Heterogeneous Association of Tooth Loss with Functional Limitations

Tooth loss is prevalent in older adults and associated with functional capacity decline. Studies on the susceptibility of some individuals to the effects of tooth loss are lacking. This study aimed to investigate the heterogeneity of the association between tooth loss and higher-level functional capacity in older Japanese individuals employing a machine learning approach. This is a prospective cohort study using the data of adults aged ≥65 y in Japan (N = 16,553). Higher-level functional capacity, comprising instrumental independence, intellectual activity, and social role, was evaluated using the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC). The scale ranged from 0 (lowest function) to 13 (highest function). Doubly robust targeted maximum likelihood estimation was used to estimate the population-average association between tooth loss (having <20 natural teeth) and TMIG-IC total score after 6 y. The heterogeneity of the association was evaluated by estimating conditional average treatment effects (CATEs) using the causal forest algorithm. The result showed that tooth loss was statistically significantly associated with lower TMIG-IC total scores (population-average effect: -0.14; 95% confidence interval, -0.18 to -0.09). The causal forest analysis revealed the heterogeneous associations between tooth loss and lower TMIG-IC total score after 6 y (median of estimated CATEs = -0.13; interquartile range = 0.12). The high-impact subgroup (i.e., individuals with estimated CATEs of the bottom 10%) were significantly more likely to be older and male, had a lower socioeconomic status, did not have a partner, and had poor health conditions compared with the low-impact subgroup (i.e., individuals with estimated CATEs of the top 10%). This study found that heterogeneity exists in the association between tooth loss and lower scores on functional capacity. Implementing tooth loss prevention policy and clinical measures, especially among vulnerable subpopulations significantly affected by tooth loss, may reduce its burden more effectively.

Post-Disaster Mental Health and Dietary Patterns among Older Survivors of an Earthquake and Tsunami

OBJECTIVES

Research suggests that cardiometabolic disease risks are elevated among survivors of natural disasters, possibly mediated by changes in diet. Using the Brief Dietary History Questionnaire, we examined (1) dietary patterns among older survivors of the 2011 Great East Japan Earthquake and Tsunami, and (2) the contribution of posttraumatic stress symptoms (PTSS)/depressive symptoms, as well as relocation to temporary housing on dietary patterns and (3) gender differences in the associations.

DESIGN, SETTING AND PARTICIPANTS

Data came from a prospective cohort study of 1,375 survivors aged 65-89 years (44.6% male).

MEASUREMENTS

PTSS/depression onset was evaluated in 2013, 2.5 years after the disaster. Dietary data was collected with a self-administered brief-type diet history questionnaire in 2020. A principal component analysis identified three posterior dietary patterns.

RESULTS

Diet 1 consisted of high intake of vegetables, soy products, and fruits; Diet 2 consisted of carbohydrate-rich foods and snacks/sweets; Diet 3 consisted of high intake of alcoholic beverages, meat, and seafood. Least-squares linear regression revealed that individuals with PTSS/depression were less likely to exhibit Diet 1, while individuals with PTSS were more likely to exhibit Diet 2 and 3. Especially, males who had depression showed an unhealthy dietary pattern. Those who have lived in a trailer-style temporary housing reported less consumption of Diet 3.

CONCLUSION

Survivors of disaster with symptoms of mental illness tended to exhibit less healthy dietary patterns after 9 years. Diet varied by type of post-disaster mental illness, gender, and current social circumstances. We lacked pre-disaster BDHQ data, which is a limitation.

Development of tumor-targeting aza-vesamicol derivatives with high affinity for sigma receptors for cancer theranostics

As sigma receptors are highly expressed on various cancer cells, radiolabeled sigma receptor ligands have been developed as imaging and therapeutic probes for cancer. Previously, we synthesized and evaluated a radioiodinated vesamicol derivative, 2-(4-[¹²⁵I](4-iodophenyl)piperidine)cyclohexanol ((+)-[¹²⁵I]pIV), and a radioiodinated aza-vesamicol derivative, trans-2-(4-(3-[¹²⁵I](4-iodophenyl)propyl)piperazin-1-yl)cyclohexan-1-ol ([¹²⁵I]2), as sigma-1 receptor-targeting probes. In order to obtain sigma receptor-targeting probes with superior biodistribution characteristics, we firstly synthesized twelve bromine-containing aza-vesamicol derivatives and evaluated their affinity for sigma receptors. One such derivative exhibited high selectivity for the sigma-1 receptor and another exhibited high affinity for both the sigma-1 and sigma-2 receptors. Thus, their halogen-substituted iodine- and radioiodine-containing compounds were prepared. The ¹²⁵I-labeled compounds exhibited high uptake in tumor and lower uptake in non-target tissues than the two previously developed and evaluated ¹²⁵I-labeled sigma receptor-targeting probes, [¹²⁵I]pIV and [¹²⁵I]2. Therefore, these novel radioiodine-labeled compounds should be promising as sigma receptor-targeting probes.

Development of Radiohalogenated Osimertinib Derivatives as Imaging Probes for Companion Diagnostics of Osimertinib

Osimertinib is an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor approved for treating non-small-cell lung cancer (NSCLC) with EGFR mutations. Genetic testing is required to detect the mutation for selecting patients who can use osimertinib. Here, we report an attempt to develop nuclear imaging probes that detect the EGFR mutations. We designed and synthesized I-osimertinib and Br-osimertinib with a radioactive or nonradioactive halogen atom at an indole ring in osimertinib and evaluated them. In vitro assays suggested that both I-osimertinib and Br-osimertinib exhibit a specifically high activity toward NSCLC with EGFR L858R/T790M mutations. In biodistribution experiments, the accumulation of both [125I]I-osimertinib and [77Br]Br-osimertinib in tumors with mutations was significantly higher than that in blood and muscle. However, these osimertinib derivatives showed a significantly higher accumulation in lungs than in tumors. Therefore, for detecting the mutations in lung cancer, further structural modifications of the probes are required.

Synthesis and evaluation of radiogallium-labeled long-chain fatty acid derivatives as myocardial metabolic imaging agents

Since long-chain fatty acids work as the primary energy source for the myocardium, radiolabeled long-chain fatty acids play an important role as imaging agents to diagnose metabolic heart dysfunction and heart diseases. With the aim of developing radiogallium-labeled fatty acids, herein four fatty acid-based tracers, [67Ga]Ga-HBED-CC-PDA, [67Ga]Ga-HBED-CC-MHDA, [67Ga]Ga-DOTA-PDA, and [67Ga]Ga-DOTA-MHDA, which are [67Ga]Ga-HBED-CC and [67Ga]Ga-DOTA conjugated with pentadecanoic acid (PDA) and 3-methylhexadecanoic acid (MHDA), were synthesized, and their potential for myocardial metabolic imaging was evaluated. Those tracers were found to be chemically stable in 0.1 M phosphate buffered saline. Initial [67Ga]Ga-HBED-CC-PDA, [67Ga]Ga-HBED-CC-MHDA, [67Ga]Ga-DOTA-PDA, and [67Ga]Ga-DOTA-MHDA uptakes in the heart at 0.5 min postinjection were 5.01 ± 0.30%ID/g, 5.74 ± 1.02%ID/g, 5.67 ± 0.22%ID/g, and 5.29 ± 0.10%ID/g, respectively. These values were significantly lower than that of [123I]BMIPP (21.36 ± 2.73%ID/g). For their clinical application as myocardial metabolic imaging agents, further structural modifications are required to increase their uptake in the heart.

