Performance evaluation of SimPET-L and SimPET-XL: MRI-compatible small-animal PET systems with rat-body imaging capability

BACKGROUND

SimPET-L and SimPET-XL have recently been introduced with increased transaxial fields of view (FOV) compared with their predecessors (SimPET™ and SimPET-X), enabling whole-body positron emission tomography (PET) imaging of rats. We conducted performance evaluations of SimPET-L and SimPET-XL and rat-body imaging with SimPET-XL to demonstrate the benefits of increased axial and transaxial FOVs.

PROCEDURES

The detector blocks in SimPET-L and SimPET-XL consist of two 4 × 4 silicon photomultiplier arrays coupled with 20 × 9 array lutetium oxyorthosilicate crystals. SimPET-L and SimPET-XL have an inner diameter (bore size) of 7.6 cm, and they are composed of 40 and 80 detector blocks yielding axial lengths of 5.5 and 11 cm, respectively. Each system was evaluated according to the National Electrical Manufacturers Association NU4-2008 protocol. Rat imaging studies, such as ¹⁸F-NaF and ¹⁸F-FDG PET, were performed using SimPET-XL.

RESULTS

The radial resolutions at the axial center measured using the filtered back projection, 3D ordered-subset expectation maximization (OSEM), and 3D OSEM with point spread functions correction were 1.7, 0.82, and 0.82 mm FWHM in SimPET-L and 1.7, 0.91, and 0.91 mm FWHM in SimPET-XL, respectively. The peak sensitivities of SimPET-L and SimPET-XL were 6.30% and 10.4% for an energy window of 100-900 keV and 4.44% and 7.25% for a window of 250-750 keV, respectively. The peak noise equivalent count rate with an energy window of 250-750 keV was 249 kcps at 44.9 MBq for SimPET-L and 349 kcps at 31.3 MBq for SimPET-XL. In SimPET-L, the uniformity was 4.43%, and the spill-over ratios in air- and water-filled chambers were 5.54% and 4.10%, respectively. In SimPET-XL, the uniformity was 3.89%, and the spill-over ratio in the air- and water-filled chambers were 3.56% and 3.60%. Moreover, SimPET-XL provided high-quality images of rats.

CONCLUSION

SimPET-L and SimPET-XL show adequate performance compared with other SimPET systems. In addition, their large transaxial and long axial FOVs provide imaging capability for rats with high image quality.

Circulation Time-Optimized Albumin Nanoplatform for Quantitative Visualization of Lung Metastasis via Targeting of Macrophages

The development of molecular imaging probes to identify key cellular changes within lung metastases may lead to noninvasive detection of metastatic lesions in the lung. In this study, we constructed a macrophage-targeted clickable albumin nanoplatform (CAN) decorated with mannose as the targeting ligand using a click reaction to maintain the intrinsic properties of albumin in vivo. We also modified the number of mannose molecules on the CAN and found that mannosylated serum albumin (MSA) harboring six molecules of mannose displayed favorable pharmacokinetics that allowed high-contrast imaging of the lung, rendering it suitable for in vivo visualization of lung metastases. Due to the optimized control of functionalization and surface modification, MSA enhanced blood circulation time and active/passive targeting abilities and was specifically incorporated by mannose receptor (CD206)-expressing macrophages in the metastatic lung. Moreover, extensive in vivo imaging studies using single-photon emission computed tomography (SPECT)/CT and positron emission tomography (PET) revealed that blood circulation of time-optimized MSA can be used to discern metastatic lesions, with a strong correlation between its signal and metastatic burden in the lung.

High-quantum yield alloy-typed core/shell CdSeZnS/ZnS quantum dots for bio-applications

Background

Quantum dots (QDs) have been used as fluorophores in various imaging fields owing to their strong fluorescent intensity, high quantum yield (QY), and narrow emission bandwidth. However, the application of QDs to bio-imaging is limited because the QY of QDs decreases substantially during the surface modification step for bio-application.

