Exploring Dimethylsulfoniopropionate as a potential treatment for Alzheimer's disease: A study using the 3 × Tg-AD mouse model.

BACKGROUND: Alzheimer's disease (AD), the most common neurodegenerative disorder, affects a broad spectrum of aging populations. AD is characterized by pathological amyloid-ß (Aß) plaques and neurofibrillary tangles, leading to neural degeneration and cognitive decline. The lack of effective treatments for AD highlights the urgent need for novel therapeutic agents, particularly in the early stages. Dimethylsulfoniopropionate (DMSP) is a natural marine compound with antioxidant and neuroprotective properties. However, studies on the efficacy of DMSP in the treatment of AD and its associated mechanisms are limited. PURPOSE: This study aimed to explore the therapeutic effects and mechanisms of action of DMSP as an AD treatment using a preclinical 3 × Tg-AD mouse model. METHODS: The research involved administering DMSP (7 µg/mL and 11 µg/mL in drinking water) to four-month-old 3 × Tg-AD mice consecutively for three months. The Y-maze test, novel object recognition test, and Morris water maze test were used to assess memory and learning ability. The relative expression levels and distribution of proteins relevant to Aß and tau pathology, synapses, and glial cells were analyzed using western blotting and immunofluorescence assays. Additionally, proteomic and bioinformatics approaches were used to explore the potential targets of DMSP treatment. RESULTS: DMSP-treated AD mice showed significantly enhanced cognitive function, suggesting that DMSP mitigates memory and learning impairments in AD. Moreover, DMSP diminished the abnormal accumulation of Aß and phosphorylated tau in both the cortex and hippocampus, which are crucial hallmarks of AD pathology. In addition to its neuroprotective properties, DMSP restored synaptic density and the expression of synaptic and neuronal proteins, which are essential for proper brain function. DMSP displayed anti-inflammatory properties, as evidenced by its ability to suppress inflammatory astrocytes and maintain microglial homeostasis. Notably, DMSP facilitated the maturation of oligodendrocytes (OLs) from oligodendrocyte progenitor cells (OPCs), a critical process in the development of the brain myelination architecture. Proteomic analysis revealed that DMSP positively influenced biological processes crucial for oligodendrocyte development, myelination, and axonal ensheathment, which are often compromised in patients with AD. Protein validation and brain tissue staining supported the role of DMSP in preserving myelin enrichment and sheath integrity. These therapeutic effects were largely attributed to the enhanced expression of myelin-associated glycoprotein (Mag) and tetraspanin Cd9. CONCLUSION: Overall, our findings highlight DMSP as a promising novel therapeutic candidate for AD, offering multifaceted benefits in cognitive and memory enhancement, reduction of Aß and tau pathology, neuronal synapse protection, anti-inflammatory effects, and myelin sheath restoration as an innovative target compared to other studies. In addition to being a potentially effective treatment for AD, DMSP may also have the potential to address other neurodegenerative diseases that are closely associated with myelin impairment.

Impact of agricultural activities on the occurrence of N-nitrosamines in an aquatic environment.

N-Nitrosamines, nitroso compounds with strong carcinogenic effects on humans, have been frequently detected in natural waters. In agricultural areas, there is typically a lack of drinking water treatment processes and distribution systems. As a result, residents often consume groundwater as drinking water which may contain N-nitrosamines, necessitating the investigation of the occurrence, sources, and carcinogenic risk of N-nitrosamines within the groundwater of agricultural areas. This study identified eight N-nitrosamines in groundwater and river water in the Jianghan Plain, a famous agricultural region in central China. N-Nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosomorpholine (NMOR), N-nitrosopyrrolidine (NPYR), and N-nitrosodi-n-butylamine (NDBA) were detected in groundwater, with NDMA being the main compound detected (up to 52 ng L-1). Comparable concentrations of these N-nitrosamines were also found in river water. From laboratory experiments, we found a tremendous potential for the formation of N-nitrosamines in groundwater. Principal component analysis and multiple linear regression analysis results showed that the primary sources of N-nitrosamines in groundwater were the uses of nitrogen fertilizers and pesticides carrying specific N-nitrosamines such as NPYR. The average total carcinogenic risk values of detected N-nitrosamines were higher than the acceptable risk level (10-5), suggesting a potential carcinogenic risk of groundwater. Further research is urgently needed to minimize N-nitrosamine levels in the groundwater of agricultural areas, particularly in those where pesticides and fertilizers are heavily used.

