Enabling Modular Click Chemistry Library through Sequential Ligations of Carboxylic Acids and Amines.

High-throughput synthesis and screening of chemical libraries play pivotal roles in drug discovery. Click chemistry has emerged as a powerful strategy for constructing highly modular chemical libraries. However, the development of new click reactions and unlocking new clickable building blocks remain exceedingly challenging. Herein, we describe a double-click strategy that enables the sequential ligations of widely available carboxylic acids and amines with fluorosulfuryl isocyanate (FSO2NCO) via a modular amidation/SuFEx (sulfur-fluoride exchange) process. This method provides facile access to chemical libraries of N-fluorosulfonyl amides (RCONHSO2F) and N-acylsulfamides (RCONHSO2NR'R'') in near-quantitative yields under simple and practical conditions. The robustness and efficiency of this double click strategy is showcased by the facile construction of chemical libraries in 96-well microtiter plates from a large number of carboxylic acids and amines. Preliminary biological activity screening reveals that some compounds exhibit high antimicrobial activities against Gram-positive bacterium S. aureus and drug-resistant MRSA (MIC up to 6.25 µg ⋅ mL-1). These results provide compelling evidence for the potential application of modular click chemistry library as an enabling technology in high-throughput medicinal chemistry.

An adaptive kernel dictionary-based low-rank representation method for subspace clustering.

Low-rank representation (LRR) is a classic subspace clustering (SC) algorithm, and many LRR-based methods have been proposed. Generally, LRR-based methods use denoized data as dictionaries for data reconstruction purpose. However, the dictionaries used in LRR-based algorithms are fixed, leading to poor clustering performance. In addition, most of these methods assume that the input data are linearly correlated. However, in practice, data are mostly nonlinearly correlated. To address these problems, we propose a novel adaptive kernel dictionary-based LRR (AKDLRR) method for SC. Specifically, to explore nonlinear information, the given data are mapped to the Hilbert space via the kernel technique. The dictionary in AKDLRR is not fixed; it adaptively learns from the data in the kernel space, making AKDLRR robust to noise and yielding good clustering performance. To solve the AKDLRR model, an efficient procedure including an alternative optimization strategy is proposed. In addition, a theoretical analysis of the convergence performance of AKDLRR is presented, which reveals that AKDLRR can converge in at most three iterations under certain conditions. The experimental results show that AKDLRR can achieve the best clustering performance and has excellent speed in comparison with other algorithms.

Robust Least Squares Regression for Subspace Clustering: A Multi-View Clustering Perspective.

Recently, with the assumption that samples can be reconstructed by themselves, subspace clustering (SC) methods have achieved great success. Generally, SC methods contain some parameters to be tuned, and different affinity matrices can obtain with different parameter values. In this paper, for the first time, we study a method for fusing these different affinity matrices to promote clustering performance and provide the corresponding solution from a multi-view clustering (MVC) perspective. That is, we argue that the different affinity matrices are consistent and complementary, which is similar to the fundamental assumption of MVC methods. Based on this observation, in this paper, we use least squares regression (LSR), which is a typical SC method, as an example since it can be efficiently optimized and has shown good clustering performance and we propose a novel robust least squares regression method from an MVC perspective (RLSR/MVCP). Specifically, we first utilize LSR with different parameter values to obtain different affinity matrices. Then, to fully explore the information contained in these different affinity matrices and to remove noise, we further fuse these affinity matrices into a tensor, which is constrained by the tensor low-rank constraint, i.e., the tensor nuclear norm (TNN). The two steps are combined into a framework that is solved by the augmented Lagrange multiplier (ALM) method. The experimental results on several datasets indicate that RLSR/MVCP has very encouraging clustering performance and is superior to state-of-the-art SC methods.

Discovery, biosynthesis, organic synthesis, and bioactivities of meroterpenoids from Rhododendron species.

Meroterpenoids discovered in Rhododendrons species possess unique chemical structures and biological activities and are expected to become new drug targets for Alzheimer's disease, metabolic disorders, and chronic kidney disease, and these compounds have attracted increasing attention in recent years. In this study, Rhododendron meroterpenoids and their structures, classifications, racemate distribution, biosynthetic pathways, chemical synthesis, and bioactivities are reviewed prior to 2023.

