Bonding Performance of Universal Adhesive Systems Applied in Etch-and-Rinse and Self-Etch Strategies on Natural Dentin Caries.

OBJECTIVE: This study investigated the bonding performance of three universal adhesive systems applied using etch-and-rinse (ER) or self-etch (SE) strategies on natural dentin caries. MATERIALS AND METHODS: Sixty human third molars were selected for this study: 30 naturally carious (CAD) and 30 sound (SD) teeth. The dentin surfaces were exposed, and teeth were randomly assigned to each evaluated adhesive system: Scotchbond Universal (SBU), Futurabond U (FBU), and Prime&Bond Elect (PBE) and an adhesive strategy: ER or SE. The adhesive systems were applied following the manufacturer's instructions, and the teeth were restored using a resin composite (Filtek Supreme Ultra, 3M). After 24 hours (distilled water at 37°C), samples were sectioned and evaluated using microtensile bond strength analysis (µTBS), micro-Raman spectroscopy to evaluate the degree of conversion within the hybrid layer (DC), and scanning electronic microscopy (SEM) to describe the morphology of the hybrid layer. The µTBS and DC data were analyzed using three-way analysis of variance and Tukey's test for means comparison (α=0.05). The SEM images were analyzed qualitatively. RESULTS: Reduced µTBS values were observed when comparing CAD with SD, regardless of adhesive system or strategy (p<0.0001). SBU showed statistically higher µTBS for both dentin substrates and strategies (p<0.0001). Furthermore, SBU showed greater integrity of the hybrid layer and resin tag formation compared with FBU and PBE. Mean µTBS values for FBU were higher for SD in the SE mode, whereas higher mean µTBS values were observed for CAD in the ER mode, both compared with PBE (p<0.001). CONCLUSION: Bonding performance is reduced on a caries-affected substrate. The ER strategy was not able to improve the bonding performance on natural CAD for universal adhesive systems. Improved bonding performance was obtained when using the Scotchbond Universal system.

Genetic parameters for stayability to consecutive calvings in Zebu cattle.

Longer-lived cows tend to be more profitable and the stayability trait is a selection criterion correlated to longevity. An alternative to the traditional approach to evaluate stayability is its definition based on consecutive calvings, whose main advantage is the more accurate evaluation of young bulls. However, no study using this alternative approach has been conducted for Zebu breeds. Therefore, the objective of this study was to compare linear random regression models to fit stayability to consecutive calvings of Guzerá, Nelore and Tabapuã cows and to estimate genetic parameters for this trait in the respective breeds. Data up to the eighth calving were used. The models included the fixed effects of age at first calving and year-season of birth of the cow and the random effects of contemporary group, additive genetic, permanent environmental and residual. Random regressions were modeled by orthogonal Legendre polynomials of order 1 to 4 (2 to 5 coefficients) for contemporary group, additive genetic and permanent environmental effects. Using Deviance Information Criterion as the selection criterion, the model with 4 regression coefficients for each effect was the most adequate for the Nelore and Tabapuã breeds and the model with 5 coefficients is recommended for the Guzerá breed. For Guzerá, heritabilities ranged from 0.05 to 0.08, showing a quadratic trend with a peak between the fourth and sixth calving. For the Nelore and Tabapuã breeds, the estimates ranged from 0.03 to 0.07 and from 0.03 to 0.08, respectively, and increased with increasing calving number. The additive genetic correlations exhibited a similar trend among breeds and were higher for stayability between closer calvings. Even between more distant calvings (second v. eighth), stayability showed a moderate to high genetic correlation, which was 0.77, 0.57 and 0.79 for the Guzerá, Nelore and Tabapuã breeds, respectively. For Guzerá, when the models with 4 or 5 regression coefficients were compared, the rank correlations between predicted breeding values for the intercept were always higher than 0.99, indicating the possibility of practical application of the least parameterized model. In conclusion, the model with 4 random regression coefficients is recommended for the genetic evaluation of stayability to consecutive calvings in Zebu cattle.

