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N6-methyladenosine (m6A) modification, a eukaryotic messenger RNA modification catalyzed by methyltransferase-like 3 (METTL3), plays a pivotal role in stem cell fate determination. Calvarial bone development and maintenance are orchestrated by the cranial sutures. Cathepsin K (CTSK)–positive calvarial stem cells (CSCs) contribute to mice calvarial ossification. However, the role of m6A modification in regulating Ctsk+ lineage cells during calvarial development remains elusive. Here, we showed that METTL3 was colocalized with cranial nonosteoclastic Ctsk+ lineage cells, which were also associated with GLI1 expression. During neonatal development, depletion of Mettl3 in the Ctsk+ lineage cells delayed suture formation and decreased mineralization. During adulthood maintenance, loss of Mettl3 in the Ctsk+ lineage cells impaired calvarial bone formation, which was featured by the increased bone porosity, enhanced bone marrow cavity, and decreased number of osteocytes with the less-developed cellular outline. The analysis of methylated RNA immunoprecipitation sequencing and RNA sequencing data indicated that loss of METTL3 reduced Hedgehog (Hh) signaling pathway. Restoration of Hh signaling pathway by crossing Sufufl/+ alleles or by local administration of SAG21 partially rescued the abnormity. Our data indicate that METTL3 modulates Ctsk+ lineage cells supporting calvarial bone formation by regulating the Hh signaling pathway, providing new insights for clinical treatment of skull vault osseous diseases. [ABSTRACT FROM AUTHOR]

The oral gingival barrier is a constantly stimulated and dynamic environment where homeostasis is often disrupted, resulting in inflammatory periodontal diseases. Type 2 diabetes (T2D) has been reported to be associated with gingival barrier dysfunction, but the effect and underlying mechanism are inconclusive. Herein, we performed single-cell RNA sequencing (scRNA-seq) of gingiva from leptin receptor-deficient mice (db/db) to examine the gingival heterogeneity in the context of T2D. Periodontal health of control mice is characterized by populations of Krt14+-expressing epithelial cells and Col1a1+-fibroblasts mediating immune homeostasis primarily through the enrichment of innate lymphoid cells. The db/db gingiva exhibited decreased epithelial/stromal ratio and dysfunctional barrier. We further observed stromal, particularly fibroblast immune hyperresponsiveness, linked to the recruitment of myeloid-derived cells at the db/db gingiva. Both scRNA-seq and histological analysis suggested the inflammatory signaling between fibroblasts and neutrophils as a potential driver of diabetes-induced periodontal damage. Notably, the "immune-like" stromal cells were wired toward the induction of gingival IL-17A hyperresponsiveness in db/db mice. Our work reveals that the "immune-like" fibroblasts with transcriptional diversity are involved in the innate immune homeostasis at the diabetic gingiva. It highlights a potentially significant role of these cell types in its pathogenesis. [ABSTRACT FROM AUTHOR]

Calvaria development is distinct from limb formation. Craniosynostosis is a skull deformity characterized by premature cranial suture fusion due to the loss of the GNAS gene and, consequently, its encoded protein Gαs. This birth defect requires surgery, with potential lethal consequences. So far, hardly any early-stage nonsurgical interventions for GNAS loss-related craniosynostosis are available. Here, we investigated the role of the Gnas gene in mice in guarding the distinctiveness of intramembranous ossification and how loss of Gnas triggered endochondral-like ossification within the cranial sutures. Single-cell RNA sequencing (scRNA-seq) of normal neonatal mice cranial suture chondrocytes showed a Hedgehog (Hh) inactivation pattern, which was associated with Gαs signaling activation. Loss of Gnas evoked chondrocyte-to-osteoblast fate conversion and resulted in cartilage heterotopic ossification (HO) within cranial sutures and fontanels of the mouse model, leading to a skull deformity resembling craniosynostosis in patients with loss of GNAS. Activation of ectopic Hh signaling within cranial chondrocytes stimulated the conversion of cell identity through a hypertrophy-like stage, which shared features of endochondral ossification in vivo. Reduction of Gli transcription activity by crossing with a loss-of-function Gli2 allele or injecting GLI1/2 antagonist hindered the progression of cartilage HO in neonatal stage mice. Our study uncovered the role of Gαs in maintaining cranial chondrocyte identity during neonatal calvaria development in mice and how reduction of Hh signaling could be a nonsurgical intervention to reduce skull deformity in craniosynostosis due to loss of GNAS. [ABSTRACT FROM AUTHOR]