Visualization of Dynamic Expression of Myocardial Sigma-1 Receptor After Myocardial Ischemia and Reperfusion Using Radioiodine-Labeled 2-[4-(2-iodophenyl)piperidino]cyclopentanol (OI5V) Imaging

BACKGROUND

This study chronologically evaluated the expression of the intensity and distribution of the sigma-1 receptor (σ1R) demonstrated by radiolabeled 2-[4-(2-iodophenyl)piperidino]cyclopentanol (OI5V) in a rat model of myocardial ischemia and reperfusion.Methods and Results:The left coronary artery was occluded for 30 min, followed by reperfusion. Dual-tracer autoradiography with 125I-OI5V and 99 mTc-MIBI was performed to assess the spatiotemporal changes in 125I-OI5V uptake (n=5-6). Significant and peaked 125I-OI5V uptake in the ischemic area was observed at 3 days after reperfusion, and the 125I-OI5V uptake ratio of ischemic area to normally perfused left ventricular area decreased gradually from 3 to 28 days (mean value±SD; 0.90±0.12 at 1 day, 1.89±0.19 at 3 days, 1.52±0.17 at 7 days, 1.34±0.13 at 14 days, and 1.16±0.14 at 28 days, respectively). Triple-tracer autoradiography with 125I-OI5V, 99 mTc-MIBI, and 201TlCl was performed to evaluate 125I-OI5V uptake in the ischemic area in relation to the residual perfusion at 7 days (n=4). The 125I-OI5V uptake ratio of the non-salvaged area was higher compared to that of the salvaged area in the ischemic area. 123I-OI5V and 99 mTc-MIBI SPECT/CT was performed 3 days after reperfusion (n=3), and the in vivo images showed clear uptake of 123I-OI5V in the perfusion defect area.

CONCLUSIONS

The present study confirmed the spatiotemporal expression pattern of σ1R expression. Non-invasive σ1R imaging with 123I or 125I-OI5V was feasible to monitor the expression of σ1R after myocardial ischemia and reperfusion.

68Ga- and 211At-Labeled RGD Peptides for Radiotheranostics with Multiradionuclides

Probes for radiotheranostics could be produced by introducing radionuclides with similar chemical characteristics into the same precursors. We recently developed an ²¹¹At-labeled RGD peptide and a corresponding radioiodine-labeled RGD peptide. Both labeled peptides accumulated in large quantities in the tumor with similar biodistribution, demonstrating their usefulness for radiotheranostics. In this study, we hypothesized that probes for radiotheranostics combined with multiradionuclides, such as ⁶⁸Ga and ²¹¹At, have useful clinical applications. New radiolabeled RGD peptide probes were synthesized via a molecular design approach, with two labeling sites for metal and halogen. These probes were evaluated in biodistribution experiments using tumor-bearing mice. [⁶⁷Ga]Ga-DOTA-c[RGDf(4-I)K] ([⁶⁷Ga]4), Ga-DOTA-[¹²⁵I]c[RGDf(4-I)K] ([¹²⁵I]4), and Ga-DOTA-[²¹¹At]c[RGDf(4-At)K] ([²¹¹At]7) showed similar biodistribution, with high and equivalent accumulation in tumors. These results indicate the usefulness of these probes in radiotheranostics with multiradionuclides, such as a radiometal and a radiohalogen, and they could contribute to a personalized medicine regimen.

In vitro and in vivo evaluation of [125/123I]-2-[4-(2-iodophenyl)piperidino]cyclopentanol([125/123I]-OI5V) as a potential sigma-1 receptor ligand for SPECT

INTRODUCTION

We investigated the characteristics of radio-iodinated 2-[4-(2-iodophenyl)piperidino]cyclopentanol (OI5V) as a single photon emission computed tomography (SPECT) ligand for mapping sigma-1 receptor (σ-1R), which plays an important role in stress remission in many organs.

METHODS

OI5V was synthesized from o-bromobenzaldehyde in three steps. OI5V was evaluated for its affinity to VAChT, σ-1 and σ-2 receptor by in vitro competitive binding assays using rat tissues and radioligands, [3H]vesamicol, ( +)-[3H]pentazocine and [3H]DTG, respectively. [125/123I]OI5V was prepared from o-trimethylstannyl-cyclopentanevesamicol (OT5V) by the iododestannylation reaction under no-carrier-added conditions. In vivo biodistribution study of [125I]OI5V in blood, brain regions and major organs of rats was performed at 2, 10, 30 and 60 min post-injection. In vivo blocking study and ex vivo autoradiography were performed to assess the binding selectivity of [125I]OI5V for σ-1 receptor. SPECT-CT imaging study was performed using [123I]OI5V.

RESULTS

OI5V demonstrated high selective binding affinity for σ-1R in vitro. In the biodistribution study, the blood-brain barrier (BBB) permeability of [125I]OI5V was high and the accumulation of [125I]OI5V in the rat cortex at 2 min post-injection exceeded 2.00%ID/g. In the in vivo blocking study, the accumulation of [125I]OI5V in the brain was significantly blocked by co-administration of 0.5 μmol of SA4503 and 1.0 μmol of pentazocine. Ex vivo autoradiography revealed that the regional brain accumulation of [125I]OI5V was similar to σ-1R-rich regions of the rat brain. SPECT images of [123I]OI5V in the rat brain reflected the distribution of sigma receptors in the brain.

CONCLUSIONS

This study confirmed that [125/123I]OI5V selectively binds σ-1R in the rat brain in vivo. [123I]OI5V was suggested to be useful as a σ-1R ligand for SPECT.

Colchicine treatment early after infarction attenuates myocardial inflammatory response demonstrated by 14C-methionine imaging and subsequent ventricular remodeling by quantitative gated SPECT

OBJECTIVE

Colchicine has been used as an anti-inflammatory agent and may be cardioprotective after acute myocardial infarction (AMI). We investigated how colchicine administration after AMI affects the myocardial inflammatory response using ¹⁴C-methionine and subsequent ventricular remodeling using single-photon emission computed tomography (SPECT) in a rat model of AMI.

METHODS

The left coronary artery (LCA) was occluded for 30 min followed by reperfusion. ¹⁴C-methionine was injected at 20 min before sacrifice. The LCA was re-occluded at 1 min before sacrifice and ^99mTc-methoxyisobutylisonitrile (^99mTc-MIBI) was injected. Colchicine was administered intraperitoneally from day 1 to the day before ¹⁴C-methionine injection. Dual-tracer autoradiography of the left ventricular short-axis slices was performed. The methionine uptake ratio in an ischemic area was calculated. ^99mTc-MIBI gated SPECT assessed end-diastolic volume (EDV), end-systolic volume (ESV) and left ventricular ejection fraction (LVEF). On Cluster of Differentiation 68 with 4',6-diamidino-2-phenylindole (CD68/DAPI) staining the positive myocardial cell percentage in an ischemic area was calculated.

RESULTS

In control rats, ¹⁴C-methionine uptake ratios on day 3 and 7 were 1.87 ± 0.15 and 1.39 ± 0.12, respectively. With colchicine, the uptake was reduced on days 3 (1.56 ± 0.26, p = 0.042) and 7 (1.23 ± 0.10, p = 0.030). Colchicine treated rats showed smaller EDV, ESV, and higher LVEF compared with control rats. At 8 weeks, those in control rats were 864 ± 115 μL, 620 ± 100 μL, 28.4 ± 2.5%, and in colchicine rats 665 ± 75 μL, 390 ± 97 μL, 42.2 ± 8.5% (p = 0.012, 0.0061, 0.0083), respectively. In control rats, CD68/DAPI positive myocardial cell percentages on days 3 and 7 were 38.4 ± 1.9% and 24.0 ± 2.4%, respectively. With colchicine, the percentages were reduced significantly on both days 3 (31.5 ± 2.0%, p < 0.0001) and 7 (12.0 ± 1.6%, p < 0.0001) as compared with the control.

CONCLUSIONS

Short-term colchicine treatment after AMI attenuated the post-AMI inflammatory response and subsequent ventricular remodeling and dysfunction. ¹⁴C-methionine imaging and gated ^99mTc-MIBI SPECT would be feasible to monitor the effectiveness of anti-inflammatory therapy and left ventricular function.