Fluoride occurrence in geothermal water of fault zone area, Southeast China.

Fluoride (F-) is a common trace component in groundwater, and long-term exposure to high-F- groundwater is harmful to human health. Fluoride concentrations that exceed the World Health Organization guideline for drinking water (1.5 mg/L) have been detected in thermal and non-thermal groundwater from Southeast China, where the causes of the high fluoride occurrence are lack of study. To study the formation and migration mechanism of high fluoride groundwater from Southeast China, we carried out a systemic sampling of water samples in the surrounding area of Heyuan deep fault zone and Zijin-Boluo fault zone, then a comprehensive discussion including water hydrogeochemical, stable isotope composition, as well as hydrogeology analysis was conducted. Fluoride concentrations in geothermal and non-thermal water samples range from 1.11 to 22.76 mg/L and 0.04-8.3 mg/L, respectively. High temperature, alkaline conditions, and the depleted Ca2+ by reverse cation exchange and calcite precipitation would promote the release of fluoride from host rock to geothermal water. The availability of Ca-bearing and F-bearing minerals in host rock causes significant differences in fluoride concentrations between carbonate reservoir and granite reservoir. Hydrochemical diagrams reveal that the composition of groundwater is affected by mixing and that fractures act as the mixing channels in our study area. The addition of cold groundwater limits the fluoride concentrations by lowing temperature and increasing Ca2+ levels of geothermal water. Additionally, the relationship between F- and SiO2 indicates that geothermal water promotes the fluoride enrichment in cold groundwater, especially in confined aquifers which are more susceptible to geothermal water. The direct input of geothermal fluoride and secondary enrichment caused by alkaline condition contribute to the formation of high F- concentrations (7.2-8.3 mg/L) in confined groundwater. Our findings highlight that the natural evolution of geothermal systems in fault zone can result in the formation of geogenic contaminated groundwater.

The therapeutic mechanism of Yuye decoction on type 2 diabetes mellitus based on network pharmacology and experimental verification.

ETHNOPHARMACOLOGICAL RELEVANCE: Yuye decoction (YYD) has been widely used as a folk Chinese herbal formula in clinical treatment of type 2 diabetes mellitus(T2DM) for many years. However, its mechanism is still unclear. AIM OF THE STUDY: The aim of this study was to explore the potential mechanism of YYD against T2DM initially by UHPLC-MS/MS combining with network pharmacology, molecular docking techniques and experimental validation. MATERIALS AND METHODS: The main ingredients in the water extract of YYD were initially identified using UHPLC-MS/MS analysis. Combined with network pharmacology and molecular docking techniques, the YYD key compounds-core targets-key signaling pathways network was constructed and the binding activity of key components to core targets was validated. The T2DM rat model was induced by Streptozotocin combined with high glucose and high fat diets. The apoptosis cell model of mouse islet ß-cell of Min6 was induced by high-glucose and palmitic acid. Histopathological and immunofluorescence satining were used to evaluate pancreatic islet ß-cell function and apoptosis in rats. Min6 cell viability and apoptosis ratio were evaluated by CCK-8 and TUNEL staining. The predicted targets and pathways were validated by experiments in vitro and in vivo. RESULTS: The 56 compounds from YYD were identified by UHPLC-MS/MS. The potential targets of the above compounds were predicted by online compound target database, among of which 362 targets were associated with T2DM. Protein-protein interaction analysis identified the main targets such as SRC, MAPK1, PIK3R1, AKT1, HRAS and HSP90AA1, which were considered as the therapeutic targets of YYD on against T2DM. Functional enrichment analysis revealed that PI3K/AKT, FoxO and apoptosis signaling pathways were significantly enriched. Molecular docking results showed that compounds of monolinolein, neomangiferin, mangiferin, pelargonidin-3-O-glucoside and acacetin from YYD had high binding activities to PIK3R1, AKT1, Sirt1 and FoxO1. Therefore, PI3K/AKT1, Sirt1/FoxO1 and apoptotic signaling pathways were considered as predicted targets for experimental validation study. Animal experiments showed that YYD reduced blood glucose levels, improved pancreatic dysfunction and pancreatic islet ß-cells apoptosis in T2DM rats which contributed to the activation of AKT1 and FoxO1 and their related signaling molecules. These results were confirmed in Min6 cell model induced by high-glucose and palmitic acid. CONCLUSIONS: In summary, this study systematically visualized the possible therapeutic effects and mechanisms of YYD on T2DM through the network pharmacology approach and experimental study. The results indicated that YYD could prevent pancreatic islet dysfunction and reverse islet of ß-cells apoptosis possibly via PI3K/AKT1, Sirt1/FoxO1 signaling pathways.

