New Insights into the Cooperativity and Dynamics of Dimeric Enzymes.

A survey of protein databases indicates that the majority of enzymes exist in oligomeric forms, with about half of those found in the UniProt database being homodimeric. Understanding why many enzymes are in their dimeric form is imperative. Recent developments in experimental and computational techniques have allowed for a deeper comprehension of the cooperative interactions between the subunits of dimeric enzymes. This review aims to succinctly summarize these recent advancements by providing an overview of experimental and theoretical methods, as well as an understanding of cooperativity in substrate binding and the molecular mechanisms of cooperative catalysis within homodimeric enzymes. Focus is set upon the beneficial effects of dimerization and cooperative catalysis. These advancements not only provide essential case studies and theoretical support for comprehending dimeric enzyme catalysis but also serve as a foundation for designing highly efficient catalysts, such as dimeric organic catalysts. Moreover, these developments have significant implications for drug design, as exemplified by Paxlovid, which was designed for the homodimeric main protease of SARS-CoV-2.

In Situ Formed Microalgae-Integrated Living Hydrogel for Enhanced Tumor Starvation Therapy and Immunotherapy through Photosynthetic Oxygenation.

The effectiveness of various cancer therapies for solid tumors is substantially limited by the highly hypoxic tumor microenvironment (TME). Here, a microalgae-integrated living hydrogel (ACG gel) is developed to concurrently enhance hypoxia-constrained tumor starvation therapy and immunotherapy. The ACG gel is formed in situ following intratumoral injection of a biohybrid fluid composed of alginate, Chlorella sorokiniana, and glucose oxidase, facilitated by the crossing-linking between divalent ions within tumors and alginate. The microalgae Chlorella sorokiniana embedded in ACG gel generate abundant oxygen through photosynthesis, enhancing glucose oxidase-catalyzed glucose consumption and shifting the TME from immunosuppressive to immunopermissive status, thus reducing the tumor cell energy supply and boosting antitumor immunity. In murine 4T1 tumor models, the ACG gel significantly suppresses tumor growth and effectively prevents postoperative tumor recurrence. This study, leveraging microalgae as natural oxygenerators, provides a versatile and universal strategy for the development of oxygen-dependent tumor therapies.

Role of ERK in gender difference of fibromyalgia pain.

This study investigated the ERK pathway of the peripheral nervous system and discovered a gender-specific pattern of ERK activation in the dorsal root ganglion of an acid-induced chronic widespread muscular pain model. We employed a twice acid-induced chronic musculoskeletal pain model in rats to evaluate mechanical pain behavior in both male and female groups. We further conducted protein analysis of dissected dorsal root ganglions from both genders. Both male and female rats exhibited a similar pain behavior trend, with females demonstrating a lower pain threshold. Protein analysis of the dorsal root ganglion (DRG) showed a significant increase in phosphorylated ERK after the second acid injection in all groups. However, phosphorylation of ERK was observed in the dorsal root ganglion, with higher levels in the male ipsilateral group compared to the female group. Moreover, there was a no difference between the left and right sides in males, whereas the significant difference was observed in females. In conclusions, the administration of acid injections induced painful behavior in rats, and concurrent with this, a significant upregulation of pERK was observed in the dorsal root ganglia, with a greater magnitude of increase in males than females, and in the contralateral side compared to the ipsilateral side. Our findings shed light on the peripheral mechanisms underlying chronic pain disorders and offer potential avenues for therapeutic intervention.

Maternal exposure to fine particulate matter and congenital heart defects during preconception and pregnancy period: A cohort-based case-control study in the Taiwan maternal and child health database.