Promoter region sequence differences in the A and G gamma globin genes of Brazilian sickle cell anemia patients

Fetal hemoglobin (HbF), encoded by the HBG2 and HBG1 genes, is the best-known genetic modulator of sickle cell anemia, varying dramatically in concentration in the blood of these patients. This variation is partially associated with polymorphisms located in the promoter region of the HBG2 and HBG1 genes. In order to explore known and unknown polymorphisms in these genes, the sequences of their promoter regions were screened in sickle cell anemia patients and correlated with both their HbF levels and their ƒÀS-globin haplotypes. Additionally, the sequences were compared with genes from 2 healthy groups, a reference one (N = 104) and an Afro-descendant one (N = 98), to identify polymorphisms linked to the ethnic background.The reference group was composed by healthy individuals from the general population. Four polymorphisms were identified in the promoter region of HBG2 and 8 in the promoter region of HBG1 among the studied groups. Four novel single nucleotide polymorphisms (SNP) located at positions -324, -317, -309 and -307 were identified in the reference group. A deletion located between -396 and -391 in the HBG2 promoter region and the SNP -271 C¨T in the HBG1 promoter region were associated with the Central African Republic ƒÀS-globin haplotype. In contrast, the -369 C¨G and 309 A¨G SNPs in the HBG2 promoter region were correlated to the Benin haplotype. The polymorphisms -396_-391 del HBG2, -369 SNP HBG2 and -271 SNP HBG1 correlated with HbF levels. Hence, we suggest an important role of HBG2 and HBG1 gene polymorphisms on the HbF synthesis.

Promoter region sequence differences in the A and G gamma globin genes of Brazilian sickle cell anemia patients.

Fetal hemoglobin (HbF), encoded by the HBG2 and HBG1 genes, is the best-known genetic modulator of sickle cell anemia, varying dramatically in concentration in the blood of these patients. This variation is partially associated with polymorphisms located in the promoter region of the HBG2 and HBG1 genes. In order to explore known and unknown polymorphisms in these genes, the sequences of their promoter regions were screened in sickle cell anemia patients and correlated with both their HbF levels and their betaS-globin haplotypes. Additionally, the sequences were compared with genes from 2 healthy groups, a reference one (N = 104) and an Afro-descendant one (N = 98), to identify polymorphisms linked to the ethnic background.The reference group was composed by healthy individuals from the general population. Four polymorphisms were identified in the promoter region of HBG2 and 8 in the promoter region of HBG1 among the studied groups. Four novel single nucleotide polymorphisms (SNP) located at positions -324, -317, -309 and -307 were identified in the reference group. A deletion located between -396 and -391 in the HBG2 promoter region and the SNP -271 C-->T in the HBG1 promoter region were associated with the Central African Republic betaS-globin haplotype. In contrast, the -369 C-->G and 309 A-->G SNPs in the HBG2 promoter region were correlated to the Benin haplotype. The polymorphisms -396_-391 del HBG2, -369 SNP HBG2 and -271 SNP HBG1 correlated with HbF levels. Hence, we suggest an important role of HBG2 and HBG1 gene polymorphisms on the HbF synthesis.

Characterization of pectin lyase produced by an endophytic strain isolated from coffee cherries.

AIMS: The effect of endophytic bacterial activity on the quality of coffee beverage was studied. METHODS AND RESULTS: A survey of the micro-organisms in coffee cherries was performed before harvesting, and their growth on the main nutrients available in coffee cherries was determined in vitro. CONCLUSION: Many endophytic bacteria were isolated from surface-sterilized coffee cherries. One of the pectinolytic strains was physiologically and phenotypically characterized, and was tentatively identified by partial 16S rDNA sequencing as Paenibacillus amylolyticus. This endophytic strain produced an extracellular pectinase with maximal activity at 40 degrees C and pH 7.9, and was thermostable up to 45 degrees C. EDTA and metal ions had little effect on pectin lyase activity. Km and Vmax values were 4.6 mg ml(-1) and 94.0 10(-8) mol min(-1) ml(-1), respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: Pectin lyases have been found in fungi but rarely in bacteria, and this isolate is a promising tool for regulation studies of these enzymes.

