Comparison of different compressed sensing algorithms for low SNR 19F MRI applications—Imaging of transplanted pancreatic islets and cells labeled with perfluorocarbons

Transplantation of pancreatic islets is a possible treatment option for patients suffering from Type I diabetes. In vivo imaging of transplanted islets is important for assessment of the transplantation site and islet distribution. Thanks to its high specificity, the absence of intrinsic background signal in tissue and its potential for quantification, ¹⁹F MRI is a promising technique for monitoring the fate of transplanted islets in vivo. In order to overcome the inherent low sensitivity of ¹⁹F MRI, leading to long acquisition times with low signal‐to‐noise ratio (SNR), compressed sensing (CS) techniques are a valuable option. We have validated and compared different CS algorithms for acceleration of ¹⁹F MRI acquisition in a low SNR regime using pancreatic islets labeled with perfluorocarbons both in vitro and in vivo. Using offline simulation on both in vitro and in vivo low SNR fully sampled ¹⁹F MRI datasets of labeled islets, we have shown that CS is effective in reducing the image acquisition time by a factor of three to four without seriously affecting SNR, regardless of the particular algorithms used in this study, with the exception of CoSaMP. Using CS, signals can be detected that might have been missed by conventional ¹⁹F MRI. Among different algorithms (SPARSEMRI, OMMP, IRWL1, Two‐level and CoSAMP), the two‐level l₁ method has shown the best performance if computational time is taken into account. We have demonstrated in this study that different existing CS algorithms can be used effectively for low SNR ¹⁹F MRI. An up to fourfold gain in SNR/scan time could be used either to reduce the scan time, which is beneficial for clinical and translational applications, or to increase the number of averages, to potentially detect otherwise undetected signal when compared with conventional ¹⁹F MRI acquisitions. Potential applications in the field of cell therapy have been demonstrated.     

Food allergy knowledge,perception of food allergy labeling,and level of dietary practice: A comparison between children with and without food allergy experience

BACKGROUND/OBJECTIVESThe prevalence of food allergies in Korean children aged 6 to 12 years increased from 10.9% in 1995 to 12.6% in 2012 according to nationwide population studies. Treatment for food allergies is avoidance of allergenic-related foods and epinephrine auto-injector (EPI) for accidental allergic reactions. This study compared knowledge and perception of food allergy labeling and dietary practices of students.SUBJECTS/METHODSThe study was conducted with the fourth to sixth grade students from an elementary school in Yongin. A total of 437 response rate (95%) questionnaires were collected and statistically analyzed.RESULTSThe prevalence of food allergy among respondents was 19.7%, and the most common food allergy-related symptoms were urticaria, followed by itching, vomiting and nausea. Food allergens, other than 12 statutory food allergens, included cheese, cucumber, kiwi, melon, clam, green tea, walnut, grape, apricot and pineapple. Children with and without food allergy experience had a similar level of knowledge on food allergies. Children with food allergy experience thought that food allergy-related labeling on school menus was not clear or informative.CONCLUSIONTo understand food allergies and prevent allergic reactions to school foodservice among children, schools must provide more concrete and customized food allergy education.     

FDA有关仿制药和抗肿瘤药说明书的2个指导原则介绍

美国食品药品管理局（FDA）于2022年1月发布了“参比制剂（RLD）说明书修订后简化新药申请（ANDA）说明书的修订”供企业用的指导原则草案。该指导原则提供了多种获取RLD说明书变更信息的方法，还告知提交修改后的仿制药说明书的具体资料。2020年11月FDA发布了“联合方案中的抗肿瘤药物的交叉说明书”供企业用的指导原则草案。所谓“交叉说明书”是指被批准用于联合方案的抗肿瘤药物的说明书纳入的相关信息。该指导原则指出，其中新药的交叉说明书“应包括有关联合用药安全有效的信息以及仅限于各自药物的信息”；而其中已批准的药物的交叉说明书，“应包括在联合方案中该药物与其他药物合用的安全有效性信息”。该指导原则还对交叉说明书一些具体项目的内容提出了建议。而我国目前尚没有类似的指导原则。详细介绍FDA这2个指导原则，期望对中国RLD说明书修订后的仿制药说明书的修订以及联合用药方案中的抗肿瘤药的“交叉说明”的实施有帮助；对这两种情况的说明书的监管也有所启迪。     

Folding and ligand recognition of the TPP riboswitch aptamer at single-molecule resolution