Oral ulcer is a common oral inflammatory lesion accompanied by severe pain but with few effective treatments. Cannabidiol (CBD) is recently emerging for its therapeutic potential in a range of diseases, including inflammatory conditions and cancers. Here we show that CBD oral spray on acid- or trauma-induced oral ulcers on mice tongue inhibits inflammation, relieves pain, and accelerates lesion closure. Notably, the enrichment of genes associated with the NOD, LRR, and NLRP3 pyrin domain–containing protein 3 (NLRP3) inflammasome pathway is downregulated after CBD treatment. The expression of cleaved-gasdermin D (GSDMD) and the percentage of pyroptotic cells are reduced as well. In addition, CBD decreases the expression of cytidine/uridine monophosphate kinase 2 (CMPK2), which subsequently inhibits the generation of oxidized mitochondria DNA and suppresses inflammasome activation. These immunomodulating effects of CBD are mostly blocked by peroxisome proliferator activated receptor γ (PPARγ) antagonist and partially antagonized by CB1 receptor antagonist. Our results demonstrate that CBD accelerates oral ulcer healing by inhibiting CMPK2-mediated NLRP3 inflammasome activation and pyroptosis, which are mediated mostly by PPARγ in the nucleus and partially by CB1 in the plasma membrane. [ABSTRACT FROM AUTHOR]

Tooth eruption is a complex process requiring precise interaction between teeth and adjacent tissues. Molecular analysis demonstrates that bone remodeling plays an essential role during eruption, suggesting that a parathyroid hormone 1 receptor (PTH1R) gene mutation is associated with disturbances in bone remodeling and results in primary failure of eruption (PFE). Recent research reveals the function of PTH1R signaling in mesenchymal progenitors, whereas the function of PTH1R in mesenchymal stem cells during tooth eruption remains incompletely understood. We investigated the specific role of PTH1R in Prx1+ progenitor expression during eruption. We found that Prx1+-progenitors occur in mesenchymal stem cells residing in alveolar bone marrow surrounding incisors, at the base of molars and in the dental follicle and pulp of incisors. Mice with conditional deletion of PTH1R using the Prx1 promoter exhibited arrested mandibular incisor eruption and delayed molar eruption. Micro-computed tomography, histomorphometry, and molecular analyses revealed that mutant mice had significantly reduced alveolar bone formation concomitant with downregulated gene expression of key regulators of osteogenesis in PTH1R-deficient cells. Moreover, culturing orofacial bone-marrow-derived mesenchymal stem cells (OMSCs) from Prx1Cre;PTH1Rfl/fl mice or from transfecting Cre recombinase adenovirus in OMSCs from PTH1Rfl/fl mice suggested that lack of Pth1r expression inhibited osteogenic differentiation in vitro. However, bone resorption was not affected by PTH1R ablation, indicating the observed reduced alveolar bone volume was mainly due to impaired bone formation. Furthermore, we found irregular periodontal ligaments and reduced Periostin expression in mutant incisors, implying loss of PTH1R results in aberrant differentiation of periodontal ligament cells. Collectively, these data suggest that PTH1R signaling in Prx1+ progenitors plays a critical role in alveolar bone formation and periodontal ligament development during eruption. These findings have implications for our understanding of the physiologic and pathologic function of PTH1R signaling in tooth eruption and the progression of PFE. [ABSTRACT FROM AUTHOR]

Stem cells play a critical role in bone regeneration. Multiple populations of skeletal stem cells have been identified in long bone, while their identity and functions in alveolar bone remain unclear. Here, we identified a quiescent leptin receptor-expressing (LepR+) cell population that contributed to intramembranous bone formation. Interestingly, these LepR+ cells became activated in response to tooth extraction and generated the majority of the newly formed bone in extraction sockets. In addition, genetic ablation of LepR+ cells attenuated extraction socket healing. The parabiosis experiments revealed that the LepR+ cells in the healing sockets were derived from resident tissue rather than peripheral blood circulation. Further studies on the mechanism suggested that these LepR+ cells were responsive to parathyroid hormone/parathyroid hormone 1 receptor (PTH/PTH1R) signaling. Collectively, we demonstrate that LepR+ cells, a postnatal skeletal stem cell population, are essential for alveolar bone regeneration of extraction sockets. [ABSTRACT FROM AUTHOR]

