Characterization of Effective Native Lactic Acid Bacteria as Potential Oral Probiotics on Growth Inhibition of Streptococcus mutans

Background and Objective: Probiotics' effects on harmful oral bacteria have been verifed. As antibiotic resistance becomes a major problem, searching for novel potential species is important. The objective of this study was to select novel safe strains of lactic acid bacteria with potentials as oral probiotics. Furthermore, ability of these strains to suppress growth and attachment of Streptococcus mutans as the most important cariogenic bacteria in tooth decay was investigated. Material and Methods: Initial identification tests, including Gram staining and catalase and oxidase tests, were carried out on 22 strains of lactic acid bacteria isolated from Iranian traditional dairy products. Safety of the strains was assessed using hemolysis test and antibiotic resistance assessment. Strains were then assessed for probiotic characteristics such inhibition of Streptococcus mutans growth, tolerance to lysozyme enzymes and ability of adhesion as well as ability of decreasing Streptococcus mutans adhesion. Selected strains were identified using16S rRNA molecular method. Results and Conclusion: Of all strains, four strains with the optimal probiotic characteristics were selected. These included one Lactobacillus brevis, one Lactobacillus casei and two Lactobacillus paraceasei. These four strains showed strong antimicrobial characteristics against Streptococcus mutans, were resistant to oral lysozyme enzymes and included high adhesion abilities to polystyrene wells. Furthermore, they decreased Streptococcus mutans attachment; thus, biofilm formation by this bacterium was prevented. These strains were recognized as safe strains since they were approved in assessments of antibiotic susceptibility and hemolytic activity. Therefore, these four strains are suggested as oral probiotics. Conflict of interest: The authors declare no conflict of interest

Endodontic Treatment of a Mandibular Second Premolar with Type XVII Sert and Bayirli’s Canal Anatomy

For a successful root canal treatment, it is critical for the clinician to have a complete knowledge of the root canal morphology, interprets radiographs critically and properly assesses the pulp chamber floor. Anatomical variations are critical in diagnosis and a successful treatment outcome in endodontics. Knowledge of root canal morphology and anomalies is essential to succeed in root canal therapy. Mandibular premolars are famous for their atypical morphology. But the occurrence of type XVII Sert and Bayirli’s root canal type is very rare in them. The purpose of this case report is to present treatment of a seldom root canal system in a mandibular second premolar. Reports of unusual cases cause clinicians to do an accurate clinical examination and radiographic interpretation and consider atypical root canal configurations.Keywords: Anatomy; Mandible; Root Canal; Second Premola

Understanding the Role of Data Analytics in Driving Discriminatory Managerial Decisions

Data analytics has been accused of contributing to discriminatory managerial decisions in organizations’ marketing strategies. To date, most studies have focused on the technical antecedents of such discriminations and, therefore, little is known about the role of human factors in making these discriminatory decisions. This work-in-progress study aims at addressing this gap by opening the black box between data analytics use in organizations and making discriminatory decisions. Drawing upon the theory of moral disengagement, we posit that four dimensions of moral disengagement, namely, dehumanization, euphemistic labeling, displacement of responsibility, and disregard of consequences are the mechanisms through which the use of data analytics tools in organizations could bring about discriminatory decisions. Moreover, data size and employees’ competency are discussed as having moderating impacts on some of these mechanisms. A survey-based methodology to empirically validate the proposed model is outlined. Potential contributions to theory and practice are delineated

Selective Surface Chemistry of Bifunctional Carboxylic acid, Aldehyde and Alcohol on Si(100)2x1: Exploring Competition between Alkyl, Alkenyl, Carboxyl, Hydroxyl, and Carbonyl Groups in Surface Functionalization