Thiamine pyrophosphate (TPP)-sensitive mRNA domains are the most prevalent riboswitches known. Despite intensive investigation, the complex ligand recognition and concomitant folding processes in the TPP riboswitch that culminate in the regulation of gene expression remain elusive. Here, we used single-molecule fluorescence resonance energy transfer imaging to probe the folding landscape of the TPP aptamer domain in the absence and presence of magnesium and TPP. To do so, distinct labeling patterns were used to sense the dynamics of the switch helix (P1) and the two sensor arms (P2/P3 and P4/P5) of the aptamer domain. The latter structural elements make interdomain tertiary contacts (L5/P3) that span a region immediately adjacent to the ligand-binding site. In each instance, conformational dynamics of the TPP riboswitch were influenced by ligand binding. The P1 switch helix, formed by the 5′ and 3′ ends of the aptamer domain, adopts a predominantly folded structure in the presence of Mg²⁺ alone. However, even at saturating concentrations of Mg²⁺ and TPP, the P1 helix, as well as distal regions surrounding the TPP-binding site, exhibit an unexpected degree of residual dynamics and disperse kinetic behaviors. Such plasticity results in a persistent exchange of the P3/P5 forearms between open and closed configurations that is likely to facilitate entry and exit of the TPP ligand. Correspondingly, we posit that such features of the TPP aptamer domain contribute directly to the mechanism of riboswitch-mediated translational regulation.     

EFFECT OF GROWTH FACTORS ON DNA LABELING AND CYTOSKELETAL PROTEIN EXPRESSION IN 17-β-ESTRADIOL AND BASIC FIBROBLAST GROWTH FACTOR PRE-TREATED ASTROCYTE CULTURES

Astrocytes react to all noxae which damage neurons. Their reactions include degeneration, hypertrophy, hyperplasia and fibre formation. Growth factors inducing proliferation and differentiation of both neurons and astrocytes in culture play a pivotal role in the dynamic flow of signaling molecules between neurons and astroglia. Estrogens as well influence astroglia and are neuroprotectants. This study has investigated the interactions between growth factors and estrogens on DNA labeling and cytoskeletal protein [glial fibrillary acidic protein (GFAP) and vimentin] expression in 22 DIV astrocyte cultures treated for 24 or 36?h under different experimental conditions.

Contemporary addition of 17-β-estradiol (E₂) with two or three growth factors for 24?h, significantly stimulated methyl-[³H]thymidine incorporation into DNA from 22 days in vitro (DIV) astrocyte cultures.

This effect reached a peak when E₂ was co-added with epidermal growth factor (EGF), basic fibroblast growth factor (bFGF) and insulin. In astrocyte cultures treated for 36?h with E₂ and EGF+insulin or bFGF+insulin added in the last 12?h, DNA labeling was remarkably increased. The parallel cyclin D1 expression positively correlated with ERK2 activation. Western blot analysis for cytoskeletal proteins showed also changes of both GFAP and vimentin expression. The above data suggest the occurrence of a scheduled interaction between “competence” or “progression” growth factors and estrogens on DNA labeling and cytoskeletal protein expression during astroglial cell proliferation and differentiation in culture. A better understanding of the mechanisms of these interactions may contribute to develop strategies for controlling astroglial reaction in cerebrovascular disease including stroke and hypertensive brain damage.     

Mapping glycan-mediated galectin-3 interactions by live cell proximity labeling

Galectin-3 is a glycan-binding protein (GBP) that binds β-galactoside glycan structures to orchestrate a variety of important biological events, including the activation of hepatic stellate cells and regulation of immune responses. While the requisite glycan epitopes needed to bind galectin-3 have long been elucidated, the cellular glycoproteins that bear these glycan signatures remain unknown. Given the importance of the three-dimensional (3D) arrangement of glycans in dictating GBP interactions, strategies that allow the identification of GBP receptors in live cells, where the native glycan presentation and glycoprotein expression are preserved, have significant advantages over static and artificial systems. Here we describe the integration of a proximity labeling method and quantitative mass spectrometry to map the glycan and glycoprotein interactors for galectin-3 in live human hepatic stellate cells and peripheral blood mononuclear cells. Understanding the identity of the glycoproteins and defining the structures of the glycans will empower efforts to design and develop selective therapeutics to mitigate galectin-3–mediated biological events.