Pulmonary Hypertension Induces Serotonin Hyperreactivity and Metabolic Reprogramming in Coronary Arteries via NOX1/4-TRPM2 Signaling Pathway.

BACKGROUND: Clinical evidence revealed abnormal prevalence of coronary artery (CA) disease in patients with pulmonary hypertension (PH). The mechanistic connection between PH and CA disease is unclear. Serotonin (5-hydroxytryptamine), reactive oxygen species, and Ca2+ signaling have been implicated in both PH and CA disease. Our recent study indicates that NOXs (NADPH [nicotinamide adenine dinucleotide phosphate] oxidases) and TRPM2 (transient receptor potential cation channel subfamily M member 2) are key components of their interplay. We hypothesize that activation of the NOX-TRPM2 pathway facilitates the remodeling of CA in PH. METHODS: Left and right CAs from chronic hypoxia and monocrotaline-induced PH rats were collected to study vascular reactivity, gene expression, metabolism, and mitochondrial function. Inhibitors or specific siRNA were used to examine the pathological functions of NOX1/4-TRPM2 in CA smooth muscle cells. RESULTS: Significant CA remodeling and 5-hydroxytryptamine hyperreactivity in the right CA were observed in PH rats. NOX1/4-mediated reactive oxygen species production coupled with TRPM2-mediated Ca2+ influx contributed to 5-hydroxytryptamine hyperresponsiveness. CA smooth muscle cells from chronic hypoxia-PH rats exhibited increased proliferation, migration, apoptosis, and metabolic reprogramming in an NOX1/4-TRPM2-dependent manner. Furthermore, the NOX1/4-TRPM2 pathway participated in mitochondrial dysfunction, involving mitochondrial DNA damage, reactive oxygen species production, elevated mitochondrial membrane potential, mitochondrial Ca2+ accumulation, and mitochondrial fission. In vivo knockdown of NOX1/4 alleviated PH and suppressed CA remodeling in chronic hypoxia rats. CONCLUSIONS: PH triggers an increase in 5-hydroxytryptamine reactivity in the right CA and provokes metabolic reprogramming and mitochondrial disruption in CA smooth muscle cells via NOX1/4-TRPM2 activation. This signaling pathway may play an important role in CA remodeling and CA disease in PH.

[The Optimal Storage Condition and Storage Time of Umbilical Cord Blood from Collection to Preparation].

OBJECTIVE: To explore the optimal storage condition and time of umbilical cord blood from collection to preparation. METHODS: Collect cord blood samples from 30 healthy newborns, with each new born's umbilical cord blood was divided into two parts on average. One part was stored in cold storage (4 ℃) and the other was stored at room temperature (20-24 ℃). Samples were taken at 24, 36, 48, 60 and 72 h, respectively, total nucleated cells (TNC) count and TNC viability was analyzed. Flow cytometry was used to detect the ratio of viable CD34+ cells to viable CD45+ cells and viability of CD34+ cells, and colony-forming unit-granulocyte-macrophage (CFU-GM) count was performed by hematopoietic progenitor cell colony culture. The change trend of each index over time was observed, and the differences in each index was compared between cold storage and room temperature storage under the same storage time. RESULTS: The TNC count (r 4 ℃=-0.9588， r 20-24 ℃=-0.9790), TNC viability (r 4 ℃=-0.9941， r 20-24 ℃=-0.9970), CD34+ cells viability (r 4 ℃=-0.9932， r 20-24 ℃=-0.9828) of cord blood stored in cold storage (4 ℃) and room temperature storage (20-24 ℃) showed a consistent downward trend with the prolongation of storage time. The percentage of viable CD34+ cells (r 4 ℃=0.9169， r 20-24 ℃=0.7470) and CFU-GM count (r 4 ℃=-0.2537， r 20-24 ℃=-0.8098) did not show consistent trends. When the storage time was the same, the TNC count, TNC viability, CD34+ cells viability and CFU-GM count of cord blood stored in cold storage were higher than those stored at room temperature. Under the same storage time (24, 36, 48, 60 or 72 h), TNC viability in room temperature storage was significantly lower than that in cold storage (P <0.001), but TNC count, percentage of viable CD34+ cells and CFU-GM count were not significantly different between room temperature storage and cold storage. When stored at room temperature for 24 h and 36 h, the viability of CD34+ cells was significantly lower than that in cold storage (P <0.001, P <0.01), when the storage time for 48, 60 and 72 h, there was no significant difference in the CD34+ cells viability between room temperature storage and cold storage. CONCLUSION: It is recommended that cord blood be stored in cold storage (4 ℃) from collection to preparation, and processed as soon as possible.