BACKGROUND: Few studies have explored the association between maternal exposure to particulate matter with an aerodynamic diameter of ≤2.5 µm (PM2.5) and congenital heart defects occurring before and during pregnancy. We aimed to investigate the association and the critical time windows between the maternal exposure to PM2.5 and congenital heart defects. METHOD: We conducted a cohort-based case-control study of 507,960 participants obtained from the Taiwan Maternal and Child Health Database between 2004 and 2015. We applied satellite-based spatiotemporal models with 1-km resolution to calculate the average PM2.5 concentration during preconception and the specific periods of pregnancy. We also performed conditional logistic regression with distributed lag non-linear models (DLNMs) to assess the effects of weekly average PM2.5 on both congenital heart defects and their isolated subtypes, as well as the concentration-response relationships. RESULTS: In DLNMs, exposure to PM2.5 (per 10 µg/m3) during weeks 7-12 before conception and weeks 3-9 after conception was associated with congenital heart defects. The strongest association at 12 weeks before conception (odds ratio [OR] = 1.026, 95% confidence intervals [CI]: 1.012-1.040) and 7 weeks after conception (OR = 1.024, 95% CI: 1.012-1.036) for every 10 µg/m3 increase in PM2.5 concentration. In modification analysis, strongest associations were observed for low SES. CONCLUSIONS: Our study revealed that exposure to ambient PM2.5 raises the risk of congenital heart defects, particularly among individuals with lower socioeconomic status. Moreover, our findings suggest that preconception exposure to PM2.5 may be a crucial period for the development of congenital heart defects.

PD-L1 and AKT Overexpressing Adipose-Derived Mesenchymal Stem Cells Enhance Myocardial Protection by Upregulating CD25+ T Cells in Acute Myocardial Infarction Rat Model.

This study explores the synergistic impact of Programmed Death Ligand 1 (PD-L1) and Protein Kinase B (Akt) overexpression in adipose-derived mesenchymal stem cells (AdMSCs) for ameliorating cardiac dysfunction after myocardial infarction (MI). Post-MI adult Wistar rats were allocated into four groups: sham, MI, ADMSC treatment, and ADMSCs overexpressed with PD-L1 and Akt (AdMSC-PDL1-Akt) treatment. MI was induced via left anterior descending coronary artery ligation, followed by intramyocardial AdMSC injections. Over four weeks, cardiac functionality and structural integrity were assessed using pressure-volume analysis, infarct size measurement, and immunohistochemistry. AdMSC-PDL1-Akt exhibited enhanced resistance to reactive oxygen species (ROS) in vitro and ameliorated MI-induced contractile dysfunction in vivo by improving the end-systolic pressure-volume relationship and preload-recruitable stroke work, together with attenuating infarct size. Molecular analyses revealed substantial mitigation in caspase3 and nuclear factor-κB upregulation in MI hearts within the AdMSC-PDL1-Akt group. Mechanistically, AdMSC-PDL1-Akt fostered the differentiation of normal T cells into CD25+ regulatory T cells in vitro, aligning with in vivo upregulation of CD25 in AdMSC-PDL1-Akt-treated rats. Collectively, PD-L1 and Akt overexpression in AdMSCs bolsters resistance to ROS-mediated apoptosis in vitro and enhances myocardial protective efficacy against MI-induced dysfunction, potentially via T-cell modulation, underscoring a promising therapeutic strategy for myocardial ischemic injuries.

Solving Inverse Electrocardiographic Mapping Using Machine Learning and Deep Learning Frameworks.

Electrocardiographic imaging (ECGi) reconstructs electrograms at the heart's surface using the potentials recorded at the body's surface. This is called the inverse problem of electrocardiography. This study aimed to improve on the current solution methods using machine learning and deep learning frameworks. Electrocardiograms were simultaneously recorded from pigs' ventricles and their body surfaces. The Fully Connected Neural network (FCN), Long Short-term Memory (LSTM), Convolutional Neural Network (CNN) methods were used for constructing the model. A method is developed to align the data across different pigs. We evaluated the method using leave-one-out cross-validation. For the best result, the overall median of the correlation coefficient of the predicted ECG wave was 0.74. This study demonstrated that a neural network can be used to solve the inverse problem of ECGi with relatively small datasets, with an accuracy compatible with current standard methods.

Critical Computational Evidence Regarding the Long-Standing Controversy over the Main Electrophilic Species in Hypochlorous Acid Solution.