Development of Radiogallium-Labeled Peptides for Platelet-Derived Growth Factor Receptor β (PDGFRβ) Imaging: Influence of Different Linkers

The purpose of this study is to develop peptide-based platelet-derived growth factor receptor β (PDGFRβ) imaging probes and examine the effects of several linkers, namely un-natural amino acids (D-alanine and β-alanine) and ethylene-glycol (EG), on the properties of Ga-DOTA-(linker)-IPLPPPRRPFFK peptides. Seven radiotracers, ⁶⁷Ga-DOTA-(linker)-IPLPPPRRPFFK peptides, were designed, synthesized, and evaluated. The stability and cell uptake in PDGFRβ positive peptide cells were evaluated in vitro. The biodistribution of [⁶⁷Ga]Ga-DOTA-EG₂-IPLPPPRRPFFK ([⁶⁷Ga]27) and [⁶⁷Ga]Ga-DOTA-EG₄-IPLPPPRRPFFK ([⁶⁷Ga]28), which were selected based on in vitro stability in murine plasma and cell uptake rates, were determined in BxPC3-luc-bearing nu/nu mice. Seven ⁶⁷Ga-labeled peptides were successfully synthesized with high radiochemical yields (>85%) and purities (>99%). All evaluated radiotracers were stable in PBS (pH 7.4) at 37 °C. However, only [⁶⁷Ga]27 and [⁶⁷Ga]28 remained more than 75% after incubation in murine plasma at 37 °C for 1 h. [⁶⁷Ga]27 exhibited the highest BxPC3-luc cell uptake among the prepared radiolabeled peptides. As regards the results of the biodistribution experiments, the tumor-to-blood ratios of [⁶⁷Ga]27 and [⁶⁷Ga]28 at 1 h post-injection were 2.61 ± 0.75 and 2.05 ± 0.77, respectively. Co-injection of [⁶⁷Ga]27 and an excess amount of IPLPPPRRPFFK peptide as a blocking agent can significantly decrease this ratio. However, tumor accumulation was not considered sufficient. Therefore, further probe modification is required to assess tumor accumulation for in vivo imaging.

Combination of gemcitabine and anti-PD-1 antibody enhances the anticancer effect of M1 macrophages and the Th1 response in a murine model of pancreatic cancer liver metastasis

BACKGROUND

Pancreatic ductular adenocarcinoma (PDAC) is among the most dreadful of malignancies, in part due to the lack of efficacious chemotherapy. Immune checkpoint inhibitors, including anti-programmed cell death 1 (anti-PD-1) antibodies, are novel promising forms of systemic immunotherapy. In the current study, we assessed whether gemcitabine (GEM) combined with anti-PD-1 antibody treatment was efficacious as immunochemotherapy for advanced PDAC using a murine model of liver metastasis.

METHODS

The murine model of PDAC liver metastasis was established by intrasplenically injecting the murine pancreatic cancer cell line PAN02 into immunocompetent C57BL/6J mice. The mice were treated with an anti-PD-1 antibody, GEM, or a combination of GEM plus anti-PD-1 antibody, and compared with no treatment (control); liver metastases, immune cell infiltration, gene expression, immune cell response phenotypes, and overall survival were investigated.

RESULTS

In the metastatic tumor tissues of mice treated with GEM plus anti-PD-1 antibody, we observed the increased infiltration of Th1 lymphocytes and M1 macrophages. Gene expression profile analysis of peripheral blood cells obtained from mice treated with GEM plus anti-PD-1 antibody clearly highlighted T cell and innate immune signaling pathways. Survival of PDAC liver metastasis mice was significantly prolonged by the combination therapy (median survival, 66 days) when compared with that of GEM alone treatment (median survival, 56 days). Expanded lymphocytes, which were isolated from the splenocytes of PDAC liver metastasis mice treated with GEM plus anti-PD-1 antibody, had an increased number of M1 macrophages.

CONCLUSION

The combination of anti-PD-1 antibody immunotherapy with GEM was beneficial to treat a murine model of PDAC liver metastasis by enhancing the immune response mediated by Th1 lymphocytes and M1 macrophages and was associated with CD8+ T cells.

Plasma half-life and tissue distribution of leukocyte cell-derived chemotaxin 2 in mice

Leukocyte cell-derived chemotaxin 2 (LECT2) is a hepatokine that causes skeletal muscle insulin resistance. The circulating levels of LECT2 are a possible biomarker that can predict weight cycling because they reflect liver fat and precede the onset of weight loss or gain. Herein, to clarify the dynamics of this rapid change in serum LECT2 levels, we investigated the in vivo kinetics of LECT2, including its plasma half-life and tissue distribution, by injecting ¹²⁵I-labelled LECT2 into ICR mice and radioactivity tracing. The injected LECT2 was eliminated from the bloodstream within 10 min (approximate half-life, 5 min). In the kidneys, the radioactivity accumulated within 10 min after injection and declined thereafter. Conversely, the radioactivity in urine increased after 30 min of injection, indicating that LECT2 is mainly excreted by the kidneys into the urine. Finally, LECT2 accumulated in the skeletal muscle and liver until 30 min and 2 min after injection, respectively. LECT2 accumulation was not observed in the adipose tissue. These findings are in agreement with LECT2 action on the skeletal muscle. The present study indicates that LECT2 is a rapid-turnover protein, which renders the circulating level of LECT2 a useful rapid-response biomarker to predict body weight alterations.

Decreasing undesirable absorbed radiation to the intestine after administration of radium-223 dichloride for treatment of bone metastases

[223Ra]RaCl2 is the first alpha-particle emitting radiopharmaceutical to be used for castration-resistant prostate cancer patients with bone metastases because of its excellent therapeutic effects. [223Ra]RaCl2 is excreted via the intestine into feces, and some is absorbed from the intestine into the blood, which may be undesirable in terms of the exposure to radiation. Recently, we showed that a complex of myo-inositol-hexakisphosphate (InsP6) with zinc is a useful decorporation agent against radiostrontium. In this study, we hypothesized that Zn-InsP6 could bind to not only strontium but also to radium, and could inhibit the absorption of radium from the intestine. In in vitro binding experiments, Zn-InsP6 showed a high binding affinity for radium. In in vivo biodistribution experiments by intravenous injection of [223Ra]RaCl2 after treatment of Zn-InsP6, mice treated with Zn-InsP6 showed significantly lower bone accumulation of radioactivity (34.82 ± 1.83%Dose/g) than the mice in the non-treatment control group (40.30 ± 2.78%Dose/g) at 48 h postinjection. These results indicate that Zn-InsP6 bound radium in the intestine and inhibited the absorption of radium into the blood. Therefore, the insoluble Zn-InsP6 complex has high potential to decrease the side effects of [223Ra]RaCl2.

Synthesis and Fundamental Evaluation of Radioiodinated Rociletinib (CO-1686) as a Probe to Lung Cancer with L858R/T790M Mutations of Epidermal Growth Factor Receptor (EGFR)

Rociletinib (CO-1686), a 2,4-diaminopyrimidine derivative, is a highly potent tyrosine kinase inhibitor (TKI) that acts on epidermal growth factor receptor (EGFR) with L858R/T790M mutations. We supposed radioiodinated CO-1686 would function as a useful tool for monitoring EGFR L858R/T790M mutations. To aid in patient selection before therapy with EGFR-TKIs, this study aimed to develop a 125I-labeled derivative of CO-1686, N-{3-[(2-{[4-(4-acetylpiperazin-1-yl)-2-methoxyphenyl]amino}-5-(trifluoromethyl)pyrimidine-4-yl] amino}-5-([125I]iodophenyl)acrylamide ([125I]ICO1686) and evaluate its selectivity toward EGFR L858R/T790M. Radiosynthesis was performed by iododestannylation of the corresponding tributylstannyl precursor with [125I]NaI and N-chlorosuccinimide. The selectivity of the tracer for detecting EGFR L858R/T790M was evaluated using three relevant non-small cell lung cancer (NSCLC) cell lines-H1975, H3255 and H441 overexpressing the dual mutation EGFR L858R/T790M, active mutant EGFR L858R and wild-type EGFR, respectively. The nonradioactive ICO1686 and the precursor compound were successfully synthesized. A novel radiolabeled probe, [125I]ICO1686, was prepared with high radiochemical yield (77%) and purity (>99%). ICO1686 exhibited high cytotoxicity toward H1975 (IC50 0.20 ± 0.05 μM) and H3255 (IC50 0.50 ± 0.21 μM), which is comparable to that of CO-1686. In contrast, the cytotoxicity of ICO1686 toward H441 was 10-fold lower than that toward H1975. In the cell uptake study, the radioactivity uptake of [125I]ICO1686 in H1975 was 101.52% dose/mg, whereas the uptakes in H3255 and H441 were 33.52 and 8.95% dose/mg, respectively. The uptake of [125I]ICO1686 in H1975 was greatly reduced to 45.61% dose/mg protein by treatment with excess CO-1686. In vivo biodistribution study of the radiotracer found that its accumulation in H1975 tumor (1.77 ± 0.43% ID/g) was comparable to that in H3255 tumor (1.63 ± 0.23% ID/g) and the accumulation in H1975 tumor was not reduced by pretreatment with an excess dose of CO-1686. Although this radiotracer exhibited highly specific in vitro uptake in target cancer cells, structural modification is required to improve in vivo biodistribution.