Results

In this study, we fabricated alloy-typed core/shell CdSeZnS/ZnS quantum dots (alloy QDs) that showed higher quantum yield and stability during the surface modification for hydrophilization compared with conventional CdSe/CdS/ZnS multilayer quantum dots (MQDs). The structure of the alloy QDs was confirmed using time-of-flight medium-energy ion scattering spectroscopy. The alloy QDs exhibited strong fluorescence and a high QY of 98.0%. After hydrophilic surface modification, the alloy QDs exhibited a QY of 84.7%, which is 1.5 times higher than that of MQDs. The QY was 77.8% after the alloy QDs were conjugated with folic acid (FA). Alloy QDs and MQDs, after conjugation with FA, were successfully used for targeting human KB cells. The alloy QDs exhibited a stronger fluorescence signal than MQD; these signals were retained in the popliteal lymph node area for 24 h.

Conclusion

The alloy QDs maintained a higher QY in hydrophilization for biological applications than MQDs. And also, alloy QDs showed the potential as nanoprobes for highly sensitive bioimaging analysis.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01227-2.

Extracellular Vesicles Induce an Aggressive Phenotype in Luminal Breast Cancer Cells Via PKM2 Phosphorylation

BACKGROUND

Aerobic glycolysis is a hallmark of glucose metabolism in cancer. Previous studies have suggested that cancer cell-derived extracellular vesicles (EVs) can modulate glucose metabolism in adjacent cells and promote disease progression. We hypothesized that EVs originating from cancer cells can modulate glucose metabolism in recipient cancer cells to induce cell proliferation and an aggressive cancer phenotype.

METHODS

Two breast cancer cell lines with different levels of glycolytic activity, MDA-MB-231 cells of the claudin-low subtype and MCF7 cells of the luminal type, were selected and cocultured as the originating and recipient cells, respectively, using an indirect coculture system, such as a Transwell system or a microfluidic system. The [18F]fluorodeoxyglucose (FDG) uptake by the recipient MCF7 cells was assessed before and after coculture with MDA-MB-231 cells. Proteomic and transcriptomic analyses were performed to investigate the changes in gene expression patterns in the recipient MCF7 cells and MDA-MB-231 cell-derived EVs.

RESULTS

FDG uptake by the recipient MCF7 cells significantly increased after coculture with MDA-MB-231 cells. In addition, phosphorylation of PKM2 at tyrosine-105 and serine-37, which is necessary for tumorigenesis and aerobic glycolysis, was highly activated in cocultured MCF7 cells. Proteomic profiling revealed the proliferation and dedifferentiation of MCF7 cells following coculture with MDA-MB-231 cells. Transcriptomic analysis demonstrated an increase in glycolysis in cocultured MCF7 cells, and the component analysis of glycolysis-related genes revealed that the second most abundant component after the cytoplasm was extracellular exosomes. In addition, proteomic analysis of EVs showed that the key proteins capable of phosphorylating PKM2 were present as cargo inside MDA-MB-231 cell-derived EVs.

CONCLUSIONS

The phenomena observed in this study suggest that cancer cells can induce a phenotype transition of other subtypes to an aggressive phenotype to consequently activate glucose metabolism via EVs. Therefore, this study could serve as a cornerstone for further research on interactions between cancer cells.

Extracellular vesicle-associated miR-135b and -135a regulate stemness in Group 4 medulloblastoma cells by targeting angiomotin-like 2

Background

Extracellular vesicles (EVs) secreted by tumours, including exosomes, are important factors that regulate cell–cell interactions in oncogenesis. Although EV studies are ongoing, the biological understanding of EV-miRNAs derived from brain tumour spheroid-forming cells (BTSCs) of medulloblastoma is poor.

Purposes

We explored the specific cellular miRNAs and EV-miRNAs in medulloblastoma BTSCs to determine their potential biological function.

Methods

Bulk tumor cells (BTCs) and BTSCs were cultured under different conditions from medulloblastoma tissues (N = 10).