Seroprevalence of Transfusion Transmissible Infections and Associated Risk Factors in Hospitalized Patients before Transfusion in Jinling Hospital Nanjing University: A Three-Year Retrospective Study.

Transfusion-transmitted infections (TTIs), such as hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and treponema pallidum (TP), must be detected before blood transfusion. However, few studies have been conducted on the prevalence and accuracy of positive results in hospitalized patients. The purpose of this study was to investigate the real seroprevalence of TTIs among patients before blood transfusion and analyze the characteristics of false-positive results in Jinling Hospital, Nanjing University, China. TTI results were collected from medical records and analyzed retrospectively. Additionally, we also used confirmatory assays to verify the accuracy of positive results. The overall prevalence of TTI was 8.96%, which was related to gender and age. The real positive rates were 86.67% (HBV), 35.09% (HCV), 20.75% (HIV), and 100% (TP). Our results also showed that high-speed centrifugation can reduce the false-positive rate of HBsAg. In summary, the results demonstrated that the positive rates of TTIs in hospitalized patients are higher than those in the general population. We also confirmed the existence of false-positive results in serological screening for TTIs. The method of processing specimens through high-speed centrifugation could reduce the false-positive results of detecting antigens effectively.

Comparative Proteomic Analysis Reveals the Effect of Selenoprotein W Deficiency on Oligodendrogenesis in Fear Memory.

The essential trace element selenium plays an important role in maintaining brain function. Selenoprotein W (SELENOW), the smallest selenoprotein that has been identified in mammals, is sensitive to selenium levels and abundantly expressed in the brain. However, its biological role in the brain remains to be clarified. Here, we studied the morphological and functional changes in the brain caused by SELENOW deficiency using its gene knockout (KO) mouse models. Histomorphological alterations of the amygdala and hippocampus, specifically in the female SELENOW KO mice, were observed, ultimately resulting in less anxiety-like behavior and impaired contextual fear memory. Fear conditioning (FC) provokes rapidly intricate responses involving neuroplasticity and oligodendrogenesis. During this process, the females generally show stronger contextual FC than males. To characterize the effect of SELENOW deletion on FC, specifically in the female mice, a Tandem mass tag (TMT)-based comparative proteomic approach was applied. Notably, compared to the wildtype (WT) no shock (NS) mice, the female SELENOW KO NS mice shared lots of common differentially expressed proteins (DEPs) with the WT FC mice in the hippocampus, enriched in the biological process of ensheathment and oligodendrocyte differentiation. Immunostaining and Western blotting analyses further confirmed the proteomic results. Our work may provide a holistic perspective of gender-specific SELENOW function in the brain and highlighted its role in oligodendrogenesis during fear memory.

High Expression of Long Non-Coding RNA TMCO1-AS1 is Associated With Poor Prognosis of Hepatocellular Carcinoma.

Background: The molecular pathways along with the clinical significance of long non-coding RNAs (lncRNAs) in hepatocellular carcinoma (HCC) remain uncertain. Our study sought to identify and characterize lncRNAs associated with HCC. Methods: LncRNA TMCO1-AS1 was identified by differential expression analysis, receiver operating characteristic (ROC) analysis, and univariate analysis using RNA sequencing and clinical information of HCC from the public database. Then clinical correlations and survival analysis were conducted to further appraise the prognostic significance of lncRNA TMCO1-AS1 in HCC. Hepatoma and adjoining normal tissues from 66 patients who received surgical operation at our center were used to verify the results of the bioinformatics analysis. A survival prognostic model was established combining TMCO1-AS1 expression and other clinical characteristics. Results: Bioinformatics analysis showed the aberrant high expression of TMCO1-AS1 in HCC tissue. TMCO1-AS1 expression was positively correlated with alpha-fetoprotein (AFP) level, vascular invasion, tumor stage, as well as tumor differentiation. Moreover, survival analysis found a significant inverse association between the expression of TMCO1-AS1 and the survival of patients with HCC. Cox analysis indicated that TMCO1-AS1 was an independent factor for HCC prognosis. Analysis of the HCC tissues from patients at our center provided results similar to those of the bioinformatics analysis. Risk models for overall survival (OS) and recurrence-free survival (RFS) incorporating TMCO1-AS1 exhibited better sensitivity and specificity than using clinical characteristics alone. Conclusion: High TMCO1-AS1 expression is significantly correlated with the unfavorable poor prognosis of HCC, indicating its potential of being a novel prognostic marker for HCC.

