Dimeric Proanthocyanidins on the Stability of Dentin and Adhesive Biointerfaces.

A dentin biomodification strategy with selective proanthocyanidin (PAC)-enriched extracts reinforces dentin and dentin-resin interfaces. Enrichment of the extracts according to the degree of polymerization allows exploration of bioactive principles of PACs and structure-activity relationships. This study investigated the sustained dentin matrix biomodification and dentin-resin bioadhesion of 2 fractions consisting exclusively of B-type PAC dimers with or without a single galloyl motif (specifically, DIMERG and DIMERNG) and their precursor material, enriched grape seed extract (e-GSE; Vitis vinifera). The biomodification potential was determined by long-term evaluation of the apparent modulus of elasticity and collagen solubility (hydroxyproline release). Chemical characterization of the dentin matrix was performed by attenuated total reflectance-Fourier-transform infrared spectroscopy. The bioadhesive properties were assessed by a microtensile bond strength test at different time points, and macro-hybrid layers were produced to verify the degree of conversion of the adhesive resin. Fractions consisting of DIMERG, DIMERNG, and their precursor, e-GSE, increased the modulus of elasticity at all time points and reduced collagen degradation. Specimens treated with DIMERNG remained stable throughout 12 mo of storage, whereas a significant drop in the modulus of elasticity was observed for the DIMERG and e-GSE groups at 6 mo. The fractions and precursor did not affect the degree of resin conversion at the hybrid layer. Changes in infrared resonances corresponding to collagen cross-links in the dentin matrix occurred for all treatments. Higher bond strength was observed for dentin treated with e-GSE as compared with DIMERG and DIMERNG; all biointerfaces remained stable after 12 mo. Nongalloylated PACs mediate stable dentin biomodification, which includes protective activity against collagen degradation and reinforcement of the anchoring dentin matrix. Collectively, PACs with a higher degree of oligomerization offer a robust bioadhesion between the hydrophilic dentin matrix and the hydrophobic adhesive.

CO2 Laser Glazing Treatment of a Veneering Porcelain: Effects on Porosity, Translucency, and Mechanical Properties.

This work tested CO2 laser as a glazing agent and investigated the effects of irradiation on the porosity, translucency, and mechanical properties of veneering porcelain. Sixty discs (diameter 3.5 × 2.0 mm) of veneering porcelain for Y-TZP frameworks (VM9, VITA Zahnfabrik) were sintered and had one of their faces mirror polished. The specimens were divided into six groups (n=10/group) according to surface treatment, as follows: no treatment-control; auto-glaze in furnace following manufacturer's instructions (G); and CO2 laser (45 or 50 W/cm(2)) applied for four or five minutes (L45/4, L45/5, L50/4, L50/5). Optical microscopy (Shimadzu, 100×) was conducted and the images were analyzed with Image J software for the determination of the following porosity parameters: area fraction, average size, and Feret diameter. The translucency parameter studied was masking ability, determined by color difference (ΔE) over black and white backgrounds (CM3370d, Konica Minolta). Microhardness and fracture toughness (indentation fracture) were measured with a Vickers indenter (HMV, Shimadzu). Contact atomic force microscopy (AFM) (50 × 50 µm(2), Nanoscope IIIA, Veeco) was performed at the center of one sample from each group, except in the case of L45/5. With regard to porosity and translucency parameters, auto-glazed and laser-irradiated specimens presented statistical similarity. The area fraction of the surface pores ranged between 2.4% and 5.4% for irradiated specimens. Group L50/5 presented higher microhardness when compared to the G group. The higher (1.1) and lower (0.8) values for fracture toughness (MPa.m(1/2)) were found in laser-irradiated groups (L50/4 and L45/4, respectively). AFM performed after laser treatment revealed changes in porcelain surface profile at a submicrometric scale, with the presence of elongated peaks and deep valleys.

Structural study of the porcine Na+/H+ exchanger NHE1 gene and its 5'-flanking region.

The Na+/H+ exchanger is an ubiquitous mammalian plasma membrane protein that is important for the regulation of intracellular pH and cell volume. In order to provide some insight into the molecular basis of NHE1 expression we have isolated and characterized genomic DNA clones containing the coding region and 5'-flanking region of the porcine NHE1 gene. The gene spans more than 30 kb in length and consists of twelve exons that are flanked by typical splice donor and acceptor sequences at the exon-intron boundaries. The positions of the splicing sites are conserved in relation to the human NHE1 gene. The 5' distal transcription initiation site, identified by primer extension analysis, is positioned 766 bp upstream of the translation initiation codon and 36 bp downstream of a TATA box. A 5'-flanking region of 1.62 kb in length contains a number of potential regulatory elements, and exhibits several features that distinguish the pig gene from those of rabbit, mouse and human. The NHE1 gene is located in a CpG island. The promoter sequence of 500 bp is compared with that for NHE1 genes from different species. The homology between the porcine and the human, rabbit and mouse genes is 78, 76 and 75%, respectively. Several consensus elements for transcription factors, including AP-1, C/EBP, and Sp1 are phylogenetically conserved between pig and human, while AP3 and PEA3 are found only in pig. Some conserved elements are found in the pig in multiple copies. These results suggest broadly similar regulatory mechanisms for NHE1 transcription among the different mammalian species but show some species or tissue-specific differences.

[Health assistance model and nursing care given to women planning to breast feed]. / O modelo assistencial de saúde e o atendimento de enfermagem prestado à mulher com vistas ao aleitamento materno (AM).

The present study shows that the nursing practices used on women's assistance, looking forward breast-feeding, transcend an individual technical action. It is known that the kind of assistance practiced will depend on the guidelines set by each institutional organization. These guidelines are based on a prevailed health model which is determined by social and organizational relations that are part of different societies and institutions. The objective of this study is to analyse the relation between the model of breast-feeding assistance established by SUS (Unique Health System) and the actual nursing practice within the Basic Health Units (UBS) of SMS-RP (Municipal Health Office of Ribeirão Preto). Semi-structured interviews with nursing workers were adopted in order to have a report of their practices concerning breast-feeding assistance. The data was examined on the basis of the analyses of content of Bardin (1977). Results showed that there is a considerable difference between the theoretical postulate, and the assistance that is actually practiced. This happens because the nursing practices are submitted to a biomedical model, centered on patients' complaints, which favors medical assistance actions and reinforces prompt assistance. For this reason the study couldn't detect any significant changes regarding the uniqueness of health actions. It was observed that some nursing workers were closer to a better understanding of women care assistance, however the daily determinations have hindered more concrete actions that could transform this practice.