(-)-o-[11 C]methyl-trans-decalinvesamicol ((-)-[11 C]OMDV) as a PET ligand for the vesicular acetylcholine transporter

To develop a PET imaging agent to visualize brain cholinergic neurons and synaptic changes caused by Alzheimer's disease, (-)- and (+)-o-[¹¹ C]methyl-trans-decalinvesamicol ([¹¹ C]OMDV) were isolated and investigated for differences in not only their binding affinity and selectivity to vesicular acetylcholine transporter (VAChT), but also their in vivo activities. [¹¹ C]OMDV has a high binding affinity for VAChT both in vitro and in vivo. Racemic OMDV and o-trimethylstannyl-trans-decalinvesamicol (OTDV), which are precursors for synthesis of [¹¹ C]OMDV, were separated into (-)-optical isomers ((-)-OMDV and (-)-OTDV) and (+)-optical isomers ((+)-OMDV and (+)-OTDV) by HPLC. In the in vitro binding assay, (-)-OMDV(7.2 nM) showed eight times higher binding affinity (Ki) to VAChT than that of (+)-OMDV(57.5 nM). In the biodistribution study, the blood-brain barrier permeability of both enantiomers ((-)-[¹¹ C]OMDV and (+)-[¹¹ C]OMDV) was similarly high (about 1.0%ID/g) at 2 min post-injection. However, (+)-[¹¹ C]OMDV clearance from the brain was faster than (-)-[¹¹ C]OMDV. In the in vivo blocking study, accumulation of (-)-[¹¹ C]OMDV in the cortex was markedly decreased (approximately 30% of control) by coadministration of vesamicol, and brain uptake of (-)-[¹¹ C]OMDV was not significantly altered by coadministration of (+)-pentazocine or (+)-3-(3-hydroxyphenyl)-N-propylpiperidine ((+)-3-PPP). PET-CT imaging revealed inhibition of the rat brain uptake of (-)-[¹¹ C]OMDV by coadministration of vesamicol. In conclusion, (-)-[¹¹ C]OMDV, which is an enantiomer of OMDV, selectively binds to VAChT with high affinity in the rat brain in vivo. (-)-[¹¹ C]OMDV may be utilized as a potential PET ligand for studying presynaptic cholinergic neurons in the brain.

Sarcopenic obesity is associated with a faster decline in renal function in people with type 2 diabetes

AIM

To evaluate the association between sarcopenic obesity and the decline in estimated GFR in people with type 2 diabetes.

METHODS

We enrolled 745 people with type 2 diabetes (mean age 64.6 years, 53.6% men). Body composition was evaluated using dual-energy X-ray absorptiometry. Skeletal muscle index, calculated as appendicular non-fat mass (kg) divided by height squared (m² ), was used to determine sarcopenia. Sarcopenic obesity was defined as the coexistence of sarcopenia and a ratio of android to gynoid fat mass greater than the median values in each gender. The association of sarcopenic obesity both with the annual rate of decline in estimated GFR and a >30% decline in estimated GFR was evaluated using multivariate linear regression models and Cox proportional hazard models, respectively.

RESULTS

Participants with sarcopenic obesity were at an increased risk of a high annual rate of decline in estimated GFR, even after adjustment for the confounding variables (standardized β = -0.228, P <0.001). Sarcopenic obesity was also significantly associated with risk of a >30% decline in estimated GFR (hazard ratio 4.52, 95% CI 2.16-9.47; P < 0.01) in multivariate model.

CONCLUSIONS

Sarcopenic obesity evaluated by dual energy X-ray absorptiometry is associated with a faster decline in renal function in people with type 2 diabetes.

Postconditioning Accelerates Myocardial Inflammatory Resolution Demonstrated by 14C-Methionine Imaging and Attenuates Ventricular Remodeling After Ischemia and Reperfusion

BACKGROUND

Methionine uptake after myocardial infarction has been proven to reflect myocardial inflammation. The effect of postconditioning on the post-infarction inflammatory process, however, remains to be elucidated.Methods and Results:In control (n=22) and postconditioning rats (n=23), the left coronary artery was occluded for 30 min, followed by reperfusion for 1, 3, 7, and 14 days. Postconditioning was performed immediately following the reperfusion. ¹⁴C-methinine (0.74 MBq) and ²⁰¹Tl (14.8 MBq) were injected 20 and 10 min prior to sacrifice, respectively. One minute before sacrifice, 150-180 MBq of ^{99 m}Tc-MIBI was injected immediately following the re-occlusion of the left coronary artery to verify the area at risk, and left ventricular triple-tracer autoradiography was performed. To examine the ventricular remodeling, echocardiography was performed 2 months after reperfusion in both groups (n=6 each). In the control rats, the methionine uptake ratios on days 1, 3, 7, and 14 were 0.74±0.12, 1.85±0.16, 1.48±0.10, 1.25±0.04, respectively. With postconditioning, methionine uptake was similar on day 3 (1.90±0.21), but was lower on day 7 (1.23±0.22, P<0.05) and day 14 (1.08±0.09, P<0.005). Echocardiography revealed that postconditioning reduced the ventricular end-diastolic (0.97±0.16 to 0.78±0.12 cm, P<0.05) and systolic (0.85±0.21 to 0.55±0.23 cm, P<0.05) dimensions and improved ventricular percentage fractional shortening (12±6.2 to 29±12 %, P=0.01).

CONCLUSIONS

¹⁴C-methinine imaging revealed that postconditioning accelerated resolution of inflammation and attenuated ventricular remodeling.

Syntheses and evaluation of a homologous series of aza-vesamicol as improved radioiodine-labeled probes for sigma-1 receptor imaging

Sigma-1 receptor imaging probes for determining the expression levels are desirable for diagnoses of various diseases and companion diagnoses of therapeutic agents targeting the sigma-1 receptor. In this study, we aimed to develop probes with higher affinity for the sigma-1 receptor. For this purpose, we synthesized and evaluated compounds, namely, vesamicol derivatives, in which alkyl chains of varying chain length were introduced between a piperazine ring and a benzene ring. The binding affinity of the vesamicol derivatives for the sigma-1 receptor tended to increase depending on the length of the alkyl chain between the benzene ring and the piperazine ring. The sigma-1 receptor of 2-(4-(3-phenylpropyl)piperazin-1-yl)cyclohexan-1-ol (5) (Ki = 5.8 nM) exhibited the highest binding affinity; therefore, we introduced radioiodine into the benzene ring in 5. The radioiodine labeled probe [125I]2-(4-(3-(4-iodophenyl)propyl)piperazin-1-yl)cyclohexan-1-ol ([125I]10) showed high accumulation in the sigma-1 receptor expressing DU-145 cells both in vitro and in vivo. Co-injection of [125I]10 with an excess level of a sigma receptor ligand, haloperidol, resulted in a significant decrease in the tumor accumulation in vitro and in vivo, indicating sigma receptor-mediated tumor uptake. These results provide useful information for developing sigma-1 receptor imaging probes.

Fundamental study of radiogallium-labeled aspartic acid peptides introducing octreotate derivatives

OBJECTIVE

Somatostatin receptors are highly expressed in neuroendocrine tumors, and many radiolabeled somatostatin analogs for diagnosis and treatment have been developed. To simultaneously detect not only primary cancer but also bone metastases, this study aimed to develop a positron emission tomography probe using generator-produced nuclide Gallium-68 (T_1/2 = 68 min), in which a carrier for primary cancer, a carrier for bone metastases lesions, and a stable gallium complex are introduced into the one molecule. Based on this strategy, the somatostatin receptor-targeted peptide, [Tyr³]-octreotate (TATE), aspartic acid peptide (D_n) with high binding affinity for hydroxyapatite, and Ga-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) as a stable gallium complex were selected. The novel complexes, Ga-DOTA-D_n-TATE (n = 0, 2, 5, 8, or 11), were designed, synthesized, and evaluated. The radiogallium complexes were prepared using the easy-to-handle radioisotope ⁶⁷Ga due to relatively long half-life.

