Search Results (907)

Chlorophyll (Chl) b is crucial for assembly of the light-harvesting antennae that are required for optimal photosynthetic activity in plants and green algae. Synthesis of its precursor, chlorophyllide (Chlide) b, is catalyzed by Chlide a oxygenase (CAO), which contains a stable tyrosyl radical. Studies with the model organism Chlamydomonas reinhardtii y-1 suggested that protochlorophyllide (Pchlide) a is a substrate for the enzyme in the dark when a ‘cofactor’ is present to form a heterodimer, which apparently decreases the redox potential of Pchlide a. Data described in the literature are consistent with reduction in the redox potential of Chlide a by dimerization, which produces a substrate that allows rapid synthesis and accumulation of Chl b during chloroplast development in oxygenic photosynthetic organisms. In this article, we provide an emerging perspective on CAO’s structure, its assumed radical-mediated catalytic mechanism, and its role in planta. Full article

Oca (Oxalis tuberosa) skin is considered an agroindustrial waste byproduct, which currently holds no economic value. Nevertheless, this waste is a natural source of antioxidant compounds, which can be recovered through the use of sustainable technologies. Thus, this study aims to evaluate and compare the efficacy of 15% ethanol combined with two extraction techniques like solid–liquid extraction (SLE) and pressurized liquid extraction (PLE) for the recovery of antioxidant compounds from five oca skin cultivars. Regardless of the oca cultivar, the use of PLE was more efficient for obtaining extracts rich in polyphenol with high antioxidant capacity compared to the SLE process. Under PLE conditions, Pachatusan and Yawar cultivars presented the highest value of total polyphenols and antioxidant capacity. In comparison, the QuesWe and Pachatusan cultivars presented the lowest values. Polyphenol profile analysis showed that the PLE process effectively disrupted the cell wall matrix, resulting in a greater release of monomers (gallic acid, catechin, and epicatechin) and procyanidin B2 compared to the SLE process, while procyanidin A2 was more efficiently recovered under SLE, particularly in the Pachatusan cultivar. Principal component analysis (PCA) confirmed cultivar-dependent polyphenolic patterns, explaining 81.7% and 84.8% of total variance for SLE and PLE, respectively, with PLE generating more pronounced differentiation among cultivars driven by catechin, epicatechin, and gallic acid. The integration of PLE technology with the Oca skin framework facilitates the standardized production of extracts rich in antioxidants. Future research should concentrate on evaluating the stability of these specific dimers within food matrices, as well as their bioavailability in human clinical models. Full article

Background: The mucosal barrier presents a significant challenge for non-invasive delivery of macromolecular therapeutics, often requiring administration with poor bioavailability and increased toxicity risks. The polymeric immunoglobulin receptor (pIgR) contains an extracellular secretory component (SC) for immunoglobulin binding and a membrane-anchored stem domain capable of apical-to-basolateral transcytosis. We hypothesized that targeting the stem domain could enable active drug transport across mucosal barriers. Methods: Using phage display, we identified four high-affinity nanobodies against human and murine pIgR. Two lead candidates (3LTHMP-4 and 3LTHMP-5) demonstrated efficient apical-to-basolateral transport in vitro (Transwell assays) and in vivo (fluorescence imaging). Engineered bispecific antibodies fusing these nanobodies with anti-IL-5 mAb reslizumab were administered via inhalation in a murine asthma model at one-tenth the intraperitoneal reslizumab dose. Resluts: The bispecific antibodies showed significant therapeutic efficacy, while reslizumab alone at equivalent concentrations failed to demonstrate efficacy. Hydrogen–Deuterium Exchange Mass Spectrometry (HDX-MS) revealed that both 3LTHMP-4 and 3LTHMP-5 specifically bind to the pIgR stem domain (residues 578–612), a region distinct from the dimeric IgA binding site. Conclusions: These findings suggest that stem domain-specific binding may facilitate transport across the mucosal barrier while preserving native receptor physiology, offering a potential strategy for effective transmucosal delivery of biologics. Full article

