Transition of signal requirement in hematopoietic stem cell development from hemogenic endothelial cells.

Hematopoietic stem cells (HSCs) develop from hemogenic endothelial cells (HECs) in vivo during mouse embryogenesis. When cultured in vitro, cells from the embryo phenotypically defined as pre-HSC-I and pre-HSC-II have the potential to differentiate into HSCs. However, minimal factors required for HSC induction from HECs have not yet been determined. In this study, we demonstrated that stem cell factor (SCF) and thrombopoietin (TPO) induced engrafting HSCs from embryonic day (E) 11.5 pre-HSC-I in a serum-free and feeder-free culture condition. In contrast, E10.5 pre-HSC-I and HECs required an endothelial cell layer in addition to SCF and TPO to differentiate into HSCs. A single-cell RNA sequencing analysis of E10.5 to 11.5 dorsal aortae with surrounding tissues and fetal livers detected TPO expression confined in hepatoblasts, while SCF was expressed in various tissues, including endothelial cells and hepatoblasts. Our results suggest a transition of signal requirement during HSC development from HECs. The differentiation of E10.5 HECs to E11.5 pre-HSC-I in the aorta-gonad-mesonephros region depends on SCF and endothelial cell-derived factors. Subsequently, SCF and TPO drive the differentiation of E11.5 pre-HSC-I to pre-HSC-II/HSCs in the fetal liver. The culture system established in this study provides a beneficial tool for exploring the molecular mechanisms underlying the development of HSCs from HECs.

Using capillary electrophoresis sodium dodecyl sulfate (CE-SDS) and liquid chromatograph mass spectrometry (LC-MS) to identify glycosylated heavy chain heterogeneity in the anti-VEGFR-2 monoclonal antibody.

The size variant, which can be measured by capillary electrophoresis sodium dodecyl sulfate (CE-SDS), is a critical quality attribute of monoclonal antibodies (mAbs). The CE-SDS size heterogeneity can hardly be identified by tandem mass spectrometry, which is an intractable obstacle of mAb development and quality control across the industry. We analyzed the purity of an anti-vascular endothelial growth factor receptor 2 (VEGFR-2) mAb, an antagonist of the human VEGFR-2, through reduced CE-SDS and observed glycosylated heavy chain heterogeneity. The heterogeneity has potential impact on safety, efficacy, and stability of drugs for clinical use. Therefore, it should be characterized so as to evaluate its potential risk. In order to identify the heterogeneity, we used mass spectrometry to confirm that the molecular size heterogeneity was not due to peptide bond cleavage in the heavy chain. Subsequently, we employed mass-spectrometry-glycosylation profiling and CE-SDS analysis of various glycosidase-treated samples, in addition to the preparation of mAb references with different glycoforms. Ultimately, we demonstrated that the heavy chain heterogeneity was induced by different levels of galactosylation modifications which will potentially impact the efficacy of antibody drugs (i.e., complement-dependent cytotoxicity). In this study, potential risk caused by heavy chain size heterogeneity was evaluated, which addressed the obstacle of mAb development and quality control. Therefore, this study offers a feasible approach for the investigation and identification of heavy chain heterogeneity in reduced CE-SDS, providing a novel strategy for mAb quality control and evaluation.

Antibody-Drug Conjugate Overview: a State-of-the-art Manufacturing Process and Control Strategy.

Antibody-drug conjugates (ADCs) comprise an antibody, linker, and drug, which direct their highly potent small molecule drugs to target tumor cells via specific binding between the antibody and surface antigens. The antibody, linker, and drug should be properly designed or selected to achieve the desired efficacy while minimizing off-target toxicity. With a unique and complex structure, there is inherent heterogeneity introduced by product-related variations and the manufacturing process. Here this review primarily covers recent key advances in ADC history, clinical development status, molecule design, manufacturing processes, and quality control. The manufacturing process, especially the conjugation process, should be carefully developed, characterized, validated, and controlled throughout its lifecycle. Quality control is another key element to ensure product quality and patient safety. A patient-centric strategy has been well recognized and adopted by the pharmaceutical industry for therapeutic proteins, and has been successfully implemented for ADCs as well, to ensure that ADC products maintain their quality until the end of their shelf life. Deep product understanding and process knowledge defines attribute testing strategies (ATS). Quality by design (QbD) is a powerful approach for process and product development, and for defining an overall control strategy. Finally, we summarize the current challenges on ADC development and provide some perspectives that may help to give related directions and trigger more cross-functional research to surmount those challenges.

