammonia specifically in cerebellum.

[Assessment of validity of the archived standard curve in endotoxin assay].

The archived standard curve of endotoxin assay was evaluated to be possible to be used for the endotoxin assay as the reliable standard curve, instead the standard curve was produced each time of the assay. The archived standard curve shall be produced from three standard curves for three days, following the guidance issued from FDA in 1991, and the evaluation whether the archived standard curves can be applicable to use daily was performed with the recovery rate of the concentrations obtained from the archived standard curves against the true values. The three case studies were prepared: (1) the same person, who prepared the archived standard curves, performed this assay with the standard solutions (repeatability condition with the same tester, at the same facility), (2) the person, who did not prepare the archived standard curves, performed this assay with standard solutions (reproducibility condition with the different tester and dates), (3) the same preparation as (1), but using different three lots of lysates. The recovery rates were (1) 85-127%, (2) 86-124%, (3) 64-156%, respectively. From this data, the endotoxin concentration calculated with the archived standard curves were not varied very much, compared to the true values, but further discussion are necessary when the archived standard curves would be applied in daily analysis of PET drugs, regarding the protocol, the requirement to use the archived standard curve and the daily internal control as system suitability tests.

Hematopoiesis in the spleen after engraftment in unrelated cord blood transplantation evaluated by 18F-FLT PET imaging.

Cord blood is an important donor source for allogeneic hematopoietic stem cell transplantation (allo-HSCT), with its unique composition and quality of hematopoietic cells. The proliferation site and potency of infused hematopoietic stem cells in humans may vary between stem cell sources. We investigated this possibility in a prospective, exploratory study to assess hematopoietic dynamics using the radiopharmaceutical 3'-deoxy-3'-18F-fluorothymidine (18F-FLT), a thymidine analog used in positron emission tomography imaging, before allo-HSCT and on days 50 and 180 after allo-HSCT. We evaluated 11 patients with hematological malignancies who underwent allo-HSCT [five with peripheral blood stem cell transplantation (PBSCT) and six with unrelated cord blood transplantation (UCBT)]. Before allo-HSCT, 18F-FLT uptake did not differ between the two groups. At day 50, 18F-FLT uptake in the spleen was significantly greater in the UCBT group than in the PBSCT group (p = 0.0043), with no difference in whole-body bone marrow. At day 180, the differences in spleen uptake had diminished, and there were no differences between groups in whole-body bone marrow or the spleen, except for the sternum. The persistence of splenic hematopoiesis after engraftment in the UCBT group may reflect the complex systemic homing and proliferation mechanisms of cord blood hematopoietic cells.

[18F]FES PET Resolves the Diagnostic Dilemma of COVID-19-Vaccine-Associated Hypermetabolic Lymphadenopathy in ER-Positive Breast Cancer.

Coronavirus disease (COVID-19) vaccination is known to cause a diagnostic dilemma due to false-positive findings on [18F]FDG PET in vaccine-associated hypermetabolic lymphadenopathy. We present two case reports of women with estrogen-receptor (ER)-positive cancer of the breast who were vaccinated for COVID-19 in the deltoid muscle. [18F]FDG positron emission tomography (PET) demonstrated primary breast cancer and multiple axillary lymph nodes with increased [18F]FDG uptake, diagnosed as vaccine-associated [18F]FDG-avid lymph nodes. Subsequent [18F]FES PET revealed single axillary lymph node metastasis in the vaccine-associated [18F]FDG-avid lymph nodes. To the best of our knowledge, this is the first study showing the usefulness of [18F]FES PET in diagnosing axillary lymph node metastasis in COVID-19-vaccinated patients harboring ER-positive breast cancer. Thus, [18F]FES PET has potential applications in the detection of true-positive metastatic lymph nodes in patients with ER-positive breast cancer regardless of the ipsilateral or contralateral side, who have received COVID-19 vaccination.

Feasibility of Renal Blood Flow Measurement Using 64Cu-ATSM PET/MRI: A Quantitative PET and MRI Study.