Cyclic AMP and low molecular weight effector(s) present in yeast extract are involved in pectin lyase production by Penicillium griseoroseum cultured on sucrose.

Pectin lyase (PL) induction by organic and inorganic components of yeast extract (YE) was evaluated in Penicillium griseoroseum, cultured in a mineral medium containing sucrose, by determining PL activity (A235) and mycelial growth (mycelial dry weight). The lowest YE concentration that promoted significant PL induction without acting as a carbon source for the fungus corresponded to 0.0075%. Neither calcined YE nor a nutrient solution containing micronutrients induced PL production, indicating that the inducer was an organic compound. Vitamins, phospholipid components, amino acids, and nitrogenous bases were tested in place of YE and promoted no significant PL induction. A PL inducer compound was found to be soluble in the nucleotide fraction obtained during extraction of YE. The inducer was shown to be a thermostable polar substance dialyzable at 2000 Daltons, hydrolyzable by HCl, and activated by boiling for up to 60 min. Cyclic AMP (cAMP) exogenously added to the culture medium at 5 and 10 mM was capable of inducing PL in P. griseoroseum grown on sucrose, suggesting that at least one compound may be present in YE acting in a cooperative fashion for the maintenance of high levels of cAMP into the cell. PL activity and the level of cAMP inside the fungal cells increased after the addition of YE to the culture medium, suggesting the participation of this messenger in this enzyme's synthesis.

Production of pectin lyase by Penicillium griseoroseum as a function of the inoculum and culture conditions.

Optimum activity of an extracellular pectin lyase produced by Penicillium griseoroseum in submerged culture was after 120 h using 0.1% (w/v) citrus pectin as substrate. Sucrose at 0.1% (w/v) stimulated enzyme production and citrus pectin gave the highest activity of enzyme per unit growth.

Partial purification and properties of pectin lyase from Penicillium expansum.

A pectin lyase, poly(methoxygalacturonide) lyase, EC 4.2.2.10, from a culture filtrate of Penicillium expansum was partially purified 33-fold with 7.3% yield. The enzyme was monomeric with a molecular mass of 36.5 kDa. The enzyme did not contain pectate lyase activity and degraded citrus and apple pectin best at pH 7.0 and 40 to 45°C. The K m for citrus pectin was 9 mg ml(-1).

Sobrevivencia de Salmonella em carne bovina moida armazenada em baixas tem peraturas. / Survival of Salmonella in ground beef under low storage temperature

Amostras de carne bovina moida, de cinco acougues da cidade de Vicosa, MG, foram armazenadas a 4 graus C por 14 dias, a 0 graus C e 18 graus C por 90 dias, para analise das populacoes de bacterias nao fermentadoras de lactose (Lac-) e determinacao da sobrevivencia e da resistencia de Salmonella a drogas antimicrobianas. As amostras, submetidas ao pre-enriquecimento em caldo lactosado, apresentaram-se com populacoes de bacterias Lac-superiores as amostras sem o pre-enriquecimento. Foi observado aumento nas populacoes de celulas Lac-, nos primeiros dias de armazenamento a 4graus C e a 0graus C. Apos 21 dias,houve reducao do numero de celulas Lac- nas amostras conservadas a 0graus C. Nas amostras a 18 graus C foi observada tendencia de reducao das populacoes de celulas Lacao longo do periodo de armazenamento. Celulas de Salmonella foram isoladas de amostras em todos os tempos e temperatura.o nivel de resistencia, aos varios antibioticos, das celulas de Salmonella, foi baixo

Regulatory interactions among the cya, crp and pts gene products in Salmonella typhimurium.

A well-characterized set of pts deletion mutants of Salmonella typhimurium were used to re-evaluate the purported role of the PTS in the inducer exclusion process and in regulation cAMP synthesis. During the course of these studies a class of secondary mutations was isolated which suppress the inhibition of cAMP synthesis caused by pts mutations. These suppressor mutations were traced to the crp locus and tentatively designated as acr (adenylate cyclase regulation) mutations. A new model is proposed in which CRP rather than adenylate cyclase is believed to be the central regulatory element in the catabolite repression phenomenon.