Oral midazolam vs. intranasal dexmedetomidine plus oral midazolam for sedation of pediatric outpatients: a double-blinded randomized controlled trial.

BACKGROUND: Moderate to deep sedation is required for dental treatment of children with dental anxiety. Midazolam is the most commonly used sedative, whereas intranasal dexmedetomidine is increasingly used in pediatric sedation. OBJECTIVE: The aim of this trial was to compare the sedative efficacy of oral midazolam alone with that of intranasal dexmedetomidine plus oral midazolam during dental treatment of children with dental anxiety. DESIGN: In total, 83 children (aged 3-12 years) scheduled to undergo dental sedation were randomized to receive oral midazolam (0.5 mg/kg) and intranasal placebo, or oral midazolam (0.5 mg/kg) plus intranasal dexmedetomidine (2 µg/kg). The primary outcome was the rate of successful sedation for dental treatment. Secondary outcomes were the onset time and adverse events during and after treatment. Data analyses involved descriptive statistics and nonparametric tests. RESULTS: The rate of successful sedation was significantly higher in combination group (P = 0.007), although the sedation onset time was significantly longer in combination group (17.5 ± 2.4 min) than in monotherapy group (15.7 ± 1.8) (P = 0.003). No children required medical intervention or oxygen therapy for hemodynamic disturbances, and the incidences of adverse events had no significant difference between groups (P = 0.660). CONCLUSION: Combined treatment with oral midazolam (0.5 mg/kg) and intranasal dexmedetomidine (2 µg/kg) is more significantly effective for managing the behavior of non-cooperative children during dental treatment, compared to oral midazolam (0.5 mg/kg) alone. (Chinese Clinical Trial Registry: ChiCTR2100042300) TRIAL REGISTRATION: ChiCTR2100042300, Clinical trial first registration date: 17/01/2021.

Alteration of circular RNA expression in rat dental follicle cells during osteogenic differentiation.

Circular RNAs (circRNAs) are novel noncoding RNAs and play crucial roles in various biological processes. However, little is known about the functions of circRNAs in osteogenic differentiation. The current study aimed to investigate the differential expression of circRNAs in rat dental follicle cells (rDFCs) during osteogenic differentiation, identified by RNA high-throughput sequencing and quantitative real-time polymerase chain reaction. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to further explore the biofunctions of circRNA biofunctions. Two hundred sixty-six differentially-expressed circRNAs that are involved in several important signaling pathways, including mitogen-activated protein kinases (MAPK) and transforming growth factor-ß (TGF-ß) signaling pathways were revealed. Among these, circFgfr2 and its predicted downstream targets, miR-133 and BMP6 (bone morphogenetic protein-6), were identified both in vivo and in vitro. For further validation, circFgfr2 was overexpressed in rDFCs, the results showed that the expression of miR-133 was downregulated and the expression of BMP6 was upregulated. Taken together, the results revealed the circRNA expression profiles and indicated the importance of circRNAs of rDFCs. In addition, circFgfr2 might promote osteogenesis by controlling miR-133/BMP6, which is a potential new target for the manipulation of tooth regeneration and bone formation.

Effect of erythropoietin on angiogenic potential of dental pulp cells.

Erythropoietin (EPO) is a 34-kDa glycoprotein that possesses the potential for angiogenesis, as well as anti-inflammatory and anti-apoptotic properties. The present study aimed to examine the effect of EPO on the angiogenesis of dental pulp cells (DPCs) and to explore the underlying mechanisms of these effects. It was demonstrated that EPO not only promoted DPCs proliferation but also induced angiogenesis of DPCs in a paracrine fashion. EPO enhanced the angiogenic capacity by stimulating DPCs to secrete a series of angiogenic cytokines. ELISA confirmed that high concentrations of EPO increased the production of MMP-3 and angiopoietin-1 but decreased the secretion of IL-6. Furthermore, EPO activated the ERK1/2 and p38 signaling pathways in DPCs, while inhibition of these pathways diminished the angiogenesis capacity of DPCs. The present study suggested that EPO may have an important role in the repair and regeneration of dental pulp.