Results

Twenty-four miRNAs were simultaneously increased in both cells and EVs derived from BTSCs in comparison to BTCs. After inhibition of miR-135b or miR135a which were the most significantly increased in BTSCs, cell viability, self-renewal and stem cell marker expression decreased remarkably. Through integrated analysis of mRNAs and miRNAs data, we found that angiomotin-like 2 (AMOTL2), which was significantly decreased, was targeted by both miR-135b and miR-135a. STAT6 and GPX8 were targeted only by miR-135a. Importantly, low expression of AMOTL2 was significantly associated with overall poor survival in paediatric Group 3 and Group 4 medulloblastoma patients.

Conclusion

Our results indicated that inhibition of miR-135b or miR-135a leads to suppress stemness of BTSC through modulation of AMOTL2.

Systemic delivery of microRNA-21 antisense oligonucleotides to the brain using T7-peptide decorated exosomes

Antisense miRNA oligonucleotides against miR-21 (AMO-21) have a therapeutic potential for treatment of glioblastoma. However, glioblastoma-targeted delivery through systemic injection requires development of an efficient targeting carrier. For this purpose, a glioblastoma-targeting carrier was developed using the T7 peptide and exosomes. The transferrin receptor is overexpressed on the surface of glioblastoma cells, and T7 is a transferrin receptor-binding peptide. A T7 peptide-decorated exosome (T7-exo) was produced by incorporation of T7 into the exosome membrane as a fusion protein of T7 and Lamp2b. As a control, rabies virus glycoprotein (RVG) peptide targeting brain neuron cells was incorporated into the exosome membrane. AMO-21 was loaded into the exosomes by electroporation. In vitro studies of AMO-21 delivery showed that T7-exo had a higher delivery efficiency to C6 glioblastoma cells than unmodified exosome (Unmod-exo) and RVG-decorated exosome (RVG-exo). For in vivo delivery studies, T7-exo with AMO-21 was delivered into intracranial glioblastoma rat models by intravenous injection through the tail vein. The results showed that T7-exo delivered AMO-21 into the brain more efficiently than Unmod-exo and RVG-exo. In addition, delivery of AMO-21 using T7-exo reduced the miR-21 level in the glioblastoma efficiently. Reduction of miR-21 by AMO-21 induced the expression of PDCD4 and PTEN in tumors, resulting in reduction of tumor sizes. Taken together, these findings indicate that T7-exo is an efficient carrier of AMO-21 into the glioblastoma and may be useful in development of glioblastoma therapy.

Biguanides Metformin and Phenformin Generate Therapeutic Effects via AMP-Activated Protein Kinase/Extracellular-Regulated Kinase Pathways in an In Vitro Model of Graves' Orbitopathy

BACKGROUND

It was hypothesized that the biguanides metformin and phenformin, which are anti-hyperglycemic drugs used for diabetes mellitus, would have therapeutic effects in an in vitro model of Graves' orbitopathy (GO). Because adipogenesis, hyaluronan production, and inflammation are considered important in the pathogenesis of GO, this study aimed to determine the therapeutic effects and underlying mechanisms of biguanides on these parameters.

METHODS

In vitro experiments were performed using primary cultured orbital fibroblasts from patients with GO. Orbital preadipocyte fibroblasts were allowed to differentiate into adipocytes and were treated with various concentrations of metformin or phenformin. Oil Red O staining was performed to evaluate lipid accumulation within the cells. Western blot analysis was used to measure the expression of adipogenic transcription factors and the phosphorylation of AMP-activated protein kinase and mitogen-activated protein kinase signaling proteins. Hyaluronan production was measured using enzyme-linked immunosorbent assay, and mRNA levels of proinflammatory molecules were determined using real-time polymerase chain reaction after interleukin (IL)-1β stimulation with or without biguanide treatment.

