Structural mechanism for specific binding of chemical compounds to amyloid fibrils.

Amyloid fibril is an important pharmaceutical target for diagnostic and therapeutic treatment of neurodegenerative diseases. However, rational design of chemical compounds that interact with amyloid fibrils is unachievable due to the lack of mechanistic understanding of the ligand-fibril interaction. Here we used cryoelectron microscopy to survey the amyloid fibril-binding mechanism of a series of compounds including classic dyes, (pre)clinical imaging tracers and newly identified binders from high-throughput screening. We obtained clear densities of several compounds in complex with an α-synuclein fibril. These structures unveil the basic mechanism of the ligand-fibril interaction, which exhibits remarkable difference from the canonical ligand-protein interaction. In addition, we discovered a druggable pocket that is also conserved in the ex vivo α-synuclein fibrils from multiple system atrophy. Collectively, these findings expand our knowledge of protein-ligand interaction in the amyloid fibril state, which will enable rational design of amyloid binders in a medicinally beneficial way.

Enantioselective Transformations in the Synthesis of Therapeutic Agents.

The proportion of approved chiral drugs and drug candidates under medical studies has surged dramatically over the past two decades. As a consequence, the efficient synthesis of enantiopure pharmaceuticals or their synthetic intermediates poses a profound challenge to medicinal and process chemists. The significant advancement in asymmetric catalysis has provided an effective and reliable solution to this challenge. The successful application of transition metal catalysis, organocatalysis, and biocatalysis to the medicinal and pharmaceutical industries has promoted drug discovery by efficient and precise preparation of enantio-enriched therapeutic agents, and facilitated the industrial production of active pharmaceutical ingredient in an economic and environmentally friendly fashion. The present review summarizes the most recent applications (2008-2022) of asymmetric catalysis in the pharmaceutical industry ranging from process scales to pilot and industrial levels. It also showcases the latest achievements and trends in the asymmetric synthesis of therapeutic agents with state of the art technologies of asymmetric catalysis.

Selective Manipulation of the Mitochondria Oxidative Stress in Different Cells Using Intelligent Mesoporous Silica Nanoparticles to Activate On-Demand Immunotherapy for Cancer Treatment.

Herein, the vitamin K2 (VK2)/maleimide (MA) coloaded mesoporous silica nanoparticles (MSNs), functional molecules including folic acid (FA)/triphenylphosphine (TPP)/tetrapotassium hexacyanoferrate trihydrate (THT), as well as CaCO3 are explored to fabricate a core-shell-corona nanoparticle (VMMFTTC) for on-demand anti-tumor immunotherapy. After application, the tumor-specific acidic environment first decomposed CaCO3 corona, which significantly levitates the pH value of tumor tissue to convert M2 type macrophage to the antitumor M1 type. The resulting VMMFTT would then internalize in both tumor cells and macrophages via FA-assisted endocytosis and free endocytosis, respectively. These distinct processes generate different amount of VMMFTT in above two cells followed by 1) TPP-induced accumulation in the mitochondria, 2) THT-mediated effective capture of various signal ions to cut off signal transmission and further inhibit glutathione (GSH) generation, 3) ions catalyzed reactive oxygen species (ROS) production through Fenton reaction, 4) sustained release of VK2 and MA to further enhance the ROS production and GSH depletion, which caused significant apoptosis of tumor cells and additional M2-to-M1 macrophage polarization via different processes of oxidative stress. Moreover, the primary tumor apoptosis further matures surrounding immature dendritic cells and activates T cells to continuously promote the antitumor immunotherapy.

Synergistic Regulation of Targeted Organelles in Tumor Cells to Promote Photothermal-Immunotherapy Using Intelligent Core-Satellite-Like Nanoparticles for Effective Treatment of Breast Cancer.

