Search Results (8,119)

Osteoarthritis involves complex interactions between articular joint tissues and the immune system, which is implicated in molecular trafficking via barrier-function modulating cytokines. The current study aims to test effects of an acute spike in TNF-α or TGF-β on vascular barrier function at multiple length scales, from the heart to tissue compartments of the knee, and cellular inhabitants of those respective compartments, in a spontaneous guinea pig model of osteoarthritis. First we quantified the intensity of a fluorescent-tagged 70 kDa tracer, similar in size to albumin, the most prevalent transporter protein in the blood, in tissue compartments of bone (periosteum, marrow space, compact bone, and epiphyseal bone) and cartilage (superficial cartilage, calcified cartilage, and the interface between, i.e., the epiphyseal line), as well as at sites of tendon attachment to bone (entheses). We then examined tracer presence and intensity in the respective pericellular and extracellular matrix zones of bone and cartilage. Acute exposure to TGF-β reduced barrier function (increased permeability) at nearest vascular interfaces in four of eight tissue compartments studied, compared to TNF-α where one of eight tissue compartments showed significant diminishment in barrier function. The increase in permeability associated with reduced barrier function was observed at both tissue compartment and cellular length scales. The observation of pericellular transport of the albumin-sized molecules to osteocytes contrasts with previous observations of barrier function in healthy, untreated animals and is indicative of increased molecular transport in pericellular regions of musculoskeletal tissues in cytokine-treated animals. Understanding age- and disease-related changes in molecular transport within musculoskeletal structures, such as the knee joint, is crucial for elucidating the etiology and pathogenesis of osteoarthritis. Full article

In recent years, apatite-based materials have garnered significant interest, particularly for applications in tissue engineering. Apatite is most commonly employed as a coating for metallic implants, as a component in composite materials, and as scaffolds for bone and dental tissue regeneration. Among its various forms, hydroxyapatite (HAP) is the most widely used, owing to its natural occurrence in human and animal hard tissues. An emerging area of research involves the use of fluoride-substituted apatite, particularly fluorapatite (FAP), which can serve as a direct fluoride source at the implant site, potentially offering several biological and therapeutic advantages. However, substituting HAP with FAP may lead to unforeseen changes in material behavior due to the differing physicochemical properties of these two calcium phosphate phases. This study investigates the effects of replacing hydroxyapatite with fluorapatite in ceramic–polymer composite materials incorporating β-1,3-glucan as a bioactive polymeric binder. The β-1,3-glucan polysaccharide was selected for its proven biocompatibility, biodegradability, and ability to form stable hydrogels that promote cellular interactions. Nitrogen adsorption analysis revealed that FAP/glucan composites had a significantly lower specific surface area (0.5 m²/g) and total pore volume (0.002 cm³/g) compared to HAP/glucan composites (14.15 m²/g and 0.03 cm³/g, respectively), indicating enhanced ceramic–polymer interactions in fluoride-containing systems. Optical profilometry measurements showed statistically significant differences in profile parameters (e.g., Rp: 134 μm for HAP/glucan vs. 352 μm for FAP/glucan), although average roughness (Ra) remained similar (34.1 vs. 27.6 μm, respectively). Microscopic evaluation showed that FAP/glucan composites had smaller particle sizes (1 μm) than their HAP counterparts (2 μm), despite larger primary crystal sizes in FAP, as confirmed by TEM. XRD analysis indicated structural differences between the apatites, with FAP exhibiting a reduced unit cell volume (524.6 ų) compared to HAP (528.2 ų), due to substitution of hydroxyl groups with fluoride ions. Spectroscopic analyses (FTIR, Raman, ³¹P NMR) confirmed chemical shifts associated with fluorine incorporation and revealed distinct ceramic–polymer interfacial behaviors, including an upfield shift of PO₄³⁻ bands (964 cm⁻¹ in FAP vs. 961 cm⁻¹ in HAP) and OH vibration shifts (3537 cm⁻¹ in FAP vs. 3573 cm⁻¹ in HAP). The glucan polymer showed different hydrogen bonding patterns when combined with FAP versus HAP, as evidenced by shifts in polymer-specific bands at 888 cm⁻¹ and 1157 cm⁻¹, demonstrating that fluoride substitution significantly influences ceramic–polymer interactions in these bioactive composite systems. Full article

