Noble metal nanoparticle-based localized surface plasmon resonance (LSPR) is an advanced and powerful label-free biosensing technique which is well-known for its high sensitivity to the surrounding ...refractive index change in the local environment caused by the biomolecular interactions around the sensing area. The characteristics of the LSPR effect in such sensors are highly dependent on the size, shape and nature of the material properties of the metallic nanoparticles considered. Among the various types of metallic nanoparticles used in studies employing the LSPR technique, the use of gold nanorods (GNRs) has attracted particular attention for the development of sensitive LSPR biosensors, this arising from the unique and intriguing optical properties of the material. This paper provides a detailed review of the key underpinning science for such systems and of recent progress in the development of a number of LSPR-based biosensors which use GNR as the active element, including an overview of the sensing principle, the synthesis of GNRs, the fabrication of a number of biosensors, techniques for surface modification of GNRs and finally their performance in several biosensing applications. The review ends with a consideration of key advances in GNR-based LSPR sensing and prospects for future research and advances for the development of the GNR-based LSPR biosensors.
G-protein-coupled receptors (GPCRs) can modulate diverse signaling pathways, often in a ligand-specific manner. The full range of functionally relevant GPCR conformations is poorly understood. Here, ...we use NMR spectroscopy to characterize the conformational dynamics of the transmembrane core of the β2-adrenergic receptor (β2AR), a prototypical GPCR. We labeled β2AR with 13CH3ε-methionine and obtained HSQC spectra of unliganded receptor as well as receptor bound to an inverse agonist, an agonist, and a G-protein-mimetic nanobody. These studies provide evidence for conformational states not observed in crystal structures, as well as substantial conformational heterogeneity in agonist- and inverse-agonist-bound preparations. They also show that for β2AR, unlike rhodopsin, an agonist alone does not stabilize a fully active conformation, suggesting that the conformational link between the agonist-binding pocket and the G-protein-coupling surface is not rigid. The observed heterogeneity may be important for β2AR’s ability to engage multiple signaling and regulatory proteins.
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► NMR using 13CH3-ε-Met reveals dynamics of β2 adrenergic receptor (β2AR) ► NMR and computational approaches show unanticipated conformational states ► Conformational heterogeneity is observed in both unliganded and antagonist-bound β2AR ► Agonist alone does not fully stabilize the active conformation of the β2AR
NMR studies reveal that β2 adrenergic receptor experiences conformational heterogeneity until both agonist and a G protein mimetic bind, shifting the receptor into its active conformation.
Ubiquitin-conjugating enzyme E2C (UBE2C) has been shown to be associated with the occurrence of various cancers and involved in many tumorigenic processes. This study aimed to investigate the ...specific molecular mechanism through which UBE2C affects breast cancer (BC) proliferation.
BC-related datasets were screened according to filter criteria in the Gene Expression Omnibus (GEO) database and The Cancer Genome Atlas (TCGA) database. Then differentially expressed genes (DEGs) were identified using Venn diagram analysis. By using DEGs, we conducted the following analyses including Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), protein-protein interaction (PPI), and survival analysis, and then validated the function of the hub gene UBE2C using quantitative reverse transcription-polymerase chain reaction (RT-qPCR), cell counting kit-8 (CCK-8) assay, transwell assay, and Western blot assay.
In total, 151 DEGs were identified from the GEO and TCGA databases. The results of GO analysis demonstrated that the DEGs were significantly enriched with mitotic nuclear division, lipid droplet, and organic acid-binding. KEGG analysis showed that the peroxisome proliferators-activated receptor (PPAR) signaling pathway, regulation of lipolysis in adipocytes, and proximal tubule bicarbonate reclamation were significantly enriched in the signal transduction pathway category. The top three hub genes that resulted from the PPI network were FOXM1, UBE2C, and CDKN3. The results of survival analysis showed a close relationship between UBE2C and BC. The results of CCK-8 and transwell assays suggested that the proliferation and invasion of UBE2C knockdown cells were significantly inhibited (P < 0.050). The results of Western blot assay showed that the level of phosphorylated phosphatase and tensin homology deleted on chromosome 10 (p-PTEN) was obviously increased (P < 0.050), whereas the levels of phosphorylated protein kinase B (p-AKT), phosphorylated mammalian target of rapamycin (p-mTOR), and hypoxia-inducible factor-1 alpha (HIF-1α) were dramatically decreased (P < 0.050) in the UBE2C knockdown cell.
UBE2C can promote BC proliferation by activating the AKT/mTOR signaling pathway.
