Tooth whitening: current status and prospects.

As a safe, effective, economical, and convenient technique, tooth whitening is one of the most popular treatments for improving tooth discoloration. This review summarizes the theoretical and recent research developments in the classification and mechanisms of tooth discoloration, as well as the principles, agents, effects, and side effects of tooth whitening techniques. The aim is to provide a basis for the clinical treatment of tooth whitening techniques and to suggest possible new ideas for further research. The accepted mechanism of whitening is the redox reaction of oxides in the whitening reagent, and the whitening effect is remarkable. However, side effects such as tooth sensitivity and irritation of gum and other oral soft tissues can still occur. It is recommended that more monitoring be carried out in the clinic to monitor these side effects, and care should be taken to protect the soft tissues in the mouth during office whitening procedures. Furthermore, there is a need to develop new additives or natural whitening products to reduce the occurrence of side effects.

Abnormal histidine metabolism promotes macrophage lipid accumulation under Ox-LDL condition.

Distinct macrophage populations exert highly heterogeneity and perform various functions, among which, a crucial function of lipid metabolism is highlighted. However, the role of histidine metabolism disorder in macrophage lipid metabolism remains elusive. Addressed this question, we sorted and cultured the bone marrow-derived macrophages (BMDMs) of histidine decarboxylase (Hdc) knockout (Hdc-/-) mice with an in vitro oxidized low-density lipoprotein (ox-LDL) model, and detected the intracellular lipids by Oil Red O staining as well as lipid probe staining. Astemizole, a canonical and long-acting histamine H1 receptor (H1R) antagonist, was applied to elucidate the impact of antagonizing the H1R-dependent signaling pathway on macrophage lipid metabolism. Subsequently, the differential expressed genes were screened and analyzed in the bone marrow-derived CD11b+ immature myeloid cells of Hdc-/- and Hdc+/+ mice with a high fat diet by the microarray study. The expression levels of cholesterol metabolism-related genes were examined by qRT-PCR to explore underlying mechanisms. Lastly, we used a high-sensitivity histidine probe to detect the intracellular histidine in the BMDMs after oxidative stress. The results revealed that histidine metabolism disorder and histamine deficiency aggravated lipid accumulation in the ox-LDL-treated BMDMs. The expression level of H1R gene in the BMDMs was down-regulated after ox-LDL stimulation. The disruption of the H1R-dependent signaling pathway by astemizole further exacerbated ox-LDL-induced lipid deposition in the BMDMs partly by up-regulating scavenger receptor class A (SR-A) for lipid intake, down-regulating neutral cholesteryl ester hydrolase (nCEH) for cholesterol esterification and down-regulating ATP-binding cassette transporters A1 (ABCA1) and ABCG1 for reverse cholesterol transport. The intracellular histidine increased under ox-LDL condition, which was further increased by Hdc knockout. Collectively, these results partially reveal the relationship between histidine metabolism and lipid metabolism in the BMDMs and offer a novel strategy for lipid metabolism disorder-associated diseases.

Degradation of 3,5,6-trichloro-2-pyridinol by a microbial consortium in dryland soil with anaerobic incubation.

Biodegradation of 3,5,6-trichloro-2-pyridinol (TCP) in drylands is an important biological process of detoxification. Flooding in drylands can result in the formation of anaerobic habitats. However, little is known about the microbial metabolism of TCP in dryland soil under anaerobic conditions. Here, chlorpyrifos-contaminated dryland soil was incubated to enrich the TCP-degrading microbial consortium under anaerobic conditions. Chloridion and CO2 were released with TCP degradation, and the enrichment cultures of dryland soil could metabolize 97% of TCP (100 mg/L) within 20 h. Both reductive and hydrolysis dechlorination mechanisms were involved in TCP biodegradation under anaerobic conditions. Bacterial taxonomic analysis revealed that the aerobic TCP-degrading bacteria Ochrobactrum and dechlorination bacteria Delftia were the dominant genera. Anaerobic and facultative bacteria; i.e., Bacteroides, Bacillus, and Cupriavidus had lower relative abundances, but they were significantly enriched following treatment with TCP. These results indicate that the enrichment cultures of dryland soil dominated by aerobic bacteria could dechlorinate and degrade TCP under anaerobic conditions.

