An analysis of influencing factors of oral frailty in the elderly in the community.

OBJECTIVE: This study aimed to investigate the current situation of oral frailty (OF) in the elderly in the community in China and analyse its influencing factors. METHODS: Using convenience sampling, 380 elderly people from three communities in our city were selected as participants in the study. The Oral Frailty Index-8, the Frailty Scale, the Oral Health Assessment Tool, the Mini-nutritional Assessment Scale and the Pittsburgh Sleep Quality Index were used to investigate and analyse OF influencing factors. RESULTS: In this study, the 380 elderly participants were categorized into three groups: frailty, pre-frailty, and non-physical frailty, based on their responses to the questionnaires.The influencing factor analysis showed that age, gender, education level, frailty score, frailty stage, number of dentures, dry mouth, subjective chewing difficulty, oral health score and sleep quality were the influencing factors of OF in the elderly in the community (R2 = 0.712, F = 434.73, P < 0.05). The evaluation of the prediction results showed that the frailty score (area under the curve [AUC]: 0.751, 95% confidence interval [CI]: 0.683-0.862), subjective chewing difficulty (AUC: 0.765, 95% CI: 0.655-0.831) and sleep quality (AUC: 0.736, 95% CI: 0.652-0.781) had a higher predictive value for OF. CONCLUSION: The main OF influencing factors in the elderly in the community are age, gender, education level, physical frailty (PF) score, PF stage, number of dentures, dry mouth, subjective chewing difficulties, oral health score and sleep quality. Nursing staff should pay attention to the OF of the elderly in the community and take targeted intervention measures in time to reduce and control OF occurrence and progression.

Membrane-enclosed Pseudomonas quinolone signal attenuates bacterial virulence by interfering with quorum sensing.

Outer membrane vesicle (OMV)-delivered Pseudomonas quinolone signal (PQS) plays a critical role in cell-cell communication in Pseudomonas aeruginosa. However, the functions and mechanisms of membrane-enclosed PQS in interspecies communication in microbial communities are not clear. Here, we demonstrate that PQS delivered by both OMVs from P. aeruginosa and liposome reduces the competitiveness of Burkholderia cenocepacia, which usually shares the same niche in the lungs of cystic fibrosis patients, by interfering with quorum sensing (QS) in B. cenocepacia through the LysR-type regulator ShvR. Intriguingly, we found that ShvR regulates the production of the QS signals cis-2-dodecenoic acid (BDSF) and N-acyl homoserine lactone (AHL) by directly binding to the promoters of signal synthase-encoding genes. Perception of PQS influences the regulatory activity of ShvR and thus ultimately reduces QS signal production and virulence in B. cenocepacia. Our findings provide insights into the interspecies communication mediated by the membrane-enclosed QS signal among bacterial species residing in the same microbial community.IMPORTANCEQuorum sensing (QS) is a ubiquitous cell-to-cell communication mechanism. Previous studies showed that Burkholderia cenocepacia mainly employs cis-2-dodecenoic acid (BDSF) and N-acyl homoserine lactone (AHL) QS systems to regulate biological functions and virulence. Here, we demonstrate that Pseudomonas quinolone signal (PQS) delivered by outer membrane vesicles from Pseudomonas aeruginosa or liposome attenuates B. cenocepacia virulence by targeting the LysR-type regulator ShvR, which regulates the production of the QS signals BDSF and AHL in B. cenocepacia. Our results not only suggest the important roles of membrane-enclosed PQS in interspecies and interkingdom communications but also provide a new perspective on the use of functional nanocarriers loaded with QS inhibitors for treating pathogen infections.

Sedative and adverse effect comparison between oral midazolam and nitrous oxide inhalation in tooth extraction: a meta-analysis.

OBJECTIVE: Oral midazolam and nitrous oxide inhalation were commonly used sedative and analgesic techniques during tooth extraction. It is still controversial whether oral midazolam can replace the nitrous oxide inhalation for sedative and analgesic treatment of tooth extraction. Therefore, we conducted this study in order to provide a reference for doctors to choose effective sedative and analgesic treatment in tooth extraction. METHODS: We searched the Chinese and English databases including PubMed, Embase, the Cochrane Library, China National Knowledge Infrastructure, Wanfang and VIP information databases. RESULTS: Through this meta-analysis, we found that the success rate of sedation and analgesia treatment with oral midazolam during tooth extraction was 75.67% and the incidence of adverse reactions was 21.74%. The success rate of sedation and analgesia treatment using nitrous oxide inhalation during tooth extraction was 93.6% and the incidence of adverse reactions was 3.95%. CONCLUSION: The use of nitrous oxide inhalation for sedation and analgesia during tooth extraction is very effective, and oral midazolam can be used as an alternative to nitrous oxide inhalation.