The normal operation of organelles is critical for tumor growth and metastasis. Herein, an intelligent nanoplatform (BMAEF) is fabricated to perform on-demand destruction of mitochondria and golgi apparatus, which also generates the enhanced photothermal-immunotherapy, resulting in the effective inhibition of primary and metastasis tumor. The BMAEF has a core of mesoporous silica nanoparticles loaded with brefeldin A (BM), which is connected to ethylenebis(oxyethylenenitrilo)tetraacetic acid (EGTA) and folic acid co-modified gold nanoparticles (AEF). During therapy, the BMAEF first accumulates in tumor cells via folic acid-induced targeting. Subsequently, the schiff base/ester bond cleaves in lysosome to release brefeldin A and AEF with exposed EGTA. The EGTA further captures Ca2+ to block ion transfer among mitochondria, endoplasmic reticulum, and golgi apparatus, which not only induced dysfunction of mitochondria and golgi apparatus assisted by brefeldin A to suppress both energy and material metabolism against tumor growth and metastasis, but causes AEF aggregation for tumor-specific photothermal therapy and photothermal assisted immunotherapy. Moreover, the dysfunction of these organelles also stops the production of BMI1 and heat shock protein 70 to further enhance the metastasis inhibition and photothermal therapy, which meanwhile triggers the escape of cytochrome C to cytoplasm, leading to additional apoptosis of tumor cells.

Enhancement of multilayer lithium storage in a ß12-borophene/graphene heterostructure with built-in dipoles.

The combination of borophene with a supporting metallic layer is beneficial in stabilizing its structure and promoting its application in energy storage. Here, through first-principles calculations, we screen a ß12-borophene/graphene (ß12-B/G) heterostructure with superior structural integrity, strong interlayer binding, and high thermodynamic stability among different B/G heterostructures. Besides, it is noteworthy that ß12-B/G has been recently synthesized, further opening the possibility of expanding its use in energy storage. Then the selected target is systematically investigated as an anode material for lithium-ion batteries (LIBs). Compared with each monolayer component, multiple lithium-ion adsorption is achieved in the ß12-B/G heterostructure, resulting in an ultra-high theoretical specific capacity of 2267 mA h g-1. In addition, a lower diffusion energy barrier indicates faster electron transport and lithium-ion diffusion in the ß12-B/G heterostructure. Notably, the multilayer lithium adsorption avoids the formation of dendritic deposits, as evidenced by complete ionization of the cationic layers. Moreover, the disparity in the work functions of the individual layers gives rise to a built-in dipole in ß12-B/G, further enhancing the multilayer lithium storage and ion migration. All these results suggest that the construction of borophene-based heterostructures with built-in dipoles is a feasible way to design high-performance LIB anode materials.

The Realities and Needs of Nursing Assistants Caring for Disabled Patients with Fecal Incontinence During Hospitalization: A Qualitative Study.

Objective: To explore the experience, role, and needs of medical nursing assistants during hospitalization in patients with incapacitated fecal incontinence. Methods: Qualitative study using reflexive thematic analysis. Semi-structured interviews were conducted with 21 medical nursing assistants from three hospitals in Southern China. Results: Four themes were constructed from the data: (1) Role perception. All participants described the multiple roles they played during care and knowledge and familiarity with the roles were seen as providing high-quality care to patients. (2) Career cognition. Overall, participants had a positive view of nurse assistants as a career. They believed that nursing experience was more important than training. (3) emotional belonging. The multiple roles of medical nursing assistants give them very mixed emotions. (4) Potential needs. Participants reported that the fatigue of repeatedly scrubbing and cleaning stools, the negative emotions that could not be faced and resolved, and their special status made them overwhelmed, potentially reflecting that they needed more support. Conclusions: This study highlights the roles, experiences, confusions, and needs of nursing assistants in caring for patients with disabling fecal incontinence. Suggested areas for improvement include the development of more intelligent fecal incontinence collection devices and the development of management and training strategies by health managers based on the specific context of medical nursing assistants to emphasize the role of medical nursing assistants and improve the quality of clinical care.

Comprehensive analysis of the lncRNAs-related immune gene signatures and their correlation with immunotherapy in lung adenocarcinoma.

BACKGROUND: Long non-coding RNAs (lncRNAs)-related immune genes (lrRIGs) play a crucial role in the development and progression of lung adenocarcinoma (LUAD). However, reliable prognostic signatures based on lrRIGs have not yet been identified. METHODS: We screened lrRIGs associated with the prognosis of LUAD using The Cancer Genome Atlas (TCGA) database and then established a novel prognostic nine-gene signature composed of CD79A, INHA, SHC3, LIFR, TNFRSF11A, GPI, F2RL1, SEMA7A and WFDC2 through bioinformatic approaches. A risk score derived from this gene signature was used to divide LUAD patients into the low- and high-risk groups. The latter was confirmed to have markedly worse overall survival (O.S.). A nomogram was developed using the risk score and other independent prognostic elements, demonstrating excellent performance in predicting the O.S. rate of LUAD patients. RESULTS: We observed that the infiltration of diverse immune cell subtypes and response to immunotherapy and chemotherapy significantly differed between the low- and high-risk groups. CONCLUSIONS: Overall, stratification based on this gene signature could be used to guide better therapeutic management and improve outcomes for LUAD patients.