[Corrigendum] Nkd2 promotes the differentiation of dental follicle stem/progenitor cells into osteoblasts.

After the publication of the article, the authors realized that the surname of the author listed second on the paper was spelt incorrectly as 'Zhan' instead of 'Zhang'; the corrected name is now featured above. The authors regret that this error was not corrected prior to the publication of their paper, and apologize for any inconvenience caused. [the original article was published in International Journal of Molecular Medicine 42: 2403­2414, 2018; DOI: 10.3892/ijmm.2018.3822].

Heterologous expression, purification and biochemical characterization of a glutamate racemase (MurI) from Streptococcus mutans UA159.

BACKGROUND: Glutamate racemase (MurI) is a cofactor-independent enzyme that is essential to the bacterial peptidoglycan biosynthesis pathway and has therefore been considered an attractive target for the development of antimicrobial drugs. While in our previous study the essentiality of the murI gene was shown in Streptococcus mutans, the primary aetiologic agent of human dental caries, studies on S. mutans MurI have not yet provided definitive results. This study aimed to produce and characterize the biochemical properties of the MurI from the S. mutans UA159 genome. METHODS: Structure characterization prediction and multiple sequence alignment were performed by bioinformatic analysis. Recombinant His6-tagged S. mutans MurI was overexpressed in the expression vector pColdII and further purified using a Ni2+ affinity chromatography method. Protein solubility, purity and aggregation state were analyzed by SDS-PAGE, Western blotting, native PAGE and SEC-HPLC. Kinetic parameters were assessed by a circular dichroism (CD) assay. Kinetic constants were calculated based on the curve fit for the Michaelis-Menten equation. The effects of temperature and pH on enzymatic activity were determined by a series of coupled enzyme reaction mixtures. RESULTS: The glutamate racemase gene from S. mutans UA159 was amplified by PCR, cloned and expressed in Escherichia coli BL21 (DE3). The 264-amino-acid protein, as a mixture of dimeric and monomeric enzymes, was purified to electrophoretic homogeneity. In the CD assay, S. mutans MurI displayed unique kinetic parameters (K m, d-Glu→l-Glu = 0.3631 ± 0.3205 mM, V max, d-Glu→l-Glu = 0.1963 ± 0.0361 mM min-1, k cat, d-Glu→l-Glu = 0.0306 ± 0.0065 s-1, k cat/K m, d-Glu→l-Glu = 0.0844 ± 0.0128 s-1 mM-1, with d-glutamate as substrate; K m, l-Glu→d-Glu = 0.8077 ± 0.5081 mM, V max, l-Glu→d-Glu = 0.2421 ± 0.0418 mM min-1, k cat , l - Glu→d-Glu = 0.0378 ± 0.0056 s-1, k cat/K m, l-Glu→d-Glu = 0.0468 ± 0.0176 s-1 mM-1, with l-glutamate as substrate). S. mutans MurI possessed an assay temperature optimum of 37.5 °C and its optimum pH was 8.0. CONCLUSION: The findings of this study provide insight into the structure and biochemical traits of the glutamate racemase in S. mutans and supply a conceivable guideline for employing glutamate racemase in anti-caries drug design.

Nkd2 promotes the differentiation of dental follicle stem/progenitor cells into osteoblasts.

Dental follicle stem/progenitor cells have the potential to undergo osteogenesis. naked cuticle homolog 2 (Nkd2) is a signal­inducible feedback antagonist of the canonical Wnt signaling pathway. The purpose of the present study was to investigate the function of Nkd2 in the differentiation of dental follicle stem/progenitor cells (DFSCs) into osteoblasts. Immunohistochemistry, reverse transcription­quantitative polymerase chain reaction and western blotting were employed to detect Nkd2 expression in rat DFSCs. In addition, rat DFSCs (rDFSCs) were transfected with small interfering RNAs to examine the effect of Nkd2 on the differentiation of these cells into osteoblasts. Furthermore, the function of Nkd2 in the Wnt/ß­catenin pathway in rDFSCs was investigated using ß­catenin/T­cell factor luciferase activity assays and western blotting. It was revealed that the expression of Nkd2 was upregulated during the differentiation of rDFSCs into osteoblasts. Furthermore, osteoblast differentiation ability and Wnt/ß­catenin pathway activity were significantly decreased in Nkd2­silenced rDFSCs compared with the si­NC group (P<0.05 and P<0.001, respectively). The results suggest that Nkd2 promotes the differentiation of rDFSCs into osteoblasts through Wnt/ß­catenin signaling.