Enzymatic properties of ß-N-acetylglucosaminidases.

ß-N-Acetylglucosaminidases (GlcNAcases) hydrolyse N-acetylglucosamine-containing oligosaccharides and proteins. These enzymes produce N-acetylglucosamine (GlcNAc) and have a wide range of promising applications in the food, energy, and pharmaceutical industries, such as synergistic degradation of chitin with endo-chitinases and using GlcNAc to produce sialic acid, bioethanol, single-cell proteins, and pharmaceutical therapeutics. GlcNAcases also play an important role in the dynamic balance of cellular O-linked GlcNAc levels, catabolism of ganglioside storage in Tay-Sachs disease, and bacterial cell wall recycling and flagellar assembly. In view of these important biological functions and the wide range of industrial applications of GlcNAcases, this review aims to provide a better understanding of various advances for these enzymes. It focuses on enzymatic properties of GlcNAcases, including substrate specificity, catalytic activity, pH optimum, temperature optimum, thermostability, the effects of various metal ions and organic reagents, and transglycosylation.

Water regime-nitrogen fertilizer incorporation interaction: Field study on methane and nitrous oxide emissions from a rice agroecosystem in Harbin, China.

Water regime and nitrogen (N) fertilizer are two important factors impacting greenhouse gases (GHG) emission from paddy field, whereas their effects have not been well studied in cold region. In this study, we conducted a two-year field experiment to study the impacts of water regime and N fertilizer on rice yields and GHG emissions in Harbin, China, a cold region located in high latitudes. Our results showed that intermittent irrigation significantly decreased methane (CH4) emission compared with continuous flooding, however, the decrement was far lower than the global average level. The N2O emissions were very small when flooded but peaked at the beginning of the disappearance of floodwater. The N fertilizer treatments increased CH4 emissions at low level (75kgN/ha). But both CH4 and N2O emissions were uninfluenced at the levels of 150kgN/ha and 225kgN/ha. Rice yields increased under intermittent irrigation and were highest at the level of 150kgN/ha. From our results, we recommended that the intermittent irrigation and 150kgN/ha as the ideal water regime-nitrogen fertilizer incorporation for this area to achieve low GHG emissions without impacting rice yields.

Distinctive molecular and biochemical characteristics of a glycoside hydrolase family 20 ß-N-acetylglucosaminidase and salt tolerance.

BACKGROUND: Enzymatic degradation of chitin has attracted substantial attention because chitin is an abundant renewable natural resource, second only to lignocellulose, and because of the promising applications of N-acetylglucosamine in the bioethanol, food and pharmaceutical industries. However, the low activity and poor tolerance to salts and N-acetylglucosamine of most reported ß-N-acetylglucosaminidases limit their applications. Mining for novel enzymes from new microorganisms is one way to address this problem. RESULTS: A glycoside hydrolase family 20 (GH 20) ß-N-acetylglucosaminidase (GlcNAcase) was identified from Microbacterium sp. HJ5 harboured in the saline soil of an abandoned salt mine and was expressed in Escherichia coli. The purified recombinant enzyme showed specific activities of 1773.1 ± 1.1 and 481.4 ± 2.3 µmol min-1 mg-1 towards p-nitrophenyl ß-N-acetylglucosaminide and N,N'-diacetyl chitobiose, respectively, a V max of 3097 ± 124 µmol min-1 mg-1 towards p-nitrophenyl ß-N-acetylglucosaminide and a K i of 14.59 mM for N-acetylglucosamine inhibition. Most metal ions and chemical reagents at final concentrations of 1.0 and 10.0 mM or 0.5 and 1.0% (v/v) had little or no effect (retaining 84.5 - 131.5% activity) on the enzyme activity. The enzyme can retain more than 53.6% activity and good stability in 3.0-20.0% (w/v) NaCl. Compared with most GlcNAcases, the activity of the enzyme is considerably higher and the tolerance to salts and N-acetylglucosamine is much better. Furthermore, the enzyme had higher proportions of aspartic acid, glutamic acid, alanine, glycine, random coils and negatively charged surfaces but lower proportions of cysteine, lysine, α-helices and positively charged surfaces than its homologs. These molecular characteristics were hypothesised as potential factors in the adaptation for salt tolerance and high activity of the GH 20 GlcNAcase. CONCLUSIONS: Biochemical characterization revealed that the GlcNAcase had novel salt-GlcNAc tolerance and high activity. These characteristics suggest that the enzyme has versatile potential in biotechnological applications, such as bioconversion of chitin waste and the processing of marine materials and saline foods. Molecular characterization provided an understanding of the molecular-function relationships for the salt tolerance and high activity of the GH 20 GlcNAcase.

