Sequential appetite suppression by oral and visceral feedback to the brainstem.

The termination of a meal is controlled by dedicated neural circuits in the caudal brainstem. A key challenge is to understand how these circuits transform the sensory signals generated during feeding into dynamic control of behaviour. The caudal nucleus of the solitary tract (cNTS) is the first site in the brain where many meal-related signals are sensed and integrated1-4, but how the cNTS processes ingestive feedback during behaviour is unknown. Here we describe how prolactin-releasing hormone (PRLH) and GCG neurons, two principal cNTS cell types that promote non-aversive satiety, are regulated during ingestion. PRLH neurons showed sustained activation by visceral feedback when nutrients were infused into the stomach, but these sustained responses were substantially reduced during oral consumption. Instead, PRLH neurons shifted to a phasic activity pattern that was time-locked to ingestion and linked to the taste of food. Optogenetic manipulations revealed that PRLH neurons control the duration of seconds-timescale feeding bursts, revealing a mechanism by which orosensory signals feed back to restrain the pace of ingestion. By contrast, GCG neurons were activated by mechanical feedback from the gut, tracked the amount of food consumed and promoted satiety that lasted for tens of minutes. These findings reveal that sequential negative feedback signals from the mouth and gut engage distinct circuits in the caudal brainstem, which in turn control elements of feeding behaviour operating on short and long timescales.

Effect of different techniques on removal of residual resin cement and marginal roughness of porcelain laminate veneers.

STATEMENT OF PROBLEM: A consensus regarding how to effectively remove residual resin cement and polish the restoration margin during the cementation of porcelain laminate veneers (PLVs) is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effect of different cleaning and polishing techniques on the removal of residual resin cement and margin surface roughness of PLVs. MATERIAL AND METHODS: PLVs were bonded to prepared buccal surfaces of extracted human premolars. All specimens were randomly divided by using a random number table into 8 groups (n=6): curette (C); brush (B); curette + polisher (CP); curette + rotary instrument (CR); curette + rotary instrument + polisher (CRP); brush + polisher (BP); brush + rotary instrument (BR); brush + rotary instrument + polisher (BRP). The relative amount of residual cement along the PLV margins were observed with a stereomicroscope and evaluated with a software program of Image J. The surface roughness and 3-dimensional (3D) morphology of the restoration margins were evaluated with a 3D topography scanner. Scanning electron microscopy (SEM) was used to detect the microscopic morphological characteristics of the restoration margins. Statistical analysis was performed by 2-way analysis of variance (α=.05). RESULTS: Different techniques were associated with significantly different efficiencies in terms of removing residual cement and the surface roughness at the restoration margins (P<.001). The lowest relative amount of residual cement, as well as the lowest surface roughness, was detected in the BRP group (P<.001). SEM observation indicated that the BRP technique also maintained the integrity of the cement layer. CONCLUSIONS: The removal of excess cement before polymerization using a brush, followed by sequential polishing with high-speed rotary instruments and low-speed polishers represents an effective technique in the removal of residual cement and smoothing the restoration margin without impairing the integrity of the bonded interface.

The impact of different states of type 2 diabetes when stratified by baseline HbA1c on the periodontal outcomes of non-surgical periodontal treatment: A systematic review and network meta-analysis.

BACKGROUND: Type 2 diabetes mellitus (T2DM) has been considered by many studies to have a bidirectional relationship with periodontitis. This systematic review and network meta-analysis aimed to investigate the impact of different states of T2DM when stratified by baseline HbA1c on the clinical outcomes of non-surgical periodontal treatment (NSPT). METHODS: This study followed the Preferred Reporting Items for Meta-Analyses (PRISMA) guidelines and involved an electronic literature search (from inception to the 2nd of January 2023). The study included at least two groups of patients: chronic periodontitis only (No-DM) or periodontitis and well-controlled/poorly controlled type 2 diabetes mellitus (WC/PC-T2DM). Clinical outcomes included probing depth (PD) reduction, bleeding on probing reduction, and clinical attachment level (CAL) gain. Direct and indirect comparisons between groups were assessed by network meta-analysis, thus allowing us to establish a treatment ranking. RESULTS: Ten prospective cohort studies (11 data sets) were included for qualitative analysis and network meta-analysis. The data included in this study had high consistency; in addition, a funnel plot and Egger's test showed that the articles had low publication bias. Network meta-analysis showed that the effect of NSPT in the No-DM group was significantly better than the WC-T2DM group [weighted mean difference (WMD) = 0.09, 95% confidence interval (CI) (0.01, 0.18)] and the PC-T2DM group [WMD = 0.09, 95% CI (0.01, 0.18)] in terms of CAL gain and better than the PC-T2DM group [WMD = 0.15, 95% CI (0.02, 0.28)] in terms of PD reduction. According to the surface under the cumulative ranking value, the No-DM group had the highest probability of achieving the best outcome following NSPT. CONCLUSIONS: Collectively, our analyses show that T2DM exerts significant effects on the outcomes of NSPT.

