Spin-Orbit and Zeeman Effects on the Electronic Properties of Single Quantum Rings: Applied Magnetic Field and Topological Defects.

Within the framework of effective mass theory, we investigate the effects of spin-orbit interaction (SOI) and Zeeman splitting on the electronic properties of an electron confined in GaAs single quantum rings. Energies and envelope wavefunctions in the system are determined by solving the Schrödinger equation via the finite element method. First, we consider an inversely quadratic model potential to describe electron confining profiles in a single quantum ring. The study also analyzes the influence of applied electric and magnetic fields. Solutions for eigenstates are then used to evaluate the linear inter-state light absorption coefficient through the corresponding resonant transition energies and electric dipole matrix moment elements, assuming circular polarization for the incident radiation. Results show that both SOI effects and Zeeman splitting reduce the absorption intensity for the considered transitions compared to the case when these interactions are absent. In addition, the magnitude and position of the resonant peaks have non-monotonic behavior with external magnetic fields. Secondly, we investigate the electronic and optical properties of the electron confined in the quantum ring with a topological defect in the structure; the results show that the crossings in the energy curves as a function of the magnetic field are eliminated, and, therefore, an improvement in transition energies occurs. In addition, the dipole matrix moments present a non-oscillatory behavior compared to the case when a topological defect is not considered.

Optical Properties in a ZnS/CdS/ZnS Core/Shell/Shell Spherical Quantum Dot: Electric and Magnetic Field and Donor Impurity Effects.

A theoretical analysis of optical properties in a ZnS/CdS/ZnS core/shell/shell spherical quantum dot was carried out within the effective mass approximation. The corresponding Schrödinger equation was solved using the finite element method via the 2D axis-symmetric module of COMSOL-Multiphysics software. Calculations included variations of internal dot radius, the application of electric and magnetic fields (both oriented along z-direction), as well as the presence of on-center donor impurity. Reported optical properties are the absorption and relative refractive index change coefficients. These quantities are related to transitions between the ground and first excited states, with linearly polarized incident radiation along the z-axis. It is found that transition energy decreases with the growth of internal radius, thus causing the red-shift of resonant peaks. The same happens when the external magnetic field increases. When the strength of applied electric field is increased, the opposite effect is observed, since there is a blue-shift of resonances. However, dipole matrix moments decrease drastically with the increase of the electric field, leading to a reduction in amplitude of optical responses. At the moment impurity effects are activated, a decrease in the value of the energies is noted, significantly affecting the ground state, which is more evident for small internal radius. This is reflected in an increase in transition energies.

Antibiofilm effect of cleaning agents for ocular prostheses.

Introduction: This study aimed to evaluate the antibiofilm effect of different agents (neutral soap, 4% chlorhexidine, Efferdent effervescent tablets, 1% triclosan, and citronella essential oil) used for ocular prosthesis cleaning. Material and Methods: Biofilms of S. aureus and S. epidermidis were formed on 60 ocular prosthesis acrylic resin specimens. The specimens were cleaned with the studied agents with different techniques. Microorganism counting was performed. Data were submitted to ANOVA and HSD Tukey-Kramer (p<.01). Results: When compared to the control group, all cleaning protocols promoted a reduction in growth of microorganisms. The 4% chlorhexidine, effervescent tablets, and 1% triclosan cleaning agents eliminated biofilm in all groups. Conclusion: Therefore, immersion in 4% chlorhexidine, effervescent tablets, and 1% triclosan could be the best protocols indicated for ocular prosthesis cleaning due to their ability to eliminate biofilm.

Influence of Manganese Oxide on the Esthetic Efficacy and Toxicity Caused by Conventional In-office Tooth Bleaching Therapy.