In the snake-infested mountainous regions of China, Saxifraga stolonifera L. Meeb is widely utilized as an immediate remedy for venomous snake bites. However, the scientific understanding of S. ...stolonifera's efficacy in snakebite treatment remains limited and requires further investigation.
The aim of this study was to assess the inhibitory effects of Saxifraga stolonifera phenolic extracts (SSPE) on Deinagkistrodon acutus venom (DAV) and explore the potential of S. stolonifera as a valuable candidate for antivenom development.
We employed our previously optimized extraction conditions to obtain SSPE. In vitro experiments utilizing diverse models were conducted to assess the inhibitory effects of the extracted phenolic compounds on DAV, specifically targeting phospholipase A2 (PLA2), proteolytic, fibrinolytic, and hyaluronidase enzymes. Furthermore, in vivo investigations were conducted to evaluate the inhibitory potential of the extracted compounds against DAV-induced hemorrhagic and edematogenic activity. To elucidate the chemical composition of the phenolic extracts, Ultra Performance Liquid Chromatography-mass spectrometry (UPLC-MS) analysis was performed.
Our in vitro inhibition study showed that S. stolonifera was able to inhibit the activities of PLA2 enzyme, proteolytic enzyme, hyaluronidase and fibrinogenolytic. The median effective dose (ED50) values of SSPE for inhibiting PLA2 enzyme, proteolytic enzyme and hyaluronidase activities were 0.115 mg/mL, 0.026 mg/mL and 0.238 mg/mL, respectively. The DAV-induced hemorrhagic and edematogenic effects of the SSPE were also successfully inhibited in vivo, and the high SSPE concentration was able to completely inhibit the hemorrhage and edema. It is noteworthy that the mice suffered no harm from the high SSPE concentration. The composition analysis showed that the phenolic substances contained in SSPE are gallic acid, protocatechuic acid, chlorogenic acid, rutin, kaempferol-3-O-ɑ-L-rhamnoside, kaempferol-3-O-β-D-glucopyranoside, quercetin and kaempferol.
This study provides scientific validation of the inhibitory efficacy of S. stolonifera as an emergency treatment for venomous snake bites, offering a theoretical foundation for future drug development strategies targeting snakebite.
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•Inhibitory effect of S. stolonifera on Deinagkistrodon acutus venom was evaluated.•Phenolics were found to be significant contributors to anti-venom activity.•Analyze qualitatively the phenolic composition of the S. stolonifera extract.•Saxifraga stolonifera is a promising natural antivenom source.
To assess the relationship between novel insulin resistance (IR) indices and the presence and severity of diabetic retinopathy (DR) in patients with type 2 diabetes.
This is a cross-sectional study ...involving 2211 patients. The study outcomes were DR events. The study exposures were IR indices including estimated glucose disposal rate (eGDR), natural logarithm of glucose disposal rate (lnGDR), metabolic insulin resistance score (METS-IR), triglyceride glucose index-body mass index (TyG-BMI), triglyceride glucose index-waist-to-hip ratio (TyG-WHR), and triglyceride/high-density lipoprotein cholesterol(TG/HDL-c ratio). We used binary and multivariate ordered logistic regression models to estimate the association between different IR indices and the presence and severity of DR. Subject work characteristic curves were used to assess the predictive power of different IR indices for DR.
DR was present in 25.4% of participants. After adjusting for all covariates, per standard deviation (SD) increases in eGDR (ratio OR 0.38 95% CI 0.32-0.44), lnGDR (0.34 0.27-0.42) were negatively associated with the presence of DR. In contrast, per SD increases in METS-IR (1.97 1.70-2.28), TyG-BMI (1.94 1.68-2.25), TyG-WHR (2.34 2.01-2.72) and TG/HDL-c ratio (1.21 1.08-1.36) were positively associated with the presence of DR. eGDR was strongly associated with severity of DR. Of all variables, eGDR had the strongest diagnostic value for DR (AUC = 0.757).
Of the six IR indices, eGDR was significantly associated with the presence and severity of DR in patients with type 2 diabetes. eGDR has a good predictive value for DR. Thus, eGDR maybe a stronger marker of DR.