Robust DNA Cross-Linked Polymeric Lighting-Up Nanogel Facilitates Sensitive Live Cell MicroRNA Imaging.

Accurate and specific imaging of low-abundance intracellular microRNAs (miRNAs) is crucial for monitoring cellular processes and disease diagnosis. Despite the fact that nucleic acid amplification technologies have shown great advantages for the detection of trace targets, their live cell imaging applications remain a major challenge because of the insufficient stability and slow reaction kinetics of the probes in cellular delivery and imaging. Herein, we demonstrate the synthesis of DNA-cross-linked polymeric lighting-up nanogels (DPLNs) through the DNA hairpin-based hybridization chain reaction within nanoscale-confined space for monitoring and imaging live cell miRNA-21 with high sensitivity. Cascaded catalytic hairpin assembly of two hairpin signal probes confined in the DPLNs can be triggered by the target miRNA, causing substantially amplified fluorescence resonance energy transfer signals with accelerated reaction kinetics. Moreover, the DPLNs show low cytotoxicity and highly enhanced nuclease resistance and can be successfully delivered into live cells for imaging low levels of miRNA-21. In addition, the DPLN probes can be readily tuned by specific sequences for monitoring various molecular targets in live cells for important biological and biomedical applications.

Spatiotemporally comparative analysis of three common infectious diseases in China during 2013-2015.

BACKGROUND: Dengue fever (DF), influenza, and hand, foot, and mouth disease (HFMD) have had several various degrees of outbreaks in China since the 1900s, posing a serious threat to public health. Previous studies have found that these infectious diseases were often prevalent in the same areas and during the same periods in China. METHODS: This study combined traditional descriptive statistics and spatial scan statistic methods to analyze the spatiotemporal features of the epidemics of DF, influenza, and HFMD during 2013-2015 in mainland China at the provincial level. RESULTS: DF got an intensive outbreak in 2014, while influenza and HFMD were stable from 2013 to 2015. DF mostly occurred during August-November, influenza appeared during November-next March, and HFMD happened during April-November. The peaks of these diseases form a year-round sequence; Spatially, HFMD generally has a much higher incidence than influenza and DF and covers larger high-risk areas. The hotspots of influenza tend to move from North China to the southeast coast. The southeastern coastal regions are the high-incidence areas and the most significant hotspots of all three diseases. CONCLUSIONS: This study suggested that the three diseases can form a year-round sequence in southern China, and the southeast coast of China is a particularly high-risk area for these diseases. These findings may have important implications for the local public health agency to allocate the prevention and control resources.

Sequential acid/reduction response of triblock copolymeric nanomicelles to release camptothecin and toll-like receptor 7/8 agonist for orchestrated chemoimmunotherapy.

BACKGROUND: Immunosuppressive tumor immune microenvironment (TIME) lowers immunotherapy effectiveness. Additionally, low penetration efficiency and unpredictable drug release in tumor areas restrict tumor therapy. METHODS: A triblock copolymeric micelle (NanoPCPT+PIMDQ) was developed to carry the chemotherapeutic drug camptothecin (CPT) and the TLR7/8 agonist 1-(4-(aminomethyl)benzyl)-2-butyl-1H-imidazo[4,5-c] quinoline-4-amine (IMDQ) to achieve deep tumor penetration and on-demand drug release by responding to acid and reduction stimuli sequentially. The synergistic antitumour efficacy of NanoPCPT+PIMDQ was assessed both in vitro and in vivo. RESULTS: NanoPCPT+PIMDQ is composed of a hydrophilic PEG(polyethylene glycol) outer layer, an acid-sensitive EPEMA middle layer, and a drug inner core. Upon intratumoral injection, (i) NanoPCPT+PIMDQ first responds to the acidic tumor microenvironment and disintegrates to PIMDQ and PCPT, penetrating deep regions of the tumor; (ii) tumor cells are killed by the released CPT; (iii) DCs are activated by PIMDQ to increase the infiltration of cytotoxic T lymphocyte (CTL); and (iv) both downregulated Foxp3+ Tregs by CPT and repolarized M2 macrophages by PIMDQ can relieve the TIME. CONCLUSION: This pH/GSH-responsive triblock polymer-drug conjugate reduces immunosuppression and enhances the infiltration of CTLs by codelivering CPT and IMDQ in a controllable manner, providing a promising platform for synergistic tumor chemoimmunotherapy.