OBJECTIVE: This study aimed to evaluate the esthetic efficacy, cytotoxicity, and kinetics of decomposition of hydrogen peroxide (H2O2) present in a commercial bleaching gel with 35% H2O2 (BG35%) chemically activated with manganese oxide (MnO2). METHODS AND MATERIALS: After incorporating 2 mg/mL, 6 mg/mL, and 10 mg/mL of MnO2 into BG35%, the stability of pH and temperature of the products were analyzed. To assess the esthetic efficacy (ΔE and ΔWI), the BG35%s with MnO2 were applied for 45 minutes on enamel/dentin discs (DiE/D). BG35% or no treatment were used as positive (PC) and negative (NC) controls, respectively. To analyze the cell viability (CV) and oxidative stress (OXS), the same bleaching protocols were performed on DiE/D adapted to artificial pulp chambers. The extracts (culture medium + gel components that diffused through the discs) were applied to pulp cells and submitted to H2O2 quantification. BG35% with MnO2 that showed the best results was evaluated relative to kinetic decomposition of H2O2, with consequent generation of free radicals (FR) and hydroxyl radicals (OH•). The data were submitted to the one-way analysis of variance complemented by Tukey post-test (α=0.05). Data on kinetics of H2O2 decomposition were submitted to the Student's-t test (α=0.05). RESULTS: All the BG35%s with MnO2 showed stability of pH and temperature, and the gel with 10 mg/mL of this activator had an esthetic efficacy 31% higher than that of the PC (p<0.05). Reduction in OXS and trans-amelodentinal diffusion of H2O2 occurred when all the BG35%s with MnO2 were used. The addition of 6 and 10 mg/mL of MnO2 to BG35% increased the CV in comparison with PC, confirmed by the cell morphology analysis. An increase in FR and OH• formation was observed when 10 mg/mL of MnO2 was added to BG35%. CONCLUSION: Catalysis of BG35% with MnO2 minimized the trans-amelodentinal diffusion of H2O2 and toxicity of the product to pulp cells. BG35% containing 10 mg/mL of MnO2 potentiated the decomposition of H2O2, enhancing the generation of FR and OH•, as well as the efficacy of the in-office tooth therapy.

Electronic structure of vertically coupled quantum dot-ring heterostructures under applied electromagnetic probes. A finite-element approach.

We theoretically investigate the electron and hole states in a semiconductor quantum dot-quantum ring coupled structure, inspired by the recent experimental report by Elborg and collaborators (2017). The finite element method constitutes the numerical technique used to solve the three-dimensional effective mass equation within the parabolic band approximation, including the effects of externally applied electric and magnetic fields. Initially, the features of conduction electron states in the proposed system appear discussed in detail, under different geometrical configurations and values of the intensity of the aforementioned electromagnetic probes. In the second part, the properties of an electron-hole pair confined within the very kind of structure reported in the reference above are investigated via a model that tries to reproduce as close as possible the developed profile. In accordance, we report on the energies of confined electron and hole, affected by the influence of an external electric field, revealing the possibility of field-induced separate spatial localization, which may result in an indirect exciton configuration. In relation with this fact, we present a preliminary analysis of such phenomenon via the calculation of the Coulomb integral.

Magnetoconductivity in quasiperiodic graphene superlattices.

The magnetoconductivity in Fibonacci graphene superlattices is investigated in a perpendicular magnetic field B. It was shown that the B-dependence of the diffusive conductivity exhibits a complicated oscillatory behavior whose characteristics cannot be associated with Weiss oscillations, but rather with Shubnikov-de Haas ones. The absense of Weiss oscillations is attributed to the existence of two incommensurate periods in Fibonacci superlattices. It was also found that the quasiperiodicity of the structure leads to a renormalization of the Fermi velocity [Formula: see text] of graphene. Our calculations revealed that, for weak B, the dc Hall conductivity [Formula: see text] exhibits well defined and robust plateaux, where it takes the unexpected values [Formula: see text], indicating that the half-integer quantum Hall effect does not occur in the considered structure. It was finally shown that [Formula: see text] displays self-similarity for magnetic fields related by [Formula: see text] and [Formula: see text], where [Formula: see text] is the golden mean.

Pyramidal core-shell quantum dot under applied electric and magnetic fields.

We have theoretically investigated the electronic states in a core/shell pyramidal quantum dot with GaAs core embedded in AlGaAs matrix. This system has a quite similar recent experimental realization through a cone/shell structure [Phys. Status Solidi-RRL 13, 1800245 (2018)]. The research has been performed within the effective mass approximation taking into account position-dependent effective masses and the presence of external electric and magnetic fields. For the numerical solution of the resulting three-dimensional partial differential equation we have used a finite element method. A detailed study of the conduction band states wave functions and their associated energy levels is presented, with the analysis of the effect of the geometry and the external probes. The calculation of the non-permanent electric polarization via the off-diagonal intraband dipole moment matrix elements allows to consider the related optical response by evaluating the coefficients of light absorption and relative refractive index changes, under different applied magnetic field configurations.