A Shinella ß-N-acetylglucosaminidase of glycoside hydrolase family 20 displays novel biochemical and molecular characteristics.

ß-N-Acetylglucosaminidases (GlcNAcases) are important for many biological functions and industrial applications. In this study, a glycoside hydrolase family 20 GlcNAcase from Shinella sp. JB10 was expressed in Escherichia coli BL21 (DE3). Compared to many GlcNAcases, the purified recombinant enzyme (rJB10Nag) exhibited a higher specificity activity (538.8 µmol min-1 mg-1) or V max (1030.0 ± 82.1 µmol min-1 mg-1) toward p-nitrophenyl ß-N-acetylglucosaminide and N,N'-diacetylchitobiose (specificity activity of 35.4 µmol min-1 mg-1) and a higher N-acetylglucosaminide tolerance (approximately 50% activity in 70.0 mM N-acetylglucosaminide). The degree of synergy on enzymatic degradation of chitin by a commercial chitinase and rJB10Nag was as high as 2.35. The enzyme was tolerant to most salts, especially 3.0-15.0% (w/v) NaCl and KCl. These biochemical characteristics make the JB10 GlcNAcase a candidate for use in many potential applications, including processing marine materials and the bioconversion of chitin waste. Furthermore, the enzyme has the highest proportions of alanine (16.5%), glycine (10.5%), and random coils (48.8%) with the lowest proportion of α-helices (24.9%) among experimentally characterized GH 20 GlcNAcases from other organisms.

Characterization of a NaCl-tolerant ß-N-acetylglucosaminidase from Sphingobacterium sp. HWLB1.

ß-N-Acetylglucosaminidases serve important biological functions and various industrial applications. A glycoside hydrolase family 3 ß-N-acetylglucosaminidase gene was cloned from Sphingobacterium sp. HWLB1 and expressed in Escherichia coli BL21 (DE3). The purified recombinant enzyme (rNag3HWLB1) showed apparent optimal activity at pH 7.0 and 40 °C. In the presence of 0.5-20.0 % (w/v) NaCl, the activity and stability of rNag3HWLB1 were slightly affected or not affected. The enzyme could even retain 73.6 % activity when 30.0 % (w/v) NaCl was added to the reaction mixture. The half-life of the enzyme was approximately 10 min at 37 °C without the addition of NaCl. However, the enzyme was stable at 37 °C in the presence of 3.0 % (w/v) NaCl. A large negatively charged surface in the catalytic pocket of the enzyme was observed and might contribute to NaCl tolerance and thermostability improvement. The degree of synergy between a commercial endochitinase and rNag3HWLB1 on chitin enzymatic degradation ranged from 3.11 to 3.74. This study is the first to report the molecular and biochemical properties of a NaCl-tolerant ß-N-acetylglucosaminidase.

Potential implication of serum lipid levels as predictive indicators for monitoring oral lichen planus.

Compelling evidence indicates that dyslipidemia is positively associated with oral lichen planus (OLP). The types and magnitude of lipid metabolism disturbance in peripheral blood of OLP patients have been investigated in different studies. Yet, consensus on how these different lipid components varied in levels for the development of OLP lesions has not been reached so far. Herein, a total of 8 eligible studies were recognized, which enrolled 533 cases of OLP and 499 healthy controls. The analysis showed that the average total triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) levels were considerably higher, and high-density lipoprotein cholesterol (HDL-C) levels were significantly lower in OLP patients compared to healthy controls. Collectively, the lipid profile panel maybe serve as the potential predictive indicator for screening OLP.

A bibliometric study on research trends and hotspots of recurrent aphthous stomatitis.