Site-Specific Conjugation of a Selenopolypeptide to Alpha-1-antitrypsin Enhances Oxidation Resistance and Pharmacological Properties.

Human alpha-1-antitrypsin (A1AT), a native serine-protease inhibitor that protects tissue damage from excessive protease activities, is used as an augmentation therapy to treat A1AT-deficienct patients. However, A1AT is sensitive to oxidation-mediated deactivation and has a short circulating half-life. Currently, there is no method that can effectively protect therapeutic proteins from oxidative damage in vivo. Here we developed a novel biocompatible selenopolypeptide and site-specifically conjugated it with A1AT. The conjugated A1AT fully retained its inhibitory activity on neutrophil elastase, enhanced oxidation resistance, extended the serum half-life, and afforded long-lasting protective efficacy in a mouse model of acute lung injury. These results demonstrated that conjugating A1AT with the designed selenopolymer is a viable strategy to improve its pharmacological properties, which could potentially further be applied to a variety of oxidation sensitive biotherapeutics.

Spiro Scaffold Chiral Organocatalyst of 3,2'-Pyrrolidinyl Spiro-oxindole Amine and Its Catalytic Evaluation in the Enantioselective Aldol Condensation between 3-(3-Hydroxy-1H-pyrazol-1-yl)-Oxindole and Paraformaldehyde.

The spiro scaffold chiral organocatalyst of 3,2'-pyrrolidinyl spiro-oxindole amine was successfully prepared from racemic spiro-oxindole amine using l-menthol as a chiral pool in 4 steps in 28%-40% overall yields with at least 99% ee in scale-up preparation, and its catalytic activity was evaluated in the enantioselective aldol condensation between 3-(3-hydroxy-1H-pyrazol-1-yl)-oxindole and paraformaldehyde. The spiro organocatalyst showed superior catalytic activity and selectivity compared with its counterparts, and most substrates offered good to excellent results with up to 96% yield in 96% ee.

Sutured Scleral Fixation of Posterior Chamber Intraocular Lens in Children under the Age of 9 with Congenital Ectopia Lentis.

INTRODUCTION: This study aimed to report the visual acuity outcomes and complications of sutured scleral fixation of posterior chamber intraocular lens (IOL) in children under 9 years old with congenital ectopia lentis. METHODS: Twenty-six children (47 eyes) with congenital ectopia lentis were included in this study. The mean age at surgery was 61.6 ± 22.3 months (range, 32-94). Patients underwent lens extraction, anterior vitrectomy, and sutured scleral fixation of posterior chamber IOL. The implanted IOL included rigid polymethyl methacrylate (PMMA) IOL (CZ70BD, n = 36) and foldable IOL (SA60AT, n = 9, and LI61SE, n = 2). The outcome measures used to assess the benefits were uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refraction, intraocular pressure, and any associated complications. Median follow-up was 33.0 months (range, 4-129). RESULTS: After surgery, the median UCVA (1.30 vs. 0.35 logMAR) and BCVA (0.82 vs. 0.15 logMAR) improved significantly (p < 0.001). The median absolute spherical values decreased considerably (9.00 vs. 0.75 D; p < 0.001). The median astigmatism was lower in foldable IOL compared to rigid PMMA IOL (1.0 vs. 2.5 D; p = 0.026), but neither the UCVA nor BCVA was significantly different. There was no intraoperative complication. Postoperative complications included pupillary capture in 4 eyes (9%), IOL decentration in 4 eyes (9%), choroid edema in 1 eye (2%), and subretinal hemorrhage in 1 eye (2%). The rate of secondary surgery was 9%, caused by IOL decentration of IOL haptics which was broken in 3 eyes and suture degradation in 1 eye. CONCLUSION: Sutured scleral fixation of posterior chamber IOL provided good visual outcomes in children under 9 years of age with congenital ectopia lentis. Although there were some risks of secondary surgery, the complications were acceptable.