Donor impurity energy and optical absorption in spherical sector quantum dots.

The properties of the conduction band energy states of an electron interacting with a donor impurity center in spherical sector-shaped GaAs-Al0.3Ga0.7As quantum dots are theoretically investigated. The study is performed within the framework of the effective mass approximation through the numerical solution of the 3D Schrödinger equation for the envelope function via the finite element method. The modifications undergone by the spectrum due to the changes in the conical structure geometry (radius and apical angle) as well as in the position of the donor atom are discussed. With the information regarding electron states the linear optical absorption coefficient associated with transition between confined energy levels is evaluated and its features are discussed. The comparison of results obtained within the considered model with available experimental data in GaAs truncated-whisker-like quantum dots shows very good agreement. Besides, our simulation leads to identify the lowest energy photoluminescence peak as donor-related, instead of being associated to acceptor atoms, as claimed after experimental measurement (Hiruma et al. (1995) [14]). Also, a checking of our numerical approach is performed by comparing with analytical solutions to the problem of a spherical cone-shaped GaN with infinite confinement and donor impurity located at the cone apex. Coincidence is found to be remarkable.

Effects of Lactobacillus reuteri as an adjunct to the treatment of periodontitis in smokers: randomised clinical trial.

The aim of this randomised clinical trial was to evaluate the effect of Lactobacillus reuteri in chewable tablets as an adjunct to non-surgical periodontal treatment of chronic periodontitis in smoking patients. 34 patient smokers were selected and randomly divided into two groups. The SRP group (n=17) received scaling and root planing (SRP) in one session and a placebo; the PRO group (n=17) received SRP in one session and 2 probiotic tablets 2× per day, for 21 days. Bleeding on probing (BOP), probing depth (PD), clinical attachment level (CAL), gingival recession (GR), and pockets with PD≥5 mm and bleeding were measured at baseline and 90 days. After 90 days of treatment, the PD and pockets with PD≥5 mm and bleeding were significantly lower in both groups compared to baseline (P<0.05). In the PRO group, the BOP had significantly reduced at 90 days when compared with the baseline (P<0.05). There was statistically significant reduction in PD between baseline and 90 days in the PRO group in deep pockets (P<0.05). There was no statistically significant difference between the groups in the reduction in PD (P=0.95) or gain in CAL (P=0.97) in moderate and deep pockets. The adjuvant use of L. reuteri in the treatment of chronic periodontitis was effective in controlling gingival inflammation because reduced bleeding on probing which means reduced gingival inflammation and was effective in reducing deep pocket in manner clinically relevant.

Electronic states in GaAs-(Al,Ga)As eccentric quantum rings under nonresonant intense laser and magnetic fields.

The features of the electron energy spectrum in eccentric two-dimensional GaAs-AlGaAs quantum rings of circular shape are theoretically investigated taking into account the effect of externally applied magnetic and intense laser fields. Analytical expressions for the laser-dressed confining potential in this kind of quantum ring geometry are reported for the first time. Finite element method is used to solve the resulting single-particle effective mass two-dimensional partial differential equation. It is shown that the allowed level spectrum is greatly influence by the external probe as well as by the breaking of geometric symmetry related to the changes in eccentricity. In presence of an intense laser field, the conduction band confining profile suffers strong modifications along the structure, with an additional contribution to symmetry breaking. These modifications of electronic quantum states reflect in the intraband optical absorption. Accordingly, the features of the intraband transitions are discussed in detail, revealing the significant influence of the magnetic field strength and laser field intensity and polarization, together with eccentricity, in the allowing of ground-to-excited states transitions and their corresponding intensities.

Effect of photopolymerized glaze application on bacterial adhesion on ocular acrylic resin surfaces submitted to accelerated ageing.

