Polysaccharide-based layer-by-layer nanoarchitectonics with sulfated chitosan for tuning anti-thrombogenic properties.

The development of blood-interacting surfaces is critical to fabricate biomaterials for medical use, such as prostheses, implants, biosensors, and membranes. For instance, thrombosis is one of the leading clinical problems when polymer-based materials interact with blood. To overcome this limitation is necessary to develop strategies that limit platelets adhesion and activation. In this work, hyaluronan (HA)/chitosan (Chi) based-films, recently reported in the literature as platforms for tumor cell capture, were developed and, subsequently, functionalized with sulfated chitosan (ChiS) using a layer-by-layer technique. ChiS, when compared to native Chi, presents the unique abilities to confer anti-thrombogenic properties, to reduce protein adsorption, and also to limit calcification. Film physicochemical characterization was carried out using FTIR and XPS for chemical composition assessment, AFM for the surface morphology, and contact angle for hydrophilicity evaluation. The deposition of ChiS monolayer promoted a decrease in both roughness and hydrophilicity of the HA/Chi films. In addition, the appearance of sulfur in the chemical composition of ChiS-functionalized films confirmed the film modification. Biological assay indicated that the incorporation of sulfated groups limited platelet adhesion, mainly because a significant reduction of platelets adhesion to ChiS-functionalized films was observed compared to HA/Chi films. On balance, this work provides a new insight for the development of novel antithrombogenic biomaterials, opening up new possibilities for devising blood-interaction surfaces.

Efficacy of a single session protocol for endodontic treatment in primary teeth: in vivo study.

AIMS: To determine the efficacy of a single session protocol (SSP) in the reduction of septic content of primary teeth root canals and identify the persistence of bacterial species associated with unsuccessful treatment. METHODS: Primary teeth root canals (16) with pulp necrosis and peri-radicular lesions were treated. Samples were collected at baseline (T1), and after chemo-mechanical preparation, before filling (T2). Identification of the microorganisms was determined using checkerboard DNA-DNA hybridisation. STATISTICAL ANALYSIS: Wilcoxon test was applied for comparison of mean number of species, proportion and mean count of each species between the evaluation times. RESULTS: Significant reductions were found in the mean number of bacteria species between T1 and T2 (p < 0.05), but not for the reduction in proportion (p > 0.05). There was a reduction (6.0-4.6) of the mean number of species associated with failure, without statistical significance. CONCLUSION: The SSP was capable of significantly reducing the septic content, even though, many of the bacteria associated with failure persisted at the time of root canal filling.

Genetic variability in three populations of Hypostomus hermanni (Teleostei: Loricariidae) found in the basins of Ivaí River, Tietê River, and Sapucaí-Mirim River of Brazil.

The genetic variability in three populations of Hypostomus hermanni from the tributaries of the rivers Ivaí (Keller), Tietê (Piracicaba), and Sapucaí (Sapucaí-Mirim) was determined using electrophoresis on starch gel. The variability in the genes for eight enzymes, namely, aspartate aminotransferase (EC 2.6.1.1), glucose-6-phosphate isomerase (EC 5.3.1.9), glycerol-3-phosphate dehydrogenase (EC 1.1.1.8), isocitrate dehydrogenase (EC 1.1.1.42), -lactate dehydrogenase (EC 1.1.1.27), malate dehydrogenase (EC 1.1.1.37), malate dehydrogenase NADP+ (EC 1.1.1.40), and phosphoglucomutase (EC 5.4.2.2), was assessed. Three loci with seven alleles were obtained in the population of Keller River whereas eight loci with 20 alleles and six loci with 16 alleles were present in the populations of Piracicaba and Sapucaí-Mirim rivers, respectively. Individuals analyzed in the three watersheds presented all the detected polymorphic loci. The average heterozygosity was 0.0527, 0.1742, and 0.1299 in the Keller, Piracicaba, and Sapucaí-Mirim River populations, respectively. On the basis of identity values and genetic distances, all the three populations were determined to be genetically very similar.

Effect of a glass ionomer cement and a fluoride varnish on cross-sectional microhardness values of artificial occlusal caries: in vitro study.