METHODS

The radiogallium complex precursor DOTA-D_n-TATE was synthesized by the Fmoc-based solid-phase method and by the air oxidation method to form the disulfide bond. [⁶⁷Ga]Ga-DOTA-D_n-TATE was synthesized by reacting DOTA-D_n-TATE and ⁶⁷Ga. Hydroxyapatite binding assays, in vitro cellular uptake experiments in AR42J tumor cells, in biodistribution experiments in AR42J tumor-bearing mice, were performed using [⁶⁷Ga]Ga-DOTA-D_n-TATE.

RESULTS

The radiochemical purities of [⁶⁷Ga]Ga-DOTA-D_n-TATE were > 96.0%. In in vitro and in vivo experiments, [⁶⁷Ga]Ga-DOTA-D₁₁-TATE had a high affinity for hydroxyapatite and highly accumulated in bone. However, the uptake of [⁶⁷Ga]Ga-DOTA-D₁₁-TATE into somatostatin receptor-positive AR42J cells was lower than that of [⁶⁷Ga]Ga-DOTA-TATE, and the accumulation of [⁶⁷Ga]Ga-DOTA-D₁₁-TATE in tumor was significantly low.

CONCLUSION

Ga-DOTA-D₁₁-TATE may not be recognized by somatostatin receptor by the introduction of D₁₁, and the charge adjustment may be important for somatostatin receptor-positive cell uptake.

Radiobrominated benzimidazole-quinoline derivatives as Platelet-derived growth factor receptor beta (PDGFRβ) imaging probes

Platelet-derived growth factor receptor beta (PDGFRβ) affects in numerous human cancers and has been recognized as a promising molecular target for cancer therapies. The overexpression of PDGFRβ could be a biomarker for cancer diagnosis. Radiolabeled ligands having high affinity for the molecular target could be useful tools for the imaging of overexpressed receptors in tumors. In this study, we aimed to develop radiobrominated PDGFRβ ligands and evaluate their effectiveness as PDGFRβ imaging probes. The radiolabeled ligands were designed by modification of 1-{2-[5-(2-methoxyethoxy)-1H- benzo[d]imidazol-1-yl]quinolin-8-yl}piperidin-4-amine (1), which shows selective inhibition profile toward PDGFRβ. The bromine atom was introduced directly into C-5 of the quinoline group of 1, or indirectly by the conjugation of 1 with the 3-bromo benzoyl group. [77Br]1-{5-Bromo-2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinoline-8-yl}piperidin-4-amine ([77Br]2) and [77Br]-N-3-bromobenzoyl-1-{2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinolin-8-yl}-piperidin-4-amine ([77Br]3) were prepared using a bromodestannylation reaction. In a cellular uptake study, [77Br]2 and [77Br]3 more highly accumulatd in BxPC3-luc cells (PDGFRβ-positive) than in MCF7 cells (PDGFRβ-negative), and their accumulation was significantly reduced by pretreatment with inhibitors. In biodistribution experiments, [77Br]2 accumulation was higher than [77Br]3 accumulation at 1 h postinjection. These findings suggest that [76Br]2 is more promising for positron emission tomography (PET) imaging of PDGFRβ than [76Br]3.

Development of a novel radiobromine-labeled sigma-1 receptor imaging probe

INTRODUCTION

Sigma-1 receptor is a target for tumor imaging. In a previous study, we synthesized a vesamicol analog, (+)-2-[4-(4-bromophenyl)piperidino]cyclohexanol [(+)-pBrV], with a high affinity for sigma-1 receptor, and synthesized radiobrominated (+)-pBrV. This radiobrominated (+)-pBrV showed high tumor uptake in tumor-bearing mice; however, radioactivity accumulation in normal tissues, such as the liver, was high. We assumed that the accumulation of (+)-pBrV in the non-target tissues was partially derived from its high lipophilicity; therefore, we synthesized and evaluated (+)-4-[1-(2-hydroxycyclohexyl)piperidine-4-yl]-2-bromophenol [(+)-BrV-OH], which is a more hydrophilic compound. Although we aimed to develop a PET tracer using 76Br, in these initial studies, we used 77Br because of its longer half-life.

METHODS

(+)-[77Br]BrV-OH was synthesized using the chloramine-T method with a radiochemical purity of 95%. Lipophilicity and affinity for sigma-1 receptor of (+)-[77Br]BrV-OH were determined, and biodistribution experiments were performed. We also performed an in vivo blocking study by co-injecting excess amounts of the sigma-1 receptor ligand, SA4503, into mice.

RESULTS

The lipophilicity and affinity for sigma-1 receptor of (+)-[77Br]BrV-OH were lower than those of (+)-[77Br]pBrV. (+)-[77Br]BrV-OH also showed high tumor uptake in biodistribution experiments in DU-145 tumor-bearing mice,. Although (+)-[77Br]pBrV was retained in most tissues, (+)-[77Br]BrV-OH was cleared from these tissues. In blocking studies, the co-injection of SA4503 significantly decreased the tumor uptake of (+)-[77Br]BrV-OH.

CONCLUSION

These results indicate that (+)-[76Br]BrV-OH has potential as a PET probe for sigma-1 receptor imaging.

Quantification of Myocardial Perfusion Defect Size in Rats: Comparison between Quantitative Perfusion SPECT and Autoradiography

PURPOSE

Ultra-high resolution single-photon emission computed tomography (SPECT) system, using multiple pinhole collimators, has been applied to the imaging of small rodents. We aimed to compare the myocardial infarction (MI) area on quantitative perfusion single-photon emission computed tomography (QPS; Cedars-Sinai Medical Center, USA) with that on high-resolution autoradiography in rat model to determine the accuracy of perfusion defect measurement by QPS.

PROCEDURES

After thoracotomy, rats (n = 9) had their left coronary arteries occluded and reperfused before injection with 185 MBq [^99mTc] methoxyisobutylisonitrile ([^99mTc]MIBI) for SPECT and autoradiography. Healthy rats (n = 28) were similarly scanned to create a normal database on which to base QPS. The MI area on SPECT images was analysed automatically by QPS software. For the autoradiography images, regions of interest for MI were set at 1 mm intervals.

RESULTS

In normal rats, [^99mTc]MIBI accumulated throughout the left ventricles, and a polar map of ventricular perfusion showed the lowest and highest uptakes in the inferior (68 % ± 4 %) and anterior (92 % ± 5 %) walls, respectively. In the rat MI model, the percentage of polar map with reduced [^99mTc]MIBI uptake correlated strongly with the percentage of left ventricle with MI on autoradiography (r² = 0.90).

CONCLUSIONS

QPS can quantitatively evaluate MI severity on myocardial perfusion images in rats, with comparable results to autoradiography. This widely available software could promote the development of new techniques for analysing cardiac images in small animals.

Deposition of a titania layer on spherical porous silica particles and their nanostructure-induced vapor sensing properties

A titania-stearic acid hybrid layer was deposited onto well-defined silica-hexadecyltrimethylammonium hybrid spherical particles with 854 nm size to obtain nanoporous particles with a useful hierarchical core-shell structure. The deposition of a 35 nm-thick titania layer was confirmed by transmission electron microscopy. The core-shell particles were washed with acidic ethanol (solvent extraction) and calcined at 550 °C for 5 h to remove the template, resulting in the formation of nanoporous titania coated nanoporous silica spherical particles, which have a bimodal pore size distribution attributed to the hierarchical porous core and porous shell structure. The nanoporous titania coated particles exhibited an unusual crystal phase transition; only anatase was present even after the calcination at 1000 °C for 1 h. This would be due to the interfacial bonding between the core silica and the shell titania, preventing the crystal phase transition from anatase to rutile. On the other hand, the direct calcination of the titania-stearic acid coated particles without solvent extraction led to a shell composed of both anatase and rutile. The transformation to rutile could be caused by the strong exothermic reaction during the oxidative decomposition of the occluded stearic acid. Furthermore, the intense exothermic reaction induced the formation of a yolk-shell structure, which played a role in the sensitive/selective sensing properties for acetic acid when the yolk-shell particles were coated onto a nanomechanical Membrane-type Surface stress Sensor (MSS).