Although hypochlorous acid (HOCl) solution has become a popular electrophilic reagent for industrial uses, the question of which molecule (HOCl or Cl2) undergoes electrophilic addition with olefins remains a controversial issue in some literature and textbooks, and this problem has been largely underexplored in theoretical studies. In this work, we computationally studied the electrophilic addition mechanism of olefins using three experimentally predicted effective electrophilic chlorinating agents, i.e., HOCl, Cl2, and Cl2O molecules. Our results demonstrate that Cl2 and Cl2O are the main electrophilic agents in HOCl solution, whereas the HOCl molecule cannot be the electrophile since the energy barrier when directly adding HOCl molecule to olefins is too high to overcome and the "anti-Markovnikov" regioselectivity for tri-substituted olefin is not consistent with experiments. Notably, the HOCl molecule prefers to form oxonium ion intermediate with a double bond, rather than the generally believed chlorium ion intermediate. This work could benefit mechanistic studies of critical biological and chemical processes with HOCl solution and may be used to update textbooks.

Organocatalytic Atroposelective Synthesis of N-N Axially Chiral Indoles and Pyrroles by De Novo Ring Formation.

The first highly atroposelective construction of N-N axially chiral indole scaffolds was established via a new strategy of de novo ring formation. This strategy makes use of the organocatalytic asymmetric Paal-Knorr reaction of well-designed N-aminoindoles with 1,4-diketones, thus affording N-pyrrolylindoles in high yields and with excellent atroposelectivities (up to 98 % yield, 96 % ee). In addition, this strategy is applicable for the atroposelective synthesis of N-N axially chiral bispyrroles (up to 98 % yield, 97 % ee). More importantly, such N-N axially chiral heterocycles can be converted into chiral organocatalysts with applications in asymmetric catalysis, and some molecules display potent anticancer activity. This work not only provides a new strategy for the atroposelective synthesis of N-N axially chiral molecules but also offers new members of the N-N atropisomer family with promising applications in synthetic and medicinal chemistry.

Application of 3-Alkyl-2-vinylindoles in Catalytic Asymmetric Dearomative (2+3) Cycloadditions.

The first application of 3-alkyl-2-vinylindoles in catalytic asymmetric dearomative cycloadditions was established by chiral phosphoric acid (CPA)-catalyzed (2+3) cycloaddition with azoalkenes, leading to the generation of chiral pyrroloindolines bearing two tetrasubstituted stereogenic centers in good yields (61-96%) and excellent stereoselectivities (all >95:5 dr, 86-99% ee). This reaction has realized the first enantioselective dearomative cycloaddition of 3-alkyl-2-vinylindoles, which brings a new reactivity to this class of vinylindoles and will enrich the chemistry of 3-alkyl-2-vinylindoles. In addition, this approach has provided a useful strategy for the construction of enantioenriched pyrroloindoline skeletons bearing two tetrasubstituted stereogenic centers. More importantly, the bioassay of these chiral pyrroloindolines has revealed that some compounds exhibit strong anti-cancer activity against Hela and MCF-7 cell lines, which will be helpful for discovering anti-cancer drug candidates.

Sex differences in long-term cardiovascular outcomes among patients with acute myocardial infarction: A population-based retrospective cohort study.

BACKGROUND: Whether a sex difference exists in long-term cardiovascular (CV) outcomes after acute myocardial infarction (AMI) is worth exploration. This study is sought to investigate the relationships among sex, age, and the long-term prognosis after AMI. METHODS: This population-based retrospective cohort study used Taiwan's National Health Insurance Research Database to investigate the sex differences in in-hospital and long-term CV outcomes in patients with AMI. We enrolled patients who were first diagnosed with AMI from January 1, 2000 to December 31, 2013. The outcomes of interest included all-cause mortality, CV death, non-fatal stroke, non-fatal heart failure, and AMI recurrence during hospitalization and 5-year follow up. The CV outcomes were also analyzed by age stratification. RESULTS: Overall, 201 921 patients with AMI were analyzed; 68.72% were men and 31.28% were women, with mean ages of 65.34 ± 14.12 and 73.05 ± 12.22 years, respectively. Major adverse cardiac events during hospitalization and up to 5 years were consistently greater in women than in men. Multivariable regression analysis revealed no sex difference existed in long-term all-cause and CV mortality. Men of all age groups consistently showed higher risk of both short- and long-term recurrence of AMI. Nonetheless, the female sex still independently predicted increased risk of non-fatal stroke and heart failure from hospitalization until 3-year follow up. CONCLUSION: Women with AMI had poorer short-term and long-term outcomes. The sex differences in long-term all-cause and CV death disappear after multivariate analysis. Nonetheless, female AMI patients independently predicted higher risk of stroke and heart failure from hospitalization until a 3-year follow-up. To better understand the pathophysiology of female patients with AMI and develop more effective management, more studies in this field are necessary in the future.