CONTEXT: Active white spot lesions (WSLs) are a great concern to clinicians. AIMS: This in vitro experiment analyzed cross-sectional microhardness (CSMH) values of occlusal artificially induced active WSLs (control groups D/A, D/B and D/C) along with experimental groups where these lesions were: Exposed to an artificial high risk cariogenic challenge (HRCC) using pH cycling; treated with a glass ionomer cement (GIC) and then exposed to artificial HRCC; or a fluoride varnish (FV) and afterwards submitted to the same artificial HRCC. MATERIALS AND METHODS: Sixty unerupted human third molars were sectioned buccolingually on the occlusal surface and demineralized for 42 days. One half of each tooth was allocated to control groups (D/A, D/B, and D/C) and the other were used as test groups: A (pH cycling); B (GIC + pH cycling); and C (FV + pH cycling). CSMH test was performed for sound, demineralized, and treated specimens. STATISTICAL ANALYSIS USED: Different depths for CSMH values did not have a normal distribution (Kolmogrov-Smirnov test) and for that matter Wilcoxon and T Test were applied (significance level of 5%). RESULTS: Mean depth of the lesion was 120 µm. A number of samples both in the test groups (n = 37) as in control groups (n = 47) had a lower Knoo p value (softening) or surface erosion. Comparisons between control and test groups only showed statistical difference at a depth 140 µm (P = 0.010) in control group D/A and for test group B at 20 µm (P = 0.004) and at 40 µm (P = 0.007). CONCLUSIONS: This in vitro study demonstrated that the use of GIC over an artificial active WSLs and exposed to an artificially HRCC setting tend to express some effect in increased surface KHN values.

Effect of fluoride gels on occlusal fissures in primary molars: an in vitro study.

AIM: To assess the effect of the application of fluoride gels on the acid resistance of occlusal enamel in primary molars. STUDY DESIGN: Forty-five primary second molars were randomly assigned to three groups: a) control (pH-cycling); b) 2% NaF gel/pH-cycling; and c) 1.23% APF gel/pH-cycling. METHODS: Specimens were longitudinally sectioned in the buccal-lingual direction and used for cross-sectional microhardness testing. Knoop hardness values were converted into vol.% mineral and mineral loss (ΔZ) was then calculated. STATISTICS: The response variables were vol.% mineral and ΔZ. Data were tested using parametric tests at a significance level of 5%. RESULTS: No statistically significant differences were found between groups regarding vol.% mineral or ΔZ. CONCLUSIONS: A single application of a high concentration fluoride compound does not promote greater resistance to demineralisation in enamel pits and fissures, regardless of the product used.

Erosive effects of acidic center-filled chewing gum on primary and permanent enamel.

BACKGROUND: The higher incidence of dental erosion in children and teenagers possibly reflects a high intake of acidic food and beverages as well as a more frequent diagnosis on this condition. AIM: The aim of this study was to evaluate the erosive potential of acidic filling of chewing gum in primary and permanent enamel. METHODS AND MATERIALS: Eighty enamel blocks (40 primary and 40 permanent teeth) were used and randomly distributed into eight groups. Groups were divided according to types of dental substrates (permanent or primary), frequency of exposure to the acidic substance (2X or 4X/day), and concentration (pure or diluted). Exposure time to the acidic content of the chewing gum was five minutes under agitation, during five days. RESULTS: All groups showed a significant decrease in surface microhardness (P P = 0.002), D3 (pure, 4X/day) and D4 (diluted, 4X/day) (P = 0.009) regarding the concentration, then the diluted acid content was associated with a greater decrease in microhardness. CONCLUSION: It is concluded that the acidic filling of a chewing gum reduced the microhardness of primary and permanent enamel.

Marginal leakage in direct and indirect composite resin restorations in primary teeth: an in vitro study.

OBJECTIVE: The aim of this study was to evaluate the marginal leakage in class II preparations, with margins in enamel, restored with composite resin indirect and direct restorations. METHODS: Twenty extracted primary molars were chosen and divided at random into two groups: G1 (n=10) restored by a direct technique and G2 (n=10) restored by an indirect technique. The composite resin Filtek Z250 (3M) and the Adper Single Bond adhesive (3M) were used in both groups. Teeth were stored in a humid environment at 37 degrees C for 1 week, thermo cycled (500 cycles, 5 degrees C and 55 degrees C), sealed and immersed in a 0.5% basic fuchsine dye for 24h. Teeth were longitudinally sectioned, in a mesio-distal direction and leakage was assessed. RESULTS: No leakage in the specimens from G2 and leakage in four specimens from G1, but the Mann-Whitney test showed that there was no statistically significant difference between the groups, either for occlusal box (p=0.317) and proximal box (p=0.067). CONCLUSION: This study demonstrated that direct and indirect class II composite resin restorations with cervical margins in enamel show similar results regarding marginal leakage.