Conditions of the acrylic resin (AR) surface, such as roughness, can promote a favourable environment for the adhesion of micro-organisms, even on the surface of ocular prostheses. This study evaluated the influence of photopolymerized glaze application on the roughness of ARs and adhesion of Staphylococcus aureus and Staphylococcus epidermidis on ocular AR surfaces submitted to accelerated ageing. Two hundred and eighty-eight samples of white colour (N1) and colourless ARs were distributed in eight groups (n = 9), based on surface treatments (glaze or ARs submitted to only a final polishing), accelerated ageing (before and after) and periods of microbial growth (24- and 48-h). The roughness average (Ra) and total height of roughness profile (Rt) values were greater for the groups with glaze and increased for all groups after ageing. The microbial adhesion among the groups with and without glaze did not present a statistically significant difference. The ageing did not statistically affect the adhesion of Staph. epidermidis, but affected the adhesion of Staph. aureus, which presented an increase after 24 h of growth on only N1 AR with glaze. These results demonstrate that the glaze did not contribute to adhesion of Staph. aureus and Staph. epidermidis, which are responsible for most ocular prosthetic infections. SIGNIFICANCE AND IMPACT OF THE STUDY: Some recent evidence suggested that the surface finish of ocular prostheses influences the accumulation of deposits that can affect the interaction with pathogenic bacteria, increasing the probability of infections. In addition, surface deterioration over time can increase the roughness and, consequently, biofilm formation. Thus, a better understanding of the influence of surface finish on bacterial adhesion becomes extremely important. In this study, we tested a glaze for surface polishing compared to mechanical polishing, before and after ageing. The results suggest that the glaze did not contribute to microbial adhesion and might be useful in preventing possible prosthetic infections.

Effects of Geometry on the Electronic Properties of Semiconductor Elliptical Quantum Rings.

The electronic states in GaAs-AlxGa1-xAs elliptically-shaped quantum rings are theoretically investigated through the numerical solution of the effective mass band equation via the finite element method. The results are obtained for different sizes and geometries, including the possibility of a number of hill-shaped deformations that play the role of either connected or isolated quantum dots (hills), depending on the configuration chosen. The quantum ring transversal section is assumed to exhibit three different geometrical symmetries - squared, triangular and parabolic. The behavior of the allowed confined states as functions of the cross-section shape, the ring dimensions, and the number of hills-like structures are discussed in detail. The effective energy bandgap (photoluminescence peak with electron-hole correlation) is reported as well, as a function of the Al molar fraction.

Migration, TB control and elimination: Whom to screen and treat.

Tuberculosis (TB) in migrants represents an important clinical and public health threat, particularly in low TB incidence countries. The current review is aimed to assess issues related to screening and treatment of migrants with latent TB infection or TB disease.

Influence of enamel/dentin thickness on the toxic and esthetic effects of experimental in-office bleaching protocols.

OBJECTIVES: This paper aims to assess the whitening effectiveness and toxicity of tooth-bleaching protocols applied to enamel/dentin disks simulating mandibular incisors (ICs) and premolars (PMs). MATERIALS AND METHODS: A 10% hydrogen peroxide (H2O2) gel was applied for 3 × 15, 1 × 15, or 1 × 5 min to enamel/dentin disks simulating mandibular ICs and PMs, and the trans-enamel and trans-dentinal diffusion products were applied to human dental pulp cells (1 h). Professional therapy (35% H2O2-3 × 15 min) was used as positive control, and non-bleached samples were used as negative control. Cell viability and morphology, oxidative stress generation, and odontoblastic marker expression were assessed. The H2O2 diffusion and enamel color change (ΔE) were also analyzed. RESULTS: The 10% H2O2 gel induced significant cell viability reduction only when applied 3 × 15 min, with the intensity of oxidative stress and down-regulation of odontoblastic markers being higher in the IC group. The other experimental bleaching protocols caused slight alterations regarding the cell parameters evaluated, with intensity being related to enamel/dentin thickness. These effects were also correlated with higher H2O2 diffusion in the IC group. ΔE values similar as positive control were found for the 10% 3 × 15 and 1 × 15 protocols on IC group, after 4 and 6 sessions. CONCLUSION: Application of a 10% H2O2 bleaching gel for 15 or 45 min to thin dental substrate significantly minimizes cell toxicity in comparison with highly concentrated gels associated with similar esthetic outcomes by increasing the number of bleaching sessions. CLINICAL RELEVANCE: Bleaching gels with 10% H2O2 applied in small teeth for short periods may be an interesting alternative to obtain whitening effectiveness without causing toxicity to pulp cells, which may be able to reduce the tooth hypersensitivity claimed by patients.

Effect of low-level laser therapy as an adjuvant in the treatment of periodontitis induced in rats subjected to 5-fluorouracil chemotherapy.