With the advance in science and technology as well as the improvement of living standards, the function of food is no longer just to meet the needs of survival. Food science and its associated ...nutritional health issues have been increasingly debated. Lipids, as complex metabolites, play a key role both in food and human health. Taking advantages of mass spectrometry (MS) by combining its high sensitivity and accuracy with extensive selective determination of all lipid classes, MS‐based lipidomics has been employed to resolve the conundrum of addressing both qualitative and quantitative aspects of high‐abundance and low‐abundance lipids in complex food matrices. In this review, we systematically summarize current applications of MS‐based lipidomics in food field. First, common MS‐based lipidomics procedures are described. Second, the applications of MS‐based lipidomics in food science, including lipid composition characterization, adulteration, traceability, and other issues, are discussed. Third, the application of MS‐based lipidomics for nutritional health covering the influence of food on health and disease is introduced. Finally, future research trends and challenges are proposed. MS‐based lipidomics plays an important role in the field of food science, promoting continuous development of food science and integration of food knowledge with other disciplines. New methods of MS‐based lipidomics have been developed to improve accuracy and sensitivity of lipid analysis in food samples. These developments offer the possibility to fully characterize lipids in food samples, identify novel functional lipids, and better understand the role of food in promoting healt.
G-protein-coupled receptors (GPCRs) transduce signals from the extracellular environment to intracellular proteins. To gain structural insight into the regulation of receptor cytoplasmic ...conformations by extracellular ligands during signaling, we examine the structural dynamics of the cytoplasmic domain of the β2-adrenergic receptor (β2AR) using 19F-fluorine NMR and double electron-electron resonance spectroscopy. These studies show that unliganded and inverse-agonist-bound β2AR exists predominantly in two inactive conformations that exchange within hundreds of microseconds. Although agonists shift the equilibrium toward a conformation capable of engaging cytoplasmic G proteins, they do so incompletely, resulting in increased conformational heterogeneity and the coexistence of inactive, intermediate, and active states. Complete transition to the active conformation requires subsequent interaction with a G protein or an intracellular G protein mimetic. These studies demonstrate a loose allosteric coupling of the agonist-binding site and G-protein-coupling interface that may generally be responsible for the complex signaling behavior observed for many GPCRs.
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•Two inactive states predominate in unliganded and antagonist-bound β2AR•Agonists increase structural heterogeneity in β2AR cytoplasmic domains•The agonist-binding pocket and cytoplasmic surface have weak allosteric coupling•Complete receptor activation requires G protein or a mimetic nanobody
A combination of spectroscopic methods examining the dynamics and structure of the β2-adrenergic receptor reveals a loose allosteric coupling of the agonist-binding site and G-protein-coupling interface that shapes downstream signaling pathways.
The opioid receptor family comprises three members, the µ-, δ- and κ-opioid receptors, which respond to classical opioid alkaloids such as morphine and heroin as well as to endogenous peptide ligands ...like endorphins. They belong to the G-protein-coupled receptor (GPCR) superfamily, and are excellent therapeutic targets for pain control. The δ-opioid receptor (δ-OR) has a role in analgesia, as well as in other neurological functions that remain poorly understood. The structures of the µ-OR and κ-OR have recently been solved. Here we report the crystal structure of the mouse δ-OR, bound to the subtype-selective antagonist naltrindole. Together with the structures of the µ-OR and κ-OR, the δ-OR structure provides insights into conserved elements of opioid ligand recognition while also revealing structural features associated with ligand-subtype selectivity. The binding pocket of opioid receptors can be divided into two distinct regions. Whereas the lower part of this pocket is highly conserved among opioid receptors, the upper part contains divergent residues that confer subtype selectivity. This provides a structural explanation and validation for the 'message-address' model of opioid receptor pharmacology, in which distinct 'message' (efficacy) and 'address' (selectivity) determinants are contained within a single ligand. Comparison of the address region of the δ-OR with other GPCRs reveals that this structural organization may be a more general phenomenon, extending to other GPCR families as well.
G protein coupled receptors (GPCRs) exhibit a spectrum of functional behaviors in response to natural and synthetic ligands. Recent crystal structures provide insights into inactive states of several ...GPCRs. Efforts to obtain an agonist-bound active-state GPCR structure have proven difficult due to the inherent instability of this state in the absence of a G protein. We generated a camelid antibody fragment (nanobody) to the human β
2
adrenergic receptor (β
2
AR) that exhibits G protein-like behavior, and obtained an agonist-bound, active-state crystal structure of the receptor-nanobody complex. Comparison with the inactive β
2
AR structure reveals subtle changes in the binding pocket; however, these small changes are associated with an 11Å outward movement of the cytoplasmic end of transmembrane segment 6, and rearrangements of transmembrane segments 5 and 7 that are remarkably similar to those observed in opsin, an active form of rhodopsin. This structure provides insights into the process of agonist binding and activation.
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