The relationship between different types of caries and periodontal disease severity in middle-aged and elderly people: findings from the 4th National Oral Health Survey of China.

BACKGROUND: The relationship between dental caries and periodontal disease is still controversial. The objective of this study was to explore the relationship between different types of caries and periodontal disease severity in middle-aged and elderly people in China. METHODS: The study population consisted of 4407 middle-aged and 4117 elderly subjects. Caries were divided into the following three types: type A, crown caries; type B, lesions involving both the crown and root, representing mixed-type caries; and type C, root caries. These three types together represent the overall caries situation, which we call type ABC. Caries were quantitated by decayed and filled teeth (DFT index). Periodontitis was evaluated by clinical attachment loss. RESULTS: Middle-aged people with periodontitis had a significant association with DFT type B (OR: 1.21, 95% CI 1.17-1.25) and type C (OR: 1.40, 95% CI 1.24-1.56). Elderly people with periodontitis had a significant association with DFT type C (OR: 1.28, 95% CI 1.21-1.35). CONCLUSIONS: In China, caries types B/C were positively correlated with periodontitis in the middle-aged group, and only caries type C was positively correlated with periodontitis in the elderly group.

A two-week single-group longitudinal test of a new sonic-powered toothbrush simulating the 'bass brushing technique' with tapered bristles on the brush head for reduction of dental plaque and gingivitis.

OBJECTIVE: To investigate the effect of a new powered toothbrush with tapered bristles on the brush head for the reduction of dental plaque and gingivitis. METHODS: This was a single-centre, single-group, longitudinal clinical trial. Thirty-two participants who were typical manual toothbrush users were recruited and assigned the sonic-powered brush. Interviews were arranged on the 1st , 4th , and 15th days which represented the baseline (T1 ), middle (T2 ) and final (T3 ) time points, respectively. At each visit, the plaque index (PlI), gingival index (GI), bleeding on probing (BOP) and probing depth (PD) were recorded for the Ramfjord index teeth, gingival crevicular fluid(GCF) samples were collected and the proportions of eight periodontal pathogenic bacteria were analysed. Repeated-measures analysis of variance (ANOVA) was used for comparisons at different time points. RESULTS: PlI was significantly reduced by 41.67% from T1 to T2 (p<0.001) and decreased by 18.57% from T2 to T3 (p=0.003). GI also varied significantly from T1 to T2 (p=0.018) and T1 to T3 (p=0.037). A 35.86% reduction in the BOP percentage occurred after using the sonic-powered toothbrush for 3 days (p=0.001). However, no significant difference was observed in the mean values of PD at different examination intervals (p=0.529). There was no significant difference in the proportions of bacteria between T1 and T3 (p>0.05). CONCLUSION: This research demonstrated the efficacy of the sonic-powered brush handle together with tapered bristles on the brush in reducing plaque and gingivitis within a short time period.

[Research progress on chemical compositions and pharmacological action of Drynariae Rhizoma].

Drynariae Rhizoma is warm in nature and bitter in taste, mainly acting on liver and kidney systems. It is a common Chinese herbal medicine for the treatment of fracture and bone injury. The chemical compositions of Drynariae Rhizoma mainly include flavonoids, triterpenoids, phenylpropanoids and lignans. At present, modern pharmacological and clinical studies have shown that Drynariae Rhizoma has the effects of anti osteoporosis, promoting fracture healing, kidney protection, anti-inflammatory, promoting tooth growth, preventing and treating aminoglycoside ototoxicity and lowering blood lipid. In addition, the toxicity evaluation experiment of Drynariae Rhizoma has also shown that it has no obvious toxic and side effects. Naringin is a kind of dihydroflavone in Drynariae Rhizoma. Many studies have shown that naringin and other total flavonoids play an important role in anti-osteoporosis, promoting fracture healing, anti-inflammation, promoting tooth growth and lowering blood lipid. In this study, the research progresses on chemical consti-tuents and pharmacological activities of Drynariae Rhizoma in recent years were reviewed, and some mechanisms of action were summarized, to provide references for the further research and development of Drynariae Rhizoma.