GmFULc Is Induced by Short Days in Soybean and May Accelerate Flowering in Transgenic Arabidopsis thaliana.

Flowering is an important developmental process from vegetative to reproductive growth in plant; thus, it is necessary to analyze the genes involved in the regulation of flowering time. The MADS-box transcription factor family exists widely in plants and plays an important role in the regulation of flowering time. However, the molecular mechanism of GmFULc involved in the regulation of plant flowering is not very clear. In this study, GmFULc protein had a typical MADS domain and it was a member of MADS-box transcription factor family. The expression analysis revealed that GmFULc was induced by short days (SD) and regulated by the circadian clock. Compared to wild type (WT), overexpression of GmFULc in transgenic Arabidopsis caused significantly earlier flowering time, while ful mutants flowered later, and overexpression of GmFULc rescued the late-flowering phenotype of ful mutants. ChIP-seq of GmFULc binding sites identified potential direct targets, including TOPLESS (TPL), and it inhibited the transcriptional activity of TPL. In addition, the transcription levels of FLOWERING LOCUS T (FT), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and LEAFY (LFY) in the downstream of TPL were increased in GmFULc- overexpressionArabidopsis, suggesting that the early flowering phenotype was associated with up-regulation of these genes. Our results suggested that GmFULc inhibited the transcriptional activity of TPL and induced expression of FT, SOC1 and LFY to promote flowering.

Fermented cassava bioethanol waste as substitute of protein in diet for growth performance and carcass evaluation on meat ducks.

The effect of dietary supplementation with fermented cassava bioethanol waste (FCBW) on the growth performance and meat quality was evaluated in 80 15-day-old male Cherry Valley meat ducks with an initial body weight (BW) of 250.67 ± 7.50 g. The experiment has 5 replications and 4 treatments and 4 ducks per treatment. Four groups (groups I, II, III, IV) supplemented with 0%, 5%, 10%, and 15% FCBW substituted for part of maize, soybean meal, and bran in basal diet and were fed for 29 days; the metabolizable energy and content of lysine in the four groups were equal. The results indicated that there were no significant differences in average daily weight gain and average daily feed intake among the four groups (P > 0.05). The digestibility rate of dry matter, ash, and phosphorus in group IV was significantly lower than that in group I by 5.23%, 6.25%, and 6.40% respectively (P < 0.05), but the digestibility rate of crude fat was significantly higher than that in group I by 8.30% (P < 0.05). No significant differences were presented among different levels of FCBW supplementation in carcass yield, eviscerated carcass yield, and semi-eviscerated carcass yield (P > 0.05), but 5% FCBW can improve the carcass yield relatively. In conclusion, with dietary supplementation of 5% FCBW, a better growth performance in meat ducks could be achieved.

miR-124-3p functions as a tumor suppressor in breast cancer by targeting CBL.