Inhibition of oral biofilm formation by zwitterionic nonfouling coating.

Inhibition of oral biofilm formation is critical to prevent and treat dental caries and periodontal diseases. In this study, we synthesized zwitterionic poly(carboxybetaine) (pCB) based polymer as a nonfouling coating to provide anti-bacterial properties to tooth surfaces. Four catechol derived l-3,4-dihydroxyphenylalanine (DOPA) groups were conjugated to pCB to serve as a surface anchoring group. The pCB-(DOPA)4 polymer was coated on the hydroxyapatite (HA) and enamel samples by simple immersion and characterized by Raman spectroscopy. The nonfouling effectiveness of the pCB based coating was determined by protein adsorption and bacterial adhesion assays. The coating was transparent on sample surfaces. The protein adsorption was significantly reduced to 8.2% and 6.9%, respectively, on pCB-(DOPA)4 coated HA and enamel samples. The pCB-(DOPA)4 -coated samples also demonstrated significantly fewer adhered Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus mutants compared to the control. This novel coating material provides an innovative approach to resist biofilm formation on tooth surfaces and has great potential in future dental clinical applications.

Serologic false-positive reactions for syphilis in children of adenoidal hypertrophy:2 case reports and review of the literature.

Adenoid hypertrophy (AH) is a common disease in children. We describe two cases of AH in children with syphilis enzyme-linked immunosorbent assay (EIA) for false-positive. To our knowledge, there are few reports of false-positive in syphilis EIA in children with AH. Two cases of AH children with syphilis EIA positive samples were confirmed by TPPA and LIA, both showed negative reaction. Therefore, the occurrence of syphilis EIA positive reactions in such diseases should dramatically arouse the attention of docimasters and doctors so as to avoid misdiagnosis caused by false-positive in children with AH.

Progress in evaluating the status of hepatitis C infection based on the functional changes of hepatic stellate cells (Review).

Hepatitis C virus (HCV) infection is a global public health problem. Cirrhosis and hepatocellular carcinoma are the main causes of death in patients with chronic hepatitis C (CHC) infection. Liver fibrosis is an important cause of cirrhosis and end­stage liver disease after CHC infection. Along with the course of infection, liver fibrosis exhibits a progressive exacerbation. Hepatic stellate cells (HSCs) are involved in both physiological and pathological processes of the liver. During the chronic liver injury process, the activated HSCs transform into myofibroblasts, which are important cells in the development of liver fibrosis. At present, HCV infection still lacks specific markers for the accurate detection of the disease condition and progression. Therefore, the present review focused on HSCs, which are closely related to HCV­infected liver fibrosis, and analyzed the changes in the HSCs, including their surface­specific markers, cytokine production, activation, cell function and morphological structure. The present review aimed to propose novel diagnostic markers, at both the cellular and molecular level, which would be of great significance for the timely diagnosis of the disease. According to this aim, the characteristic changes of HSCs during HCV infection were reviewed in the present article.

Low expression of long noncoding RNA CTC-297N7.9 predicts poor prognosis in patients with hepatocellular carcinoma.

BACKGROUND: Long noncoding RNAs (lncRNAs) are reported to play important roles in tumorigenesis of various malignant tumors. However, the clinical significance of aberrant lncRNA expression in hepatocellular carcinoma (HCC) is still elusive. METHODS: Firstly, a differentially expressed lncRNA CTC-297N7.9 in HCC was detected by analyzing the data from The Cancer Genome Atlas (TCGA). Secondly, the expression level of CTC-297N7.9 was examined in four HCC cell lines and 60 pairs of HCC tissues by polymerase chain reaction (PCR) assay at our center. Thirdly, receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic value of CTC-297N7.9 for HCC. Correlation and survival analysis of HCC patients from the TCGA and our center were also carried out to assess the predictive value of CTC-297N7.9. Finally, survival prognostic models were established combining lncRNA expression and other clinical parameters. RESULTS: The expression of CTC-297N7.9 was downregulated in HCC cell lines and HCC tissues. ROC curve revealed its significant diagnostic value in HCC. CTC-297N7.9 expression correlated with serum alpha-fetal protein (AFP), tumor stage, and tumor differentiation. Survival analysis indicated that overall survival (OS) and disease-free survival (DFS) are all positively associated with CTC-297N7.9 expression, especially in patients without viral hepatitis or cirrhosis. Cox regression analysis showed that CTC-297N7.9 expression level is an independent prognostic factor for both OS and DFS in HCC patients. Based on the model, CTC-297N7.9 was observed to be negatively correlated to risk score, indicating its role as a protective factor for HCC. CONCLUSION: Our study demonstrated that the low expression of CTC-297N7.9 is associated with poor prognosis in HCC patients, suggesting its possible role as a potential prognostic marker for HCC.