Background/Objectives: The accurate prediction of postprocedural mortality is critical for clinical decision-making; however, research on mortality risk models for patients undergoing mechanical thrombectomy remains limited. This study aimed to develop and validate machine learning models for predicting 90-day post-mechanical thrombectomy mortality. Methods: A retrospective-prospective cohort study involving 699 retrospective patients (January 2019–December 2022) and 274 prospective patients (January 2023–June 2024) from a single institution in Sichuan was conducted. The primary outcome was all-cause mortality within 90 days, ascertained via telephone follow-up. Predictors were identified using univariate analysis and LASSO regression. Eight predictive models were developed and evaluated using existing machine learning methods via 10-fold cross-validation. Model performance was assessed through discrimination, calibration, decision curve analysis, and interpretability via Shapley additive explanations. Results: The final dataset included 593 patients in the modeling set and 247 in the validation set. The 90-day mortality rates were 25.6% and 32.0%, respectively. Key predictors included age, hyperlipidemia, atrial fibrillation, pre-stroke statin use, antiplatelet/anticoagulant therapy within 48 h of onset, dysphagia, D-dimer levels, and activities of daily living scores. Logistic regression demonstrated superior performance in the modeling cohort (AUC = 0.87), whereas the multilayer perceptron model exhibited the greatest efficacy in the validation cohort (AUC = 0.77). Conclusions: Machine learning algorithms can accurately predict 90-day mortality among patients undergoing mechanical thrombectomy. The multilayer perceptron model demonstrated robust validation performance and offers a potential tool for personalized risk assessment and optimization of clinical decision-making. Full article

Venous Thrombosis is a frequent and clinically significant complication in lymphoma patients, resulting in increased morbidity, mortality and therapeutic challenges. The pathophysiological mechanisms underlying lymphoma-associated thrombosis are multifactorial, involving patients’ clinical characteristics, tumour biology, systemic inflammation, endothelial dysfunction and therapy-induced prothrombotic changes. Traditional predictive tools for cancer-associated thrombosis (CAT) have shown suboptimal application in lymphoma patients due to disease-specific heterogeneity. The ThroLy score was developed as a lymphoma-specific model incorporating parameters such as extranodal involvement, mediastinal disease, performance status, a prior venous thromboembolic event, and specific laboratory values. While it shows improved predictive value compared with general CAT models, its accuracy remains limited, particularly across different lymphoma subtypes and treatment regimens. Research in the field has therefore focused on evaluating emerging biomarkers—D-dimer, microparticles and inflammatory cytokines—as risk assessment tools. Integrative approaches that combine clinical variables with such biomarkers may yield a more dynamic and individualised risk-prediction model to guide thromboprophylactic strategies. The present review summarises current knowledge on thrombotic risk assessment across lymphoma subtypes and highlights the potential role of novel biomarkers in developing a more precise approach to thrombosis prevention and management. Importantly, it provides a comprehensive overview of currently available literature, highlighting the need for personalised thrombosis risk stratification strategies in lymphoma. Full article

Background/Objectives: Acute pulmonary embolism (PE) and hospitalization-requiring community-acquired pneumonia (CAP) may present with overlapping clinical, laboratory, and radiological features. Soluble CD40 ligand (sCD40L) is a platelet-derived thrombo-inflammatory mediator that may be influenced by both thrombotic and inflammatory processes. This study retrospectively compared on-admission serum sCD40L concentrations between selected hospitalized patients with established acute PE and selected patients with hospitalization-requiring CAP. Methods: This single-center retrospective exploratory comparative biomarker study included 82 hospitalized adults: 48 with computed tomography pulmonary angiography (CTPA)-confirmed acute PE and 34 with hospitalization-requiring CAP defined using CURB-65-supported admission criteria. Stored admission serum samples were used for sCD40L measurement. Between-group comparison was the primary analysis; receiver operating characteristic (ROC) analysis was performed as a secondary exploratory description of the apparent within-sample discriminatory signal. Results: sCD40L was higher in acute PE than in hospitalization-requiring CAP (median 821.3 vs. 629.0 pg/mL; p < 0.001). ROC analysis demonstrated a strong exploratory within-sample discriminatory signal (AUC 0.951, 95% CI 0.905–0.997). After excluding five patients with recorded antiplatelet or rivaroxaban exposure, the apparent signal remained similar (AUC 0.945; bootstrap 95% CI 0.891–0.984), and sCD40L remained associated with PE in a Firth-penalized model adjusted for platelet count and COPD (OR 3.39 per 50 pg/mL, 95% CI 2.00–7.71; p < 0.001). Conclusions: In this retrospective selected two-group comparison, on-admission serum sCD40L concentrations were higher in established acute PE than in hospitalization-requiring CAP. ROC-derived estimates should be interpreted only as apparent within-sample discrimination and not as a replacement for D-dimer, clinical probability assessment, or imaging-based PE diagnosis. Prospective validation in unselected suspected-PE cohorts is required before any diagnostic or clinical use can be considered. Full article