BACKGROUND: The origin and development of breast cancer remain complex and obscure. Recently, microRNA (miRNA) has been identified as an important regulator of the initiation and progression of breast cancer, and some studies have shown the essential role of miR-124-3p as a tumor suppressor in breast tumorigenesis. However, the detailed role of miR-124-3p in breast cancer remains poorly understood. METHODS: Quantitative RT-PCR and western blotting assays were used to measure miR-124-3p and CBL expression levels in breast cancer tissues, respectively. Luciferase reporter assay was employed to validate the direct targeting of CBL by miR-124-3p. Cell proliferation and invasion assays were performed to analyze the biological functions of miR-124-3p and CBL in breast cancer cells. RESULTS: In the present study, we found that miR-124-3p was consistently downregulated in breast cancer tissues. Moreover, we showed that miR-124-3p significantly suppressed the proliferation and invasion of breast cancer cells. In addition, we investigated the molecular mechanism through which miR-124-3p contributes to breast cancer tumorigenesis and identified CBL (Cbl proto-oncogene, E3 ubiquitin protein ligase) as a direct target gene of miR-124-3p. Moreover, we found that ectopic expression of CBL can attenuate the inhibitory effect of miR-124-3p on cell proliferation and invasion in breast cancer cells. CONCLUSIONS: This study identified a new regulatory axis in which miR-124-3p and CBL regulate the proliferation and invasion of breast cancer cells.

Negative feedback control of hypothalamic feeding circuits by the taste of food.

The rewarding taste of food is critical for motivating animals to eat, but whether taste has a parallel function in promoting meal termination is not well understood. Here, we show that hunger-promoting agouti-related peptide (AgRP) neurons are rapidly inhibited during each bout of ingestion by a signal linked to the taste of food. Blocking these transient dips in activity via closed-loop optogenetic stimulation increases food intake by selectively delaying the onset of satiety. We show that upstream leptin-receptor-expressing neurons in the dorsomedial hypothalamus (DMHLepR) are tuned to respond to sweet or fatty tastes and exhibit time-locked activation during feeding that is the mirror image of downstream AgRP cells. These findings reveal an unexpected role for taste in the negative feedback control of ingestion. They also reveal a mechanism by which AgRP neurons, which are the primary cells that drive hunger, are able to influence the moment-by-moment dynamics of food consumption.

A combined pig model to determine the net absorption of volatile fatty acids in the large intestine under different levels of crude fiber.

BACKGROUND: This study aimed to develop a combined model to quantify the net absorption of volatile fatty acids (VFA) in the large intestine (LI) of pigs. METHODS: Fifteen female growing pigs (Duroc × Large White × Landrace) were ranked by body weight (30 ± 2.1 kg) on day 0 and assigned to one of three treatments, namely the basal diet containing different crude fiber (CF) levels (LCF: 3.0% CF, MCF: 4.5% CF, and HCF: 6.0% CF). The pigs were implanted with the terminal ileum fistula and the cannulation of the ileal mesenteric vein (IMV), portal vein (PV), and left femoral artery (LFA) from days 6 to 7. [13 C]-Labeled VFA and P-aminohippuric acid were constantly perfused into the terminal ileum fistula and the cannulation of the IMV (day 15), respectively. Blood samples were collected from the PV and the LFA during perfusion (5 h), and LI samples were collected. RESULTS: The net flux of [12 C]-acetic acid in the PV was greater for LCF versus MCF (p = 0.045), but no difference was observed in the net flux of [12 C]-propionic acid (p = 0.505) and [12 C]-butyric acid (p = 0.35) in the PV among treatments. The deposition of [12 C]-acetic acid in the LI was greater for LCF versus MCF (p = 0.014), whereas the deposition of [12 C]-propionic acid (p = 0.007) and [12 C]-butyric acid (p = 0.037) in the LI was greater for LCF versus HCF. CONCLUSIONS: In conclusion, this pig model was found conducive to study the net absorption of VFAs in the LI, and LCF had more net absorption of VFAs in the LI than MCF and HCF.

Effect of Dietary Supplementation with Mannose Oligosaccharides on the Body Condition, Lactation Performance and Their Offspring of Heat-Stressed Sows.