The dissociative adsorption of three carboxylic acids (acetic acid, propanoic acid, and acrylic acid), allyl alcohol, and allyl aldehyde on Si(100)2×1 at room temperature has been investigated by X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD), as well as density-functional theory (DFT) calculations. The C 1s features obtained by XPS measurement for acetic acid, propanoic acid, and acrylic acid show that formation of bidentate carboxylate at a low exposure is followed by that of unidentate carboxylate at a higher exposure, with approximately equal population for both adstructures. The signatures of C 1s features attributed to methyl (285.7 eV), ethyl (285.3 eV), ethenyl (285.0 eV), and bidentate carboxyl (286.8 eV) and unidentate carboxyl (289.8-289.3 eV) carbons were observed for the studied carboxylic acids. The results showed that the carboxyl group is more reactive than the alkyl or alkenyl group towards the Si(100)2×1 surface, with O−H dissociation preferred over [2+2] C=C cycloaddition and the other plausible reaction products. This was also supported by our DFT calculation which showed that the bidentate carboxylate adstructure is the most stable configuration among the calculated adstructures for the aforementioned carboxylic acids. The combined temperature-dependent XPS and TPD studies provided strong evidence for the formation of ketene, acetaldehyde and CO from acetic acid, CO and ethylene from propanoic acid, and CO, ethylene, acetylene, and propene from acrylic acid. Furthermore, the TPD results provided further evidence for the preferred structure of the adsorbate from each of the carboxylic acid on the surface. In addition to carboxyl group, reactivity of the hydroxyl and carbonyl functional groups relative to that of ethenyl group was studied by investigating the reaction of allyl alcohol and allyl aldehyde on Si(100)2×1 at room temperature. The C 1s XPS results supported O−H dissociation for allyl alcohol and [2+2] C=O cycloaddition for allyl aldehyde over the [2+2] C=C cycloaddition. The similarity between the observed C 1s features for allyl alcohol and allyl aldehyde helped to identify the structure of the adsorption products of these two molecules on the surface. The presence of the related C 1s feature of C=C for allyl alcohol and allyl aldehyde, and the absence of C 1s feature of C=O for allyl aldehyde provided strong evidence to support that [2+2] C=C cycloaddition does not occur in the presence of hydroxyl or carbonyl groups. Furthermore, by comparing the experimental results and the adsorption energies of the adstructures calculated by DFT, it was concluded that these molecules do not react with the Si dimers through both of their functional groups, while the reaction of only one of the two functional groups is preferred on the surface. Formation of ethylene, acetylene, and propene from allyl alcohol and allyl aldehyde, simultaneously to CO from allyl alcohol, was concluded from the corresponding TPD results, which also confirm the structure of the adsorbates on the surface. The present research shows that reactions involving oxygen-containing functional groups are favoured over the other plausible reactions including [2+2] C=C cycloaddition on the Si(100)2×1. The preference of the surface to react with one of the two functional groups calls for future studies for the selective functionalization of Si(100)2×1 with potential applications in molecular electronics

Growth Optimization of Lactobacillus plantarum T5jq301796.1, an Iranian Indigenous Probiotic in Lab Scale Fermenter

Background and Objective: Lactobacillus plantarum is one of the probiotics species used in functional food products. These bacteria or their purified bacteriocins are used as biological preservatives in the food industry. The first step in production of an array of probiotic products is optimizing production in fermentors. This study aimed to examine factors affecting the in vitro growth optimization of Lactobacillus plantarum T5JQ301796.1 in a lab scale fermentor.Materials and Methods: Following 24 hours of anaerobic culture of the lactobacillus at 37°C, the pre-culture was ready and was inoculated to a 5 liter fermentor at 37°C and stirred at 40 rpm. Then factors affecting lactobacillus growth including carbon and nitrogen sources and pH were studied. The results were interpreted using response surface methodology (RSM), and optimal conditions for the equipment were determined.Results and Conclusion: For optimal growth of Lactobacillus plantarum T5JQ301796.1 in lab scale fermentor, the optimal conditions were 25.96 gl-1 of glucose, 1.82% of yeast extract, pH of 7.26, and stirring at 40 rpm at optimum temperature between 37-40°C. In this condition, maximum viable cell in the batch fermentation was 1.25×1010 CFU ml-1. Application of central composite design for the growth optimization of this bacterium led to maximum viable cells equal to 1.25×1010 CFU ml-1. So the mentioned features can lead to optimum industrial scale production and usage of this probiotic strain in probiotic products.Conflict of interest: The authors declare that there is no conflict of interest