Synthesis and evaluation of radioiodinated 1-{2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinolin-8-yl}piperidin-4-amine derivatives for platelet-derived growth factor receptor β (PDGFRβ) imaging

Platelet-derived growth factor receptor β (PDGFRβ) is a transmembrane tyrosine kinase receptor and it is upregulated in various malignant tumors. Radiolabeled PDGFRβ inhibitors can be a convenient tool for the imaging of tumors overexpressing PDGFRβ. In this study, [¹²⁵I]-1-{5-iodo-2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinoline-8-yl}piperidin-4-amine ([¹²⁵I]IIQP) and [¹²⁵I]-N-3-iodobenzoyl-1-{2-[5-(2-methoxyethoxy)-1H-benzo[d]imidazol-1-yl]quinolin-8-yl}-piperidin-4-amine ([¹²⁵I]IB-IQP) were designed and synthesized, and their potential as PDGFRβ imaging agents was evaluated. In cellular uptake experiments, [¹²⁵I]IIQP and [¹²⁵I]IB-IQP showed higher uptake by PDGFRβ-positive cells than by PDGFRβ-negative cells, and the uptake in PDGFRβ-positive cells was inhibited by co-culture with PDGFRβ ligands. The biodistribution of both radiotracers in normal mice exhibited hepatobiliary excretion as the main route. In mice inoculated with BxPC3-luc (PDGFRβ-positive), the tumor uptake of radioactivity at 1h after the injection of [¹²⁵I]IIQP was significantly higher than that after the injection of [¹²⁵I]IB-IQP. These results indicated that [¹²⁵I]IIQP can be a suitable PDGFRβ imaging agent. However, further modification of its structure will be required to obtain a more appropriate PDGFRβ-targeted imaging agent with a higher signal/noise ratio.

Hybrid preparation of terbium(iii)-doped mesoporous silica particles with calcium phosphates

Terbium-doped mesoporous silica/calcium phosphate interfacial hybrid particles were prepared to demonstrate characteristic luminescence behavior.

Controlled growth of silica-titania hybrid functional nanoparticles through a multistep microfluidic approach

Silica/titania-based functional nanoparticles were prepared through controlled nucleation of titania and subsequent encapsulation by silica through a multistep microfluidic approach, which was successfully applied to obtaining aminopropyl-functionalized silica/titania nanoparticles for a highly sensitive humidity sensor.

Evaluation of Chlorella as a Decorporation Agent to Enhance the Elimination of Radioactive Strontium from Body

Background

Release of radionuclides, such as ¹³⁷Cs and ⁹⁰Sr, into the atmosphere and the ocean presents an important problem because internal exposure to ¹³⁷Cs and ⁹⁰Sr could be very harmful to humans. Chlorella has been reported to be effective in enhancing the excretion of heavy metals; thus, we hypothesized that Chlorella could also enhance the elimination of ¹³⁷Cs or ⁹⁰Sr from the body. We evaluated the potential of Chlorella as a decorporation agent in vitro and in vivo, using ⁸⁵Sr instead of ⁹⁰Sr.

Methods

In vitro experiments of adsorption of ¹³⁷Cs and ⁸⁵Sr to Chlorella were performed under wide pH conditions. The maximum sorption capacity of Chlorella to strontium was estimated using the Langmuir model. A ⁸⁵Sr solution was orally administrated to mice pretreated with Chlorella. At 48 h after ⁸⁵Sr administration, the biodistribution of radioactivity was determined.

Results

In the in vitro experiments, although ⁸⁵Sr barely adsorbed to Chlorella at low pH, the ⁸⁵Sr adsorption ratio to Chlorella increased with increasing pH. The maximum sorption capacity of Chlorella to strontium was 9.06 mg / g. ¹³⁷Cs barely adsorbed to Chlorella under any pH conditions. In the biodistribution experiments, bone accumulation of radioactivity after ⁸⁵Sr administration was significantly decreased in the Chlorella pretreatment group compared with the non-treatment control group.

Conclusions

In conclusion, these results indicated that Chlorella could inhibit the absorption of ⁹⁰Sr into the blood and enhance the elimination of ⁹⁰Sr from the body through adsorption in intestine. Further studies are required to elucidate the mechanism and the components of Chlorella needed for adsorption to strontium and could promote the development of more effective decorporation agents.

In Vivo Differences between Two Optical Isomers of Radioiodinated o-iodo-trans-decalinvesamicol for Use as a Radioligand for the Vesicular Acetylcholine Transporter

PURPOSE

To develop a superior VAChT imaging probe for SPECT, radiolabeled (-)-OIDV and (+)-OIDV were isolated and investigated for differences in their binding affinity and selectivity to VAChT, as well as their in vivo activities.

PROCEDURES

Radioiodinated o-iodo-trans-decalinvesamicol ([125I]OIDV) has a high binding affinity for vesicular acetylcholine transporter (VAChT) both in vitro and in vivo. Racemic [125I]OIDV was separated into its two optical isomers (-)-[125I]OIDV and (+)-[125I]OIDV by HPLC. To investigate VAChT binding affinity (Ki) of two OIDV isomers, in vitro binding assays were performed. In vivo biodistribution study of each [125I]OIDV isomer in blood, brain regions and major organs of rats was performed at 2,30 and 60 min post-injection. In vivo blocking study were performed to reveal the binding selectivity of two [125I]OIDV isomers to VAChT in vivo. Ex vivo autoradiography were performed to reveal the regional brain distribution of two [125I]OIDV isomers and (-)-[123I]OIDV for SPECT at 60 min postinjection.

RESULTS

VAChT binding affinity (Ki) of (-)-[125I]OIDV and (+)-[125I]OIDV was 22.1 nM and 79.0 nM, respectively. At 2 min post-injection, accumulation of (-)-[125I]OIDV was the same as that of (+)-[125I]OIDV. However, (+)-[125I]OIDV clearance from the brain was faster than (-)-[125I]OIDV. At 30 min post-injection, accumulation of (-)-[125I]OIDV (0.62 ± 0.10%ID/g) was higher than (+)-[125I]OIDV (0.46 ± 0.07%ID/g) in the cortex. Inhibition of OIDV binding showed that (-)-[125I]OIDV was selectively accumulated in regions known to express VAChT in the rat brain, and ex vivo autoradiography further confirmed these results showing similar accumulation of (-)-[125I]OIDV in these regions. Furthermore, (-)-[123I]OIDV for SPECT showed the same regional brain distribution as (-)-[125I]OIDV.

CONCLUSION

These results suggest that radioiodinated (-)-OIDV may be a potentially useful tool for studying presynaptic cholinergic neurons in the brain.

Simultaneous acquisition of (99m)Tc- and (123)I-labeled radiotracers using a preclinical SPECT scanner with CZT detectors

OBJECTIVE

Simultaneous acquisition of (99m)Tc and (123)I was evaluated using a preclinical SPECT scanner with cadmium zinc telluride (CZT)-based detectors.

METHODS

10-ml cylindrical syringes contained about 37 MBq (99m)Tc-tetrofosmin ((99m)Tc-TF) or 37 MBq (123)I-15-(p-iodophenyl)-3R,S-methyl pentadecanoic acid ((123)I-BMIPP) were used to assess the relationship between these SPECT radioactive counts and radioactivity. Two 10-ml syringes contained 100 or 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP to assess the influence of (99m)Tc upscatter and (123)I downscatter, respectively. A rat-sized cylindrical phantom also contained both 100 or 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP. The two 10-ml syringes and phantom were scanned using a pinhole collimator for rats. Myocardial infarction model rats were examined using 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP. Two 1-ml syringes contained 105 MBq (99m)Tc-labeled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) and 35 MBq (123)I-labeled N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane ((123)I-FP-CIT). The two 1-ml syringes were scanned using a pinhole collimator for mice. Normal mice were examined using 105 MBq (99m)Tc-HMPAO and 35 MBq (123)I-FP-CIT.