The aim of this study was to determine the effects of dietary supplementation with mannose oligosaccharide (MOS) on the condition of the body and the reproductive and lactation performances of sows. Eighty pregnant sows were randomly assigned to four groups with a 2 × 2 factorial design: with or without MOS (1 g/kg) and with or without heat stress (HS) challenge. The temperature in the HS groups (HS and HM group) was controlled at 31.56 ± 1.22 °C, while the temperature in the active cooling (AC) groups (AC and AM group) was controlled at 23.49 ± 0.72 °C. The weight loss of sows in the AC group was significantly lower than that of sows in the HS group (p < 0.01). The weight and backfat thickness loss of sows supplemented with MOS displayed a downward trend. The average birth weight of the litter significantly increased in the HM group (basic diet + MOS) compared with the HS group (p < 0.05). The milk protein of sows significantly decreased under the HS condition at 2 and 12 h after delivery (p < 0.05). However, the milk immunoglobin G (IgG) of sows in the HS group increased significantly compared with that of sows in the HM group (p < 0.05) at 12 and 24 h after delivery. The levels of serum urea nitrogen (UREA) and glucose (GLU) decreased significantly under the HS condition (p < 0.05), while the level of interleukin-6 (IL-6) increased significantly under the HS condition (p < 0.05). Dietary supplementation with MOS also significantly reduced TNF-α under the AC conditions (p < 0.05). In conclusion, HS significantly affected the body condition, lactation performances and their offspring of sows. However, dietary supplementation with 1 g/kg MOS did not result in statistically significant changes.

Trigger factor of Streptococcus suis is involved in stress tolerance and virulence.

Streptococcus suis serotype 2 is an important zoonotic pathogen that causes serious diseases such as meningitis, septicemia, endocarditis, arthritis and septic shock in pigs and humans. Little is known about the regulation of virulence gene expression in S. suis serotype 2. In this study, we cloned and deleted the entire tig gene from the chromosome of S. suis serotype 2 SC21 strain, and constructed a mutant strain (Δtig) and a complementation strain (CΔtig). The results demonstrated that the tig gene, encoding trigger factor from S. suis serotype 2 SC21, affects the stress tolerance and the expression of a few virulence genes of S. suis serotype 2. Deletion of the tig gene of S. suis serotype 2 resulted in mutant strain, ΔTig, which exhibited a significant decrease in adherence to cell line HEp-2, and lacked hemolytic activity. Tig deficiency diminishes stresses tolerance of S. suis serotype 2 such as survive thermal, oxidative and acid stresses. Quantification of expression levels of known S. suis serotype 2 SC21 virulence genes by real-time polymerase chain reaction in vitro revealed that trigger factor influences the expression of epf, cps, adh, rpob, fbps, hyl, sly, mrp and hrcA virulence-associated genes. ΔTig was shown to be attenuated in a LD50 assay and bacteriology, indicating that trigger factor plays an important part in the pathogenesis and stress tolerance of. S. suis serotype 2 infection. Mutant ΔTig was 100% defective in virulence in CD1 mice at up to 107 CFU, and provided 100% protection when challenged with 107 CFU of the SC21 strain.

A regression for estimating metabolizable glucose in diets of weaned piglets for optimal growth performance.

OBJECTIVE: Two experiments were conducted to provide a new approach for evaluating feed nutritional value by metabolizable glucose (MG) in piglet diets with different levels of starch and crude fiber. In Exp 1, a regression equation for MG was generated. In Exp 2, the equation was verified, and the optimal growth performance of piglets under appropriate MG levels was tested. METHODS: In Exp 1, 20 weaned piglets (7.74±0.81 kg body weight [BW]) were randomly assigned to 1 of 4 treatments, including the basal diet containing different levels of MG (starch, 25.80%, 31.67%, 45.71%, 49.36%; crude fiber, 1.23%, 1.35%, 1.80%, 1.51%). The piglets were implanted with an ileal fistula, cannulation of the carotid artery, portal vein, and mesenteric artery. The chyme from the ileum fistula and blood samples were collected. In Exp 2, 30 weaned piglets (8.96±0.50 kg BW) were randomly assigned to 1 of 5 treatments, including the experimental diets with different levels of MG (37.6, 132.5, 300.0, 354.3, and 412.5 g/kg). The piglets' BW, and feed consumption were recorded to calculate growth performance during the 28-d experiment. RESULTS: In Exp 1, the MG levels in 4 diets were 239.62, 280.68, 400.79, and 454.35 g/kg. The regression equation for the MG levels and dietary nutrients was: Y (MG) = 12.13×X1 (starch)+23.18×X2 (crude fiber)-196.44 (R2 = 0.9989, p = 0.033). In Exp 2, treatments with 132.5 and 300.0 g/kg MG significantly (p<0.05) increased average daily gain and feed conversion efficiency of weaned piglets, increased digestibility of crude fat, and had no effect on digestibility of crude protein compared to 300.0 to 412.5 g/kg MG. CONCLUSION: The pig model combining the ileum fistula and cannulation of blood vessels was successfully used to determine the dietary MG levels. The recommended MG level in weaned pig diets is 132.5 to 300.0 g/kg.