Molecular investigation of CTX-M gene in Extended Spectrum β Lactamases (ESBLs) producing Pseudomonas aeruginosa isolated from Iranian patients with burn wound infection

Background: Pseudomonas aeruginosa (P. aeruginosa) is one of the most important causes of infection in burns and intensive care units. Extended-spectrum β-lactamases (ESBLs) production in P. aeruginosa is a major factor in the antibiotic resistance and is thought of as a serious threat to the currently available antibiotic armory. The purpose of this study was to determine the prevalence of CTX-M gene in ESBL-producing P. aeruginosa isolates in burn wound samples.Materials and methods: In this cross-sectional survey, a total of 60 clinical isolates of P. aeruginosa were obtained from patients suffering from burn wound infection referred to major hospitals of Tehran, Iran. After verification by biochemical tests and antimicrobial susceptibility testing, CTX-M gene was identified using PCR method.Results: The results of the molecular analysis of CTX-M gene showed that the prevalence of isolates of P. aeruginosa harboring CTX-M gene was 20% (12/60).Conclusion: The results from this study showed high levels of antibiotic resistance and CTX-M gene among P. aeruginosa isolated samples of burn-wound infections which condition may result in the increased the emergence of multidrug-resistant strains and the failure of therapy This study suggests that detailed data on the CTX-M gene frequency can be useful to achieve the best therapy for infections caused by ESBLs producing P. aeruginosa

Repair bond strength of composite : effect of surface treatment and type of composite

Background: By an increase in use of composite restorations, some defects are also seen in these restorations, which need to be repaired. Since complete replacement of an old restoration may compromise the tooth structure, repair of defect is a more practical approach if there is no caries recurrence. Risk of pulp injury also decreases as such. One major challenge in restoration repair is to obtain a durable bond between the new and old composite. Laser irradiation has been suggested for surface preparation of old composite. This study aimed to assess the effect of composite surface preparation with Er,Cr:YSGG laser on microtensile bond strength to new composite. Material and Methods: A total of 18 blocks were fabricated in three groups of nanohybrid, microhybrid and Beautiful II giomer measuring 4x7x7 mm and subjected to 10,000 thermal cycles between 5-55°C with 30 seconds of dwell time. The samples were randomly assigned to no surface treatment (etching and bonding) or laser plus etching and bonding groups. Composite cylinders measuring 4x7x7 mm were fabricated of Beautiful, nanohybrid and microhybrid composites on old composite surfaces and subjected to 500 thermal cycles for 50 seconds between 5-55°C with 30 seconds of dwell time. Each block was sectioned into 10 samples and they were subjected to microtensile bond strength test. Data were analyzed using ANOVA and Tukey?s test. Results: In all composites, the mean bond strength in laser subgroups was higher than that in control subgroups except for giomer, which showed lower bond strength in laser subgroup. The lowest mean bond strength was noted in repair of Z350XT with Z350XT when the surface of old composite was etched (10.92 MPa). The highest mean bond strength was noted in repair of Z250 with giomer when the old composite surface was irradiated with laser (30.55 MPa). Conclusions: Er,Cr:YSGG laser plus etching increased the bond strength in all groups except for giomer group, which showed a reduction in bond strength

Production and Characterization of Biosurfactants Using Bacteria Isolated from Acidic Hot Springs