Development and validation of a Decision-Making Ability Scale for postpartum urinary incontinence women engaging in pelvic floor physical therapy.

OBJECTIVE: This study aimed to develop and validate a Decision-Making Ability Scale (DMA-S) for postpartum urinary incontinence (PPUI) women engaging in pelvic floor physical therapy (PFPT). METHODS: Items were created in line with a review of the literature and exploratory qualitative study with 22 women. The items were submitted for expert opinion and a pilot implementation was made with 58 women with PPUI. Furthermore, the construct validity of the scale was tested with exploratory factor analysis (EFA) (n = 220) and confirmatory factor analysis (CFA) (n = 240). Internal consistency for the Chronbach's α and test-retest reliability for the intraclass correlation coefficient (ICC) were also investigated for the DMA-S in the study. RESULTS: The results of the EFA indicated a Kaiser-Meyer-Olkin value of 0.85 and Bartlett's test of sphericity showed a χ2 value of 8352.101, p < 0.001. After removing one item with factor loading values below 0.50, the resulting factor structure accounted for 83.38% of the total variance. The fit indices of the scale model tested in the CFA were determined as χ2 /df = 1.08 < 3, root mean square error of approximation = 0.018 < 0.08, comparative fit index = 0.996 > 0.90, Tucker-Lewis index = 0.995 > 0.90, goodness-of-fit index (GFI) = 0.933 > 0.90, adjusted GFI = 0.916 > 0.90, and incremental fit index = 0.996 > 0.90. The Cronbach's α values were 0.95-0.97 for the subdimensions of the scale and 0.93 for the total scale. Data also showed a good test-retest stability (ICC = 0.984). CONCLUSION: The DMA-S is a reliable and valid tool for assessing the decision-making ability for PPUI women engaging in PFPT.

Interleukin-16 genetic polymorphisms in Guangxi Chinese with hepatitis B virus-related liver cirrhosis.

BACKGROUND: Our previous study has reported that interleukin-16 (IL-16) genetic polymorphisms are significantly related to chronic hepatitis B (CHB) and hepatitis B virus-related (HBV-related) hepatocellular carcinoma (HCC). As CHB, liver cirrhosis (LC), and HCC are development processes, this study aimed to determine genetic correlation of IL-16 polymorphisms with HBV-related LC in a Chinese population. METHODS: IL-16 gene rs11556218, rs4072111, and rs4778889 polymorphism in 129 patients with HBV-related LC and 168 healthy individuals were genotyped via polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). PCR-RFLP results were verified by DNA sequencing. RESULTS: The allelic and genotypic distributions of IL-16 rs11556218, rs4072111, and rs4778889 polymorphisms in HBV-related LC patients showed no significant difference from those in healthy controls. Furthermore, no relationship was observed between the haplotype distribution and susceptibility to HBV-related LC. CONCLUSIONS: This work provided the first evidence that the IL-16 genetic polymorphisms may not be associated with HBV-related LC risk.

Attitude Correlated Frames Based Calibration Method for Star Sensors.

Star sensors undergo laboratory calibration before they leave the factory. In addition, recalibration is necessary after they experience vibration, deformation, etc. Using the analysis of attitude-dependent and attitude-independent interstar angular invariance calibration methods (IAICMs) as a reference, an attitude-correlated frame-based calibration method (ACFCM) is proposed in this work, which combines the advantages of both methods. Using outdoor star observations, the ACFCM correlates star image frames obtained at different times via a strapdown gyro unit. As a result, the number of efficient star images for calibration increases rapidly and the distribution of star images becomes much more uniform, thus improving the calibration accuracy of the star sensor. A simulation and experimental tests were designed and carried out. Both the simulation and experimental results verify the feasibility of the proposed ACFCM method. Furthermore, by comparing our method with the IAICMs, the repeatability and reliability of the principal point obtained from the calibration with the ACFCM method proposed in this work were significantly improved.