Identification and Regulation of Hypoxia-Tolerant and Germination-Related Genes in Rice.

In direct seeding, hypoxia is a major stress faced by rice plants. Therefore, dissecting the response mechanism of rice to hypoxia stress and the molecular regulatory network is critical to the development of hypoxia-tolerant rice varieties and direct seeding of rice. This review summarizes the morphological, physiological, and ecological changes in rice under hypoxia stress, the discovery of hypoxia-tolerant and germination-related genes/QTLs, and the latest research on candidate genes, and explores the linkage of hypoxia tolerance genes and their distribution in indica and japonica rice through population variance analysis and haplotype network analysis. Among the candidate genes, OsMAP1 is a typical gene located on the MAPK cascade reaction for indica-japonica divergence; MHZ6 is involved in both the MAPK signaling and phytohormone transduction pathway. MHZ6 has three major haplotypes and one rare haplotype, with Hap3 being dominated by indica rice varieties, and promotes internode elongation in deep-water rice by activating the SD1 gene. OsAmy3D and Adh1 have similar indica-japonica varietal differentiation, and are mainly present in indica varieties. There are three high-frequency haplotypes of OsTPP7, namely Hap1 (n = 1109), Hap2 (n = 1349), and Hap3 (n = 217); Hap2 is more frequent in japonica, and the genetic background of OsTPP7 was derived from the japonica rice subpopulation. Further artificial selection, natural domestication, and other means to identify more resistance mechanisms of this gene may facilitate future research to breed superior rice cultivars. Finally, this study discusses the application of rice hypoxia-tolerant germplasm in future breeding research.

Spiroligustolides A and B: Two pairs of enantiomeric spiro-orthoester-containing phthalide dimers as Cav3.1 calcium channel inhibitors from Ligusticum Chuanxiong Hort.

Two pairs of unprecedented enantiomeric phthalide dimers, spiroligustolides A (1a/1b) and B (2a/2b), featuring a unique spiroorthoster linkage between two monomeric units to form a 5/6/5/6/6-fused ring system, were isolated from the roots of Ligusticum chuanxiong. The structures and relative configurations of 1 and 2 were determined by HR-ESI-MS, IR, and NMR spectroscopic data, coupled with single-crystal X-ray diffraction analysis, and the absolute configurations of 1a, 1b, 2a, and 2b were established by comparing the experimental and calculated electronic circular dichroism (ECD) data. Plausible biosynthetic pathway for 1 and 2 was proposed. Moreover, compounds 1, 1b, and 2b showed remarkable inhibitory activities on Cav3.1 calcium channel with IC50 values of 8.34, 7.08, and 8.60 µM, respectively.

Hypopurolides A - G, Labdane Diterpenoids from Hypoestes purpurea and Their Nitric Oxide Inhibitory Activity.

Seven new labdane diterpenoids, hypopurolides A-G (1-7) were discovered from the aerial part of Hypoestes purpurea, along with one known analog, hypopurin D (8). The structures of 1-7 were characterized based on 1 H-, 13 C-, and 2D-NMR, and HR-ESI-MS spectra. The absolute configurations of 1-7 were defined by single-crystal X-ray diffraction and electronic circular dichroism (ECD) data. Compounds 1-8 were tested for their nitric oxide (NO) inhibitory and cytotoxic effects. Compound 6 displayed moderate inhibitory effect toward LPS-induced NO release in RAW 264.7 cells with an IC50 value of 41.50 µM.

Selecting optimal calibration samples using proximal sensing EM induction and γ-ray spectrometry data: An application to managing lime and magnesium in sugarcane growing soil.