An RNAi screen for secreted factors and cell-surface players in coordinating neuron and glia development in Drosophila.

The establishment of the functional nervous system requires coordinated development of neurons and glia in the embryo. Our understanding of underlying molecular and cellular mechanisms, however, remains limited. The developing Drosophila visual system is an excellent model for understanding the developmental control of the nervous system. By performing a systematic transgenic RNAi screen, we investigated the requirements of secreted proteins and cell-surface receptors for the development of photoreceptor neurons (R cells) and wrapping glia (WG) in the Drosophila visual system. From the screen, we identified seven genes whose knockdown disrupted the development of R cells and/or WG, including amalgam (ama), domeless (dome), epidermal growth factor receptor (EGFR), kuzbanian (kuz), N-Cadherin (CadN), neuroglian (nrg), and shotgun (shg). Cell-type-specific analysis revealed that ama is required in the developing eye disc for promoting cell proliferation and differentiation, which is essential for the migration of glia in the optic stalk. Our results also suggest that nrg functions in both eye disc and WG for coordinating R-cell and WG development.

Comparative study of yeast selenium vs. sodium selenite on growth performance, nutrient digestibility, anti-inflammatory and anti-oxidative activity in weaned piglets challenged by Salmonella typhimurium.

The present study was conducted to investigate the effects of dietary supplementation of selenium from different sources on the growth performance, nutrient digestibility, and blood immune indices of piglets orally challenged with Salmonella typhimurium (ST). In a 2 × 2 factorial arrangement, 32 piglets (6.43 ± 0.54 kg of body mass) were assigned into four groups with or without dietary inclusion of sodium selenite (SS) or yeast selenium (YS) and with or without ST challenge (5 ml 1 × 109 cfu/ml ST or 5 ml saline) on d 13. In each period, YS increased average daily feed intake and average daily gain but did not reach statistical significance. During the challenged stage, piglets fed YS had higher digestibility of dry matter, crude protein, crude fat, and YS reduced the amount of Escherichia coli in feces. Additionally, YS regulated the composition of T-lymphocyte subset and influenced the production of inflammatory cytokines. In conclusion, in this study selenium-enriched yeast was more effective in enhancing nutrient digestibility, and inhibiting inflammation and oxidative stress by inducing the activity of the lymphocytes, expression of antioxidant enzymes and so on.

The effect of active components from citrus fruits on dentin MMPs.

OBJECTIVES: This study was aimed to evaluate the anti-matrix metalloproteinases (MMPs) ability of active components from citrus fruits (hesperetin: Hst, hesperidin: Hsd and naringenin: Nge). METHODS: Inactivation effects of citrus flavonoids (Hst, Hsd, Nge) at different concentrations on soluble collagenase were measured using a fluorometric assay. Matrix-bound endogenous MMPs activity was evaluated via dry mass loss and hydroxyproline (HYP) release of demineralized human dentin. Demineralized dentin beams were pretreated with 500µg/mL citrus flavonoids for 10min. Chlorhexidine (CHX) was used as inhibitor control. Beams pretreated with distilled water served as blank control. Dentin slabs were used for in situ zymography and evaluated under confocal microscopy. Ultrastructure of demineralized collagen fibers was exhibited by Transmission Electron Microscopy (TEM). RESULTS: Citrus flavonoids exhibited inactivation function on soluble MMPs and the extent of inactivation increased in a dose-dependent manner. The inactivation percent of citrus flavonoids reached above 90% at the concentration of 500µg/mL. Compared with control group, citrus flavonoids pretreated demineralized dentin beams exhibited less dry mass loss, lower hydroxyproline release and more intact collagen architecture after 15days storage. Dentin samples pretreated with citrus flavonoids showed lower enzymes activities in in situ zymography. CONCLUSIONS: Hst, Hsd or Nge have anti-MMPs ability and can preserve dentin collagen from degradation. CLINICAL SIGNIFICANCE: Hst, Hsd and Nge may have the potential to be used in dentin bonding systems and improve the resin-dentin bonding durability.