The noncovalent interactions between glycan-binding proteins (GBPs) and glycans dictate many important biological events. Among such GBPs is galectin-3, a 26-kDa β-galactoside GBP that plays key roles in many physiological and pathological events (1). In hepatic fibrosis, a disease that manifests as the excessive buildup of scar tissue, liver-resident macrophages secrete galectin-3 (2, 3), which then binds cell surface glycans on quiescent hepatic stellate cells (HSCs), activating them to transdifferentiate into a muscle-like phenotype. Galectin-3–null mice exhibit attenuated liver fibrosis even after induced injury, highlighting its critical role (3). Galectin-3 is also known to interact with cells of the innate immune system (4, 5) to regulate apoptosis (6) or control dendritic cell differentiation (7). In these cases, as well as in other cases in which galectin-3 is involved, the full complement of interacting glycoprotein receptors remains unknown.Despite significant advances in glycoscience, the study of GBP–glycan interactions and the identification of glycan-mediated counter-receptors remains a recurring challenge. Capturing these binding events often requires some form of artificial reconstitution to amplify individually weak interactions into high-avidity binding. Indeed, glycan microarrays with defined mixtures of homogenous glycans or recombinant GBPs have significantly propelled our understanding of glycan-mediated function (8). Conventional immunoprecipitation and lectin affinity techniques using cell lysates have similarly been used to reveal an initial catalog of 100 to 185 galectin-3–associated proteins (9–14). However, these manipulations alter the cell’s native and three-dimensional (3D) configuration and multivalent arrangement, both of which are critically important in the study of GBP–glycan interactions (15, 16).Another key issue involves the underlying glycoprotein ligand. Although many glycoproteins carry the glycan epitope for binding a GBP, only a limited set should be recognized as physiologically relevant receptors, owing to the physical constraints imposed by the living cell (17). While often overlooked, the glycoprotein carrying the glycan can impart specific biological functions to a GBP–glycan binding event (17). Recent work has put forth the concept of “professional glycoprotein ligands,” in which a specific set of glycoproteins (instead of a broadly defined glycome) can exhibit exquisite binding and functional roles (18). Thus, determining the identity of the underlying core protein that anchors the glycan can be greatly empowering. Not only can it provide an understanding of the 3D arrangement of the glycan (if the 3D structure of the core protein is known), but it can also provide additional insight into its expression levels in different cell types and tissues, further informing strategies for selective drug development.Thus, comprehensive approaches that permit the study of GBP–glycan interactions in live cells while simultaneously facilitating identification of the physiological glycoprotein receptors have great potential to impact glycoscience. We hypothesize that proximity labeling strategies (19) using an engineered ascorbate peroxidase, APEX2 (20), could be compatible for elucidating glycan-mediated GBP–glycoprotein interactions. In this approach (Fig. 1), APEX2 is fused to a protein of interest, followed by the treatment of cells with biotin-phenol and subsequently with hydrogen peroxide (H₂O₂). Under these conditions, APEX2 catalyzes the formation of highly reactive, short-lived (<1 ms), and proximally restricted (<20 nm) biotin-phenoxyl radicals that covalently tag nearby electron-rich residues. The biotinylated proteins can then be enriched and identified using quantitative mass spectrometry (MS)-based proteomics. Because the (glyco)proteins adjacent to the APEX2 fusion protein are preferentially biotinylated, the resulting MS data provide a readout of its immediate environment.Open in a separate windowFig. 1.Schematic illustration of the identification of galectin-3 (Gal-3) interacting proteins by in situ proximity labeling. Recombinant APEX2 and galectin-3 fusion proteins are applied to living cells where galectin-3 can freely diffuse to bind its cognate ligands. On addition of biotin phenol (yellow circle with “B”; 30 min) and hydrogen peroxide (H₂O₂; 1 min), APEX2 catalyzes the formation of highly-reactive biotin-phenoxyl radicals that react within a short range (<20 nm) of the galectin-3 complex within a short time frame (<1 ms). The biotin-tagged protein interactors can then be identified using MS-based proteomics.We reasoned that proximity labeling could offer significant advantages over other approaches to determining GBP–glycan interactions, including the opportunity to perform the labeling in live cells and the ability to tag weakly bound glycan-mediated interactors, as the covalent biotinylation reaction ensures that the enrichment step no longer relies on weak GBP–glycan interactions alone. When coupled with inhibitors, the proximity labeling strategy can also distinguish between glycan-mediated and non–glycan-mediated interactors. Integration of this approach with quantitative MS-based proteomics would also expedite the assignment of the interacting proteins and provide calculable measures to distinguish interactors from nonspecific binders.Here we report that the use of an APEX2 and galectin-3 fusion protein (PX-Gal3) provides a sensitive and comprehensive approach to mapping the proteome-wide glycan-mediated galectin-3 interactome in live human HSCs and peripheral blood mononuclear cells (PBMCs). We found that the exogenous incubation of cells with PX-Gal3 in HSCs leads to glycan-dependent interactions, whereas its cellular overexpression does not. We further validated the interactions between galectin-3 and candidate proteins in vitro and discovered that some proteins are direct glycan-mediated receptors. Using MS-based glycomics, we also examined the glycomes of HSC surfaces, PX-Gal3 tagged glycoproteins, and an individual glycoprotein receptor for galectin-3. Our results highlight the utility of the in situ proximity labeling approach in discovering physiologically relevant GBP interactors in living cells.     