Calcium (Ca) and magnesium (Mg) are essential for growth of sugarcane leaves and roots, as well as respiration and nitrogen metabolism, respectively. To assist farmers decide suitable application rates of lime and Mg fertiliser, respectively, the Australian sugarcane industry established the Six-Easy-Steps nutrient management guidelines based on topsoil (0-0.3 m) Ca (cmol(+) kg-1) and Mg (cmol(+) kg-1). Given the heterogeneous nature of soil, digital soil mapping (DSM) methods can be employed to allow for the precise application rate to be determined. In this study, we examine statistical models (i.e., ordinary kriging [OK], linear mixed model [LMM], quantile regression forests [QRF], support vector machine [SVM], and Cubist regression kriging [CubistRK]) to predict topsoil and subsoil (0.6-0.9) Ca and Mg, employing digital data in combination (i.e., proximal sensing electromagnetic induction (EMI) [e.g., 1mPcon, 1mHcon, etc.], gamma-ray [γ-ray] spectrometry [i.e., TC, K, U and Th] and digital elevation model [DEM] derivatives). We also investigate various sampling designs (i.e., spatial coverage [SCS], feature space coverage [FSCS], conditioned Latin hypercube [cLHS] and simple random sampling [SRS]) and calibration sample size (i.e., n = 180, 150, 120, 90, 60 and 30). The predictions are assessed using Lin's concordance correlation coefficient (LCCC) and ratio of performance to interquartile distance (RPIQ) with an independent validation dataset (i.e., n = 40). The best results were for prediction of subsoil Mg, utilising CubistRK (LCCC = 0.82) with the largest calibration sample size (n = 180), followed by LMM (0.79), SVM (0.76), QRF (0.70) and OK (0.65). This was generally the case for topsoil and subsoil Ca. We also conclude that no single sampling design was universally better, and 180 samples were necessary for predicting topsoil Ca and Mg with moderate agreement (0.65 < LCCC < 0.80). However, with FSCS, a minimum of 120 samples were enough to calibrate a CubistRK model and achieve substantial (LCCC > 0.80) agreement for predicting subsoil Ca and Mg. With respect to soil use and management according to the Six-Easy-Steps, the sandy soil in the north and south require large application rate of lime (3.5 t/ha) and Mg (125 kg/ha), respectively. Conversely, varying amounts of fertiliser rates of lime (2.0, 1.5 and 1 t/ha) and Mg (50 kg/ha) were recommended where Vertosols were previously mapped.

Eradication therapy for gastric cancer in Inner Mongolia: A single-center study over 10 years.

OBJECTIVE: To understand the characteristics, diagnosis and treatment of gastric cancer in a specific geographical region. METHODS: The retrospective study was conducted at the Affiliated Hospital of Inner Mongolia Medical University, China, and comprised clinical and pathological data of patients with gastric cancer treated from 2007 to 2017. Data was analysed according to the patients' ethnicity, gender, age, tumour location, differentiation degree, Bormann classification, tumour-nodes-metastases staging and pathological type. Statistical analysis was done using SPSS 22. RESULTS: Of the 2,049 patients, 1619(79.01%) were males and 430(20.99%) were females. The overall mean age of the sample was 60.94±10.90 years. The incidence of gastric antrum was the highest, with 830(40.51%) cases. The proportion of gastric cancers was different in different age groups (p=0.001). Of the total, 922(45%) cases were poorly differentiated adenocarcinoma. There were significant differences in the histological types of gastric cancer in different age groups (p=0.001). There were 130(6.3%) cases of Mongolian patients, and the composition ratio of each age group was not significantly different from that of Han ethnicity (p>0.05). However, location was different with 55(42.31%) cases involving oesophago-gastric junction. CONCLUSIONS: The diagnostic rate of gastric cancer in Western Inner Mongolia was relatively low. The incidence of gastric cancer among both Mongolian and Han patients was higher in elderly men. The incidence of gastric antrum was dominant in Han patients, followed by oesophago-gastric junction, while the reverse was true of Mongolian patients.

Targeted Delivery of an Activatable Fluorescent Probe for the Detection of Furin Activity in Living Cells.

Furin, a protein convertase, plays a crucial role in the progression of tumors. In this work, a new fluorescent probe consisting of a peptide, Arg-Val-Arg-Arg (RVRR), and an aminoluciferin fluorophore was designed and prepared for the responsive and activatable detection of furin activity in vitro and in living cells. We demonstrated that this probe could be responsive toward furin with an "off-on" florescence signal and generated an approximately 3.58-fold enhancement in the fluorescence intensity in vitro. Fluorescence imaging in MDA-MB-468 and LoVo cells showed that the probe could be cleaved by overexpressed furin with fluorescence turn-on in MDA-MB-468 cells, and this probe was also found to be capable of discriminating between furin-overexpressing and furin-deficient cell lines. Our research indicates that this probe has great potential for the detection of furin activity in living cells.