RESULTS

The relationship between SPECT radioactive counts and radioactivity was excellent. Downscatter contamination of (123)I-BMIPP exhibited fewer radioactive counts for 300 MBq (99m)Tc-TF without scatter correction (SC) in 125-150 keV. There was no upscatter contamination of (99m)Tc-TF in 150-175 keV. In the rat-sized phantom, the radioactive count ratio decreased to 4.0 % for 300 MBq (99m)Tc-TF without SC in 125-150 keV. In the rats, myocardial images and radioactive counts of (99m)Tc-TF with the dual tracer were identical to those of the (99m)Tc-TF single injection. Downscatter contamination of (123)I-FP-CIT was 4.2 % without SC in 125-150 keV. In the first injection of (99m)Tc-HMPAO and second injection of (123)I-FP-CIT, brain images and radioactive counts of (99m)Tc-HMPAO with the dual tracer in normal mice also were the similar to those of the (99m)Tc-HMPAO single injection. In the first injection of (123)I-FP-CIT and second injection of (99m)Tc-HMPAO, the brain images and radioactive counts with the dual tracer were not much different from those of the (123)I-FP-CIT single injection.

CONCLUSIONS

Dual-tracer imaging of (99m)Tc- and (123)I-labeled radiotracers is feasible in a preclinical SPECT scanner with CZT detector. When higher radioactivity of (99m)Tc-labeled radiotracers relative to (123)I-labeled radiotracers is applied, correction methods are not necessarily required for the quantification of (99m)Tc- and (123)I-labeled radiotracers when using a preclinical SPECT scanner with CZT detector.

Correlation between apoptosis and left ventricular remodeling in subacute phase of myocardial ischemia and reperfusion

Background

To investigate whether an apoptotic process demonstrated by ^99mTc-annexin-V (^99mTc-AV) uptake correlates with left ventricular remodeling (LVR) after myocardial infarction, we assessed ^99mTc-AV uptake in rat model of myocardial ischemia and reperfusion.

Methods

The left coronary artery (LCA) of 15 rats was occluded for 20 to 30 min, followed by reperfusion. After 2 weeks, ^99mTc-AV was injected, and then 1 h later, ²⁰¹Tl was injected after reocclusion of the LCA. Dual-tracer autoradiography was performed to assess ^99mTc-AV uptake and the area at risk (AAR) by ²⁰¹Tl defect. ^99mTc-AV uptake ratio was calculated by dividing the count density of the AAR by that of the normally perfused area. In short-axis LV slices, LV cavity dilation index (DI) was calculated by dividing the area of LV cavity by that of the whole LV area. LV wall-thinning ratio (WTR) was calculated by dividing the LV wall thickness in the AAR by that of the normally perfused area.

Results

Significant ^99mTc-AV uptake in the AAR was observed in 10 rats. DI was significantly higher in rats with positive ^99mTc-AV uptake than in rats without uptake. WTR was smaller in rats with positive ^99mTc-AV uptake than in rats without uptake.

Conclusions

The data suggest ^99mTc-AV uptake in injured myocardium might correlate with LVR at 2 weeks after myocardial ischemia and reperfusion.

Synthesis and evaluation of a new vesamicol analog o-[(11)C]methyl-trans-decalinvesamicol as a PET ligand for the vesicular acetylcholine transporter

INTRODUCTION

We focused on the vesicle acetyl choline transporter (VAChT) as target for early diagnosis of Alzheimer's diseases because the dysfunction of the cholinergic nervous system is closely associated with the symptoms of AD, such as problem in recognition, memory, and learning. Due to its low binding affinity for the sigma receptors (σ-1 and σ-2), o-methyl-trans-decalinvesamicol (OMDV) demonstrated a high binding affinity and selectivity for vesicular acetyl choline transporter (VAChT). [(11)C]OMDV was prepared and investigated the potential as a new PET ligand for VAChT imaging through in vivo evaluation.

METHOD

[(11)C]OMDV was prepared by a palladium-promoted cross-coupling reaction using [(11)C]methyl iodide, with a radiochemical yield of 60-75%, a radiochemical purity of greater than 98%, and a specific activity of 5-10 TBq/mmol 30 min after EOB. In vivo biodistribution study of [(11)C]OMDV in blood, brain regions and major organs of rats was performed at 2, 10, 30 and 60 min post-injection. In vivo blocking study and PET-CT imaging study were performed to check the binding selectivity of [(11)C]OMDV for VAChT.

RESULTS

In vivo studies demonstrated [(11)C]OMDV passage through the blood-brain barrier (BBB) and accumulation in the rat brain. The regional brain accumulation of [(11)C]OMDV was significantly inhibited by co-administration of vesamicol. In contrast, brain accumulation of [(11)C]OMDV was not significantly altered by co-administration of (+)-pentazocine, a selective σ-1 receptor ligand, or (+)-3-(3-hydroxyphenyl)-N-propylpiperidine [(+)-3-PPP], a σ-1 and σ-2 receptor ligand. PET-CT imaging revealed inhibition of [(11)C]OMDV accumulation in the brain by co-administration of vesamicol.

CONCLUSION

[(11)C]OMDV selectively binds to VAChT with high affinity in the rat brain in vivo, and that [(11)C]OMDV may be utilized in the future as a specific VAChT ligand for PET imaging.

Preparation and evaluation of an astatine-211-labeled sigma receptor ligand for alpha radionuclide therapy

INTRODUCTION

Sigma receptors are overexpressed in a variety of human tumors, making them potential targets for radionuclide receptor therapy. We have previously synthesized and evaluated (131)I-labeled (+)-2-[4-(4-iodophenyl)piperidino]cyclohexanol [(+)-[(131)I]pIV], which has a high affinity for sigma receptors. Therefore, (+)-[(131)I]pIV significantly inhibited tumor cell proliferation in tumor-bearing mice. In the present study, we report the synthesis and the in vitro and in vivo characterization of (+)-[(211)At]pAtV, an (211)At-labeled sigma receptor ligand, that has potential use in alpha-radionuclide receptor therapy.

METHODS

The radiolabeled sigma receptor ligand (+)-[(211)At]pAtV was prepared using a standard halogenation reaction generating a 91% radiochemical yield with 98% purity after HPLC purification. The partition coefficient of (+)-[(211)At]pAtV was measured. Cellular uptake experiments and in vivo biodistribution experiments were performed using a mixed solution of (+)-[(211)At]pAtV and (+)-[(125)I]pIV; the human prostate cancer cell line DU-145, which expresses high levels of the sigma receptors, and DU-145 tumor-bearing mice.

RESULTS

The lipophilicity of (+)-[(211)At]pAtV was similar to that of (+)-[(125)I]pIV. DU-145 cellular uptake and the biodistribution patterns in DU-145 tumor-bearing mice at 1h post-injection were also similar between (+)-[(211)At]pAtV and (+)-[(125)I]pIV. Namely, (+)-[(211)At]pAtV demonstrated high uptake and retention in tumor via binding to sigma receptors.

CONCLUSION

These results indicate that (+)-[(211)At]pAtV could function as an new agent for alpha-radionuclide receptor therapy.

Radiogallium Complex-Conjugated Bifunctional Peptides for Detecting Primary Cancer and Bone Metastases Simultaneously

(68)Ga (T(1/2) = 68 min, a generator-produced nuclide) is an interesting radionuclide for clinical positron emission tomography (PET). Recently, it was reported that radiogallium-labeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-conjugated (Asp)n peptide [Ga-DOTA-(Asp)n] has great potential for bone metastases imaging. In the current study, a compound containing an aspartic acid peptide linker (D11) as a carrier to bone metastases, an RGD peptide [c(RGDfK) peptide] as a carrier to the primary cancer, and Ga-DOTA as a stable radiometal complex for imaging in one molecule, Ga-DOTA-D11-c(RGDfK), was designed, prepared, and evaluated to detect both the primary cancer and bone metastases simultaneously using (67)Ga, which is easy to handle. After DOTA-D11-c(RGDfK) was synthesized using Fmoc-based solid-phase methodology, (67)Ga-DOTA-D11-c(RGDfK) was prepared by complexing DOTA-D11-c(RGDfK) with (67)Ga. Hydroxyapatite binding assays, integrin binding assays, biodistribution experiments, and single photon emission tomography (SPECT) imaging using tumor-bearing mice were performed using (67)Ga-DOTA-D11-c(RGDfK). (67)Ga-DOTA-D11-c(RGDfK) was prepared with a radiochemical purity of >97%. In vitro, (67)Ga-DOTA-D11-c(RGDfK) had a high affinity for hydroxyapatite and αvβ3 integrin. In vivo, (67)Ga-DOTA-D11-c(RGDfK) exhibited high uptake in bone and tumor. The accumulation of (67)Ga-DOTA-D11-c(RGDfK) in tumor decreased when it was co-injected with c(RGDfK) peptide. (68)Ga-DOTA-D11-c(RGDfK) has great potential as a PET tracer for the diagnosis of both the primary cancer and bone metastases simultaneously.