Right ventricular volume and function by three-dimensional echocardiography: results of the echocardiographic measurements in normal Chinese adults (EMINCA) II.

Three-dimensional (3D) echocardiography is an emerging technique for assessing right ventricular (RV) volume and function, but 3D-RV normal values from a large Chinese population are still lacking. The aim of the present study was to establish normal values of 3D-RV volume and function in healthy Chinese volunteers. A total of 1117 Han Chinese volunteers from 28 laboratories in 20 provinces of China were enrolled, and 3D-RV images of 747 volunteers with optimal image quality were ultimately analyzed by a core laboratory. Both vendor-dependent and vendor-independent software platforms were used to analyze the 3D-RV images. We found that men had larger RV volumes than women did in the whole population, even after indexing to body surface area, and older individuals had smaller RV volumes. The normal RV volume was significantly smaller than that recommended by the American Society of Echocardiography/European Association of Cardiovascular Imaging guidelines in both sexes. There were significant differences in 3D-RV measurements between the two vendor ultrasound systems and the different software platforms. The echocardiographic measurements in normal Chinese adults II study revealed normal 3D-RV volume and function in a large Chinese population, and there were significant differences between the sexes, ages, races, and vendor groups. Thus, normal 3D-RV values should be stratified by sex, age, race, and vendor.

Left ventricular global longitudinal strain using a novel fully automated method: A head-to-head comparison with a manual layer-specific strain and establishment of normal reference ranges.

BACKGROUND: A novel automated method for measuring left ventricular (LV) global longitudinal strain (GLS) along the endocardium has advantages in terms of its rapid application and excellent reproducibility. However, it remains unclear whether the available normal range for conventional GLS using the manual method is applicable to the automated GLS method. This study aimed to compare automated GLS head-to-head with manual layer-specific GLS, and to identify whether a specialized normal reference range for automated GLS is needed and explore the main determinants. METHODS: In total, 1683 healthy volunteers (men, 43%; age, 18-80 years) were prospectively enrolled from 55 collaborating laboratories. LV GLS was measured using both manual layer-specific and automated methods. RESULTS: Automated GLS was higher than endocardial, mid-myocardial, and epicardial GLS. Women had a higher automated GLS than men. GLS had no significant age dependency in men, but first increased and then decreased with age in women. Accordingly, sex- and age-specific normal ranges for automated GLS were proposed. Moreover, GLS appeared to have different burdens in relation to dominant determinants between the sexes. GLS in men showed no dominant determinants; however, GLS in women correlated with age, body mass index, and heart rate. CONCLUSIONS: Using the novel automated method, was LV GLS higher than when using the manual GLS method. The normal ranges of automated GLS stratified according to sex and age were provided, with dominant determinants showing sex disparities that require full consideration in clinical practice.

A simple and reliable PCR-restriction fragment length polymorphism assay to identify Candida albicans and its closely related Candida dubliniensis

Candida dubliniensis is an emerging pathogen capable of causing superficial as well as systemic infections. Due to its close similarity to C. albcians, conventional methods based on phenotypic traits are not always reliable in identification of C. dubliniensis. In this study, we developed a PCR-restriction fragment length polymorphism (RFLP) assay to identify and discriminate between the two closely related species. The D1/D2 region of 28S rDNA was amplified by PCR and enzymatically digested by ApaI and BsiEI respectively. PCR products of both species were digested into two fragments by ApaI, but those of other yeast species were undigested. BsiEI cut the PCR products of C. albicans into two fragments but not those of C. dubliniensis. Thus two species were differentiated. We evaluated 10 reference strains representing 10 yeast species, among which C. albicans and C. dubliniensis were successfully identified. A total of 56 phenotypically characterized clinical isolates (42 C. albicans isolates and 14 C. dubliniensis isolates) were also investigated for intra-species variability. All tested isolates produced identical RFLP patterns to their respective reference strains except one initially misidentified isolate. Our method offers a simple, rapid and reliable molecular method for the identification of C. albicans and C. dubliniensis.