Enhanced Tumor Diagnostic and Therapeutic Effect of Mesoporous Silica Nanoparticle-Mediated Pre-targeted Strategy.

PURPOSE: Improving the targeting efficiency of imaging agents or anticancer drugs has become essential in the current primary mission to enhance the diagnostic or therapeutic effects. To improve the tumor diagnosis and therapy effect, a promising drug-delivery and targeting strategy was established based on the bioorthogonal chemistry. METHOD: The delivery system was composed of the pre-targeting carrier Biotin-MSNs-DBCO nanoparticles and the azido cargoes. The fluorescence probe 1-(3-azidopropyl) fluorescein (FITC-N3) and ruthenium N-heterocyclic carbene complex N3-S-S-NHC-Ru were synthesized and served as the tumor imaging and therapy probes, respectively. The cell imaging and viability was investigated by the Biotin-MSNs-DBCO pre-targeted for 4 h in colonic carcinoma (HeLa) cells. RESULTS: For the tumor cell imaging, Biotin-MSNs-DBCO could react with FITC-N3 rapidly and completely in 20 min with 93% yields. The fluorescence intensity of tumor cells was obviously increased by the Biotin-MSNs-DBCO pre-targeted. The cytotoxicity of the ruthenium complex N3-S-S-NHC-Ru was significantly improved appropriately three times with the IC50 (half inhibitory concentration) value of 6.68 ± 1.29 µM and enhancement of the mitochondrial dysfunction. CONCLUSIONS: The pre-targeting nanoparticle Biotin-MSNs-DBCO could selectively capture the azido compounds in tumor cells, which provided a site-specific target for the cargoes and then resulted in an enhancement of diagnostic or therapeutic effects.

Celastrus orbiculatus extracts induce apoptosis in mTOR-overexpressed human hepatocellular carcinoma HepG2 cells.

BACKGROUND: Celastrus orbiculatus (Celastraceae) are used as traditional Chinese medicine to treat inflammation and cancer. This study aims to evaluate the effect of Celastrus orbiculatus extract (COE) on the apoptosis in human hepatic carcinoma HepG2 cells with mTOR overexpression. METHODS: The stable expression of mTOR in HepG2 cells (HepG2/mTOR+) were established by lipofectin transfection of GV238-mTOR recombinant plasmids and further antibiotic selection. Human hepatic carcinoma HepG2/mTOR+ cells were treated with different concentrations (20, 40, 80, 160, and 320 µg/mL) of COE for 24 h. The cell proliferation upon COE treatment was detected by MTT. Apoptosis was measured by Flow Cytometry. The activity of mTOR signaling pathway was detected by Western Blotting. RESULTS: COE significantly inhibited the proliferation of HepG2/mTOR+ cells. The expression levels of Bax and Caspase-3 protein were increased in the HepG2/mTOR+ cells in a dose-dependent manner. The proteins expression of Bcl2, Bcl-2 L12, mTOR, phospho-mTOR, 4EBP1, phospho-4EBP1, P70S6k, and phospho-P70S6k in HepG2/mTOR+ cells were reduced in dose-dependent manners. Furthermore, COE and mTOR inhibitor rapamycin (RAPA) synergistically induced apoptosis in HepG2/mTOR+ cells by regulating apoptosis-related proteins and inhibiting mTOR signaling pathways. CONCLUSION: COE could inhibit the proliferation of HepG2/mTOR+ cells, and induce the cell apoptosis. The mechanisms may be related to the regulation of the expression of Bcl-2, Bcl-2 L12, and mTOR signaling pathways. These data suggest that COE may be a potential treatment for human hepatocellular carcinoma.

Synthesis and preliminary biological evaluation of a 99m Tc-chlorambucil derivative as a potential tumor imaging agent.