Catalytic Asymmetric Synthesis of 3,3'-Bisindoles Bearing Single Axial Chirality.

A catalytic asymmetric synthesis of 3,3'-bisindoles bearing single axial chirality has been established via chiral phosphoric acid (CPA)-catalyzed enantioselective addition reaction of 3,3'-bisindoles with ninhydrin-derived 3-indolylmethanols. The selection of ninhydrin-derived 3-indolylmethanols as suitable electrophiles is based on the consideration that the symmetric and bulky moiety of ninhydrin would increase the steric congestion around the axis to generate stable axial chirality and avoid the generation of central chirality. By this approach, a series of 3,3'-bisindoles bearing single axial chirality were synthesized via the dynamic kinetic resolution (DKR) process in generally acceptable yields and considerable enantioselectivities. In addition, an in-depth investigation on the property (stability and rotation barrier) of the synthesized axially chiral 3,3'-bisindoles was carried out, thus providing useful information on this class of axially chiral frameworks. This approach makes use of the strategy of dynamic kinetic resolution of 3,3'-bisindoles, therefore expanding the generality and applicability of this strategy for catalytic asymmetric synthesis of 3,3'-bisindoles bearing single axial chirality.

Phosphine-catalyzed [4 + 2] cyclization of para-quinone methide derivatives with allenes.

The first [4 + 2] cyclization of para-quinone methide (p-QM) derivatives with allenes has been established via phosphine catalysis, which afforded a series of chroman derivatives in high yields (up to 97%) and excellent (E/Z)-selectivities (all >95 : 5 E/Z). This reaction will not only enrich the research contents of cyclization reactions involving p-QM derivatives, but also provide a good example of the application of allenes and phosphine catalysis in cyclization reactions. In addition, this approach also offers a useful method for the construction of chroman scaffolds.

Phosphine-catalyzed regiospecific (3 + 2) cyclization of 3-nitroindoles with allene esters.

A phosphine-catalyzed regiospecific (3 + 2) cyclization of 3-nitroindoles with allene esters has been established, which constructed indole-fused five-membered rings in good yields (up to 86%). This reaction serves as a powerful method for the construction of indole-fused five-membered rings. In addition, this reaction provides a useful strategy toward settling the challenge of utilizing other 1,3-dipoles or 1,3-dipole surrogates to perform (3 + 2) cyclizations with 3-nitroindoles in different catalytic modes, which will enrich the chemistry of nitroindoles and catalytic asymmetric dearomatization cyclizations.

A Strategy for Synthesizing Axially Chiral Naphthyl-Indoles: Catalytic Asymmetric Addition Reactions of Racemic Substrates.

A new strategy for enantioselective synthesis of axially chiral naphthyl-indoles has been established through catalytic asymmetric addition reactions of racemic naphthyl-indoles with bulky electrophiles. Under chiral phosphoric acid catalysis, azodicarboxylates and o-hydroxybenzyl alcohols served as bulky but reactive electrophiles that were attacked by C2-unsubstituted naphthyl-indoles, which underwent a dynamic kinetic resolution to afford two series of axially chiral naphthyl-indoles in good yields (up to 98 %) and high enantioselectivities (up to 98:2 er).

Multi-Förster Resonance Energy Transfer-Based Fluorescent Probe for Spatiotemporal Matrix Metalloproteinase-2 and Caspase-3 Imaging.

