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.

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.

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]

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.