Technetium-99m-based radiopharmaceuticals have been used widely as diagnostic agents in the nuclear medicine. Chlorambucil (CLB) as one typical alkylating drug exhibits excellent inhibition effects against many human malignancies. To develop and explore a novel potential imaging agent for early diagnosis of tumors, tricarbonyl technetium-99m and rhenium complexes on the basis of the tridentate ligand dipicolylamine (DPA) bound to the chlorambucil pharmacophore were designed and synthesized: 99m Tc-DPA-CLB (3) and Re-DPA-CLB (4). The high performance liquid chromatography analyses showed that the retention time of 3 and 4 was 13.5 and 13.6 minutes, respectively. Radiolabeling efficiency of the 99m Tc-DPA-CLB tracer was 97%, and the radiochemical purity was larger than 95% after 6 hours stored in phosphate buffered saline or human serum as observed by thin layer chromatography and high performance liquid chromatography. Biodistribution studies in a mouse model of breast cancer showed 99m Tc-DPA-CLB exhibited a favorable tumor affinity. The radiotracer cleared quickly in the first hour via hepatobiliary and renal routes of excretion, resulted in a very low background at 4 hours post injection (p.i.). It had moderate uptake ratios of tumor to blood and tumor to muscle. These results suggested 99m Tc-DPA-CLB might be a promising SPECT imaging agent for tumor diagnosis.

Correlation analysis of risk factors for cervical lymphatic metastasis in papillary thyroid carcinoma.

OBJECTIVE: This study aims to identify and analyze the risk factors associated with Cervical Lymph Node Metastasis (CNM) in Papillary Thyroid Carcinoma (PTC) patients. METHODS: We conducted a retrospective study involving the clinicopathological data of 2384 PTC patients admitted to our hospital between January 2016 and December 2020. All relevant data were statistically processed and analyzed. RESULTS: The related risk factors for Central Lymph Node Metastasis (CLNM) were gender (male), age (≤ 30 years old), tumor lesion size (> 0.855 cm), and multifocal tumor foci. The ROC curve revealed that the critical value for predicting CLNM based on tumor lesion size was 0.855 (sensitivity = 57.9%, specificity = 69%, AUC = 0.269, and P < 0.05). Lateral Lymph Node Metastasis (LLNM) was positively correlated with tumor diameter. Specifically, the LLNM rate increased with the tumor diameter. LLNM occurrence was significantly higher in zones II, III, and IV than in zones I and V. Although the BRAF gene mutation detection assay has certain clinical benefits in diagnosing PTC and LLNM, no statistically significant difference was found in its relationship with central and lateral neck lymph node metastases (P = 0.741). CONCLUSION: Our findings revealed that CLNM is associated with gender (male), age (≤ 30 years old), tumor lesion size (> 0.855 cm), and multiple tumor lesions in PTC patients. Central Lymph Node Dissection (CLND) is recommended for patients with these risk factors. On the other hand, preoperative ultrasound examination, fine-needle pathological examination, and genetic testing should be used to determine whether Lateral Cervical Lymph Node Dissection (LLND) is needed.

Chromosome balanced translocation in newborn fetus founded during prenatal diagnosis: Three cases reports.

RATIONALE: Because of the normal phenotype, carriers of specific chromosomal translocations are often diagnosed only after their development of associated malignancies, recurrent miscarriages, and reproductive difficulties. In this paper, we report primary balanced fetal chromosomal translocations by performing the necessary invasive prenatal diagnosis in couples with previous malformations coupled with prenatal testing suggesting a high risk for trisomy 21. PATIENT CONCERNS: Case 1 and Case 2 couples had malformed children, and Case 3 couples had a high risk of trisomy 21 on noninvasive preconception serological testing. DIAGNOSIS AND INTERVENTION: A balanced chromosomal translocation diagnosis was confirmed by karyotyping of fetal cells obtained by amniocentesis. OUTCOMES: All 3 couples decided to continue their pregnancies after learning about the consequences of the chromosomal abnormalities. Approximately a year after the children were born, the staff of the Prenatal Diagnostic Center followed up with a phone call and found that the children physical development and intelligence were normal. LESSON: This case report reports healthy chromosomal balanced translocation newborns born to couples with poor maternal history and couples with abnormalities suggested by preconception testing, and followed up with the newborns to provide some experience in prenatal diagnosis and genetic counseling for chromosomal balanced translocations.

Analysis of genome-wide association studies of low-temperature germination in Xian and Geng rice.