A novel single-molecular fluorescent probe was developed for spatiotemporal matrix metalloproteinase-2 (MMP-2) and caspase-3 imaging with distinct fluorescence signals. Due to the multi-Förster resonance energy transfer (FRET) processes, the probe could respond to MMP-2 and caspase-3 independently with high signal-to-noise ratio. Moreover, the overexpression of MMP-2 in cancer cell lines and the cisplatin induced cell apoptosis were spatiotemporal imaged with distinct fluorescence emissions. Because of the independent process of the probe for MMP-2 and caspase-3 imaging, the probe could meet the demands for precise disease diagnosis and cancer theranostic applications, which could extensively simplify the processes for precise cancer diagnosis and imaging.

Sore throat may be a clue to the early diagnosis of spontaneous pneumomediastinum.

Spontaneous pneumomediastinum is defined as presence of air in the mediastinum without obvious cause such as esophageal perforation or abscess formation. It is a benign condition and usually resolved by itself in 1 to 2 weeks. The main symptom of spontaneous pneumomediastinum is retrosternal chest pain. Here, we present a young adult who complained about sore throat initially. Marked retropharyngeal emphysema was noted by neck x-ray. Pneumomediastinum was confirmed with chest x-ray and computed tomographic scan later on.We want to emphasize the importance of thorough history taking and lateral soft tissue neck radiograph on retropharyngeal emphysema in real time, which is key to the diagnostic workup for patients who present with persistent sore throat and dysphagia in young adult.

Case review analysis of operating room decisions to cancel surgery.

BACKGROUND: Cancellation of surgery close to scheduled time causes a waste of healthcare resources. The current study analyzes surgery cancellations occurring after the patient has been prepared for the operating room, in order to see whether improvements in the surgery planning process may reduce the number of cancellations. METHODS: In a retrospective chart review of operating room surgery cancellations during the period from 2006 to 2011, cancellations were divided into the following categories: inadequate NPO; medical; surgical; system; airway; incomplete evaluation. The relative use of these reasons in relation to patient age and surgical department was then evaluated. RESULTS: Forty-one percent of cancellations were for other than medical reasons. Among these, 17.7% were due to incomplete evaluation, and 8.2% were due to family issues. Sixty seven percent of cancelled cases eventually received surgery. The relative use of individual reasons for cancellation varied with patient age and surgical department. The difference between cancellations before and after anesthesia was dependent on the causes of cancellation, but not age, sex, ASA status, or follow-up procedures required. CONCLUSION: Almost half of the cancellations were not due to medical reasons, and these cancellations could be reduced by better administrative and surgical planning and better communication with the patient and/or his family.

Role of low-density lipoprotein electronegativity and sexual dimorphism in contributing early ventricular tachyarrhythmias following ST-elevation myocardial infarction.