Fibroblast activation protein (FAP) has emerged as a promising target for the development of cancer radiotheranostics due to its selective overexpression in cancer-associated fibroblasts (CAFs) within the tumor stroma. Affinity and selectivity refer to the binding affinities of FAP inhibitors toward FAP and related family members, whereas the accumulation of radiolabeled-FAP inhibitors varies by tumor type. Although monomeric FAP inhibitors (FAPIs) have shown extraordinary utility in diagnostic imaging, their clinical application in radiotherapy has been limited by short tumor retention times and heterogeneous uptake. To address these challenges, homomultimeric FAPI ligands—featuring two or more identical FAP-targeting motifs—have been developed with the aim of enhancing binding avidity and prolonging tumor residence. This review comprehensively examines the evolution of homomultimeric FAPI ligands, from molecular design and preclinical validation to early clinical implementation. We highlight how dimeric and higher-order multimeric constructs improve tumor retention and therapeutic efficacy compared to monomers, while also discussing the impact of linker chemistry, valency, and scaffold architecture on pharmacokinetics and targeting efficiency. Preclinical studies demonstrate that optimized dimers and trimers achieve superior tumor-to-background ratios and sustained tumor uptake, whereas excessive multimerization can lead to steric hindrance and reduced efficacy. Clinical data from pioneering studies using agents such as [¹⁷⁷Lu]Lu-DOTAGA.(SA.FAPi)₂ and [¹⁷⁷Lu]Lu-DOTAGA.Glu.(FAPi)₂ confirm prolonged tumor retention, encouraging therapeutic responses and a favorable safety profile in advanced cancers. However, translational challenges remain, including the need for better preclinical models that reflect stromal FAP heterogeneity, optimized radiometal–chelator pairs, and standardized dosing protocols for comparative clinical trials. Overall, homomultimeric FAPI ligands represent a significant advance in FAP-targeted theranostics, offering a robust platform for personalized cancer management. Full article

Janus kinase 2 (JAK2) occupies a central position in cytokine signaling and plays essential roles in hematopoiesis, immune regulation, and cancer. Although recent advances in structural biology, cryo-EM, receptor modeling, and biophysical analysis have substantially expanded current views of JAK2 function, key mechanistic questions remain regarding how receptor geometry, JH2-mediated autoinhibition, and disease-associated mutations are structurally integrated. In this review, we discuss the multidomain organization of JAK2 and examine how the FERM–SH2 module, the pseudokinase domain (JH2), and the catalytic kinase domain (JH1) cooperate to govern receptor specificity, allosteric control, and cytokine-induced activation. We further analyze how pathogenic mutations rewire this regulatory system by weakening autoinhibitory contacts, altering linker-mediated communication, or stabilizing active dimeric conformations. Finally, we assess current and emerging therapeutic strategies, from ATP-competitive inhibitors to macrocyclic and JH2-selective allosteric modulators, with emphasis on how structural insight can guide next-generation drug design. These advances support a more integrated view of JAK2 regulation and define new opportunities for selective therapeutic intervention. Full article

The SARS-CoV-2 spike protein has been shown to activate Toll-like receptor 4 (TLR4), yet the precise molecular structures driving recognition and subsequent activation remain poorly defined. Here, we present in silico structural alignments and molecular docking simulations indicating potential spatial compatibility between the wild-type SARS-CoV-2 HR1HR2 fusion core and the human TLR4/MD-2 heterodimer. The computational models project candidate interfaces involving salt bridges, as well as polar and non-polar interactions, with both TLR4 and MD-2 dimerization partners, suggesting a theoretical topology compatible with the dimerization of two TLR4/MD-2 heterocomplexes. Notably, similar structural compatibility was modeled for related class I fusion proteins from other highly pathogenic viruses, including SARS-CoV, MERS-CoV, influenza viruses A, B, and C, respiratory syncytial virus (RSV), and partially Ebola virus. These findings offer an exploratory computational hypothesis regarding viral–host interactions with the host innate immune system, which can trigger immune recognition or detrimental hyperactivation. Full article