Background/purpose: Recurrent aphthous stomatitis (RAS) is a common oral mucosal disease. Despite a variety of scientific articles have been available till date, merely a few scientometric analyses have been systematically carried out in this field. The objective of this study was to recognize the hotspots and research trends related to RAS via bibliometric approach. Materials and methods: The Elsevier's Scopus database was searched to retrieve qualified literature through an advanced search strategy on 9 Feb 2023. The basic information was collected as following: article type, publication year, journals, impact factor, the count of citations, citation density, keywords, authors, contributing institutions and country. Results: A list of 986 publications were identified from 1933 to 2022, and the number of citations for each paper varied from 0 to 283. A steady increasing trend in the number of documents could be observed each decade with the summit in 2010s. Controlled study (n = 334) and major clinical study (n = 192) were the most common types of study design. Scully C (n = 26) was identified as the most productive author. United States (n = 166) and Turkey (n = 101) top the list of dedicating countries. Conclusion: This report would offer profound insight into the current status of RAS research and serve as a reference source for anyone planning to enhance the quality of future work.

Platelet-inspired targeting delivery for coronary heart disease.

Platelets play a pivotal role in many physiological and pathological processes, with their special targeting/adhering properties towards infarcted myocardium, injured or dysfunctional endothelium, and growing thrombus. Leveraging the site-targeting/adhering property, a variety of platelet-inspired targeting delivery（PITD）designs have been developed, the majority of which are reached by hitchhiking live platelets, cloaking nanoparticles with platelet membranes and mimicking platelet functions. With PITD, drugs or regenerative cells can directly reach targeted sites with minimized systematical distribution thus being of great clinical benefits. Coronary heart disease (CHD) is a major health burden worldwide. Plenty of PITD designs have shown promising outcomes for the treatment of CHD in preclinical models, especially in thrombolysis and post-percutaneous coronary intervention (post-PCI) anti-restenosis. Besides, PITD applications in cardiac protection and atherosclerotic plaque imaging are also under investigation. What's more, the potential benefits of PITD in the field of cell-based therapy are also attracting growing attention since it may resolve the problem of low arriving and retention efficiency, which are also particularly discussed in this review. In brief, our focus is putting on PITD strategies designed for the treatment of CHD, which hopefully can facilitate further optimization of this direction.

Targeted Delivery of Mesenchymal Stem Cell-Derived Bioinspired Exosome-Mimetic Nanovesicles with Platelet Membrane Fusion for Atherosclerotic Treatment.

Purpose: Accumulating evidence indicates that mesenchymal stem cells (MSCs)-derived exosomes hold significant potential for the treatment of atherosclerosis. However, large-scale production and organ-specific targeting of exosomes are still challenges for further clinical applications. This study aims to explore the targeted efficiency and therapeutic potential of biomimetic platelet membrane-coated exosome-mimetic nanovesicles (P-ENVs) in atherosclerosis. Methods: To produce exosome-mimetic nanovesicles (ENVs), MSCs were successively extruded through polycarbonate porous membranes. P-ENVs were engineered by fusing MSC-derived ENVs with platelet membranes and characterized using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blot. The stability and safety of P-ENVs were also assessed. The targeted efficacy of P-ENVs was evaluated using an in vivo imaging system (IVIS) spectrum imaging system and immunofluorescence. Histological analyses, Oil Red O (ORO) staining, and Western blot were used to investigate the anti-atherosclerotic effectiveness of P-ENVs. Results: Both ENVs and P-ENVs exhibited similar characteristics to exosomes. Subsequent miRNA sequencing of P-ENVs revealed their potential to mitigate atherosclerosis by influencing biological processes related to cholesterol metabolism. In an ApoE-/- mice model, the intravenous administration of P-ENVs exhibited enhanced targeting of atherosclerotic plaques, resulting in a significant reduction in lipid deposition and necrotic core area. Our in vitro experiments showed that P-ENVs promoted cholesterol efflux and reduced total cholesterol content in foam cells. Further analysis revealed that P-ENVs attenuated intracellular cholesterol accumulation by upregulating the expression of the critical cholesterol transporters ABCA1 and ABCG1. Conclusion: This study highlighted the potential of P-ENVs as a novel nano-drug delivery platform for enhancing drug delivery efficiency while concurrently mitigating adverse reactions in atherosclerotic therapy.