Background: Early ventricular tachycardia/fibrillation (VT/VF) in patients with ST-elevation myocardial infarction (STEMI) has higher morbidity and mortality. This study examines gender-differentiated risk factors and underlying mechanisms for early onset VT/VF in STEMI. Methods: We analyzed data from 2,964 consecutive STEMI patients between January 1, 2008 and December 31, 2021. Early VT/VF was defined as occurrence of spontaneous VT/VF of ≥30 s or requirement of immediate cardioversion/defibrillation within the first 48 h after symptoms. An ex vivo ischemic-reperfusion experiments were conducted in 8-week-old ApoE-/- mice fed a high-fat diet to explore the underlying mechanisms of early VT/VF. Results: In 255 of out 2,964 STEMI patients who experienced early VT/VF, the age was younger (58.6 ± 13.8 vs. 61.0 ± 13.0 years old, P = 0.008) with a male predominance. The plasma levels of L5, the most electronegative subclass of low-density lipoprotein, was higher in early VT/VF patients compared to those without early VT/VF (n = 21, L5: 14.1 ± 22.6% vs. n = 46, L5: 4.3 ± 9.9%, P = 0.016). In the experimental setup, all male mice (n = 4) developed VT/VF post sham operation, whereas no such incidence was observed in the female mice (n = 3). Significantly, male mice exhibited considerably slower cardiac conduction velocity as compared to their female counterparts in whole heart preparations (25.01 ± 0.93 cm/s vs.42.32 ± 5.70 cm/s, P < 0.001), despite analogous action potential durations. Furthermore, isolated ventricular myocytes from male mice showed a distinctly lower sodium current density (-29.20 ± 3.04 pA/pF, n = 6) in comparison to female mice (-114.05 ± 6.41 pA/pF, n = 6, P < 0.001). This decreased sodium current density was paralleled by a reduced membrane expression of Nav1.5 protein (0.38 ± 0.06 vs. 0.89 ± 0.09 A.U., P < 0.001) and increased cytosolic Nav1.5 levels (0.59 ± 0.06 vs. 0.29 ± 0.04 A.U., P = 0.001) in male mice. Furthermore, it was observed that the overall expressions of sorting nexin 27 (SNX27) and vacuolar protein sorting 26 (VPS26) were significantly diminished in male mice as compared to female littermates (0.91 ± 0.15 vs. 1.70 ± 0.28, P = 0.02 and 0.74 ± 0.09 vs. 1.57 ± 0.13, P < 0.01, respectively). Conclusions: Our findings reveal that male STEMI patients with early VT/VF are associated with elevated L5 levels. The gender-based discrepancy in early VT/VF predisposition might be due to compromised sodium channel trafficking, possibly linked with increased LDL electronegativity.

Unleashing the Power of Evolution in Xylanase Engineering: Investigating the Role of Distal Mutation Regulation.

The drive to enhance enzyme performance in industrial applications frequently clashes with the practical limitations of exhaustive experimental screening, underscoring the urgency for more refined and strategic methodologies in enzyme engineering. In this study, xylanase Xyl-1 was used as the model, coupling evolutionary insights with energy functions to obtain theoretical potential mutants, which were subsequently validated experimentally. We observed that mutations in the nonloop region primarily aimed at enhancing stability and also encountered selective pressure for activity. Notably, mutations in this region simultaneously boosted the Xyl-1 stability and activity, achieving a 65% success rate. Using a greedy strategy, mutant M4 was developed, achieving a 12 °C higher melting temperature and doubled activity. By integration of spectroscopy, crystallography, and quantum mechanics/molecular mechanics molecular dynamics, the mechanism behind the enhanced thermal stability of M4 was elucidated. It was determined that the activity differences between M4 and the wild type were primarily driven by dynamic factors influenced by distal mutations. In conclusion, the study emphasizes the pivotal role of evolution-based approaches in augmenting the stability and activity of the enzymes. It sheds light on the unique adaptive mechanisms employed by various structural regions of proteins and expands our understanding of the intricate relationship between distant mutations and enzyme dynamics.

Inhalable Capsular Polysaccharide-Camouflaged Gallium-Polyphenol Nanoparticles Enhance Lung Cancer Chemotherapy by Depleting Local Lung Microbiota.

Local lung microbiota is closely associated with lung tumorigenesis and therapeutic response. It is found that lung commensal microbes induce chemoresistance in lung cancer by directly inactivating therapeutic drugs via biotransformation. Accordingly, an inhalable microbial capsular polysaccharide (CP)-camouflaged gallium-polyphenol metal-organic network (MON) is designed to eliminate lung microbiota and thereby abrogate microbe-induced chemoresistance. As a substitute for iron uptake, Ga3+ released from MON acts as a "Trojan horse" to disrupt bacterial iron respiration, effectively inactivating multiple microbes. Moreover, CP cloaks endow MON with reduced immune clearance by masquerading as normal host-tissue molecules, significantly increasing residence time in lung tissue for enhanced antimicrobial efficacy. In multiple lung cancer mice models, microbe-induced drug degradation is remarkably inhibited when drugs are delivered by antimicrobial MON. Tumor growth is sufficiently suppressed and mouse survival is prolonged. The work develops a novel microbiota-depleted nanostrategy to overcome chemoresistance in lung cancer by inhibiting local microbial inactivation of therapeutic drugs.