RESULTS

Lipid accumulation during adipogenesis in GO orbital fibroblasts was dose-dependently suppressed by both metformin and phenformin. Adipocyte differentiation was attenuated, and the adipogenic transcription factors peroxisome proliferator-activated receptor γ and CCAAT-enhancer-binding proteins-α/β were downregulated. Furthermore, metformin and phenformin increased the phosphorylation of AMP-activated protein kinase and suppressed extracellular-regulated kinase activation. The IL-1β-induced hyaluronan production and mRNA expression of IL-6, cyclooxygenase-2, and intercellular adhesion molecule-1 were also significantly suppressed after metformin or phenformin co-treatment.

CONCLUSIONS

The present study indicates that the biguanides metformin and phenformin exert an anti-adipogenic and inhibitory effect on hyaluronan production and expression of pro-inflammatory molecules in GO orbital fibroblasts, suggesting that they could potentially be used for the treatment of GO.

Therapeutic Effect of Protocatechuic Aldehyde in an In Vitro Model of Graves' Orbitopathy

PURPOSE

Protocatechuic aldehyde (3,4-dihydroxybenzaldehyde; PCA) is extracted from Salvia miltiorrhiza, and has been reported to possess antiproliferative, antioxidant, and antiadipogenesis properties in various in vivo and in vitro experiments. This study aimed to outline the antioxidant and suppressive effects of PCA on adipogenesis and hyaluronan production in orbital fibroblasts to help with designing therapeutic approaches for Graves' orbitopathy (GO).

METHODS

We assessed the in vitro effects of PCA on orbital fibroblasts, which were cultured from orbital fat tissue obtained from patients undergoing orbital decompression for severe GO. Control tissue was obtained from patients undergoing orbital surgery with no history of GO or Graves' hyperthyroidism.

RESULTS

The 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt assay results confirmed the free radical scavenging effect of PCA after treatment. Protocatechuic aldehyde exhibited a suppressive effect on intracellular reactive oxygen species generation and upregulated heme oxygenase-1 expression in Western blot analysis. Protocatechuic aldehyde attenuated TNF-α and IL-1β-induced hyaluronan production. Oil Red-O staining results revealed a decrease in lipid droplets and suppressed expression of the adipogenesis-related proteins peroxisome proliferator-activated receptor (PPAR)-γ, CCAAT/enhancer binding protein (c/EBP)-α, and c/EBP-β upon treatment with PCA during adipose differentiation.

CONCLUSIONS

In this study, PCA exerted significant antioxidant and antiadipogenic effects and inhibited the production of hyaluronan in GO orbital fibroblasts. Accordingly, PCA potentially could be used as a novel treatment option for GO.

Prevalence and molecular characterisation of Giardia duodenalis in calves with diarrhoea

The aim of this study was to investigate the prevalence of Giardia duodenalis in diarrhoeal faeces from calves that were reared in Korea using PCR and ELISA. Diarrhoeal faecal samples were collected from 590 calves (<3 months old) throughout the country from November 2013 through March 2015. Data were analysed according to the region of collection, season, and type of diarrhoea. Of the 590 collected faecal samples, 77 (13.1 per cent) and 78 (13.2 per cent; true prevalence 9.1 per cent) tested positive by PCR and ELISA, respectively. The results from both testing methods were in agreement in 501 (84.9 per cent) samples, with a κ value of 0.34, which suggests fair agreement. The PCR results showed a higher prevalence in summer and in cases of haemorrhagic diarrhoea (P<0.05), while the ELISA results showed a lower prevalence in cases of pasty diarrhoea (P<0.05). Phylogenetic analysis of the β-giardin gene sequences of G duodenalis showed that the sequences detected in this study belonged to assemblage E, which is specific to cattle and livestock. The higher prevalence of giardiasis in calves with haemorrhagic diarrhoea found in this study differed from previous studies. Therefore, researchers and veterinarians should be aware of the possible involvement of giardiasis in haemorrhagic diarrhoea.