The cellular membrane is a dynamic structure composed of lipids and proteins organized into specialized domains that facilitate interactions between extracellular molecules and the intracellular environment. Tetraspanins are a family of transmembrane proteins involved in diverse cellular processes, including membrane stabilization and fusion, endocytosis, extracellular vesicle formation, and the organization of proteins and lipids at specific membrane sites known as Tetraspanin-Enriched Microdomains (TEMs). These lipid–protein interactions play a critical role in the replicative cycle of Orthoflavivirus, including dengue, Zika, and West Nile, by facilitating viral entry, replication, assembly, and egress. In addition, tetraspanins also regulate the biogenesis and function of extracellular vesicles, contributing to viral dissemination, persistent infection, and immune evasion. This review summarizes the current knowledge on the structural and functional aspects of tetraspanins, their interplay with lipids, and their emerging roles in the Orthoflavivirus replicative cycle. We also discuss how these insights may inform the development of antiviral strategies targeting membrane organization and virus–host interactions. Full article

Since the appearance of the Severe Acute Respiratory Syndrome (SARS) virus, there has been increased interest in understanding the role of bats in the maintenance and circulation of coronaviruses. This study aimed to describe the phylogenetic and evolutionary relationships and antigenic architecture of a new coronavirus detected in bats in the Department of Córdoba. In a surveillance study of pathogens of interest to public health, a bat Phyllostomus hastatus was captured. Rectal swabs samples were collected from the bats, and RNA was extracted and sequenced using NGS with MGI-G50 equipment. The results were analyzed using bioinformatics software. A contig of 28,619 nucleotides associated with the Coronaviridae family was obtained. Phylogenetic and molecular clock analyses of the ORF1ab gene revealed a novel divergent Alphacoronavirus that originated directly from an ancestral node. The analysis of the spike (S) protein and receptor-binding domain (RBD) is similar to that of humans (HCoV-229E) and porcine coronaviruses. In silico analysis suggests potential RBD interaction sites with human and pig cellular receptor aminopeptidase N. There is a possible risk of interspecies jumping of the new AlphaCoV/P. hastatus in humans and pigs. This is the first study to perform phylogenetic, evolutionary, and antigenic characterization of bat coronaviruses in Colombia. Full article

RNA polymerases are essential enzymes that catalyze DNA transcription into RNA, vital for protein synthesis, gene expression regulation, and cellular responses. Non-template-dependent RNA polymerases, which synthesize RNA without a template, are valuable in biological research due to their flexibility in producing RNA without predefined sequences. However, their substrate polymerization mechanisms are not well understood. This study examines Poly (A) polymerase (PAP), a nucleotide transferase superfamily member, to explore its substrate selectivity using computational methods. Previous research shows PAP’s polymerization efficiency for nucleoside triphosphates (NTPs) ranks ATP > GTP > CTP > UTP, though the reasons remain unclear. Using 500 ns Gaussian accelerated molecular dynamics simulations, stability analysis, secondary structure analysis, MM-PBSA calculations, and Markov state modeling, we investigate PAP’s differential polymerization efficiencies. Results show that ATP binding enhances PAP’s structural flexibility and increases solvent-accessible surface area, likely strengthening protein–substrate or protein–solvent interactions and affinity. In contrast, polymerization of other NTPs leads to a more open conformation of PAP’s two domains, facilitating substrate dissociation from the active site. Additionally, ATP binding induces a conformational shift in residues 225–230 of the active site from a loop to an α-helix, enhancing regional rigidity and protein stability. Both ATP and GTP form additional π–π stacking interactions with PAP, further stabilizing the protein structure. This theoretical study of PAP polymerase’s substrate selectivity mechanisms aims to clarify the molecular basis of substrate recognition and selectivity in its catalytic reactions. These findings offer valuable insights for the targeted engineering and optimization of polymerases and provide robust theoretical support for developing novel polymerases for applications in drug discovery and related fields. Full article