Evaluation of batch adsorption of chromium ions on natural and crosslinked chitosan membranes.

Removal of chromium ions from aqueous solutions by using natural and crosslinked chitosan membranes was achieved using batch adsorption experiments. The effect of pH (6.0 and 2.0), concentration of chromium ions and crosslinking agents (glutaraldehyde: GLA and epichlorohydrin: ECH) on the adsorption properties of chitosan membranes was analyzed. The experimental equilibrium data was fitted to Langmuir and Freundlich models. Through the model curves, it was possible to observe that the amount of chromium ions adsorbed was significantly higher for crosslinked membranes compared to non-crosslinked chitosan. The maximum adsorbed amount was about 1400 mg g(-1) for ECH-crosslinked chitosan at pH 6.0. The adsorption rates for crosslinked chitosan membranes with glutaraldehyde and epichlorohydrin were similar for natural chitosan. Desorption study using NaCl (1 mol L(-1)) solution was performed on chitosan membranes, in order to recover chromium ions and to determine the suitable number of cycles for repeated use of these membranes without considerable decrease in their adsorption capacity. The desorption results showed that chromium ions could be more effectively removed at pH 2.0 than pH 6.0, mainly for ECH-crosslinked chitosan.

Short resin-posts bonding to primary dentin. Microleakage and micro-morphological in vitro study.

The aim of this in vitro study was to evaluate the adhesion of two bonding systems (Single Bond and Adper Prompt L Pop, 3M ESPE) to short resin posts in the root dentin of primary teeth. Statistical analysis (Mann Whitney) revealed that there were no statistically significant differences between the materials (p= 0.75), but the Single Bond group presented a wider resin-dentin inter-diffusion zone (RDIZ). Both groups showed long resin tags. It was concluded that although Single Bond produced a wider adhesive interface than Adper Prompt L Pop, leakage levels occurred in both systems.

Selective effect of hypothyroidism on expression of myelin markers during development.

Thyroid hormones are critical for maturation of the central nervous system. In a previous study, we showed a change in the pattern of mature myelinated nerve fibers by 2'3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) in developing hypothyroid animals, which suggests a possible role for thyroid hormones in myelin compaction. The classical myelin markers myelin basic protein (MBP) and proteolipidic protein (PLP) are expressed later in oligodendroglial development, when myelin sheath formation is in progress. A myelin constituent designated myelin-associated/oligodendrocytic basic protein (MOBP) has been identified and related to myelin compaction. We assessed the developmental sequence of appearance of CNPase, MBP, MOPB, and PLP proteins in cerebellum (Cb) and corpus callosum (cc) in an experimental hypothyroidism model. The appearance of both MOBP isoforms occurred at postnatal day (P)25 and P30 in cc and Cb, respectively, followed by an increase with age in the control group. However, all the MOBP isoforms were weakly detectable in both regions at P30 from the hypothyroid (H) group, and the higher molecular weight isoform remains decreased in cc, even at P90. The developmental pattern of expression of CNPase, MBP, and PLP proteins was also delayed in the H group. CNPase and MBP expression was recovered in cc and Cb, whereas PLP remained below control levels at P90 in cc. Our data show that the experimental hypothyroidism affects the developmental pattern of the oligodendrocytic/myelin markers. Furthermore, thyroid hormone may modulate specific genes, as demonstrated by permanent down-regulation of MOBP and PLP expression in adulthood.

[Toxoplasmosis of the central nervous system in a patient without immunosupression: case report]. / Toxoplasmose do sistema nervoso central em paciente sem evidência de imunossupressão: relato de caso.

The clinical manifestations of acquired toxoplasmosis in the immunocompetent patient rarely include localized neurological signs, which are frequent in the immunosuppressed patient (Aids). The objective of this paper is to report the case of a woman with Toxoplasma gondii brain abscess, without an identified cause of immunosuppression.