Rice is the leading global staple crop. Low temperatures pose negative impacts on rice's optimal growth and development. Rice cultivars acclimating to low temperatures exhibited improved seedling emergence under direct-seeded sowing conditions, yet little is known about the genes that regulate germination at low temperatures (LTG). In this research investigation, we've performed whole genome sequencing for the 273 rice plant materials. Using the best linear unbiased prediction (BLUP) values for each rice material, we identified 7 LTG-related traits and performed the efficient genetic analysis and genome-wide association study (GWAS). As a result of this, 95 quantitative trait loci (QTLs) and 1001 candidate genes associated with LTG in rice were identified. Haplotype analysis and functional annotation of the candidate genes resulted in the identification of three promising candidate genes (LOC_Os08g30520 for regulating LTG4 and LTG5, LOC_Os10g02625 for regulating LTG6, LTg7 and LTG8, and LOC_Os12g31460 for regulating LTG7, LTg8 and LTG9) involving in the regulation of LTG in rice. This research provides a solid foundation for addressing the LTG issue in rice and will be valuable in future direct-seeded rice breeding programs.

[Retracted] Celastrus orbiculatus extracts induce apoptosis and inhibit invasion by targeting the maspin gene in human gastric adenocarcinoma cells.

[This retracts the article DOI: 10.3892/ol.2017.7341.].

Genome-Wide Association Study of Xian Rice Grain Shape and Weight in Different Environments.

Drought is one of the key environmental factors affecting the growth and yield potential of rice. Grain shape, on the other hand, is an important factor determining the appearance, quality, and yield of rice grains. Here, we re-sequenced 275 Xian accessions and then conducted a genome-wide association study (GWAS) on six agronomic traits with the 404,411 single nucleotide polymorphisms (SNPs) derived by the best linear unbiased prediction (BLUP) for each trait. Under two years of drought stress (DS) and normal water (NW) treatments, a total of 16 QTLs associated with rice grain shape and grain weight were detected on chromosomes 1, 2, 3, 4, 5, 7, 8, 11, and 12. In addition, these QTLs were analyzed by haplotype analysis and functional annotation, and one clone (GSN1) and five new candidate genes were identified in the candidate interval. The findings provide important genetic information for the molecular improvement of grain shape and weight in rice.

Genome-wide association and epistasis studies reveal the genetic basis of saline-alkali tolerance at the germination stage in rice.

Introduction: Saline-alkali stress is one of the main abiotic factors limiting rice production worldwide. With the widespread use of rice direct seeding technology, it has become increasingly important to improve rice saline-alkali tolerance at the germination stage. Methods: To understand the genetic basis of saline-alkali tolerance and facilitate breeding efforts for developing saline-alkali tolerant rice varieties, the genetic basis of rice saline-alkali tolerance was dissected by phenotyping seven germination-related traits of 736 diverse rice accessions under the saline-alkali stress and control conditions using genome-wide association and epistasis analysis (GWAES). Results: Totally, 165 main-effect quantitative trait nucleotides (QTNs) and 124 additional epistatic QTNs were identified as significantly associated with saline-alkali tolerance, which explained a significant portion of the total phenotypic variation of the saline-alkali tolerance traits in the 736 rice accessions. Most of these QTNs were located in genomic regions either harboring saline-alkali tolerance QTNs or known genes for saline-alkali tolerance reported previously. Epistasis as an important genetic basis of rice saline-alkali tolerance was validated by genomic best linear unbiased prediction in which inclusion of both main-effect and epistatic QTNs showed a consistently better prediction accuracy than either main-effect or epistatic QTNs alone. Candidate genes for two pairs of important epistatic QTNs were suggested based on combined evidence from the high-resolution mapping plus their reported molecular functions. The first pair included a glycosyltransferase gene LOC_Os02g51900 (UGT85E1) and an E3 ligase gene LOC_Os04g01490 (OsSIRP4), while the second pair comprised an ethylene-responsive transcriptional factor, AP59 (LOC_Os02g43790), and a Bcl-2-associated athanogene gene, OsBAG1 (LOC_Os09g35630) for salt tolerance. Detailed haplotype analyses at both gene promoter and CDS regions of these candidate genes for important QTNs identified favorable haplotype combinations with large effects on saline-alkali tolerance, which can be used to improve rice saline-alkali tolerance by selective introgression. Discussion: Our findings provided saline-alkali tolerant germplasm resources and valuable genetic information to be used in future functional genomic and breeding efforts of rice saline-alkali tolerance at the germination stage.

Identification of a monoclonal antibody clipping variant by cross-validation using capillary electrophoresis - sodium dodecyl sulfate, capillary zone electrophoresis - mass spectrometry and capillary isoelectric focusing - mass spectrometry.