Opaqueness of animal tissue can be attributed mostly to light absorption and light scattering. In most noncleared tissue samples, confocal images can be acquired at no more than a 100-µm depth. Tissue-clearing techniques have emerged in recent years in the neuroscience field. Many tissue-clearing methods have been developed, and they all follow similar working principles. During the tissue-clearing process, chemical or physical treatments are applied to remove components blocking or scattering the light. Finally, samples are immersed in a designated clearing medium to achieve a uniform refractive index and to gain transparency. Once the transparency is reached, images can be acquired even at several millimeters of depth with high resolution. Tissue clearing has become an essential tool for neuroscientists to investigate the neural connectome or to analyze spatial information of various types of brain cells. Other than neural science research, tissue-clearing techniques also have applications for bone research. Several methods have been developed for clearing bones. Clearing treatment enables 3-dimensional imaging of bones without sectioning and provides important new insights that are difficult or impossible to acquire with conventional approaches. Application of tissue-clearing technique on dental research remains limited. This review will provide an overview of the recent literature related to the methods and application of various tissue-clearing methods. The following aspects will be covered: general principles for the tissue-clearing technique, current available methods for clearing bones and teeth, general principles of 3-dimensional imaging acquisition and data processing, applications of tissue clearing on studying biological processes within bones and teeth, and future directions for 3-dimensional imaging. [ABSTRACT FROM AUTHOR]

Postmenopausal osteoporosis (PMO) is a risk factor for periodontitis, and current therapeutics against PMO prevent the aggravated alveolar bone loss of periodontitis in estrogen-deficient women. Gut microbiota is recognized as a promising therapeutic target for PMO. Berberine extracted from Chinese medicinal plants has shown its effectiveness in the treatment of metabolic diseases such as obesity and diabetes via regulating gut microbiota. Here, we hypothesize that berberine ameliorates periodontal bone loss by improving the intestinal barriers by regulating gut microbiota under an estrogen-deficient condition. Experimental periodontitis was established in ovariectomized (OVX) rats, and the OVX-periodontitis rats were treated with berberine for 7 wk before sacrifice for analyses. Micro-computed tomography and histologic analyses showed that berberine treatment significantly reduced alveolar bone loss and improved bone metabolism of OVX-periodontitis rats as compared with the vehicle-treated OVX-periodontitis rats. In parallel, berberine-treated OVX-periodontitis rats harbored a higher abundance of butyrate-producing gut microbiota with elevated butyrate generation, as demonstrated by 16S rRNA sequencing and high-performance liquid chromatography analysis. Berberine-treated OVX-periodontitis rats consistently showed improved intestinal barrier integrity and decreased intestinal paracellular permeability with a lower level of serum endotoxin. In parallel, IL-17A-related immune responses were attenuated in berberine-treated OVX-periodontitis rats with a lower serum level of proinflammatory cytokines and reduced IL-17A+ cells in alveolar bone as compared with vehicle-treated OVX-periodontitis rats. Our data indicate that gut microbiota is a potential target for the treatment of estrogen deficiency-aggravated periodontal bone loss, and berberine represents a promising adjuvant therapeutic by modulating gut microbiota. [ABSTRACT FROM AUTHOR]

This paper references the structural design of the novel oblique frame-grid multi-ribbed composite (MRC) wall in studying the seismic performance of frame-supported MRC (FSMRC) walls. Two 1/2-scale FSMRC wall specimens with first floors composed of frame-shear walls and second floors composed of MRC walls were tested under cyclic loading. The failure processes and force-transfer mechanisms of both the orthogonal and the oblique frame-grid specimens were then investigated. Concurrently, the hysteresis of the vertex-horizontal displacement and inter-storey displacement, the skeleton curves, the loading-strain curves of the reinforcing bars of the members, and the residual deformation ratios of the specimens were analysed. The results indicate that the FSMRC wall exhibited good seismic performance and that the oblique frame-grid design was able to improve the overall ductility, deformation capacity, seismic resistance and repairability of the wall. [ABSTRACT FROM AUTHOR]