Exosomes from EV71-infected oral epithelial cells can transfer miR-30a to promote EV71 infection.

OBJECTIVE: As an extracellular vesicle, exosomes can release from virus-infected cells containing various viral or host cellular elements and could stimulate recipient's cellular response. Enterovirus 71 (EV71), a single-strand positive-sense RNA virus, is known to cause hand, foot, and mouth disease (HFMD) in children and bring about severe clinical diseases. METHODS: Separated the human oral epithelial cells (OE cells) from normal buccal mucosa through enzyme digestion. Performed a comprehensive miRNA profiling in exosomes from EV71-infected OE cells through deep small RNA-seq. Using the Human Antiviral Response RT Profiler PCR Array profiles to explore the interactions of innate immune signaling networks with exosomal miR-30a. Knocked out the MyD88 gene in macrophages using CRISPR/Cas9-mediated genome editing method. RESULTS: Our study demonstrated that the miR-30a was preferentially enriched in exosomes that released from EV71-infected human oral epithelial cells through small RNA-seq. We found that the transfer of exosomal miR-30a to macrophages could suppress type Ⅰ interferon response through targeting myeloid differentiation factor 88 (MyD88) and subsequently facilitate the viral replication. CONCLUSIONS: Exosomes released from EV71-infected OE cells selectively packaged high level of miR-30a that can be functionally transferred to the recipient macrophages resulted in targeting MyD88 and subsequently inhibited type I interferon production in receipt cells, thus promoting the EV71 replication.

M-keratin nano-materials create a mineralized micro-circumstance to promote proliferation and differentiation of DPSCs.

As traditional root canal obturation leads to the loss of the biological activity of the tooth, it is necessary to develop a material that promotes the regeneration of dental tissue. However, this remains a challenging task. Our study aims to construct a mineralized material to support the proliferation and differentiation of dental pulp stem cells (DPSCs), and to explore a new strategy for the treatment of pulp tissue necrosis. Mineralized keratin (M-keratin), defined as keratin that has been mineralized in simulated body fluid, was first harvested to construct the root canal filling material. Characterizations indicated that new substances or components were formed on the surface of keratin particles after mineralization, and the morphology of the keratin was changed. M-keratin promoted the growth, proliferation, and differentiation of DPSCs. After cultivation with M-keratin, DPSCs exhibited more extracellular matrix proteins interacting with the culture interface, the number of these cells increased significantly, and the 3-[4,5-dimethylthiazol-2-yl-]-2,5-diphenyltetrazolium bromide values of cells in the experimental group also increased. Meanwhile, signs that the DPSCs began to differentiate into odontoblasts were observed or detected by alizarin red S staining, ELISA, RNA-Seq, and western blot. We hope that this study will contribute to the development of a new material that promotes the regeneration of dental tissue as well as providing new ideas and strategies for the treatment of dental pulp disease.

A dandelion-like liposomes-encoded magnetic bead probe-based toehold-mediated DNA circuit for the amplification detection of MiRNA.

The development of facile and sensitive miRNA quantitative detection methods is a central challenge for the early diagnosis of miRNA-related diseases. Herein, we propose a strategy for a liposome-encoded magnetic bead-based DNA toehold-mediated DNA circuit for the simple and sensitive detection of miRNA based on a toehold-mediated circular strand displacement reaction (TCSDR) coupled with a personal glucometer (PGM ). In this strategy, a glucoamylase-encapsulated liposomes (GELs)-encoded magnetic bead (GELs-MB) probe is designed to integrate target binding, magnetic separation, and signal response. Upon sensing the target miRNA-21, a GELs-MB probe-based toehold-mediated circular strand displacement reaction (TCSDR) was initiated with the help of fuel-DNA, constructing a DNA circuit system, and realizing target recycling amplification and the disassembly of the liposomes. The disassembled liposomes were finally removed via magnetic separation, and the encapsulated glucoamylase was liberated to catalyze amylose hydrolysis with multiple turnovers to glucose for a PGM readout. Benefiting from target recycling amplification initiated by the toehold-mediated DNA circuit and the liposome multiple-label amplification, a small quantity of target miRNA-21 can be transformed into a large glucose signal. The strategy realized the quantification of miRNA-21 down to a level of 0.7 fM without enzymatic amplification or precise instrumentation. Moreover, the high-density GELs-MB probe allows the sensitive detection of miRNA-21 to be accomplished within 1.5 h. Furthermore, this strategy exhibits the advantages of specificity and simplicity, since a toehold-mediated strand displacement reaction, magnetic separation and portable PGM were used. Importantly, this strategy has been demonstrated to allow the high-confidence quantification of miRNA. Therefore, with the advantages of low cost, ease of use, portability, and sensitivity, the reported method holds great potential for the early diagnosis of miRNA-related diseases.