BACKGROUND AND OBJECTIVE: This study aimed to assess the effect of multiple sessions of a low-level laser therapy (LLLT) adjuvant to scaling and root planing (SRP) on the treatment of experimental periodontitis (EP) in rats treated with 5-fluorouracil (5-FU). MATERIAL AND METHODS: A total of 120 rats were divided into five groups: no treatment (NT); treatment with 5-FU (60 and 40 mg/kg) and no local periodontal treatment (5FU); treatment with 5-FU and SRP (5FU-SRP); treatment with 5-FU, SRP and one LLLT session (660 nm; 0.035 W; 4.2 J; 120 s) (5FU-SRP-1LLLT); and treatment with 5-FU, SRP and four LLLT sessions (0, 24, 48 and 72 h) (5FU-SRP-4LLLT). EP was induced in the mandibular molars through ligature placement. The alveolar bone loss (ABL) area in the furcation region was analysed histometrically. TRAP, proliferating cell nuclear antigen, RANKL, osteoprotegerin and activated caspase-3 patterns were analysed by immunolabeling. Prostaglandin E2 was quantified using an ELISA, and tumour necrosis factor α and interleukin-6 were assessed using the multiplex method. The prevalence rates of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella nigrescens, Prevotella intermedia and Fusobacterium nucleatum were assessed using the PCR method. The data were subjected to statistical analysis (α = 5%). RESULTS: 5FU, 5FU-SRP and 5FU-SRP-1LLLT treatment groups showed higher ABL compared with the NT group (p < 0.05), whereas the 5FU-SRP-4LLLT group showed lower ABL compared with the 5FU group on day 7 and decreased RANKL immunolabeling (p < 0.05). CONCLUSION: Treatment with 5-FU worsened EP, and multiple LLLT sessions adjuvant to SRP seemed to improve periodontitis in rats subjected to 5-FU chemotherapy.

Prevalencia y factores de riesgo de estreñimiento en estudiantes de enfermería de una universidad privada colombiana / Prevalecence and risk factors of constipation in nursing students of a private colombian university / Prevalência e fatores de risco de obstipação em estudantes de enfermagem da uma universidade privada colombiana

Esta investigación buscó determinar la prevalencia de estreñimiento en los estudiantes de Enfermería de una universidad \r\nprivada colombiana e identificar algunos factores de riesgo. La carencia de datos en el medio acerca del problema y las \r\nrepercusiones que tienen en la calidad de vida de los jóvenes son algunos de los elementos que justificaron el estudio.\r\nSe desarrolló un estudio transversal. Se abordaron todos los estudiantes vinculados a la Facultad; se estudiaron los \r\n341 que aceptaron participar. La información se recolectó mediante una encuesta, se procesó en el software SPSS® \r\nversión 17,0 (SPSS Inc; Chicago, Illinois, USA) y se realizó un análisis descriptivo. Para identificar los factores de riesgo \r\nse utilizó el OR como medida de asociación, con sus respectivos intervalos de confianza al 95%; se asumió signifi\r\n-\r\ncancia estadística si el valor de p era menor de 0,05.\r\nLa prevalencia de estreñimiento encontrada, según los Criterios Roma III, fue del 41,3% (IC: 36%-47%). Los factores \r\nde riesgo que tuvieron significancia estadística se relacionan principalmente con los hábitos asociados a la defecación, \r\nhábitos alimentarios y consumo de medicamentos, entre ellos los laxantes. Las manifestaciones clínicas que acom\r\n-\r\npañan con mayor frecuencia el estreñimiento son: distensión abdominal, flatulencia y dolor abdominal. El 56,0% (79) \r\nde los estudiantes no han consultado al médico por este motivo. El 84,4% (119) emplea medidas dietéticas para aliviar \r\nel problema. Se concluye que el estreñimiento se presenta con alta frecuencia en este grupo; por tanto, debe abordarse \r\ncon acciones preventivas y de intervención.