Background: Imaging the perfusion of contrast media in breast tumors may allow improved diagnosing and treating breast cancer. Purpose: To compare the perfusion curve f (t) characteristics of contrast-enhanced ultrasonography in benign and malignant breast tumors. Material and Methods: Patients with breast tumors (n = 87) were evaluated with contrast-enhanced ultrasonography and the perfusion curve f (t) parameters were calculated using Sonoliver(®) software to compare analysis (tumor) and reference (normal) tissue areas. Differences between breast and breast tumors were assessed. Results: Compared to benign tumors, malignant tumors had faster enhancement time and a shorter mean transit time (all P values < 0.05). The intensity of the signal was also greater for malignant compared with benign tumors. Conclusion: Perfusion curve f (t) parameter measurements can distinguish differences in vascular flow between malignant and benign breast tumors and may provide a new quantitative indicator of breast tumor. [ABSTRACT FROM AUTHOR]

Scanning electron microscopy was used to observe the microstructures of a cork wood. It showed that the wood consists of countless rectangular and honeycomb wood cells. The wall of each wood cell connects with adjacent wood cells at the middle of the cell wall. More careful observation showed that the walls of the wood cells are a kind of fibre reinforced biocomposite consisting of crystalline cellulose fibre layers and hydrocarbonated polymer matrix. The crystalline cellulose fibres in different fibre layers possess different directions, which compose a kind of fibre helicoidal microstructure. In the microstructure, the helicoidal angle is very large. The maximum pullout force of the fibre helicoidal microstructure, which is closely related to the fracture toughness of the wood, was theoretically and experimentally investigated and compared with that of the fibre parallel microstructure. It showed that the maximum pullout force of the fibre helicoidal microstructure is markedly greater than that of the fibre parallel microstructure and that the larger the helicoidal angle, the more the maximum pullout force will increase compared with that of the parallel microstructure. [ABSTRACT FROM AUTHOR]

The authors describe here the chemical processing methodology and physicochemical response of superparamagnetic nickel ferrite nanoparticles, which were encapsulated and functionalised with polyethylene glycol to form a core shell structure. The outer shell was subsequently conjugated with tumour recognition moiety, folic acid and loaded with doxorubicin drug to achieve tumour specific drug delivery. Fourier transform infrared spectroscopy confirmed the functionalisation and conjugation steps used in the synthesis of the nanocarrier. The drug release response was characterised by an initial rapid release followed by a controlled release. The study also indicated that it is important to optimise the thickness of the polyethylene glycol shell on the magnetic nickel ferrite core to avoid reduction in the ability of the nanocarrier to experience alternate compressive and tensile stresses caused by the external magnetic field because this leads to reduction in the percentage of drug release. [ABSTRACT FROM AUTHOR]

Polymer nanocomposites, or more appropriately polymer nanostructured materials, represent a radical alternative to the conventional filled polymers and polymer blends, in which discrete constituents on the order of a few nanometres are incorporated in the polymer matrix. In the last decade, the utility of inorganic nanoparticles as additives to enhance polymer performance has been established and now provides numerous commercial opportunities, ranging from advanced aerospace systems to commodity plastics. The incorporation of low volume additions (1–5 wt-%) of highly anisotropic nanoparticles, such as layered silicates or carbon nanotubes, have resulted in property enhancements with respect to the neat polymer that are comparable with that achieved by conventional loadings (15–40 wt-%) of traditional fillers. The lower loadings facilitate processing and reduce component weight. In addition, unique value added properties not normally possible with traditional fillers were also observed, such as high stiffness, reduced permeability, optical clarity and electrical conductivity have been achieved. However, the development of chemical and processing procedures to disrupt the low-dimensional crystallites (tactoids and ropes) to achieve uniform distribution of the nanoelement (layered silicate and single wall carbon nanotube respectively) continues to be a challenge. Even less developed are approaches to provide spatial and orientational control of the hierarchical morphology. There exists an immense potential for polymer nanocomposites, in particular, polypropyelene–clay nanocomposites paving the way for future technologies for the materials community at large. [ABSTRACT FROM AUTHOR]