Critical quality attributes (CQAs) of recombinant monoclonal antibody therapeutics are constantly monitored throughout the life cycle of drug development and manufacturing. In the past few decades, numerous analytical techniques have been developed for the characterization of CQAs. In this regard, non-reduced and reduced capillary electrophoresis - sodium dodecyl sulfate (CE-SDS) methods have been widely adopted by the biopharmaceutical industry for the evaluation of size-related heterogeneities in biologics. In this work we demonstrate that, with recent development of capillary electrophoresis - mass spectrometry (CE-MS) technologies, a clipping variant of bevacizumab may be identified directly by both capillary zone electrophoresis - mass spectrometry (CZE-MS) and capillary isoelectric focusing - mass spectrometry (cIEF-MS) approaches, providing a powerful addition to the traditional CE-SDS analysis workflow. In this novel workflow, linear regression between the mobility and molecular weight first results in an approximate size range of this variant. The intact masses of all species in the bevacizumab are then obtained, after deconvolution of all features identified in the CZE-MS analysis. Subsequent  CZE-MS analysis of the subunits of bevacizumab leads to the confirmation of a clipped heavy chain. Furthermore, cIEF-MS of the intact bevacizumab confirms the existence of this clipping variant. The cross-validation between CE-SDS, CZE-MS, and cIEF-MS, creates a comprehensive roadmap for monoclonal antibody size variants profiling. These CE-based analytical techniques are complementary to each other, leading to orthogonal verification for size heterogeneity characterization.

One-step 18F-fluorination of smart positron emission tomography tracer for sensing furin activity in tumors.

INTRODUCTION: Peptide analogues have attracted considerable attention in the field of developing novel positron emission tomography (PET) imaging agents due to their unique properties. Nevertheless, the complicated radiolabeling process and fast metabolism usually pose challenges to the clinical applications of peptide-based molecular probes. Herein a novel PET tracer containing a specific peptide sequence Arg-Val-Arg-Arg (RVRR), Acetyl-Arg-Val-Arg-Arg-Cys(StBu)-Gly(AMB[18F]F3)-CBT ([18F]1), was designed and radiosynthesized using a simple and convenient one-step 18F-fluorination procedure. The smart tracer can be activated by the protease furin and then undergoes an intermolecular cyclization reaction in tumor cells, leading to improved PET imaging efficiency of tumor. METHODS: The radiosynthesis of the target tracer [18F]1 and the control tracer [18F]1-ctrl was performed under facile conditions in pyridazine-HCl buffer (pH~2.5) at 80 °C within 30 min. The enzyme-controlled condensation was studied for non-radioactive compound 1 in the human breast cancer cell lysates (MDA-MB-468). The cellular uptake of [18F]1 and [18F]1-ctrl was studied and compared by measuring the activity in MDA-MB-468 cells using a γ-counter after incubation with 37 kBq of [18F]1 or [18F]1-ctrl, respectively. In vivo behavior of [18F]1 was examined through PET imaging of MDA-MB-468 tumor-bearing mice and compared with that of [18F]1-ctrl as well as that of [18F]1 co-injected with non-radioactive compound 1. RESULTS: The tracer [18F]1 was obtained with a high radiochemical yield (RCY) of 42.5 ± 1.47% and an excellent radiochemical purity (RCP > 99%). Under the activation of furin and GSH, the tracer suffered a condensation reaction to form dimers and then self-assembled into nanoparticles to produce enduring signal. The cellular uptake of [18F]1 and [18F]1-ctrl was determined to be 10.2 ± 0.37 and 1.19 ± 0.25%ID at 120 min, respectively. For in vivo PET imaging, [18F]1 exhibited the optimum tumor uptake of 2.39 ± 0.31%ID/g and the tumor-to-muscle uptake ratio of 2.93 ± 0.92 at 10 min post injection. Co-injection of [18F]1 and non-radioactive compound 1 produced a high tumor uptake ranging from 2.83 ± 0.23%ID/g to 3.40 ± 0.18%ID/g at 10 min and 60 min post injection, respectively. CONCLUSIONS: The one-step labeling method of tracer [18F]1 showed advantage in simplifying the radiolabeling process with high RCY, which could enable a real kit process for the synthesis of 18F-radiopharmaceuticals and was significant for the large-scale production of tracers for clinical applications. PET imaging results suggested that the tracer [18F]1 had good tumor uptake and the co-injection strategy of [18F]1 with 1 could enhance the imaging signal in tumor.