Clcn3 deficiency ameliorates high-fat diet-induced obesity and adipose tissue macrophage inflammation in mice.

Obesity induces accumulation of adipose tissue macrophages (ATMs) and ATM-driven inflammatory responses that promote the development of glucose and lipid metabolism disorders. ClC-3 chloride channel/antiporter, encoded by the Clcn3, is critical for some basic cellular functions. Our previous work has shown significant alleviation of type 2 diabetes in Clcn3 knockout (Clcn3-/-) mice. In the present study we investigated the role of Clcn3 in high-fat diet (HFD)-induced obesity and ATM inflammation. To establish the mouse obesity model, both Clcn3-/- mice and wild-type mice were fed a HFD for 4 or 16 weeks. The metabolic parameters were assessed and the abdominal total adipose tissue was scanned using computed tomography. Their epididymal fat pad tissue and adipose tissue stromal vascular fraction (SVF) cells were isolated for analyses. We found that the HFD-fed Clcn3-/- mice displayed a significant decrease in obesity-induced body weight gain and abdominal visceral fat accumulation as well as an improvement of glucose and lipid metabolism as compared with HFD-fed wild-type mice. Furthermore, the Clcn3 deficiency significantly attenuated HFD-induced ATM accumulation, HFD-increased F4/80+ CD11c+ CD206- SVF cells as well as HFD-activated TLR-4/NF-κB signaling in epididymal fat tissue. In cultured human THP-1 macrophages, adenovirus-mediated transfer of Clcn3 specific shRNA inhibited, whereas adenovirus-mediated cDNA overexpression of Clcn3 enhanced lipopolysaccharide-induced activation of NF-κB and TLR-4. These results demonstrate a novel role for Clcn3 in HFD-induced obesity and ATM inflammation.

Influence of gingival retraction paste versus cord on periodontal health: a systematic review and meta-analysis.

OBJECTIVES: The effect of gingival retraction paste versus gingival retraction cord on periodontal tissue health is controversial. The aim of the present study was to evaluate the effect of gingival retraction paste versus gingival retraction cord on periodontal health by a systematic review and meta-analysis and to provide scientific guidelines for gingival retraction method selection in clinical work. DATA SOURCES: The databases were systematically queried to collect studies exploring the effect of gingival retraction methods on periodontal tissue health in randomized controlled trials. Literature covering the period of January 1998 to April 2017 was extracted and the quality was assessed, followed by a random-effects meta-analysis with standardized mean differences and 95% confidence intervals. Eight studies met the inclusion criteria. The result of meta-analysis revealed that gingival retraction paste exhibited a less deleterious effect on the periodontal tissue compared with the gingival retraction cord technique measured by probing depth, Gingival Bleeding Index, and bleeding on probing (P < .05). However, no statistically significant differences were found in the measurements of Plaque Index, Gingival Index, and gingival recession between these two methods (P > .05). CONCLUSIONS: Gingival retraction paste can work better than the gingival retraction cord method in protecting periodontal tissue health.

Design of carboxymethyl chitosan-based heparin-mimicking cross-linked beads for safe and efficient blood purification.