This study aimed to evaluate the renal blood flow (RBF) in patients with chronic kidney disease (CKD) using 64Cu(II)-diacetyl-bis(4-methylthiosemicarbazonate) (64Cu-ATSM) for positron emission tomography (PET)/magnetic resonance imaging (MRI). We included five healthy controls (HCs) and ten patients with CKD. The estimated glomerular filtration rate (eGFR) was calculated from the serum creatinine (cr) and cystatin C (cys) levels. The estimated RBF (eRBF) was calculated using the eGFR, hematocrit, and filtration fraction. A single dose of 64Cu-ATSM (300-400 MBq) was administered for RBF evaluation, and a 40 min dynamic PET scan was performed with simultaneous arterial spin labeling (ASL) imaging. PET-RBF images were obtained from the dynamic PET images at 3 min after injection using the image-derived input function method. The mean eRBF values calculated from various eGFR values differed significantly between the patients and HCs; both groups also differed significantly in terms of the RBF values (mL/min/100 g) measured using PET (151 ± 20 vs. 124 ± 22, p < 0.05) and ASL-MRI (172 ± 38 vs. 125 ± 30, p < 0.001). The ASL-MRI-RBF was positively correlated with the eRBFcr-cys (r = 0.858, p < 0.001). The PET-RBF was positively correlated with the eRBFcr-cys (r = 0.893, p < 0.001). The ASL-RBF was positively correlated with the PET-RBF (r = 0.849, p < 0.001). 64Cu-ATSM PET/MRI demonstrated the reliability of PET-RBF and ASL-RBF by comparing them with eRBF. This is the first study to demonstrate that 64Cu-ATSM-PET is useful for assessing the RBF and is well correlated with ASL-MRI.

Effect of newly developed scissors-attached micro-forceps on the recipient clamp time and occurrence of anastomotic site infarction after bypass surgery for moyamoya disease.

Introduction: This study aimed to examine the effect of newly developed scissors-attached micro-forceps in superficial temporal artery-to-middle cerebral artery (STA-MCA) anastomosis for moyamoya disease (MMD). Materials and methods: Of 179 consecutive STA-MCA anastomoses on 95 hemispheres of 71 MMD patients at the University of Fukui Hospital between 2009 and 2023, 49 anastomoses on 26 hemispheres of 21 patients were enrolled in this retrospective cohort clinical trial intraoperative indocyanine green video-angiography did not demonstrate bypass patency in three anastomoses in two patients who were excluded. Twenty-one anastomosis in 19 hemispheres of 16 patients were performed using the conventional micro-forceps (conventional group, CG), and 25 anastomoses in 22 hemispheres of 19 patients were performed using scissors-attached micro-forceps (scissors group, SG). A small infarction near the anastomotic site detected using postoperative diffusion-weighted imaging was defined as anastomotic site infarction (ASI). Factors affecting the occurrence of ASI were examined by univariate, logistic regression, and receiver operating curve (ROC) analysis. Results: There were no significant differences in clinical parameters such as age, sex, number of sacrificed branches, number of sacrificed large branches, and number of sutures between the CG and SG. However, the clamp time and occurrence of ASI were significantly lower in the SG than in the CG. Logistic regression analysis revealed that the clamp time was the only significant factor predicting the occurrence of ASI. A receiver operating curve analysis also revealed that the clamp time significantly predicted the occurrence of ASI (area under the curve, 0.875; cutoff value, 33.2 min). Conclusion: The newly developed scissors-attached micro-forceps could significantly reduce the clamp time and occurrence of ASI in STA-MCA anastomosis for MMD.

Norepinephrine transporter imaging in the brain of a rat model of depression using radioiodinated (2S, αS)-2-(α-(2-iodophenoxy)benzyl)morpholine.