Listeria monocytogenes (L. monocytogenes) is a Gram-positive intracellular pathogen capable of causing severe infections. The Listeria pathogenicity island 4 (LIPI-4) encodes a phosphotransferase system (PTS) with its EIIB component playing a critical role in carbohydrate phosphorylation and virulence. However, the precise function of EIIB in virulence regulation across diverse pathogenic strains remains unclear. Here, we generated an EIIB deletion mutant (LM873ΔEIIB) and its complemented strain (CLM873ΔEIIB) from the low-virulence strain LM873, and performed comparative analyses with the high-virulence strain LM928 and its corresponding mutants. Deletion of EIIB differentially modulated biofilm formation: suppressing it in LM928 while enhancing it in LM873, accompanied by corresponding transcriptional changes in biofilm-associated and virulence genes. Both mutants exhibited impaired hemolytic activity, whereas motility attenuation was specific to LM928ΔEIIB. At the cellular level, LM873ΔEIIB enhanced adhesion to and invasion of Caco-2 but impaired intracellular proliferation in JEG-3; In contrast, LM928ΔEIIB promoted Caco-2 invasion while attenuating JEG-3 adhesion, invasion, and intracellular replication, as well as reducing invasion and proliferation in RAW264.7 macrophage. Animal experiments demonstrated that EIIB deletion attenuated LM928 colonization in the liver and spleen, but had no significant impact on LM873. Collectively, our findings establish EIIB as a strain-dependent virulence regulator in L. monocytogenes, particularly modulating biofilm formation and host–pathogen interactions. Full article

Progress in clinical diagnosis increasingly relies on innovative technologies and advanced disease biomarker detection methods. While cell labeling remains a well-established technique, label-free approaches offer significant advantages, including reduced workload, minimal sample damage, cost-effectiveness, and simplified chip integration. These approaches focus on the morpho-biophysical properties of cells, eliminating the need for labeling and thus reducing false results while enhancing data reliability and reproducibility. Current label-free methods span conventional and advanced technologies, including phase-contrast microscopy, holographic microscopy, varied cytometries, microfluidics, dynamic light scattering, atomic force microscopy, and electrical impedance spectroscopy. Their integration with artificial intelligence further enhances their utility, enabling rapid, non-invasive cell identification, dynamic cellular interaction monitoring, and electro-mechanical and morphological cue analysis, making them particularly valuable for cancer diagnostics, monitoring, and prognosis. This review compiles recent label-free cancer cell detection developments within clinical and biotechnological laboratory contexts, emphasizing biophysical alterations pertinent to liquid biopsy applications. It highlights interdisciplinary innovations that allow the characterization and potential identification of cancer cells without labeling. Furthermore, a comparative analysis addresses throughput, resolution, and detection capabilities, thereby guiding their effective deployment in biomedical research and clinical oncology settings. Full article

The Krüppel-like factors (KLFs) are a family of transcriptional regulators that play crucial roles in regulating diverse cellular processes including development, proliferation, differentiation, metabolism, and carcinogenesis across various tissues. KLFs play pivotal roles in gastrointestinal pathologies, and exhibit tissue- and cell-type-specific expression patterns throughout the gastrointestinal tract. During gastrointestinal (GI) development, KLFs orchestrate the transition from embryonic to adult gene programming, with specific family members being essential for proper organogenesis and tissue formation. KLFs also function as context-dependent modulators of GI homeostasis, inflammation, and carcinogenesis in adult tissues and interact with major signaling pathways such as PI3K/AKT, NF-κB, Wnt, Notch, MAPK, and TGF-β. This review comprehensively examines the roles of KLFs in GI health and disease, focusing on their expression patterns, regulatory mechanisms, function in normal homeostasis, and therapeutic implications for gastrointestinal disorders. Full article