Epigallocatechin-3-gallate and Epigallocatechin-3-O-(3-O-methyl)-gallate Enhance the Bonding Stability of an Etch-and-Rinse Adhesive to Dentin.

This study evaluated epigallocatechin-3-gallate (EGCG) and epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG-3Me) modified etch-and-rinse adhesives (Single Bond 2, SB 2) for their antibacterial effect and bonding stability to dentin. EGCG-3Me was isolated and purified with column chromatography and preparative high performance liquid chromatography. EGCG and EGCG-3Me were incorporated separately into the adhesive SB 2 at concentrations of 200, 400, and 600 µg/mL. The effect of cured adhesives on the growth of Streptococcus mutans (S. mutans) was determined with scanning electron microscopy and confocal laser scanning microscopy; the biofilm of bacteria was further quantified via optical density 600 values. The inhibition of EGCG and EGCG-3Me on dentin-originated collagen proteases activities was evaluated with a proteases fluorometric assay kit. The degree of conversion (DC) of the adhesives was tested with micro-Raman spectrum. The immediate and post-thermocycling (5000 cycles) bond strength was assessed through Microtensile Bond Strength (MTBS) test. Cured EGCG/EGCG-3Me modified adhesives inhibit the growth of S. mutans in a concentration-dependent manner. The immediate MTBS of SB 2 was not compromised by EGCG/EGCG-3Me modification. EGCG/EGCG-3Me modified adhesive had higher MTBS than SB 2 after thermocycling, showing no correlation with concentration. The DC of the adhesive system was affected depending on the concentration of EGCG/EGCG-3Me and the depth of the hybrid layer. EGCG/EGCG-3Me modified adhesives could inhibit S. mutans adhesion to dentin-resin interface, and maintain the bonding stability. The adhesive modified with 400 µg/mL EGCG-3Me showed antibacterial effect and enhanced bonding stability without affect the DC of adhesive.

Effects of Epigallocatechin-3-gallate (EGCG) on the bond strength of fiber posts to Sodium hypochlorite (NaOCl) treated intraradicular dentin.

This study was to evaluate the effect of Epigallocatechin-3-gallate (EGCG) on the bond strength of two adhesive systems to the Sodium hypochlorite (NaOCl) treated intraradicular dentin. The roots were accepted regular root canal treatments and post space preparations, and further divided into eight groups according to the four post space pretreatments and two dentin adhesives [Single Bond 2 (SB2) and Clearfil SE Bond (CSB)] used. The push-out strength before and after thermocycling in different root region (coronal and apical), DC of the adhesive and morphologic patterns of treated post space were evaluated. NaOCl + EGCG groups showed the highest push-out strength regardless of the adhesive type, root region and time (P < 0.05). NaOCl pretreatment significantly decreased the push-out strengths and DC of CSB (P < 0.05). EGCG could improve the bonding properties of both SB2 and CSB to NaOCl treated intraradicular dentin. The effect of NaOCl on bonding of a fiber post depended on the type of the adhesive.

HIC1 and miR-23~27~24 clusters form a double-negative feedback loop in breast cancer.

MicroRNAs (miRNAs) have emerged as a major regulator of the initiation and progression of human cancers, including breast cancer. However, the cooperative effects and transcriptional regulation of multiple miRNAs, especially miRNAs that are present in clusters, remain largely undiscovered. Here we showed that all members of the miR-23~27~24 clusters are upregulated and function as oncogenes in breast cancer and simultaneously target HIC1. Furthermore, we found that HIC1 functions as a transcriptional repressor to negatively control the expression of miR-23~27~24 clusters and forms a double-negative (overall positive) feedback loop. This feedback regulatory pathway is important because overexpression of miR-23~27~24 clusters can remarkably accelerate tumor growth, whereas restoration of HIC1 significantly blocks tumor growth in vivo. A mathematical model was created to quantitatively illustrate the regulatory circuit. Our finding highlights the cooperative effects of miRNAs in a cluster and adds another layer of complexity to the miRNA regulatory network. This study may also provide insight into the molecular mechanisms of breast cancer progression.

Effect of an Antibacterial Monomer on the Antibacterial Activity of a Pit-and-Fissure Sealant.