67Ga显像对活动性肺结核的诊断价值

目的：探讨67Ga显像对活动性肺结核的诊断价值。方法：对160例非肿瘤患67Ga显像结果进行回顾性分析。诊断活动性肺结核100例，陈旧性肺结核26例，普通肺炎29例，淋巴结核5例，结果：活动性肺结核患67Ga阳性显像率72．00％（72／100），明显高于陈旧性肺结核23．08％（6／26）及普通肺炎17．24％（5／29），活动性肺结核患中， 痰菌阳性患67Ga阳性显像率79．73％（59／74），明显高于痰菌阴性50．00％（13／26），结论：67Ga显像可能在判断肺结核活动中具有一定价值。     

Preliminary evaluation of [18F]AlF-NOTA-MAL-Cys39-exendin-4 in insulinoma with PET

Background: High expression of glucagon-like peptide-1 receptor (GLP-1R) in insulinoma supplies a potential drug target for tumor imaging. Exendin-4 can specifically bind to GLP-1R as an agonist and its analogs are extensively used in receptor imaging studies.

Purpose: A new GLP-1R imaging agent, [¹⁸F]AlF-NOTA-MAL-Cys³⁹-exendin-4, was designed and prepared for insulinoma imaging.

Methods: Cys³⁹-exendin-4 was conjugated with NOTA-MAL, then the compound was radiolabeled with [¹⁸F]AlF complex to obtained [¹⁸F]AlF-NOTA-MAL-Cys³⁹-exendin-4. The tumor-targeting characters of the tracer were evaluated in INS-1 cells and BALB/c nude mice models.

Results: [¹⁸F]AlF-NOTA-MAL-Cys³⁹-exendin-4 can be efficiently produced with a yield of 17.5?±?3.2% (non-decay corrected) and radiochemical purity of >95%. The IC₅₀ value of displacement [¹⁸F]AlF-NOTA-MAL-Cys³⁹-exendin-4 with Cys³⁹-exendin-4 was 13.52?±?1.36?nM. PET images showed excellent tumor visualization with high uptake (9.15?±?1.6%ID/g at 30?min and 7.74?±?0.87%ID/g at 60?min). The tumor to muscle, pancreas and liver ratios were 63.25, 3.85 and 7.29 at 60?min after injection. GLP-1R binding specificity was demonstrated by co-injection with an excess of unlabeled Cys³⁹-exendin-4 and the tumor uptake was found to be reduced significantly.

Conclusion: [¹⁸F]AlF-NOTA-MAL-Cys³⁹-exendin-4 shows favorable characteristics for insulinoma imaging and may be translated to clinical studies.     

Quantitative toxicoproteomic analysis of zebrafish embryos exposed to a retinoid X receptor antagonist UVI3003

Retinoid X receptor (RXR) antagonists, including some environmental endocrine disruptors, have a teratogenic effect on vertebrate embryos. To investigate the toxicological mechanism on the protein expression level, a quantitative proteomic study was conducted to analyze the proteome alterations of zebrafish (Danio rerio) embryos exposed to gradient concentrations of a representative RXR antagonist UVI3003. Using isobaric Tags for Relative and Absolute Quantitation (iTRAQ) labeling coupled nano high‐performance liquid chromatography‐tandem mass spectrometry (nano HPLC‐MS/MS), in total 6592 proteins were identified, among which 195 proteins were found to be differentially expressed by more than a two‐fold change in exposed groups compared with the control. Gene ontology analysis showed that these differential proteins were mostly involved in anatomical structure development, biosynthetic process, ion binding and oxidoreductase activity. Moreover, the biological pathways of translation, lipoprotein metabolism, cell survival and gluconeogenesis were intensively inhibited after exposure. Some significantly downregulated proteins such as apolipoprotein A‐I and vitellogenin and upregulated proteins such as calcium activated nucleotidase 1b, glutathione S‐transferase and glucose 6‐dehydrogenases showed a strong dose‐dependent response. The results provided new insight into the molecular details of RXR antagonist‐induced teratogenicity and added novel information of pathways and potential biomarkers for evaluation of RXR interfering activity. Copyright © 2015 John Wiley & Sons, Ltd.