Comparison of PET tracing and biodistribution between 64Cu-labeled micro-and nano-polystyrene in a murine inhalation model

INTRODUCTION

Recent studies showed the presence of microplastic in human lungs. There remains an unmet need to identify the biodistribution of microplastic after inhalation. In this study, we traced the biodistribution of inhaled micro-sized polystyrene (mPS) and/or nano-sized PS (nPS) using 64Cu with PET in mice.

METHODS

We used 0.2-0.3-µm sized mPS and 20-nm sized nPS throughout. 64Cu-DOTA-mPS, 64Cu-DOTA-nPS and/or 64CuCl2 were used to trace the distribution in the murine inhalation model. PET images were acquired using an INVEON PET scanner at 1, 12, 24, 48, and 72 h after intratracheal instillation, and the SUVmax for interesting organs were determined, biodistribution was then determined in terms of percentage injected dose/gram of tissue (%ID/g). Ex vivo tissue-radio thin-layer chromatography (Ex vivo-radioTLC) was used to demonstrate the existence of 64Cu-DOTA-PS in tissue.

RESULTS

PET image demonstrated that the amount of 64Cu-DOTA-mPS retained within the lung was significantly higher than 64Cu-DOTA-nPS until 72 h; SUVmax values of 64Cu-DOTA-mPS in lungs was 11.7 ± 5.0, 48.3 ± 6.2, 65.5 ± 2.3, 42.2 ± 13.1, and 13.2 ± 2.3 at 1, 12, 24, 48, and 72 h respectively whereas it was 31.2 ± 3.1, 17.3 ± 5.9, 10.0 ± 3.4, 8.1 ± 2.4 and 8.9 ± 3.6 for 64Cu-DOTA-nPS at the corresponding timepoints. The biodistribution data supported the PET data with a similar pattern of clearance of the radioactivity from the lung. nPS cleared rapidly post instillation in comparison to mPS within the lungs. Higher accumulation of %ID/g for nPS (roughly 2 times) were observed compared to mPS in spleen, liver, intestine, thymus, kidney, brain, salivary gland, ovary, and urinary bladder. Ex vivo-radioTLC was used to demonstrate that the detected gamma rays originated from 64Cu-DOTA-mPS or nPS.

CONCLUSION

PET image demonstrated the differences in accumulations of mPS and/or nPS between lungs and other interesting organs. The information provided may be used as the basis for future studies on the toxicity of mPS and/or nPS.

Porphyrin-Based Brain Tumor-Targeting Agents: [64Cu]Cu-porphyrin and [64Cu]Cu-TDAP

The aim of this study is to evaluate a radioactive metal complex platform for brain tumor targeting. Herein, we introduce a new porphyrin derivative, 5,10,15,20-(tetra-N,N-dimethyl-4-aminophenyl)porphyrin (TDAP), in which four N,N-dimethyl-4-p-phenylenediamine (DMPD) moieties are conjugated to the porphyrin labeled with the radiometal 64Cu. DMPD affected the pharmacokinetics of porphyrin in terms of retention time in vivo and tumor-targeting ability relative to those of unmodified porphyrin. [64Cu]Cu-TDAP showed stronger enhancement than [64Cu]Cu-porphyrin in U87MG glioblastoma cells, especially in the cytoplasm and nucleus, indicating its tumor-targeting properties and potential use as a therapeutic agent. In the subcutaneous and orthotopic models of brain-tumor-bearing mice, [64Cu]Cu-TDAP was clearly visualized in the tumor site via positron emission tomography imaging and showed a tumor-to-brain ratio as high as 13. [64Cu]Cu-TDAP deserves attention as a new diagnostic agent that is suitable for the early diagnosis and treatment of brain tumors.

PET tracing of biodistribution for orally administered 64Cu-labeled polystyrene in mice

Plastics are used commonly in the world because of their convenience and cost effectiveness. Microplastics, an environmental threat and human health risk, are widely detected in food and consequently ingested. However, degraded plastics are found everywhere, creating an environmental threat and human health risk. Therefore, real-time monitoring of orally administered microplastics to trace them in the body is tremendously important. Methods: In this study, to visualize their absorption path, we labeled polystyrene with [⁶⁴Cu]Cu-DOTA. We prepared radiolabeled polystyrene with ⁶⁴Cu. Afterward, [⁶⁴Cu]Cu-DOTA-polystyrene was orally administered to mice, and we evaluated its transit and absorption using PET imaging. The absorption path and distribution of [⁶⁴Cu]Cu-DOTA-polystyrene were determined using PET over 48 h. Ex vivo tissue radio–thin-layer chromatography (TLC) was used to demonstrate the existence of [⁶⁴Cu]Cu-DOTA-polystyrene in tissue. Results: PET images demonstrated that [⁶⁴Cu]Cu-DOTA-polystyrene began to transit to the intestine within 1 h. Accumulation of [⁶⁴Cu]Cu-DOTA-polystyrene in the liver was also observed. The biodistribution of [⁶⁴Cu]Cu-DOTA-polystyrene confirmed the distribution of [⁶⁴Cu]Cu-DOTA-polystyrene observed on the PET images. Ex vivo radio-TLC demonstrated that the detected γ-rays originated from [⁶⁴Cu]Cu-DOTA-polystyrene. Conclusion: This study provided PET evidence of the existence and accumulation of microplastics in tissue and cross-confirmed the PET findings by ex vivo radio-TLC. This information may be used as the basis for future studies on the toxicity of microplastics.