Combined application of arbuscular mycorrhizal fungi and steel slag improves plant growth and reduces Cd, Pb accumulation in Zea mays.

Little attention has been paid to the combined use of arbuscular mycorrhizal fungus (AMF) and steel slag (SS) for ameliorating heavy metal polluted soils. A greenhouse pot experiment was conducted to study the effects of SS and AMF-Funneliformis mosseae (Fm), Glomus versiforme (Gv) and Rhizophagus intraradices (Ri) on plant growth and Cd, Pb uptake by maize grown in soils added with 5 mg Cd kg-1 and 300 mg Pb kg-1 soil. The combined usage of AMF and SS (AMF + SS) promoted maize growth, and Gv + SS had the most obvious effect. Meanwhile, single SS addition and AMF + SS decreased Cd, Pb concentrations in maize, and the greater reductions were found in combined utilization, and the lowest Cd, Pb concentrations of maize appeared in Gv + SS. Single SS amendment and AMF + SS enhanced soil pH and decreased soil diethylenetriaminepentaacetic acid (DTPA)-extractable Cd, Pb concentrations. Furthermore, alone and combined usage of AMF and SS increased contents of soil total glomalin. Our research indicated a synergistic effect between AMF and SS on enhancing plant growth and reducing Cd, Pb accumulation in maize, and Gv + SS exerted the most pronounced effect. This work suggests that AMF inoculation in combination with SS addition may be a potential method for not only phytostabilization of Pb-Cd-contaminated soil but maize safety production.

The Arabidopsis RCC1 Family Protein TCF1 Regulates Freezing Tolerance and Cold Acclimation through Modulating Lignin Biosynthesis.

Cell water permeability and cell wall properties are critical to survival of plant cells during freezing, however the underlying molecular mechanisms remain elusive. Here, we report that a specifically cold-induced nuclear protein, Tolerant to Chilling and Freezing 1 (TCF1), interacts with histones H3 and H4 and associates with chromatin containing a target gene, blue-copper-binding protein (BCB), encoding a glycosylphosphatidylinositol-anchored protein that regulates lignin biosynthesis. Loss of TCF1 function leads to reduced BCB transcription through affecting H3K4me2 and H3K27me3 levels within the BCB gene, resulting in reduced lignin content and enhanced freezing tolerance. Furthermore, plants with knocked-down BCB expression (amiRNA-BCB) under cold acclimation had reduced lignin accumulation and increased freezing tolerance. The pal1pal2 double mutant (lignin content reduced by 30% compared with WT) also showed the freezing tolerant phenotype, and TCF1 and BCB act upstream of PALs to regulate lignin content. In addition, TCF1 acts independently of the CBF (C-repeat binding factor) pathway. Our findings delineate a novel molecular pathway linking the TCF1-mediated cold-specific transcriptional program to lignin biosynthesis, thus achieving cell wall remodeling with increased freezing tolerance.

Relationship between the genetic polymorphisms of vicR and vicK Streptococcus mutans genes and early childhood caries in two-year-old children.