  Background and objective: Biosurfactants are increasingly used by food industries due to their low toxicities and unique structures. In this study, biosurfactants were produced and characterized for the first time using acidic bacteria isolated from acidic hot springs in Bushehr Province, Iran. Material and methods: Screening and identification of the most efficient species for biosurfactant production were carried out on 12 bacterial species using several experiments such as hemolysis, surface tension, emulsification index and diameter of clear zone. In addition to biosurfactant production, kinetics, stability and structural and thermal analysis were carried out for the bacterial strains using thin layer chromatography, Fourier Transform Infrared, nuclear magnetic resonance and differential scanning calorimetry. Results and conclusion: The biosurfactant from the selected bacteria (0.1 g l-1) was thermally stable at 120°C for 30 min. Stability at temperatures up to 140°C was confirmed using differential scanning calorimetry. The most significant novelty included the fact that the surface property was preserved until an osmolarity of 4% w v-1. Decreased surface tension and the emulsification potential were only reported at concentrations higher the highlighted concentration. Biological assay showed that Staphylococcus aureus was susceptible to produced biosurfactants, while no susceptibility was seen in Escherichia coli. Degeneration of SW480 cell line exposed to 0.601 µg µl-1 of the biosurfactant was detected after 24 h. The structural analysis showed that the biosurfactant was similar to surfactin as a food bioemulsifier. Conflict of interest: The authors declare that they have no conflict of interest

The effects of three remineralizing agents on regression of white spot lesions in children : a two-week, single-blind, randomized clinical trial

This study investigated the effect of three remineralizing agents on improving white spot lesions (WSLs). This clinical trial included children who had at least one WSL on anterior teeth of upper or lower jaws. The participants were randomly assigned to 4 groups by treatment: 1) a cream containing casein phosphopeptide-amorphous calcium phosphate and fluoride (MI Paste Plus); 2) a cream containing hydroxyapatite and fluoride (Remin Pro); 3) a 2% sodium fluoride gel; and 4) usual home care (control). The treatment was performed for 3 times over 10 days using special trays for retaining remineralizing agents. The area and mineral content of WSLs were measured at baseline (T1) and 1 day after finishing treatment (T2). Blinding was applied for outcome assessment. Eighty patients were assigned to MI Paste Plus, Remin Pro, NaF or control groups. The application of all remineralizing agents caused a significant decrease in area and a significant increase in mineral content of WSLs (p0.05). At T2, the area of WSLs was significantly lower in three experimental groups compared to the control group (p=0.023), but between-group difference in mineral content of WSLs failed to achieve statistical significance (p=0.08). The in-office application of either MI Paste Plus or Remin Pro was as effective as 2% NaF for reducing area and increasing mineral content of WSLs. MI Paste Plus and Remin Pro could be recommended as suitable alternatives to NaF for managing WSLs

Evaluation of Knowledge and Practice of Dentists and Assistants in Dental Clinics and Incidence of Sharp Instrument Injuries in Rafsanjan

Background: Injuries caused by sharp instruments are the most important problems that expose dentists and healthcare workers to dangerous blood-borne diseases (AIDS and hepatitis). The aim of this study was to evaluate the incidence of needle stick injuries; and the knowledge and practice of dentists and their assistants about prevention and encountering the injuries caused by sharp instruments in Rafsanjan in 2013. Methods: In this cross-sectional descriptive-analytical study, a researcher-made questionnaire (demographic information, knowledge and practice about reducing exposure and post-exposure practice) were completed by 100 dentists and 115 dental assistants. Data were analyzed using two-sample t-test and linear regression by SPSS 18. Results: During one year, 25% of dentists and 31.1% of assistants were injured by sharp instruments. The mean score of practice and knowledge in dentists was 3.31±0.70 and 3.91±1.49 from the maximum score of 10 and 11. The mean score of practice in assistants was 1.98±0.63 from the maximum score of 9. There was no significant relationship between knowledge and practice score, and gender, age, length of professional experience, and training university. Professional dentists compared to the general dentists showed better practice and knowledge (P=0.03, P=0.01). There was no significant relationship between dentists knowledge and assistants practice (P=0.063) and also between dentists practice and assistants practice (P=0.071). Conclusion: The knowledge and practice level of dentists about sharp instrument injuries and also their assistants’ practice was undesirable and implementing re-education programs seems to be necessary