Chronic wasting disease (CWD) is a prion disease of cervids marked by growing strain diversity and variation in host susceptibility. Central to this complexity are prion protein gene (Prnp) polymorphisms, which can modulate pathogenesis by altering the ability of cellular prion protein (PrP^C) to misfold into infectious prions (PrP^Sc), or by promoting the emergence of novel strains. Studies in cervids and transgenic rodent models demonstrate that individual polymorphisms influence PrP stability, conversion efficiency, and the selection of PrP^Sc conformers, with most variants conferring partial resistance but none offering complete protection. These host–strain interactions define transmission barriers and disease phenotype. Understanding how Prnp genotypes shape CWD strain diversity is essential for predicting transmission dynamics, refining surveillance, and assessing zoonotic potential as the disease continues to expand geographically and genetically. Full article

Despite numerous research efforts and several effective vaccines and therapies developed against coronavirus disease 2019 (COVID-19), drug repurposing remains an attractive alternative approach for treatment of SARS-CoV-2 variants and other viral infections that may emerge in the future. Cellular polyamines support viral propagation and tumor growth. Here we tested the antiviral activity of two polyamine metabolism-targeting drugs, an irreversible inhibitor of polyamine biosynthesis, α-difluoromethylornithine (DFMO), and a non-steroidal anti-inflammatory drug (NSAID), Sulindac, which have been previously evaluated for colon cancer chemoprevention. The drugs were tested as single agents and in combination in the human Calu-3 lung adenocarcinoma and Caco-2 colon adenocarcinoma cell lines and the K18-hACE2 transgenic mouse model of severe COVID-19. In the infected human cell lines, the DFMO/Sulindac combination significantly suppressed SARS-CoV-2 N1 Nucleocapsid mRNA by interacting synergistically when cells were pretreated with drugs and additively when treatment was applied to the infected cells. The Sulindac alone and DFMO/Sulindac combination treatments also suppressed the expression of the viral Spike protein and the host angiotensin-converting enzyme 2 (ACE2). In K18-hACE2 mice, the antiviral activity of DFMO and Sulindac as single agents and in combination was tested as prophylaxis (drug supplementation started 7 days before infection) or as treatment (drug supplementation started 24 h post-infection) at the doses equivalent to patient chemoprevention trials (835 ppm DFMO and 167 ppm Sulindac). The drugs’ antiviral activity in vivo was evaluated by measuring the clinical (survival rates and clinical scores), viral (viral load and virus infectivity), and biochemical (plasma polyamine, Sulindac, and Sulindac metabolite levels) endpoints. Prophylaxis with DFMO and Sulindac as single agents significantly increased survival rates in the young male mice (p = 0.01 and p = 0.027, respectively), and the combination was effective in the aged male mice (p = 0.042). Young female mice benefited the most from the prophylaxis with Sulindac alone (p = 0.001) and the DFMO/Sulindac combination (p = 0.018), while aged female mice did not benefit significantly from any intervention. Treatment of SARS-CoV-2-infected animals with DFMO or/and Sulindac did not significantly improve their survival rates. Overall, our studies demonstrated that DFMO and Sulindac administration as the prophylaxis regimen provided strong protection against the lethal outcome of SARS-CoV-2 infection and that male mice benefited more from the polyamine-targeted antiviral treatment than female mice. Our findings underscore the importance of evaluation of the antiviral activity of the drugs in the context of sex and age. Full article