Advances in the oral microbiota and rapid detection of oral infectious diseases.

Several studies have shown that the dysregulation of the oral microbiota plays a crucial role in human health conditions, such as dental caries, periodontal disease, oral cancer, other oral infectious diseases, cardiovascular diseases, diabetes, bacteremia, and low birth weight. The use of traditional detection methods in conjunction with rapidly advancing molecular techniques in the diagnosis of harmful oral microorganisms has expanded our understanding of the diversity, location, and function of the microbiota associated with health and disease. This review aimed to highlight the latest knowledge in this field, including microbial colonization; the most modern detection methods; and interactions in disease progression. The next decade may achieve the rapid diagnosis and precise treatment of harmful oral microorganisms.

Oral microbiota in active and passive states of recurrent aphthous stomatitis: An analysis of case-control studies.

OBJECTIVE: This study was presented to reveal the most distinct microbial prevalence in recurrent aphthous stomatitis (RAS) lesions compared to healthy controls. DESIGN: The case-control studies were selected in electronic databases until Nov 2022 with key search terms, and the eligible publications were screened and analyzed by independent authors. RESULTS: A total of 14 studies were identified, which included 531 cases of active states of RAS (AS-RAS), 92 cases of passive states of RAS (PS-RAS) and 372 healthy controls. The most sample pattern was the mucosa swab performed in 8 of 14 studies, biopsies in 3 studies, followed by micro-brush, and saliva. A variety of bacteria in higher or lower abundance were observed in RAS lesions. CONCLUSIONS: The etiopathogenesis of RAS may not be ascribed to a single pathogen. A possible explanation is that microbial interactions modify immune response or destroy the epithelial integrity, thus contributing to the development of the condition.

Potential relationship of dyslipidemia with dietary patterns in oral lichen planus patients-A case-control study.

Background/purpose: Dyslipidemia and a high fat diet may increase the predisposition for accumulating body fat in patients with oral lichen planus (OLP). This study aimed to investigate the risk factors obesity, dietary patterns, and lipid metabolism. Materials and methods: A population-based case-control study was conducted between September 2020 and October 2021, recruiting 275 pairs of OLP cases and controls. Information on lipid profiles, diet frequency and waist circumference were gathered. Principal component and factor analysis were used to analyze the semi-quantitative dietary frequency survey data of patients to extract specific dietary patterns. Results: Univariate analysis showed that total cholesterol, triglycerides, and low-density lipoprotein were significantly higher in the OLP group than the control and other oral mucosal disease groups (P < 0.05, P < 0.001, and P < 0.001, respectively). Compared with the baseline group, obese and overweight patients were more common in the OLP group. Dyslipidemia was more common in the OLP group (68%) compared to the healthy mucosa group (32%; P < 0.001, OR = 4.52, 95% CI = 2.49-8.18). Four dietary patterns were described among the subjects. The traditional prone animal food pattern (OR: 24.81, 95% CI: 6.05-101.71, P < 0.001) and animal food pattern (OR: 28.77, 95% CI: 8.10-102.15, P = 0.001) were associated with an increased risk of OLP. Conclusion: The results indicated that a high-fat diet, dyslipidemia and obesity were strongly linked to disease progression in OLP. A diet high in processed food and fat could increase the risk of OLP.

Expression Levels of WNT Signaling Pathway Genes During Early Tooth Development.

It is known to all that Wnt signaling pathway plays an important role in the early development of tooth. Our previous research found that Wnt signaling pathway played crucial roles in dental development, and mutations in antagonist of Wnt signaling pathway may lead to the formation of supernumerary teeth. However, the expression pattern of Wnt signaling molecules in early development of tooth, especially genes with stage specificity, remains unclear. Hence, we applied RNA-seq analysis to determine the expression levels of wnt signal molecules at five different stages of rat first molar tooth germ. In addition, after literature review we summarized the function of Wnt signaling molecules during tooth development and the relationship between Wnt signaling molecules variation and tooth agenesis. Our research may have implications for exploring the role of Wnt signaling molecules in different stages of tooth development.