Vasculoprotective Effects of 3-Hydroxybenzaldehyde against VSMCs Proliferation and ECs Inflammation

3-hydroxybenzaldehyde (3-HBA) is a precursor compound for phenolic compounds like Protocatechuic aldehyde (PCA). From recent reports, PCA has shown vasculoprotective potency, but the effects of 3-HBA remain unclear. The aim of this study is to investigate the vasculoprotective effects of 3-HBA in endothelial cells, vascular smooth muscle cells and various animal models. We tested effects of 3-HBA in both vitro and vivo. 3-HBA showed that it prevents PDGF-induced vascular smooth muscle cells (VSMCs) migration and proliferation from MTS, BrdU assays and inhibition of AKT phosphorylation. It arrested S and G0/G1 phase of VSMC cell cycle in PI staining and it also showed inhibited expression levels of Rb1 and CD1. In human umbilical vein endothelial cells (HUVECs), 3-HBA inhibited inflammatory markers and signaling molecules (VCAM-1, ICAM-1, p-NF-κB and p-p38). For ex vivo, 3-HBA has shown dramatic effects in suppressing the sprouting from aortic ring of Spargue Dawley (SD) rats. In vivo data supported the vasculoprotective effects of 3-HBA as it inhibited angiogenesis from Matrigel Plug assay in C57BL6 mouse, prevented ADP-induced thrombus generation, increased blood circulation after formation of thrombus, and attenuated neointima formation induced by common carotid artery balloon injury of SD rats. 3-HBA, a novel therapeutic agent, has shown vasculoprotective potency in both in vitro and in vivo.

Detection of intra-brain cytoplasmic 1 (BC1) long noncoding RNA using graphene oxide-fluorescence beacon detector

Detection of cellular expression of long noncoding RNAs (lncRNAs) was elusive due to the ambiguity of exposure of their reactive sequences associated with their secondary/tertiary structures and dynamic binding of proteins around lncRNAs. Herein, we developed graphene-based detection techniques exploiting the quenching capability of graphene oxide (GO) flakes for fluorescent dye (FAM)-labeled single-stranded siRNAs and consequent un-quenching by their detachment from GO by matching lncRNAs. A brain cytoplasmic 1 (BC1) lncRNA expression was significantly decreased by a siRNA, siBC1–1. GO quenched the FAM-labeled siBC1–1 peptide nucleic acid (PNA) probe, and this quenching was recovered by BC1. While FAM-siBC1–1-PNA-GO complex transfected spontaneously mouse or human neural stem cells, fluorescence was recovered only in mouse cells having high BC1 expression. Fluorescent dye-labeled single-stranded RNA-GO probe could detect the reactive exposed nucleic acid sequence of a cytoplasmic lncRNA expressing in the cytoplasm, which strategy can be used as a detection method of lncRNA expression.

Inhibitory Effects of α-Lipoic Acid on Oxidative Stress-Induced Adipogenesis in Orbital Fibroblasts From Patients With Graves Ophthalmopathy

A choice of the optimal treatment for Graves ophthalmopathy (GO) is a challenge due to the complexity of the pathogenesis. Alpha-lipoic acid (ALA) is well known as a multifunctional antioxidant, helping to protect cells against oxidative stress and inflammatory damage.The aim of this study was to investigate the effects of ALA on intracellular production of reactive oxygen species (ROS), inflammation, and adipogenesis using primary cultured orbital fibroblasts from patients with GO.Intracellular ROS levels and mRNA expressions of proinflammatory cytokines and chemokines including intercellular adhesion molecule-1 (ICAM-1), interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1, and regulated upon activation normal T cell expressed and presumably secreted (RANTES) were measured. After adipogenesis, the expressions of peroxisome proliferator-activated receptor (PPAR)γ, CCAAT-enhancer-binding proteins (C/EBP)α and β, and heme oxygenase-1 (HO-1) were investigated.H2O2 dose-dependently stimulated ROS production and HO-1 expression. Addition of ALA strongly attenuated ROS production and further increased HO-1 expression. However, by pretreatment of zinc protoporphyrin (ZnPP), HO-1 inhibitor, ALA inhibition of ROS generation by H2O2 was abolished. Tumor necrosis factor (TNF)α-induced mRNA expressions of ICAM-1, IL-6, MCP-1, and RANTES were inhibited by ALA treatment. In this context, TNFα-induced phosphorylation of P65 was also inhibited. In addition, ALA dose-dependently inhibited H2O2-induced intracellular accumulation of lipid droplets. The expression of adipogenic transcription factors, including PPARγ, C/EBPα, and β, was also inhibited.ALA is a potential therapeutic agent for GO because of the inhibitory effects on ROS production and gene expression of proinflammatory cytokines and chemokines, resulting in prevention of adipose-tissue expansion.