Background/Objectives: Whilst adoptive cell therapy (ACT) using chimeric antigen receptor-engineered T (CAR-T) cells represents an efficient approach for the treatment of patients suffering from several hematological malignancies, solid tumors have been shown to be far more challenging to tackle, mainly due to the hostile tumor microenvironment that inhibits optimal T cell functionality. As proven by the broad clinical success of immune checkpoint inhibitors, blocking the interaction of programmed cell death ligand 1 (PD-L1) expressed on tumor cells and the checkpoint receptor programmed cell death 1 (PD-1) expressed on activated T cells allows an intrinsic T cell-mediated anti-tumor response to be unleashed. We developed a cellular product (MDG1015) consisting of New York esophageal squamous cell carcinoma-1 (NY-ESO-1)/L antigen family member 1a (LAGE-1a)-specific CD8+ T cell receptor-transduced (TCR-)T cells co-expressing the costimulatory switch protein (CSP) PD1-41BB, which turns an inhibitory signal mediated by the PD-1:PD-L1 axis into positive T cell costimulation. Methods: In vitro co-cultures of MDG1015 and PD-L1-positive or -negative target cells were used to analyze TCR-T cell functionality, such as TCR-T (poly-)cytokine release, the killing of target cells, and TCR-T proliferation. The safety of MDG1015 was evaluated via different panels of antigen-negative cell lines or primary cells expressing or lacking PD-L1. Results: Preclinical analyses demonstrated TCR-gated activation of the CSP, leading to enhanced functionality of MDG1015 against antigen-expressing, PD-L1-positive tumor cells without any impact on antigen-negative target cells. Conclusions: The favorable, preclinical functionality and safety profile qualifies MDG1015 as a promising cellular therapy for explorative clinical testing in hard-to-treat solid tumor indications. Full article

Background: To overcome the esthetic limitations of dental monolithic zirconia restorations, multichromatic systems were developed to combine improved structural integrity with a natural shade gradient that mimics the optical properties of natural teeth. In response to the clinical demand for time-efficient, i.e., chairside fabrication of zirconia restorations, rapid sintering protocols have become necessary to adjust clinical efficiency along with material performance. This study addresses the challenges of a rapid sintering protocol related to optical performance and phase transformation of the final restoration and the zirconia–cell interaction. Methods: The influence of a rapid sintering protocol on the color stability of the final dental restoration was evaluated by the CIE L*a*b* color space. Phase transformation was assessed through X-ray diffraction analysis. Cellular behavior was evaluated by measuring wettability, the material’s surface energy, and a cell mitochondrial activity assay on human gingival fibroblasts. Results: Optical measurements demonstrated that the total color change in all layers after rapid sintering was above the perceptibility threshold (ΔE* > 1.2), while only the polished enamel layer (ΔE* = 3.01) exceeded the acceptability threshold (ΔE* > 2.7), resulting in a clinically perceptible mismatch. Results of X-ray diffraction analysis, performed for fixed occupancy at Z_0.935Y_0.065O_0.984, revealed that rapid sintering caused a decrease in the cubic (C-) phase and an increase in the total amount of tetragonal (T-) phases. Conventionally sintered zirconia consists of 54% tetragonal (T-) and 46% cubic (C-) phase, whereas in the speed-sintered specimens, an additional T1 phase was detected (T = 49%; T1 = 27%), along with a reduced cubic fraction (C = 24%). Additionally, a small amount of the monoclinic (M) phase is noticed. Although glazing as a surface finishing procedure resulted in increased hydrophilicity, both polished and glazed surface-treated specimens showed statistically comparable cell adhesion and proliferation (p > 0.05). Conclusions: Rapid sintering induced perceptible color changes only in the enamel layer of multichromatic zirconia, suggesting that even layer-specific alterations may have an impact on the overall esthetic outcome of the final prosthetic restoration. Five times higher heating and cooling rates caused difficulty in reaching equilibrium, leading to changes in lattice parameters and the formation of the metastable T1 phase. Full article