Proteomic analysis of the effects of CSF-1 and IL-1α on dental follicle cells.

Tooth eruption is a complex physiological process involving both osteogenesis and bone resorption. Signals from the dental follicle (DF) regulate bone remodeling during tooth eruption. Interleukin-1α (IL-1α) may be the initial promoter of tooth eruption, whereas colony­stimulating factor­1 (CSF­1) may attract monocytes into the DF and stimulate osteoclast differentiation. In the present study, differential proteomics was employed to explore protein changes in rat DF cells (DFCs) under the effects of CSF­1 and IL­1α. A total of 47 protein spots were differentially expressed in rat DFCs, and 40 protein spots were identified by MALDI­TOF­MS. The identified proteins were grouped into functional categories including cytoskeletal proteins, metal­binding proteins, proteins involved in secretion and degradation, cell cycle proteins and stress proteins. In IL­1α­induced rat DFCs, 31 proteins were upregulated compared with the control and included heat shock protein ß­1 (HSP25, also known as HSP27/HSPß1), vimentin, TMEM43, the GTP­binding protein Rab­3D, 6­pyruvoyl tetrahydrobiopterin synthase and actin. In total, 7 proteins were downregulated, including serum albumin, GIPC1, DNA primase large subunit, cullin­5 and cyclin­G1. In CSF­1­induced rat DFCs, 3 proteins were upregulated and 7 proteins were downregulated when compared with the controls. The upregulated proteins included the GTP­binding protein Rab­3D and α­actin. The downregulated proteins included cullin­5, serum albumin, PDZ domain­containing protein and cyclin­G1. The differential expression of vimentin, actin, HSP25 and Rab­3D was verified by western blotting and reverse transcription­quantitative polymerase chain reaction analyses. The present findings provide an insight into the mechanisms involved in tooth eruption.

Expression of matrilin-2 and -4 in human dental pulps during dentin-pulp complex wound healing.

INTRODUCTION: Matrilin-2 and matrilin-4 are members of the matrilin family displaying broad tissue distribution. We recently reported that matrilin-2 showed significant down-regulation during the odontogenic differentiation of dental pulp cells (DPCs). It is reported that matrilin-4 was the only extracellular matrix biogenesis and organization-related gene detected in odontoblasts but not DPCs. However, the exact role of matrlin-2 and -4 in dental pulps remains unclear. The aim of our study was to analyze the expression of matrilin-2 and -4 in human dental pulps and their relation to dentin-pulp complex wound healing. METHODS: Immunohistology was performed on the paraffin-embedded tissue sections of human dental pulps from sound and deep carious teeth. Matrilin-2 and -4 messenger RNAs were detected by quantitative real-time reverse-transcription polymerase chain reaction, and the proteins were shown by immunofluorescence and Western blot during odontogenic differentiation of the DPCs. RESULTS: In the sound dental pulp, matrilin-2 immunoreactivity was observed throughout the pulp, whereas matrilin-4 was observed only in the odontoblast layer. In deep carious dental pulp, matrilin-2 protein was weakly stained, whereas matrilin-4 was detected in the pulp under the carious lesion. During odontogenic differentiation of DPCs, the expression of matrilin-2 messenger RNA was down-regulated within 14 days followed by a statistical increase on day 21, and the matrilin-2 protein level was down-regulated within the 3 weeks, whereas the messenger RNA and protein expressions of matrilin-4 increased in a time-dependent manner. CONCLUSIONS: Matrilin-2 and matrilin-4 have been shown in human dental pulps and might be involved in the dentin-pulp complex wound-healing process.