This research aims to identify the prevalence and risk \r\nfactors of constipation in nursing students from a private \r\nColombian university. The lack of data about the problem \r\nand the impact on quality of life of young people were the \r\ntwo main considerations for this research A Cross Sectional Study was performed, 341 of all the \r\nnursing students agreed to participate in the research. \r\nThe information was collected through a survey and \r\nwas processed in SPSS ® software version 17.0 (SPSS \r\nInc., Chicago, Illinois, USA). In order to explore the risk \r\nfactors the OR was calculated with its confidence inter\r\n-\r\nvals of 95%, and statistical significance with p value less \r\nthan 0.05 was assumed.\r\nAccording to Rome Criteria III, the prevalence was \r\n41.3% (CI: 36%-47%). The risk factors with statistical \r\nsignificance were related to defecation habits, nutri\r\n-\r\ntional habits and medicine consumption, among them \r\nthe use of laxatives. The main clinical manifestations of \r\nconstipation are: abdominal distension, flatulence and \r\nabdominal pain. 56.0% (79) of students have not sought \r\nmedical attention due to constipation symptoms. 84.4% \r\n(119) consider dietary interventions in order to relieve \r\nthe problem. Constipation is a high frequency problem \r\nin this group and should be approached with preventive \r\nand intervention actions.

Esta investigação procura a prevalência de obstipação nos \r\nestudantes de enfermagem da uma universidade privada \r\ncolombiana e identifica os riscos do condição. A falta dos \r\ndados a respeito a problema e o efeito que tem sobre a \r\nqualidade da vida dos jovens foram duas dos elementos \r\nque justificaram o realização do estudo Um estudo transversal foi desenvolvido com 341 partici\r\n-\r\npantes, todos estudantes da faculdade. A informação foi \r\nrecolhido por uma pesquisa e processado pela programa \r\ndo computado SPSS® versão 17,0 (SPSS Inc; Chicago, \r\nIllinois, USA). Para identificar os fatores de risco o OR \r\nfoi calculado com seus intervalos de confiança a 95% e \r\na significância estatística do o valor de p menor de 0,05 \r\nfoi suposto.\r\nA prevalência de obstipação encontrada, segundo os \r\nCritérios Roma III, foi 41,3% (IC: 36%-47%). Os fatores \r\nde risco que tiveram significância estatística tenha que ver \r\nprincipalmente com os hábitos relacionados com a defe\r\n-\r\ncação, hábitos alimentares e consumo de remédios, entre \r\neles o uso dos laxantes. As sintomas que acompanham \r\nobstipação com a maior frequência são: distensão abdo\r\n-\r\nminal, flatulência e dor abdominal. 56,0% (79) dos \r\nestudantes não consultaram a atenção médico por este \r\nmotivo. 84,4% (119) consideram regimes dietéticas para \r\nse aliviar da problema. Conclui-se que a obstipação é um \r\nproblema de alta frequência neste grupo e deve ser abor\r\n-\r\ndado com ações preventivas.

Caracterización fisicoquímica de la variedad castilla del lulo (Solanum quitoense Lam) en seis estados de maduración / Physicochemical characterization of the lulo (Solanum quitoense Lam) castilla variety in six ripening stages

Background: Lulo (Solanum quitoense Lam) is considered a fruit with a high potential for exportation due to its exotic aroma, its bittersweet taste and the bright green color of its pulp. As a climacteric fruit is harvested when the fruit has reached full development, and 75% of the ripening is apparent by its characteristic yellow color with some small green points. However, this parameter is not enough to decide the right time for the crop, due to the irregularity of the fruits, especially for selling purposes in international markets, hence studies have been conducted to establish the changes during ripening and postharvest. Objectives: The aim of this work was to determine the relationship between color measurement and the other physicochemical parameters in the six ripening stages of lulo Castilla variety, in order to define the optimal harvesting time. Methods: Three fruits were studied for each stage, and were analyzed in the fresh state: ° Brix, pH, titratable acidity and color changes in the cortex, according to CIELab system. Results: The ranges obtained for the six evaluated stages were: ° Brix: 4.2 - 10.3, pH: 3.67 - 3.90, acidity: 2.63 - 3.00 and color (ΔE): 0 - 53. We found that the epicarp of the fruit varies from green to yellow intense, indicating the maturity for consumption. Total soluble solids increased with fruit maturation and the tritatable acidity decreased reaching a minimum values at stage 3, which was considered optimum for harvesting. The pH increased in stage 5 due to the drop of vacuolar H+ ion concentration. Conclusion: By measuring color parameters, 3 ripening stages were defined: green (0, 1, 2); semi ripe (3, 4) and ripe (5).

Influence of VicRK and CovR on the interactions of Streptococcus mutans with phagocytes.