Phase transition behavior of silicone based liquid crystalline polymers

Phase transition behavior of silicone based liquid crystalline (LC) polymers with variable isotropic transition temperatures (Ti), synthesized from poly(methyl hydrosiloxane), 10-undecenoic acid based crosslinking agent and cholesterol based side chain mesogen, was studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD) measurements. The chemical structure of the mesogenic monomer and the LC polymers were confirmed by Fourier transform infra-red (FT-IR) spectroscopy and 1HNMR spectroscopy. DSC studies showed that the glass transition temperatures (Tg) and Ti of the LC polymers decreased with increasing proportion of mesogenic crosslinking agent at its low proportion and at its higher proportion Ti disappeared completely indicating that the polymeric chains had less chance to orient in the network structure. The results were consistent with the XRD and POM studies.

(1)H-NMR and NOE studies of 2-cephems and 3-cephems

The(1)H-NMR signals of 2-cephems and 3-cephems have been assigned and the Nuclear Overhauser Effect (NOE) study of these compounds was undertaken.

Clinical outcomes of adjuvant treatments for invasive thymoma: Dose chemotherapy influence prognosis?

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Background: The aim of this study was to evaluate therapeutic outcomes and to validate prognostic factors, including adjuvant chemotherapy, in resected thymoma patients who received adjuvant treatment. Methods: One hundred thymoma patients who received post-surgical adjuvant therapy from 1995 to 2005 were retrospectively reviewed. 55 patients received only radiotherapy for the adjuvant therapy, while 45 patients received both radiotherapy and chemotherapy. The total radiation dose was 45–63 Gy, with a median dose of 50.4 Gy. The chemotherapy consisted of 6 cycles of doxorubicin, cisplatin, vincristine, and cyclophosphamide. Treatments were applied every 3–4 weeks. The median follow-up duration was 65 months (range, 5–200 months). Results: The 5-year overall survival (OS) and disease- free survival (DFS) rates were 75.7% (89.2% in stage II, 67.9% in stage III, and 52.1% in stage IVA) and 70.3% (83% in stage II, 62.4% in stage III, and 33.6% in stage IVA) respectively. According to multivariate analysis, the prognostic factors for OS were age, WHO histology, Masaoka stage, and recurrence, while pleural involvement and WHO histology had statistically significant impacts on DFS. Higher radiation dosage, positive resection margins, and adjuvant chemotherapy did not influence survival outcomes. The most common relapse site was the pleura (15 patients, 53.6%). The toxicity from chemotherapy and radiotherapy was manageable, with no deaths due to toxicity. Conclusion: The prognosis of invasive thymoma was poor despite adjuvant treatments with radiotherapy and chemotherapy. In addition to WHO histology, pleural involvement was the most important prognostic factor for recurrence. The pleura was the most common relapse site. Therefore, new modalities to reduce pleural recurrence are warranted.

No significant financial relationships to disclose.

A phase II study of erlotinib treatment in advanced non-small cell lung cancer after failure of gefitinib: Is a clinical benefit still achievable?