Effect of postconditioning on dynamic expression of tenascin-C and left ventricular remodeling after myocardial ischemia and reperfusion

Background

Tenascin-C (TNC), an extracellular matrix glycoprotein, is expressed transiently in distinct areas in association with active tissue remodeling. This study aimed to explore how ischemic postconditioning (PC) affects myocardial expression of TNC and ventricular remodeling using ¹²⁵I-labeled anti-TNC antibody (¹²⁵I-TNC-Ab) in a rat model of ischemia and reperfusion.

Methods

In control rats (n = 27), the left coronary artery (LCA) was occluded for 30 min followed by reperfusion for 1, 3, 7, and 14 days. PC (n = 27) was performed just after the reperfusion. At the time of the study, ¹²⁵I-TNC-Ab (1.0 to 2.5 MBq) was injected. Six to 9 h later, to verify the area at risk, ^99mTc-MIBI (100 to 200 MBq) was injected intravenously just after the LCA reocclusion, with the rats sacrificed 1 min later. Dual tracer autoradiography was performed to assess ¹²⁵I-TNC-Ab uptake and area at risk. To examine the ventricular remodeling, echocardiography was performed 2 M after reperfusion in both groups.

Results

In control rats, ¹²⁵I-TNC-Ab uptake ratio at 1 day after reperfusion was 3.73 ± 0.71 and increased at 3 days (4.65 ± 0.87), followed by a significant reduction at 7 days (2.91 ± 0.55, P < 0.005 vs 3 days) and14 days (2.01 ± 0.17, P < 0.005 vs 1 and 3 days). PC attenuated the ¹²⁵I-TNC-Ab uptake throughout the reperfusion time from 1 to 14 days; 2.59 ± 0.59 at 1 day, P < 0.05: 3.10 ± 0.42 at 3 days, P < 0.005: 1.93 ± 0.37 at 7 days, P < 0.05: 1.40 ± 0.07 at 14 days, P < 0.001. In echocardiography, PC reduced the ventricular end-diastolic and systolic dimensions (1.00 ± 0.06 cm to 0.83 ± 0.14 cm (P < 0.05) and 0.90 ± 0.15 cm to 0.62 ± 0.19 cm (P < 0.05), respectively) and prevented a decline of ventricular percentage fractional shortening (10.5 ± 3.7 to 28.2 ± 10.7, P < 0.005).

Conclusions

These data indicate that ¹²⁵I-TNC-Ab imaging may be a way to monitor myocardial injury, the subsequent repair process, and its response to novel therapeutic interventions like PC by visualizing TNC expression.

Preparation of luminescent titania/dye hybrid nanoparticles and their dissolution properties for controlling cellular environments

Monodispersed titania/octadecylamine/fluorescein-isothiocyanate hybrid nanoparticles are synthesized to demonstrate a proof-of-concept for nanomedicines: an indirect molecular delivery system with no cytotoxicity.

Anxiety- and depression-like behavior in mice lacking the CD157/BST1 gene, a risk factor for Parkinson's disease

CD157, known as bone marrow stromal cell antigen-1, is a glycosylphosphatidylinositol-anchored ADP-ribosyl cyclase that supports the survival and function of B-lymphocytes and hematopoietic or intestinal stem cells. Although CD157/Bst1 is a risk locus in Parkinson's disease (PD), little is known about the function of CD157 in the nervous system and contribution to PD progression. Here, we show that no apparent motor dysfunction was observed in young knockout (CD157 (-/-)) male mice under less aging-related effects on behaviors. CD157 (-/-) mice exhibited anxiety-related and depression-like behaviors compared with wild-type mice. These behaviors were rescued through treatment with anti-psychiatric drugs and oxytocin. CD157 was weakly expressed in the amygdala and c-Fos immunoreactivity in the amygdala was less evident in CD157 (-/-) mice than in wild-type mice. These results demonstrate for the first time that CD157 plays a role as a neuro-regulator and suggest a potential role in pre-motor symptoms in PD.

Regional brain imaging of vesicular acetylcholine transporter using o-[125 I]iodo-trans-decalinvesamicol as a new potential imaging probe

In this study, the regional rat brain distribution of radioiodinated o-iodo-trans-decalinvesamicol ([(125) I]OIDV) was determined in vivo to evaluate its potential as a single-photon emission computed tomography (SPECT) imaging probe for vesicular acetylcholine transporter (VAChT). Following intravenous injection, [(125) I]OIDV passed freely across the blood-brain barrier and accumulated in rat brain. The accumulation of [(125) I]OIDV in rat brain was significantly reduced by coadministration of (+/-)-vesamicol (0.125 µmol). In contrast, the coadministration of σ-receptor ligands, such as (+)-pentazocine (0.125 µmol) as a σ-1 receptor ligand and (+)-3-(3-hydroxyphenyl)-N-propylpiperidine (0.125 µmol) as a σ-1 and σ-2 receptor ligands, barely affected the accumulation of [(125) I]OIDV in rat brain. These findings in vivo were corroborated by autoradiographic analysis ex vivo. The authors found that the tracer binds with pharmacological selectivity to VAChT in rat brain and predicted that it may likewise serve in translational SPECT imaging studies of this marker in the integrity of cholinergic innervations.

Development and evaluation of a novel (99m)tc-labeled annexin A5 for early detection of response to chemotherapy

^99mTc-HYNIC-annexin A5 can be considered as a benchmark in the field of apoptosis imaging. However, ^99mTc-HYNIC-annexin A5 has characteristics of high uptake and long retention in non-target tissues such as kidney and liver. To minimize this problem, we developed a novel ^99mTc-labeled annexin A5 using a bis(hydroxamamide) derivative [C₃(BHam)₂] as a bifunctional chelating agent, and evaluated its usefulness as an imaging agent for detecting apoptosis. The amino group of C₃(BHam)₂ was converted to a maleimide group, and was coupled to thiol groups of annexin A5 pretreated with 2-iminothiolane. ^99mTc labeling was performed by a ligand exchange reaction with ^99mTc-glucoheptonate. Biodistribution experiments for both ^99mTc-C₃(BHam)₂-annexin A5 and ^99mTc-HYNIC-annexin A5 were performed in normal mice. In addition, in tumor-bearing mice, the relationship between the therapeutic effects of chemotherapy (5-FU) and the tumor accumulation of ^99mTc-C₃(BHam)₂-annexin A5 just after the first treatment of 5-FU was evaluated. ^99mTc-C₃(BHam)₂-annexin A5 was prepared with a radiochemical purity of over 95%. In biodistribution experiments, ^99mTc-C₃(BHam)₂-annexin A5 had a much lower kidney accumulation of radioactivity than ^99mTc-HYNIC-annexin A5. In the organs for metabolism, such as liver and kidney, radioactivity after the injection of ^99mTc-HYNIC-annexin A5 was residual for a long time. On the other hand, radioactivity after the injection of ^99mTc-C₃(BHam)₂-annexin A5 gradually decreased. In therapeutic experiments, tumor growth in the mice treated with 5-FU was significantly inhibited. Accumulation of ^99mTc-C₃(BHam)₂-annexin A5 in tumors significantly increased after 5-FU treatment. The accumulation of radioactivity in tumor correlated positively with the counts of TUNEL-positive cells. These findings suggest that ^99mTc-C₃(BHam)₂-annexin A5 may contribute to the efficient detection of apoptotic tumor response after chemotherapy.