Asymmetric Synthesis of Vicinal Tetrasubstituted Diamines via Reductive Coupling of Ketimines Templated by Chiral Diborons.

We herein describe the chiral diboron-templated asymmetric homocoupling of aryl alkyl ketimines, providing for the first time a series of chiral vicinal tetrasubstituted diamines with excellent ee values and good to high yields. The powerful and efficient diboron-participated [3,3]-sigmatropic rearrangement is successfully demonstrated by the homocoupling of a variety of ketimines thanks to the rational design and engineering of chiral diborons. Systematic DFT studies suggest that two chiral diborons adopt different conformational assembling strategies to couple the diboron template with ketimine substrates in their tight concerted transition states to ensure the excellent enantioselectivities. The synthetic value of chiral vicinal tetrasubstituted diamines is demonstrated by the asymmetric α-bromination of aliphatic aldehydes by employing a chiral vicinal tetrasubstituted diamine-based organocatalyst.

Total Syntheses of Polyhydroxylated Steroids by an Unsaturation-Functionalization Strategy.

Highly oxygenated cardiotonic steroids, such as ouabain, possess a wide spectrum of biological functions and remain significant synthetic challenges. Herein, we have applied an unsaturation-functionalization strategy and developed a synthetic method in addressing the C19-hydroxylation issue for efficient synthesis of polyhydroxylated steroids. An effective asymmetric dearomative cyclization allowed the construction of the C19-hydroxy unsaturated steroidal skeleton in only four steps from the Hajos-Parrish ketone ketal 7. The synthetic sequence featured C3-OH-directed hydrogenation/epoxidation, m-CPBA-triggered epoxidation/SN 2' nucleophilic substitution, Birch reduction of an enone, and regioselective LiAlH4 reduction to furnish the polyhydroxy functionalities on the steroid skeleton with high stereochemical control and efficiency. This approach ultimately enabled the total synthesis of 19-hydroxysarmentogenin and ouabagenin in 18 and 19 steps, respectively, overall. The synthesis of these polyhydroxylated steroids offers synthetic versatility and practicality in the search for new therapeutic agents.

Stochastic parcel tracking in an Euler-Lagrange compartment model for fast simulation of fermentation processes.

The compartment model (CM) is a well-known approach for computationally affordable, spatially resolved hydrodynamic modeling of unit operations. Recent implementations use flow profiles based on Computational Fluid Dynamics (CFD) simulations, and several authors included microbial kinetics to simulate gradients in bioreactors. However, these studies relied on black-box kinetics that do not account for intracellular changes and cell population dynamics in response to heterogeneous environments. In this paper, we report the implementation of a Lagrangian reaction model, where the microbial phase is tracked as a set of biomass-parcels, each linked with an intracellular composition vector and a structured reaction model describing their intracellular response to extracellular variations. A stochastic parcel tracking approach is adopted, in contrast to the resolved trajectories used in CFD implementations. A penicillin production process is used as a case study. We show good performance of the model compared with full CFD simulations, both regarding the extracellular gradients and intracellular pool response, using the mixing time as a matching criterion and taking into account that the mixing time is sensitive to the number of compartments. The sensitivity of the model output towards some of the inputs is explored. The coarsest representative CM requires a few minutes to solve 80 h of flow time, compared with approximately 2 weeks for a full Euler-Lagrange CFD simulation of the same case. This alleviates one of the major bottlenecks for the application of such CFD simulations towards the analysis and optimization of industrial fermentation processes.

Recent advances in total syntheses of complex dimeric natural products.

Dimeric natural products are a collection of molecules with diverse molecular architectures and significant bio-activities. In this tutorial review, total synthesis of complex dimeric natural products accomplished in recent years are summarized and various dimerization strategies are discussed. By highlighting the selected representative examples, this review aims to demonstrate the recent tactics of dimerization which is an important process integrated into the whole synthetic sequences of dimeric natural products, provide insights on structural and chemical properties of monomers and dimers of related natural products, and promote further technological advances in organic synthesis and biological studies of complex dimeric natural products.

Observational Study of Ground-Level Ozone in the Desert Atmosphere.