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Background: To evaluate the efficacy and toxicity of erlotinib in patients (pts) with advanced NSCLC who had progression after treatment with gefitinib. Methods: The study included stage IIIB/IV recurrent or metastatic NSCLC pts who have received 2 or 3 prior chemotherapy regimens and showed documented disease progression during or within 4 months after treatment with gefitinib. Pts received erlotinib 150 mg daily until disease progression or unacceptable toxicity. We analyzed EGFR mutations and other genetic abnormality from available tumor samples. Results: Pts and disease characteristics (n = 21) included median age 56 years; number of prior chemotherapy regimens (two, n=10; three, n=11); male (n=10); adenocarcinoma (n=15); and smoking status (never, n=11; former, n=3; current, n=7). Among the 17 pts with tumor samples available, EGFR mutation were detected in 5 (29.4 %). The DCR and RR for all pts were 28.6% (95% CI, 16.7 to 59.6%) and 9.5% (95% CI, 5.6 to 19.8%). All responders were EGFR nonmutants, with long duration of disease control on prior gefitinib therapy (>180 days). The median duration of disease control was 125 days (95% CI, 73–261 days). The median progression-free survival and overall survival were 60 days (95% CI, 43–77 days) and 158 days (95% CI, 141–175 days), respectively. Pts who had SD on gefitinib showed significantly higher DCR (75% vs. 17.6% in non-SD pts, P= 0.050) and RR (50.0% vs. 0% in non-SD pts, P= 0.029). These pts also showed longer median PFS (140 vs. 37 days in non-SD pts, P= 0.005) and OS (not reached vs. 120 days in non-SD pts, P= 0.043). Among 17 pts with biomarker results available, EGFR nonmutants who had SD on gefitinib showed significantly higher DCR (100% vs. 21.4% in non-SD and/or EGFR mutants, P= 0.029) and RR (RR, 66.7 % vs. 0 % in non-SD and/or EGFR mutants, P= 0.022). Conclusions: Erlotinib seems to be a potential therapeutic option for the treatment of selected pts with gefitinib-nonresponsive, EGFR nonmutant, advanced NSCLC.

No significant financial relationships to disclose.

[Table: see text]

Synthesis of 6-exomethylenepenams as beta-lactamase inhibitors

The 6,6-dibromopenam (6) was treated with CH3MgBr and carbaldehyde 5 to afford the hydroxy compound 7, which was reacted with acetic anhydride to give acetoxy compound 8. The deacetobromination of 8 with zinc and acetic acid gave 6-exomethylenepenams, E-isomer 10 and Z-isomer 9, which was oxidized to sulfone 11 by m-CPBA. The p-methoxybenzyl compounds were deprotected by AlCl3 and neutralized to give the sodium salts 12, 13 and 14.

Detection of a dup(17q) and inv(16) by fluorescence in situ hybridization in acute myelomonocytic leukemia

Two cases of acute myelomonocytic leukemia (AMMoL) of FAB type M4Eo are described in which a primary subclone containing a dup(17)(q21q25) and a subclone containing dup(17)(q21q25), inv(16)(p13q22) were seen in one patient, and -7, dup(17)(q21q25) in another. Fluorescence in situ hybridization (FISH) was carried out for the confirmation of the duplicated segment and breakpoint of inv(16). Inv(16) is a well known anomaly in AMMoL, whereas dup(17q) is rare though as not yet confirmed, this anomaly could be a nonrandom or novel change in AMMoL.

Synthesis and beta-lactamase inhibitory activity of 6-[(1-heteroarylthioethyl-1,2,3-triazol-4-yl)-methylene]penam sulfones

The synthesis of beta-lactamase inhibitory activity of a series of sodium 6-[(1-heteroarylthioethyl-1,2,3-triazol-4-yl)methylene]pe nicillanate, 1,1-dioxides are described. Their activity was compared with tazobactam and sulbactam. The Z-isomers were more active than the E-isomers. The in vitro activity of the Z-isomers of the phenylthiadiazole derivatives (13a and 15a) was better than sulbactam against the tested beta-lactamases and comparable to tazobactam especially against TEM-2 and cephalosporinase. But their synergistic activity with five antibiotics was inferior to tazobactam.

Synthesis and cytotoxic activity of (E)-1-(2-nitrovinyl) and 1-[N-(tert-butylformiminyl)]-substituted 1,4-dihydropyridines and 2-pyridones

1-(2-Nitrovinyl) derivatives of nuclear substituted 1,4-dihydropyridines (7a-c), and 1-(N-tert-butyl-formiminyl) derivatives of 1,4-dihydropyridines (9a-c) or 2-pyridones (11a-c) were synthesized for evaluation as cytotoxic agents (see Table I for structures). The in vitro cytotoxic activities, determined in the L1210 assay, indicated that the 4-substituent on a 1,4-dihydropyridine ring system was a determinant of activity in both the 1-(2-nitrovinyl) (7) and 1-(N-tert-butylformiminyl) (9) series, the relative activity order being n-Bu > Ph > Me. In the 1-(N-tert-butylformiminyl) series, the 1,4-dihydropyridine derivatives (9) were generally more cytotoxic than the 2-pyridone derivatives (11). The most active compound was 1-(N-tert-butylformiminyl)-3-(4,4-dimethyloxazolin-2-yl)-4-n -butyl-1,4- dihydropyridine (9b), but it was 2-3 log units less active than the reference standard melphalan.