This study investigates anion–anion assemblies involving perhalate anions, XO₄⁻ (X = Cl, Br, I), in crystal structures retrieved from the Cambridge Structural Database to clarify the nature of the intermolecular interactions frequently interpreted as halogen bonds. Molecular electrostatic surface potential analysis demonstrates that isolated XO₄⁻ anions do not exhibit electrophilic σ-holes on the halogen or oxygen atoms along the O–X bond extensions, thereby precluding their role as conventional halogen- or chalcogen-bond donors. Gas-phase calculations further show that direct anion–anion assemblies are intrinsically repulsive and unstable in isolation. However, when dielectric screening is introduced through implicit solvation models, metastable dimeric and oligomeric arrangements consistent with crystallographic motifs become accessible. Complementary QTAIM, IGMH, NBO, and SAPT analyses show that the observed X···O and O···O contacts are weak, environment-assisted anti-electrostatic interactions arising from a combination of dielectric screening, polarization, dispersion, and donor–acceptor contributions. The results demonstrate that the structural organization of perhalate anions in crystalline environments is governed primarily by collective environmental and crystal-packing effects rather than intrinsic attractive interactions between isolated anions. Full article

Huntington’s disease (HD) is a neurodegenerative disorder caused by the expansion of the CAG trinucleotide in the exon 1 of the huntingtin gmodellerene. This abnormal expansion produces a mutant huntingtin (mHTT) protein with extended polyglutamine (polyQ) tracts. Although the molecular mechanisms underlying HD onset and progression remain poorly understood, aberrant folding, aggregation, and membrane interactions of mHTT are considered central to disease pathogenesis. In this study, we used molecular dynamics (MD) simulations to investigate the structural properties, dimerization propensity, and membrane lipid interaction of mHTT carrying 70 polyQ repeats (mHTT-Q70). Our analyses revealed that mHTT-Q70 retains partially structured α-helical conformations with increased flexibility within the polyQ domain, thus being predisposed to misfolding. Coarse-grained MD simulations further revealed a strong tendency of mHTT-Q70 to dimerize, indicating that early oligomerization may represent a critical step in protein aggregation. Interestingly, we show that membrane cholesterol content dose-dependently promotes dimeric mHTT-Q70—but not monomeric mHTT-Q70—association with neuronal membrane models, which was observed for 70% of simulation time at 40% cholesterol content. Such a cholesterol-dependent membrane binding of dimeric mHTT-Q70 suggests that membrane lipid composition may represent a critical checkpoint in the early stages of mHTT-Q70 aggregation, and of cytotoxicity thereof. Moreover, distinct neuronal membrane lipids like phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine differently contributed to mHTT-Q70 binding, highlighting the complexity of such a lipid-dependent modulation. Taken together, these findings underscore the dynamic interplay between polyQ-driven misfolding, dimerization, and membrane lipids in HD pathogenesis, suggesting that modulation of membrane composition, and in particular of cholesterol levels, may be a novel action point to design therapeutic drugs for HD. Full article

Biflavonoids are dimeric flavonoids recognized for their diverse biological activities and significant pharmacological potential, with ginkgo (Ginkgo biloba L.) serving as a primary natural source. This study presents a comprehensive spatiotemporal characterization of the biflavonoid profile across a diverse population of 90 trees. High-resolution chromatographic analysis quantified five major biflavonoids, revealing a consistent hierarchical abundance: sciadopitysin > isoginkgetin > ginkgetin > bilobetin > amentoflavone. Notably, sciadopitysin emerged as the predominant constituent (1532.89 ± 544.13 µg/g dw). To decode the complex drivers of metabolite accumulation, we integrated Principal Component Analysis (PCA) with Piecewise Linear Regression (PLR). PCA confirmed a robust chemical structure, explaining 71.5% of the total variance, where Factor 1 represents a general biflavonoid gradient and Factor 2 captures localized environmental influences. The PLR models (R² = 0.75–0.83) identified tree age as a primary negative regulator, showing a significant decline in total biflavonoids as trees mature beyond the 30-year reproductive threshold. While sexual dimorphism and location exhibited compound-specific nonlinear effects, younger trees (10–30 years) demonstrated the highest biosynthetic plasticity and potency. These findings establish a predictive framework for optimizing the pharmaceutical harvest of ginkgo leaves, highlighting that age-related physiological shifts, rather than gender or broad geography, are the critical determinants of biflavonoids yield. Full article