Resin-based pit-and-fissure sealants are often used to form a barrier on the occlusal surface of molars to treat caries lesions; however, bacteria can remain in the pit and fissures without detection, increasing the risk of secondary caries. Sealants with antimicrobial properties or microbial repellent actions might be advantageous. The aim of this study was to assess the inhibitory effect of a 2-methacryloxylethyl dodecyl methyl ammonium bromide (MAE-DB)-incorporated sealant against Streptococcus mutans. MAE-DB (4% wt) was incorporated into a commercially available sealant, Eco-S resin-based pit-and-fissure sealant (Vericom Co., Ltd., Korea); a sealant without MAE-DB served as a negative control, and Clinpro™ Sealant (3M™ ESPE™), a fluoride-releasing resin, was used as a commercial control. The effects of the cured sealants and their eluents on the growth of S. mutans were determined according to colony-forming unit counts and metabolic tests. The effects of the cured sealants on the adherence and membrane integrity of S. mutans were investigated using confocal laser-scanning microscopy (CLSM) in conjunction with fluorescent indicators. Compared with the negative control and commercial control, the cured MAE-DB-incorporated pit-and-fissure sealant exhibited a significant inhibitory effect on the growth of S. mutans (P < 0.05), whereas the eluents did not show any detectable antibacterial activity. The commercial control also showed no detectable bactericidal activity. Moreover, the aged experimental material retained its property of contact inhibition of biofilm formation. The fluorescence analysis of CLSM images demonstrated that the cured MAE-DB-incorporated sealant could hamper the adherence of S. mutans and exert a detrimental effect on bacterial membrane integrity. The incorporation of MAE-DB can render a pit-and-fissure sealant with contact antibacterial activity after polymerization via influencing the growth, adherence, and membrane integrity of S. mutans. Therefore, MAE-DB-containing pit-and-fissure sealant shows promise for preventing or controlling dental caries on occlusal pit and fissures of molars.

The transcription factor c-Myc suppresses MiR-23b and MiR-27b transcription during fetal distress and increases the sensitivity of neurons to hypoxia-induced apoptosis.

Previous studies reported that the expression of miR-23b-27b cluster was downregulated in embryonic brain cortices during hypoxia-induced neuronal apoptosis. However, the mechanism underlying this downregulation is not completely understood. Here, we report that the transcription factor c-Myc plays an important role in regulating the expression of miR-23b-27b cluster during hypoxia. First, the c-Myc protein level was significantly elevated in embryonic brain cortices in a mouse model of fetal distress. Second, forced overexpression or knockdown of c-Myc could suppress or increase the expression of miR-23b-27b cluster polynucleotides. Third, we identified 2 conserved c-Myc binding sites (E-boxes) in the enhancer and promoter regions of miR-23b-27b cluster in the mouse genome. Finally, we showed that elevated c-Myc expression led to an increase in the Apaf-1 level by suppressing miR-23b-27b cluster expression and that this enhanced neuronal sensitivity to apoptosis. In summary, our study demonstrates that c-Myc may suppress the expression of the miR-23b-27b cluster, resulting in additional neuronal apoptosis during hypoxia.

Targeted exosome-mediated delivery of opioid receptor Mu siRNA for the treatment of morphine relapse.

Cell-derived exosomes have been demonstrated to be efficient carriers of small RNAs to neighbouring or distant cells, highlighting the preponderance of exosomes as carriers for gene therapy over other artificial delivery tools. In the present study, we employed modified exosomes expressing the neuron-specific rabies viral glycoprotein (RVG) peptide on the membrane surface to deliver opioid receptor mu (MOR) siRNA into the brain to treat morphine addiction. We found that MOR siRNA could be efficiently packaged into RVG exosomes and was associated with argonaute 2 (AGO2) in exosomes. These exosomes efficiently and specifically delivered MOR siRNA into Neuro2A cells and the mouse brain. Functionally, siRNA-loaded RVG exosomes significantly reduced MOR mRNA and protein levels. Surprisingly, MOR siRNA delivered by the RVG exosomes strongly inhibited morphine relapse via the down-regulation of MOR expression levels. In conclusion, our results demonstrate that targeted RVG exosomes can efficiently transfer siRNA to the central nervous system and mediate the treatment of morphine relapse by down-regulating MOR expression levels. Our study provides a brand new strategy to treat drug relapse and diseases of the central nervous system.