To visualize the norepinephrine transporters (NETs) in various brain diseases, we developed radioiodinated (2S,αS)-2-(α-(2-iodophenoxy)benzyl)morpholine ((S,S)-IPBM). This radioligand achieved the basic requirements for NET imaging. In this study, we assessed the potential of radioiodinated (S,S)-IPBM as an imaging biomarker of NET to obtain diagnostic information about depression in relation to NET expression in the brain using a rat depression model. The ex vivo autoradiographic experiments using the (S,S)-[125I]IPBM showed significantly lower accumulation of radioactivity in the locus coeruleus (LC) and the anteroventricular thalamic nucleus (AVTN) of the depression group than in those of the control group. Consequently, in vitro autoradiographic experiments showed that NET maximum binding (Bmax) values in the LC and AVTN, known as NET-rich regions, were significantly decreased in the rat model of depression when compared to those of the control rats. In addition, there was an extremely good correlation between NET Bmax and (S,S)-IPBM accumulation (r  =  .98), an indication of radioiodinated IPBM as a quantitative NET imaging biomarker. The reduction in (S,S)-[125I]IPBM accumulation in the rat model of depression correlated with that of NET density. These results suggest that (S,S)-[123I]IPBM has potential as an imaging biomarker of NET to obtain diagnostic information about major depression.

Radiobrominated probe targeting activated p38α in inflammatory diseases.

OBJECTIVE: p38α, a member of the mitogen-activated protein kinase superfamily, is activated by external stimuli, followed by nuclear translocation for the regulation of inflammatory responses at the transcriptional and translational levels in inflammatory diseases. Thus, activated p38α would be an appropriate target molecule for in vivo noninvasive imaging and targeted radionuclide therapy. For this purpose, we designed a radiobrominated compound, 6-(4-[77Br]bromo-2-fluorophenoxy)-8-methyl-2-(tetrahydro-2H-pyran-4-ylamino)-pyrido[2,3-d]pyrimidin-7(8H)-one ([77Br]4-BR), based on a potent p38α selective inhibitor, R1487, for use with single-photon emission computed tomography. We synthesized [77Br]4-BR and evaluated its effectiveness as an activated p38α imaging probe compared with our previous radioiodinated probe (6-(2-fluoro-4-[125I]iodophenoxy)-8-methyl-2-(tetrahydro-2H-pyran-4-ylamino)-pyrido[2,3-d]pyrimidin-7(8H)-one ([125I]4-IR)) in a mouse inflammatory model. METHODS: We designed [77Br]4-BR by replacing the radioiodine of [125I]4-IR or the fluorine of R1487 with radiobromine at the 4-position of the phenoxy ring. We synthesized 4-BR via a four-step process. The inhibitory potency of 4-BR was measured using an ADP-Glo™ kinase assay system. Radiosynthesis of [77Br]4-BR was performed via an organotin-radiobromine exchange reaction using the corresponding tributyltin precursor. Radioactivity biodistribution was evaluated in normal ddY mice and turpentine oil-induced inflammation model mice for 120 min after intravenous administration of [77Br]4-BR. The temporal changes in radioactivity in blood fractions were compared between [77Br]4-BR and [125I]4-IR. RESULTS: 4-BR was synthesized at a total yield of 9.1% and showed a p38α inhibitory potency similar to that of 4-IR. [77Br]4-BR was successfully obtained from a tributyltin precursor with high radiochemical yield (89.9%), purity (95.9%), and molar activity (2.0 TBq/µmol). [77Br]4-BR showed accumulation of high radioactivity in the inflamed tissue (3.4% ± 0.9% ID/g, peaking at 15 min), rapid delivery throughout the body, and rapid blood clearance with approximately half of the blood radioactivity existing as an intact form at 60 min. Although the maximum radioactivity accumulation in inflamed tissue after [77Br]4-BR administration was approximately half that of [125I]4-IR because of its faster blood clearance and lower free fraction in the input function, the inflamed tissue-to-blood ratio was comparable between [77Br]4-BR and [125I]4-IR. CONCLUSIONS: [77Br]4-BR would be a promising imaging agent for detecting activated p38α in inflammatory diseases.