Background/Objectives: Although COVID-19 is generally more severe in males, data on sex-specific differences in the predictive value of commonly used inflammatory biomarkers remain limited. The study aimed to evaluate the sex-specific prognostic performance of selected biomarkers during the Alpha variant wave. Methods: In single-center study, univariate and multivariable regressions analyses, along with receiver operating characteristic curve (ROC) analyses, were performed to assess the association of acute-phase proteins, cytokines, and white blood cell indices (at admission and 7 days later) and disease severity and mortality in patients with severe-to-critical COVID-19. Results: At admission, the combined assessment of ferritin and D-dimer predicted disease severity in both sexes; however, optimal cut-off values and diagnostic performance (specificity and sensitivity) differed between males and females. In males, neutrophil and lymphocyte counts provided additional clinically relevant predictive value. Seven days after admission, the combination of ferritin, D-dimer, and fibrinogen in males, and ferritin, as an independent predictor within a model including lactate dehydrogenase, in females demonstrated strong predictive performance for severe-to-critical COVID-19. At this time-point, lymphocyte count in males was also identified as an independent predictor of disease severity. Notably, C-reactive protein and neutrophil count correlated with mortality in males with severe-to-critical disease. Conclusions: Severe COVID-19 is predicted by distinct acute-phase proteins and shared, sex-specific biomarkers, but with distinct cut-offs and predictive accuracy. In males, white blood cell indices also serve as independent predictors. Furthermore, prognostic utility changes of these biomarkers over the course of the disease, suggesting sex-specific and time-dependent role in COVID-19 pathogenesis. Full article

Background: Long COVID in children is increasingly recognized, yet its clinical predictors and objective biological correlates remain insufficiently characterized. Objectives: The objective was to compare clinical, demographic, and laboratory characteristics between children with and without long COVID and to identify associated variables. Methods: We conducted a retrospective observational case–control study at the “Dr. Victor Gomoiu” Children’s Clinical Hospital, including pediatric patients with confirmed SARS-CoV-2 infection. Cases were defined as children with symptoms persisting ≥12 weeks after acute infection, while controls had no persistent symptoms at ≥12 weeks. Results: Eighty-nine children with long COVID and 88 matched controls were included. Children with long COVID were significantly older (1.79 ± 0.90 vs. 1.14 ± 0.80 years, p < 0.001) and more frequently from urban areas (86.5% vs. 69.3%, p = 0.0099). Lymphocyte, monocyte, and basophil counts were significantly lower in the Long COVID group, while D-dimer, ferritin, serum iron, urea, and creatinine levels were significantly higher. A multivariate predictive model demonstrated excellent discrimination (AUC = 0.94), with optimal sensitivity (84.3%) and specificity (89.8%) at a probability threshold of 0.48. Conclusions: Long COVID in children was associated with identifiable clinicobiological features. An exploratory composite model showed good discrimination but requires external validation. Full article

Obesity is a major global health burden that is linked to type 2 diabetes, cardiovascular disease, and metabolic syndrome. Chitosan oligosaccharides (COS) are bioactive compounds that are derived from the depolymerization of the chitosan in crustacean shells and are promising candidates for natural anti-adipogenesis effects. However, there is incomplete understanding of the molecular mechanisms by which structurally defined low-molecular-weight COS modulates adipogenic transcription networks and global transcriptional reprogramming. MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry and ¹³C NMR spectroscopy indicated a predominance of dimeric species (DP2) at m/z 344.79, which represents a lower molecular weight fraction and is proposed to improve the membrane permeability and intracellular bioavailability of COS. In a 3T3-L1 preadipocyte model, COS treatment at concentrations of 320–1280 µg/mL dose-dependently reduced intracellular lipid accumulation, triglyceride content, and adipocyte maturation while enhancing lipolysis and insulin-mediated glucose uptake. Western blot analysis indicated dose-dependent downregulation of PPARγ and C/EBPα. Transcriptomic RNA-seq analysis indicated large-scale transcriptional reprogramming with the altered expression of genes involved in PPAR signaling, PI3K-Akt, AMPK, insulin signaling, and fatty acid metabolism pathways among differentially expressed genes. These findings demonstrate that COS suppresses adipogenesis through the coordinated modulation of adipogenic transcription factors and multiple metabolic signaling pathways. The results support its potential as a promising natural compound but warrant preclinical investigation in the context of obesity and metabolic disorders. Full article