Safe and efficient carboxymethyl chitosan (CMC)-based heparin-mimicking cross-linked beads (CMC/PAMPS) as adsorbents for the clearance of low-density lipoprotein-cholesterol (LDL-c) in blood purification were prepared through hydrogen bonding interactions followed with in situ cross-linking with 2-acrylamido-2-methyl-1-propanesulfonicacid (AMPS). Fourier transform infrared spectra (FTIR), two-dimensional correlation FTIR spectroscopy (2D IR), thermal gravimetric analysis (TGA) and energy dispersive X-ray spectrometer (EDS) demonstrated the successful synthesis of CMC/PAMPS beads. The porous structures of the beads may contribute to the adsorption of toxins. Owing to their favorable hydrophilicity, when contacted with blood, the beads showed excellent hemocompatibility. The hemolysis ratios for all the beads were less than 5%, the thromboplastin time of CMC/PAMPS10 beads exceed 600 s, and they can suppress contact activation and complement activation effectively. Additionally, the beads have no obvious cytotoxicity with endothelial cells, thus could be used as a safe adsorbent for blood purification. Moreover, the CMC/PAMPS10 beads possessed a LDL-c adsorption capacity of 24.8 mg/g under static adsorption and a LDL-c adsorption capacity of 8.2 mg/g in the simulation of hemoperfusion for whole blood, due to the large surface areas and high density of functional groups. Meanwhile, the concentration of high-density lipoprotein-cholesterol (HDL-c) was almost unaffected. In general, the safe adsorbent with high LDL-c adsorption capacity has great potentials for hemoperfusion and other clinical applications.

Engineering sodium alginate-based cross-linked beads with high removal ability of toxic metal ions and cationic dyes.

Sodium alginate (SA) beads with ultrahigh adsorption capacity were prepared via hydrogen bonds between SA and 2-acrylamido-2-methylpropa-1-propanesulfonic acid (AMPS), and the AMPS was then post-cross-linked to manufacture SA/PAMPS beads. The equilibrium adsorption capacities of methylene blue (MB) and Pb2+ for the SA/PAMPS10 beads were 2977 and 2042 mg/g, respectively. Although the SA beads exhibited higher equilibrium adsorption capacities of MB and Pb2+ than those of the SA/PAMPS10 beads, the SA/PAMPS10 beads had better mechanical property and higher stability. The pseudo-second-order kinetic model and the Langmuir isotherm described the adsorption processes of the SA/PAMPS10 beads for MB well. In addition, the SA/PAMPS10 beads could be reused with stable adsorption capacity for at least three cycles. The beads also had excellent performances on absorbing methylene violet and other heavy metal ions (Cu2+, Cd2+ and Ni2+). Therefore, the SA-based beads with high adsorption capacity might be good candidates for industrial pollutant treatments.

Candida albicans and Early Childhood Caries: A Systematic Review and Meta-Analysis.

Oral Candida albicans has been detected in children with early childhood caries (ECC) and has demonstrated cariogenic traits in animal models of the disease. Conversely, other studies found no positive correlation between C. albicans and caries experience in children, while suggesting it may have protective effects as a commensal organism. Thus, this study aimed to examine whether oral C. albicans is associated with ECC. Seven electronic databases were searched. The data from eligible studies were extracted, and the risk of bias was evaluated. A fixed effects model (Mantel-Haenszel estimate) was used for meta-analysis, and the summary effect measure was calculated by odds ratio (OR) and 95% confidence interval (CI). Fifteen cross-sectional studies were included for the qualitative assessment and 9 studies for meta-analysis. Twelve studies revealed higher oral C. albicans prevalence in ECC children than in caries-free children, while 2 studies indicated an equivalent prevalence. A pooled estimate, with OR = 6.51 and 95% CI = 4.94-8.57, indicated a significantly higher ECC experience in children with oral C. albicans than those without C. albicans (p < 0.01). The odds of experiencing ECC in children with C. albicans versus children without C. albicans were 5.26 for salivary, 6.69 for plaque, and 6.3 for oral swab samples. This systematic review indicates that children with oral C. albicans have >5 times higher odds of having ECC compared to those without C. albicans. Further prospective cohort studies are needed to determine whether C. albicans could be a risk factor for ECC, and whether it is dependent on different sample sources (saliva/plaque).

Diversity in Antagonistic Interactions between Commensal Oral Streptococci and Streptococcus mutans.