Background/Objectives: Homotypic targeting refers to the ability of cells to preferentially interact with other cells of the same type. An understanding of how cells use homotypic targeting (self-homing) characteristics for tumor-targeting purposes may aid in the effective delivery of radionuclides or other drugs for imaging or therapeutic applications. Additionally, studies investigating the targeting properties of cells from the same lineage may shed light on this interesting mechanism, allowing it to be harnessed for other applications. The objective of this study was to assess the tumor-self targeting potential of PC3 prostate cancer and 4T1 breast cancer cells using a direct cell labeling technique, with a focus on evaluation of cellular labeling efficiency, cell viability, cellular efflux, and in vivo tumor-self targeting capability using both identical and dissimilar tumor models. Methods: [⁸⁹Zr]Zr-oxine was prepared and utilized for the labeling of PC3 and 4T1 cells. Following the assessment of cell labeling efficacy, viability, and efflux, PET/CT imaging and biodistribution studies were conducted with [⁸⁹Zr]Zr-oxine labeled PC3 and 4T1 cells in PC3 and 4T1 tumor-bearing mice models. Results: Both PC3 cells and 4T1 cells were radiolabeled with [⁸⁹Zr]oxine, with PC3 cells illustrating a higher labeling efficiency (86.55 ± 0.38%) than 4T1 cells (46.95 ± 1.47%). Notably, radiolabeled PC3 cells illustrated significant uptake in PC3 tumors (7.54 ± 1.07%ID/gram at 24 h and 6.95 ± 3.56%ID/gram at 48 h) with lower tumor uptake in the 4T1 xenograft model (1.79 ± 0.29%ID/gram at 24 h and 1.42 ± 0.71%ID/gram at 48 h), illustrating the potential of self-targeting. Conclusions: Both PC3 and 4T1 cells followed a similar pattern of biodistribution, with labeled PC3 cells demonstrating lower blood retention and reduced uptake in non-target organs such as lungs and heart. Taken together, these results may indicate that PC3 cells illustrate homotypic targeting, warranting further investigation of this phenomenon. Full article

The accumulation of high levels of manganese ions complexed with small molecules has been proposed as a pivotal factor contributing to the extraordinary radiation resistance of Deinococcus radiodurans. However, the molecular mechanisms governing the manganese ion homeostasis remain elusive. In this study, we characterize the role of the MntABC transporter system for Mn ion accumulation in D. radiodurans. Its cellular membrane localization is unequivocally demonstrated through fluorescence labeling techniques. Mutation of the protein components of the MntABC led to a significant decrease in intracellular Mn ion accumulation, concomitant with impaired cellular growth, decreased resistance against hydrogen peroxide, and gamma-ray irradiation-induced oxidative stresses, indicating that the MntABC system plays an indispensable role in resistance of D. radiodurans to oxidative stresses. Protein structure modeling and molecular docking are employed to analyze the key active sites of the MntABC proteins and their intermolecular interactions. The results demonstrate that the MntABC system is essential for maintaining Mn ion homeostasis and the oxidative stress resistance of D. radiodurans. Full article

Class 1 phytoglobins (Pgbs) are known for their multifunctional roles in plant stress responses, with recent studies suggesting broader interactions involving metabolic and transcriptional regulation. Interestingly, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) moonlights in many roles in colocalized spaces during cellular stress that are strikingly suitable for supporting Pgb function. This study investigates the molecular interactions of class 1 Pgb from sugar beet (Beta vulgaris), BvPgb 1.2, and an alanine-substituted mutant (C86A), focusing on their ability to bind GAPDH and DNA. Using dual-emission isothermal spectral shift (SpS) analysis, we report strong binding interactions with GAPDH, with dissociation constants (K_D) of 260 ± 50 nM for the recombinant wild-type protein (rWT) and a significantly stronger affinity for C86A (120 ± 40 nM), suggesting that the cysteine residue limits the interaction. Remarkably strong DNA-binding affinities were also observed for both variants, displaying biphasic binding. This behavior is characteristic of hexacoordinated globins and reflects the presence of two distinct species: a fast-reacting open pentacoordinated form and a slow-reacting closed hexacoordinated form with high apparent affinity. Here, the K_D in the open configuration was 120 ± 50 nm and 50 ± 20 nM for rWT and C86A, respectively. In the closed configuration, however, the cysteine appears to support the interaction, as the K_D was measured at 100 ± 10 pM and 230 ± 60 pM for rWT and C86A, respectively. Protein–protein docking studies reinforced these findings, revealing electrostatically driven interactions between BvPgb 1.2 and GAPDH, characterized by a substantial buried surface area indicative of a stable, biologically relevant complex. Protein–DNA docking similarly confirmed energetically favorable binding near the heme pocket without obstructing ligand accessibility. Together, these findings indicate a potential regulatory role for BvPgb 1.2 through its interaction with GAPDH and DNA. Full article