OBJECTIVE: Streptococcus mutans are members of the oral microbiota that are implicated in dental caries and infective endocarditis. To adapt to environmental stresses encountered during host colonization, these bacteria employ two-component regulatory systems, which modulate global changes in gene expression. These include the systems VicRK and CovR. In this study, we investigate the influence of VicRK and CovR in S. mutans interactions with mononuclear and polymorphonuclear (PMN) phagocytes. METHODS: Patterns of S. mutans uptake by murine macrophages were determined in strains, which differ in the production of proteins regulated by VicRK and CovR. Bacterial uptake by murine macrophages and by PMN in human blood was analyzed in vicK and covR knockout mutants obtained in strains UA159 and LT11. RESULTS: Inactivation of covR did not affect uptake by macrophages, while vicK inactivation transiently reduced uptake only in LT11 (P < 0.05). In the two strains, inactivation of vicK and covR impaired uptake by PMN for a period of 1 h or more (P < 0.01-0.05). Mutant complementation with vicK or covR restored the PMN uptake phenotypes. CONCLUSION: This study indicates that VicRK and CovR regulate functions that influence bacterial susceptibility to phagocytosis, suggesting a novel role for these systems in the virulence of S. mutans.

Immunological and microbiologic changes during caries development in young children.

We explored the association between caries development, colonization with caries-associated microflora, and immunity as children begin the transition to mixed dentition. Forty children received dental examinations at 3-4 years of age, repeated a year later. Children were grouped into caries-free (n = 23; CF) and caries-active (n = 17; CA ≥3 new lesions on follow-up). Salivary IgA and IgA antibody to Streptococcus mutans virulence epitopes were measured by Luminex assay. Mutans streptococci (MS), lactobacilli and total microorganisms were enumerated on selective media from plaque samples. There was no significant difference in baseline levels of MS or lactobacilli between CF and CA groups. However, both MS and lactobacilli levels were higher at follow-up in the CA group. Furthermore, children with detectable lactobacilli at baseline had significantly higher caries risk. Salivary IgA concentrations increased significantly in both groups during the study. Both CF and CA groups also displayed significant increases in salivary IgA antibody levels to glucosyltransferase, glucan-binding protein (Gbp) and antigen I/II salivary binding region. CF antibody levels to seven peptides associated with domains of biological importance increased at follow-up, in contrast to increases to only three peptides in CA saliva samples. Multivariate modeling showed that a lower baseline level of salivary IgA anti-GbpB was associated with higher caries risk. These data indicate that MS and lactobacilli are associated with caries in this population, that the secretory immune system is undergoing significant maturation during this period, and that the breadth of mucosal IgA response to epitopes of S. mutans virulence components may influence the degree to which these cariogenic microorganisms can cause disease.

Punção aspirativa com agulha fina guiada por ultrassom e biópsia por videolaparoscopia em próstata de cães / Ultrasound guided fine needle aspiration puncture and videolaparocopic biopsy of the prostate of dogs

Onze cães, sem raça definida, machos, adultos, não castrados e hígidos foram submetidos à punção aspirativa com agulha fina da próstata guiada por ultrassom para avaliação citológica e, após um período mínimo de sete dias, à videolaparoscopia para obtenção de fragmento prostático para avaliação histológica. Nos exames citológicos, dois animais apresentaram alterações celulares compatíveis com hiperplasia prostática benigna. Durante a videolaparoscopia, a colheita do fragmento prostático foi realizada de maneira rápida, não sendo observada hemorragia significativa após o procedimento. Os animais não apresentaram nenhuma complicação no período pós-operatório. Verificaram-se, ao exame histológico, morfologia e estrutura celulares e teciduais nos padrões normais do parênquima prostático em 10 animais; um único cão apresentou alterações celulares e teciduais sugestivas de hiperplasia prostática benigna.(AU)

Eleven healthy intact male mongrel dogs were submitted to prostate ultrasound fine needle aspirative puncture for cytologic exam and, after seven days or more, to videolaparoscopic fragment collection for further histologic evaluation. On cytologic exams, two animals presented changes which correlates with benign prostatic hyperplasia. During the videolaparoscopic proceedings, the prostate fragment collections were made in a quick way and no important hemorrhagic lost has been seen after the collection. The animals presented no complication after the surgeries. The histologic exams showed normal prostate parenchyma based on the cellular and tissue morphology and structure in ten dogs; only one presented cellular and tissue changes suggesting benign prostatic hyperplasia.(AU)