Classification by causes of dark circles and appropriate evaluation method of dark circles

BACKGROUND

Dark circles refer to a symptom that present darkness under the eyes. Because of improvement in the quality of life, the dark circles have been recognized as one of major cosmetic concerns. However, it is not easy to classify the dark circles because they have various causes.

METHODS

To select suitable instruments and detailed evaluation items, the dark circles were classified according to the causes through visual assessment, Wood's lamp test, and medical history survey for 100 subjects with dark circles. After the classification, were newly recruited for instrument conformity assessment. Through this, suitable instruments for dark circle evaluation were selected. We performed a randomized clinical trial for dark circles, a placebo-controlled double-blind study, using effective parameters of the instruments selected from the preliminary test.

RESULTS

Dark circles of vascular type (35%) and mixed type (54%), a combination of pigmented and vascular types, were the most common. Twenty four subjects with the mixed type dark circles applied the test product (Vitamin C 3%, Vitamin A 0.1%, Vitamin E 0.5%) and placebo on randomized split-face for 8 weeks. The effective parameters (L*, a, M.I., E.I., quasi L*, quasi a* and dermal thickness) were measured during the study period. Result showed that the L* value of Chromameter(®) , Melanin index (M.I.) of Mexameter(®) and quasi L* value obtained by image analysis improved with statistical significance after applying the test product compared with the placebo product.

CONCLUSION

We classified the dark circles according to the causes of the dark circles and verified the reliability of the parameter obtained by the instrument conformity assessment used in this study through the efficacy evaluation. Also based on this study, we were to suggest newly established methods which can be applied to the evaluation of efficacy of functional cosmetics for dark circles.

Focal Lymphocytic Thyroiditis Nodules Share the Features of Papillary Thyroid Cancer on Ultrasound

PURPOSE

It is often difficult to discriminate focal lymphocytic thyroiditis (FLT) or adenomatous hyperplasia (AH) from thyroid cancer if they both have suspicious ultrasound (US) findings. We aimed to make a predictive model of FLT from papillary thyroid cancer (PTC) in suspicious nodules with benign cytologic results.

MATERIALS AND METHODS

We evaluated 214 patients who had undergone fine-needle aspiration biopsy (FNAB) and had shown thyroid nodules with suspicious US features. PTC was confirmed by surgical pathology. FLT and AH were confirmed through more than two separate FNABs. Clinical and biochemical findings, as well as US features, were evaluated.

RESULTS

Of 214 patients, 100 patients were diagnosed with PTC, 55 patients with FLT, and 59 patients with AH. The proportion of elevated thyrotropin (TSH) levels (p=0.014) and thyroglobulin antibody (Tg-Ab) or thyroid peroxidase antibody (TPO-Ab) positivity (p<0.001) in the FLT group was significantly higher than that in the PTC group. Regarding US features, absence of calcification (p=0.006) and "diffuse thyroid disease" (DTD) pattern on US (p<0.001) were frequently seen in the FLT group. On multivariate analysis, Tg-Ab positivity, presence of a DTD pattern on US, and absence of calcification in nodules were associated with FLT with the best specificity of 99% and positive predictive value of 96%. In contrast, a taller than wide shape of nodules was the only variable significant for differentiating AH from PTC.

CONCLUSION

Suspicious thyroid nodules with cytologic benign results could be followed up with US rather than repeat FNAB, if patients exhibit Tg-Ab positivity, no calcifications in nodules, and a DTD pattern on US.