BACKGROUND: The VicRK two-component signalling system regulates virulence and cariogenicity in Streptococcus mutans (S. mutans). The purpose of this study was to explore the genetic polymorphisms of the vicR and vicK genes, which are associated with dental caries in children with S. mutans. METHODS: In this study, 121 (from each group) clinical S. mutans strains were isolated from caries-free children and children with high-severity caries to sequence the vicR and vicK genes. Genomic DNA was extracted from S. mutans strains and amplified using PCR. The PCR products were purified and sequenced. A chi-squared test and ABI Variant Reporter software were used to analyse the sequencing results. RESULTS: The 242 clinically isolated S. mutans strains contained the full-length vicR and vicK genes. No nucleotide sequence insertions or deletions were observed in the two genes. Four silent point mutations were identified in the vicR genes, and no missense mutations could be detected. Forty-one mutations were identified in the vicK genes. In addition to 32 silent mutations, 9 missense mutations at the 173, 337, 470, 1051, 1132, 1258, 1260, 1277, and 1348 bp positions were found. The distribution frequencies of the missense mutations were not significantly different between the groups, except for the C470T mutation. The frequency of the C470T missense mutation was higher in the high-severity caries group than in the caries-free group. CONCLUSIONS: vicR sequences are highly conserved in S. mutans clinical isolates. The locus 470 missense mutation of the vicK gene may be related to caries in children with S. mutans.

Sensitive and selective detection of the p53 gene based on a triple-helix magnetic probe coupled to a fluorescent liposome hybridization assembly via rolling circle amplification.

Developing a sensitive and selective sensing platform for the p53 gene and its mutation analysis is essential and may aid in early cancer screening and assessment of prognosis. Here, we developed a highly sensitive and selective p53 gene assay based on the coupling of a triple-helix magnetic probe (THMP) to a fluorescent liposome hybridization assembly, a process initiated by rolling circle amplification (RCA). In the presence of p53, the THMP unfolds and activates an enzymatic cleavage reaction, thus releasing the RCA primer and initiating the RCA product-assisted fluorescent liposome hybridization assembly. The resultant double-stranded DNA structures bind the intercalating SG dye from the fluorescent liposomes, thus dramatically enhancing the fluorescence signal. In the absence of p53, the THMP remains intact and blocks the trigger release and fluorescent liposome assembly, thus resulting in a low background signal. The THMPs were designed with integrated target recognition by Watson-Crick base-pairing, site-specific cleavage by an endonuclease and background signal elimination by magnetic isolation, thus avoiding the need to design multiple probes. Moreover, the use of fluorescent liposome assembly and magnetic isolation helps in avoiding sample matrix interference and nonspecific staining. Through cooperative amplification coupling with enzyme cleavage recycling, the RCA-assisted fluorescent liposome assembly and magnetic isolation improved the sensitivity, with a detection limit of 0.07 fM. The excellent capacity of the THMP to specifically detect the involved targets and the precise site-specific endonuclease cleavage ensured remarkable selectivity for p53 against single-base mismatches. This proposed approach worked well in biological samples, thus demonstrating great potential for biomedical and clinical diagnosis applications.

Phosphoenolpyruvate carboxylase regulation in C4-PEPC-expressing transgenic rice during early responses to drought stress.

Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) has important functions in C4 photosynthesis and biosynthesis of intermediate metabolites. In this study, the drought resistance of C4-PEPC-expressing transgenic rice (Oryza sativa, line PC) plants was assessed using simulated drought conditions [i.e. polyethylene glycol (PEG)-6000 treatment]. The dry weight of PC plants was higher than that of wild-type (WT) plants following treatment with 15% PEG-6000 for 16 days. Furthermore, the water use efficiency, relative water content and proline content in PC plants were higher than those of WT plants, as were C4-PEPC activity and transcript levels following treatment with 5% PEG-6000 for 2 h. The protein kinase activities and transcript levels of sucrose non-fermenting-1-related protein kinases (SnRKs) genes, such as SnRK1a, OsK24 and OsK35 were also higher in PC plants than in WT plants following treatment with 5% PEG-6000 for 2 h. Additionally, phosphoenolpyruvate carboxylase kinase (PPCK, EC 4.1.1.32) activities and transcript levels (e.g. PPCK1 and PPCK2) increased following drought treatment. These changes were regulated by signaling molecules, such as calcium, nitric oxide and hydrogen peroxide. Furthermore, the -1095 to -416 region of the C4-PEPC promoter in PC plants was demethylated following exposure to drought conditions for 1 h. The demethylation coincided with an increase in C4-PEPC expression. Our data suggest that the demethylation of the C4-PEPC promoter and the phosphorylation catalyzed by PPCK have key roles in conferring drought tolerance to the transgenic rice plants.