Arginine metabolism via the arginine deiminase system (ADS) of oral bacteria generates ammonia, which can increase the pH of oral biofilms and decrease the risk for dental caries. Antagonistic interactions between ADS-positive and cariogenic bacteria in oral biofilms may be an important ecological determinant of caries. This study investigated the antagonistic potential and mechanisms of clinical isolates of arginolytic streptococci on and by Streptococcus mutans UA159, a well-characterized cariogenic human isolate. Low-passage isolates of Streptococcus gordonii, Streptococcus sanguinis, Streptococcus parasanguinis, Streptococcus australis, and Streptococcus cristatus inhibited the growth of S. mutans to various degrees when they were inoculated on growth media first or simultaneously with S. mutans. The antagonistic effects of arginolytic strains against S. mutans and the production of H2O2 by these strains were enhanced during growth in a less-rich medium or when galactose was substituted for glucose as the primary carbohydrate source. Pyruvate oxidase was the dominant pathway for H2O2 production by arginolytic strains, but lactate oxidase activity was also detected in some strains of S. gordonii and S. cristatus. UA159 inhibited the growth of all tested arginolytic strains when inoculated first, especially in aerobic conditions. However, the antagonistic effects of S. mutans on certain strains of S. gordonii and S. australis were not observed during anaerobic growth in the presence of arginine. Thus, arginolytic commensal streptococci may have a synergistically positive impact on the ecology of oral biofilms by moderating biofilm pH while antagonizing the growth and virulence of caries pathogens.

Comparison of Composition and Anticaries Effect of Galla Chinensis Extracts with Different Isolation Methods.

OBJECTIVES: Galla chinensis water extract (GCE) has been demonstrated to inhibit dental caries by favorably shifting the demineralization/remineralization balance of enamel and inhibiting the biomass and acid formation of dental biofilm. The present study focused on the comparison of composition and anticaries effect of Galla chinensis extracts with different isolation methods, aiming to improve the efficacy of caries prevention. METHODS: The composition of water extract (GCE), ethanol extract (eGCE) and commercial tannic acid was compared. High performance liquid chromatography coupled to electrospray ionization-time of flight-mass spectrometry (HPLC-ESI-TOF-MS) analysis was used to analyze the main ingredients. In vitro pH-cycling regime and polymicrobial biofilms model were used to assess the ability of different Galla chinensis extracts to inhibit enamel demineralization, acid formation and biofilm formation. RESULTS: All the GCE, eGCE and tannic acid contained a high level of total phenolics. HPLC-ESI-TOF-MS analysis showed that the main ingredients of GCE were gallic acid (GA), while eGCE mainly contained 4-7 galloylglucopyranoses (GGs) and tannic acid mainly contained 5-10 GGs. Furthermore, eGCE and tannic acid showed a better effect on inhibiting enamel demineralization, acid formation and biofilm formation compared to GCE. CONCLUSIONS: Galla chinensis extracts with higher tannin content were suggested to have higher potential to prevent dental caries.

Effect of arginine on the growth and biofilm formation of oral bacteria.

BACKGROUND: Alkali production via arginine deiminase system (ADS) of oral bacteria plays a significant role in oral ecology, pH homeostasis and inhibition of dental caries. ADS activity in dental plaque varies greatly between individuals, which may profoundly affect their susceptibility to caries. OBJECTIVE: To investigate the effect of arginine on the growth and biofilm formation of oral bacteria. METHODS AND RESULTS: Polymicrobial dental biofilms derived from saliva were formed in a high-throughput active attachment biofilm model and l-arginine (Arg) was shown to reduce the colony forming units (CFU) counts of such biofilms grown for various periods or biofilms derived from saliva of subjects with different caries status. Arg hardly disturbed bacterial growth of Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis and Streptococcus gordonii in BHI medium, but only inhibited biofilm formation of S. mutans. Scanning electron microscope (SEM) showed S. mutans biofilms harboured fewer cells grown with Arg than that without Arg, even in the initial 2h and 8h phase. Confocal laser scanning microscope (CLSM) images of poly-microbial dental and S. mutans biofilms revealed the biofilms grown with Arg had lower exopolysaccharide (EPS)/bacteria ratios than those without Arg (P=0.004, 0.002, respectively). Arg could significantly reduce the production of water-insoluble EPS in S. mutans biofilms (P<0.001); however, quantitative real-time PCR (qRT-PCR) did not show significantly influence in gene expression of gtfB, gtfC or gtfD (P=0.32, 0.06, 0.44 respectively). CONCLUSIONS: Arg could reduce the biomass of poly-microbial dental biofilms and S. mutans biofilms, which may be due to the impact of Arg on water-insoluble EPS. Considering the contribution to pH homeostasis in dental biofilms, Arg may serve as an important agent keeping oral biofilms healthy thus prevent dental caries.