Arid lands such as deserts cover more than 35% of the Earth's land surface. Concerns regarding ground-level O3 pollution have been widely addressed in many regions in China, but the behavior of the O3 cycles in the desert atmosphere remains poorly understood. An 8-year observation was conducted to investigate the long-term temporal O3 variations in the atmosphere of the Taklimakan Desert, western China. The results showed that the diurnal and seasonal variations of O3 were mainly influenced by natural processes such as temperature, leading to a different temporal pattern compared with other Chinese regions under the intensive influence of anthropogenic activities. Moreover, the long-term pattern indicates that there exists decoupling trends of O3 variations between our study site (i.e., decreasing trend) and the developed regions in China (i.e., increasing trend). Knowledge of the temporal O3 patterns could therefore provide crucial insights for future effective O3 control strategies in China.

Heck Reaction of N-Heteroaryl Halides for the Concise Synthesis of Chiral α-Heteroaryl-substituted Heterocycles.

The Heck reaction between N-heteroaryl halides and heterocyclic alkenes provides a convenient approach to biologically relevant α-heteroaryl functionalized heterocycles, yet reactions of this type have been challenging due to strong N-heteroaryl coordination to palladium metal, which causes catalyst poisoning. In this report, an efficient palladium-catalyzed Heck reaction between N-heteroaryl halides and heterocyclic olefins is established, leading to a variety of α-heteroaryl substituted heterocycles. The method features an unprecedented broad substrate scope and excellent functional group compatibility. The employment of a sterically bulky P, P=O ligand containing an anthryl moiety is crucial for this transformation due to the coordinative unsaturation facilitated by its steric bulkiness. The asymmetric variant of the Heck reaction is achieved with (S)-DTBM-SEGPHOS via a cationic palladium pathway, which has enabled an efficient asymmetric synthesis of (S)-nicotine and its analogues.

Diastereodivergent Aldol-Type Coupling of Alkoxyallenes with Pentafluorophenyl Esters Enabled by Synergistic Palladium/Chiral Lewis Base Catalysis.

As a fundamental and synthetically useful C-C bond formation reaction, the aldol reaction is one of the most versatile transformations in organic synthesis. However, despite extensive research on asymmetric versions of the reaction, a unified method for stereoselective access to the complementary syn and anti diastereomeric products remains to be developed. In this study, we developed a synergistic palladium/chiral Lewis base system that overcomes the inherent diastereoselectivity bias of aldol reactions and, as a result, allowed us to achieve the first diastereodivergent coupling reactions of alkoxyallenes with pentafluorophenol esters. Computational studies suggest a mechanism involving an intermolecular protonative hydropalladation pathway rather than a palladium-hydride migratory insertion pathway. The origin of the stereochemistry for this synergistic catalysis system is rationalized by DFT calculations.

Construction of Bridged Polycyclic Skeletons via Transition-Metal Catalyzed Carbon-Carbon Bond-Forming Reactions.

Transition-metal catalysis has become one of most important methods for constructing molecules with diverse architectures. Bridged polycyclic skeletons are often considered one of most challenging structures in organic synthesis. This Minireview summarizes the recent progress on synthesis of bridged polycyclic skeletons by transition-metal-catalyzed carbon-carbon bond-forming reaction. Four main ring-forming strategies including connection via olefin or carbonyl functionality, enolate intermediacy, C-H functionality, and aryl functionality are detailed and some effective methods are discussed with particular emphasis on reaction design and mechanism.

Metal-free reduction of unsaturated carbonyls, quinones, and pyridinium salts with tetrahydroxydiboron/water.

A series of unsaturated carbonyls, quinones, and pyridinium salts have been effectively reduced to the corresponding saturated carbonyls, dihydroxybenzenes, and hydropyridines in moderate to high yields with tetrahydroxydiboron/water as a mild, convenient, and metal-free reduction system. Deuterium-labeling experiments have revealed this protocol to be an exclusive transfer hydrogenation process from water.

Enantioselective α-Carbonylative Arylation for Facile Construction of Chiral Spirocyclic ß,ß'-Diketones.

We herein describe the first enantioselective α-carbonylative arylation, providing a diverse set of chiral spiro ß,ß'-diketones bearing various ring sizes and functionalities in high yields and good to excellent enantioselectivities. Calculations suggest the transformation proceeds through reductive elimination instead of nucleophilic addition pathway.