Histamine deficiency deteriorates LPS-induced periodontal diseases in a murine model via NLRP3/Caspase-1 pathway.

Histamine is a versatile biogenic amine, generated by the unique enzyme histidine decarboxylase (Hdc). Accumulating evidence has proven that histamine plays important roles in numerous biological and pathophysiological processes. However, the role and mechanism of Hdc/Histamine signaling in periodontal diseases remain unclear. In our current study, the concentration of histamine increased in the serum, and Hdc gene expression was upregulated in the gingiva of WT mice with LPS-induced periodontal inflammation. With Hdc-GFP mice, we identified that Hdc/GFP in the periodontium was expressed in CD11b+ myeloid cells, rather than in tryptase-positive mast cells. Hdc-expressing CD11b+Gr-1+ neutrophils significantly increased in the peripheral blood of Hdc-GFP mice one day after LPS injection. Lack of histamine in Hdc-/- mice not only promoted the activation and infiltration of more CD11b+ cells into the peripheral blood but also upregulated mRNA expression levels of IL-1ß, IL-6, MCP-1and MMP9 in the gingiva compared to WT mice one day after LPS stimulation. 28 days after LPS treatment, we observed that Hdc-/- mice exhibited more alveolar bone loss and more osteoclasts than WT mice, which was slightly ameliorated by the administration of exogenous histamine. In vivo and in vitro mechanistic studies revealed that the mRNA expression levels of proinflammatory cytokines and protein levels of NLRP3, Caspase-1, and cleaved-Caspase-1 were upregulated after blocking histamine receptor 1 and 2, especially histamine receptor 1. Taken together, CD11b+Gr-1+ neutrophils are the predominant Hdc-expressing sites in periodontal inflammation, and deficiency of endogenous histamine in Hdc-/- mice exacerbates the destruction of the periodontium. Disruption of the histamine/H1R/H2R axis aggravates the inflammatory immune response via NLRP3/Casapse-1 pathway.

Rapid diagnosis of a complex oral mucosal infection using metagenomic next-generation sequencing: a case report.

The most commonly used methods for pathogen detection and identification in oral mucosal infectious diseases are DNA or RNA quantitative polymerase chain reaction detection, bacterial or fungal cultures, and immunohistochemical analysis. These traditional methods are time-consuming and can only detect one specific targeted pathogen at a time. An efficient and sensitive method with higher species richness is urgently needed. Metagenomic next-generation sequencing (mNGS) is a new method of pathogen detection with high efficiency and sensitivity. In this case report, mNGS was used to identify the pathogens in oral mucosal tissues of a patient with complex oral mucosal infections and oral leukoplakia. Candida albicans, human gamma herpesvirus 4, and many other pathogens were identified using this method. For complex oral mucosal infections, mNGS is a more efficient and sensitive approach that can replace conventional detection methods.

[Investigation of the clinical effect of 65 µm glycine powder air-polishing(GPAP) after ultrasonic scaling during subgingival polishing].

PURPOSE: To evaluate the clinical effect of 65 µm glycine powder air-polishing (GPAP) by comparing with sodium hydrogen carbonate after ultrasonic scaling during subgingival polishing. METHODS: Thirty-three patients who were systematically healthy were involved in this study. After ultrasonic scaling,they were randomly assigned to the experimental group or the control group. Patients in the control group were treated with rubber cup + sodium hydrogen carbonate, while patients in the experimental group were treated only with 65 µm GPAP therapy. The clinical parameters including probing depth(PD), bleeding index(BI), plaque index(PI), staining index(SI) were recorded at baseline, 1week, 1 month, 3 months and 6 months after treatment. The results were analyzed by paired sample Wilcoxon signed-rank test with SPSS 23.0 software package. RESULTS: Both methods had good clinical effects. PD, BI, PI and SI of the two groups at 1 month, 3 months and 6 months after treatment were significantly better than those at baseline (P<0.01). SI of the experimental groups was significantly lower than that of the control group at 1 month, 3 months and 6 months after treatment(P<0.01). CONCLUSIONS: The results indicated that 65 µm GPAP may be as effective as sodium hydrogen carbonate after ultrasonic scaling in removal of dental plaque and stain. 65 µm GPAP had the advantage of reducing restaining.