Low-resolution structural studies of human Stanniocalcin-1

Background: Stanniocalcins (STCs) represent small glycoprotein hormones, found in all vertebrates, which have been functionally implicated in Calcium homeostasis. However, recent data from mammalian systems indicated that they may be also involved in embryogenesis, tumorigenesis and in the context of the latter especially in angiogenesis. Human STCI is a 247 amino acids protein with a predicted molecular mass of 27 kDa, but preliminary data suggested its di- or multimerization. The latter in conjunction with alternative splicing and/or post-translational modification gives rise to forms described as STC(50) and "big STC", which molecular weights range from 56 to 135 kDa. Results: In this study we performed a biochemical and structural analysis of STCI with the aim of obtaining low resolution structural information about the human STCI, since structural information in this protein family is scarce. We expressed STCI in both E. coli and insect cells using the baculo virus system with a C-terminal 6 x His fusion tag. From the latter we obtained reasonable amounts of soluble protein. Circular dichroism analysis showed STCI as a well structured protein with 52% of alpha-helical content. Mass spectroscopy analysis of the recombinant protein allowed to assign the five intramolecular disulfide bridges as well as the dimerization Cys202, thereby confirming the conservation of the disulfide pattern previously described for fish STCI. SAXS data also clearly demonstrated that STCI adopts a dimeric, slightly elongated structure in solution. Conclusion: Our data reveal the first low resolution, structural information for human STCI. Theoretical predictions and circular dichroism spectroscopy both suggested that STCI has a high content of alpha-helices and SAXS experiments revealed that STCI is a dimer of slightly elongated shape in solution. The dimerization was confirmed by mass spectrometry as was the highly conserved disulfide pattern, which is identical to that found in fish STCI

A comprehensive review on the corrosion pathways of titanium dental implants and their biological adverse effects

The main aim of this work was to perform a comprehensive review of findings reported by previous studies on the corrosion of titanium dental implants and consequent clinical detrimental effects to the patients. Most studies were performed by in vitro electrochemical tests and complemented with microscopic techniques to evaluate the corrosion behavior of the protective passive oxide film layer, namely TiO2. Results revealed that bacterial accumulation, dietary, inflammation, infection, and therapeutic solutions decrease the pH of the oral environment leading to the corrosion of titanium. Some therapeutic products used as mouthwash negatively affect the corrosion behavior of the titanium oxide film and promote changes on the implant surface. In addition, toothpaste and bleaching agents, can amplify the chemical reactivity of titanium since fluor ions interacting with the titanium oxide film. Furthermore, the number of in vivo studies is limited although corrosion signs have been found in retrieved implants. Histological evaluation revealed titanium macro- and micro-scale particles on the peri-implant tissues. As a consequence, progressive damage of the dental implants and the evolution of inflammatory reactions depend on the size, chemical composition, and concentration of submicron- and nanoparticles in the surrounding tissues and internalized by the cells. In fact, the damage of the implant surfaces results in the loss of material that compromises the implant surfaces, implant-abutment connections, and the interaction with soft tissues. The corrosion can be an initial trigger point for the development of biological or mechanical failures in dental implants.This study was supported by FCT-Portugal (UID/EEA/04436/2013, NORTE-01-0145-FEDER- 000018– HAMaBICo, POCI-01-0145-FEDER-031035_LaserMULTICER) and CNPq-Brazil (CNPq/UNIVERSAL/421229/2018-7

Tooth-derived matrix granules for enhanced bone healing: chemical composition, morphological aspects, and clinical outcomes

Bone grafting has increasingly been used in surgical procedures for enhanced bone augmentation. Tooth-derived graft material has received considerable attention due to its chemical composition and autogenous source that can improve bone tissue healing. The main aim of this study was to provide a short and comprehensive review on the chemical composition, morphological aspects, and clinical outcomes of bone grafting using tooth-derived matrix granules. Dentin tissue has a chemical composition similar to that on bone tissues regarding the presence of hydroxyapatite, type I collagen, and different growth factors. Dentin-matrix granules are often processed at well-controlled size ranging from approximately 300 up to 1300 µm, while maintaining porosity and organic content. In addition, a dense collagen fiber network is still present after the milling and chemical treatment of dentin granules. Thus, dentin-matrix granules can improve the bone healing process considering their chemical composition, porous structure, and adequate size. However, further in vivo and in vitro studies should be performed taking into consideration different demineralization procedures, remnant organic content, porosity, and granule size.This study was supported by the Portuguse Foundation for Science and Technology (FCT) (POCI-01-0145-FEDER-031035_LaserMULTICER), SFRH/BPD/123769/ 2016, and CNPq-Brazil (CNPq/UNIVERSAL/421229/2018-7)

Microscopic inspection of the adhesive interface of composite onlays after cementation on low loading: an in vitro study

Purpose: This study aimed to assess the layer thickness and microstructure of traditional resin-matrix cements and flowable resin-matrix composites at dentin and enamel to composite onlay interfaces after cementation on low loading magnitude. Materials and Methods: Twenty teeth were prepared and conditioned with an adhesive system for restoration with resin-matrix composite onlays manufactured by CAD-CAM. On cementation, tooth-to-onlay assemblies were distributed into four groups, including two traditional resin-matrix cements (groups M and B), one flowable resin-matrix composite (group G), and one thermally induced flowable composite (group V). After the cementation procedure, assemblies were cross-sectioned for inspection by optical microscopy at different magnification up to ×1000. Results: The layer thickness of resin-matrix cementation showed the highest mean values at around 405 µm for a traditional resin-matrix cement (group B). The thermally induced flowable resin-matrix composites showed the lowest layer thickness values. The resin-matrix layer thickness revealed statistical differences between traditional resin cement (groups M and B) and flowable resin-matrix composites (groups V and G) (p < 0.05). However, the groups of flowable resin-matrix composites did not reveal statistical differences (p < 0.05). The thickness of the adhesive system layer at around 7 µm and 12 µm was lower at the interfaces with flowable resin-matrix composites when compared to the adhesive layer at resin-matrix cements, which ranged from 12 µm up to 40 µm. Conclusions: The flowable resin-matrix composites showed adequate flowing even though the loading on cementation was performed at low magnitude. Nevertheless, significant variation in thickness of the cementation layer was noticed for flowable resin-matrix composites and traditional resin-matrix cements that can occur in chair-side procedures due to the clinical sensitivity and differences in rheological properties of the materials.info:eu-repo/semantics/publishedVersio

Total soluble solids from banana: evaluation and optimization of extraction parameters

Banana, an important component in the diet of the global population, is one of the most consumed fruits in the world. This fruit is also very favorable to industry processes (e.g., fermented beverages) due to its rich content on soluble solids and minerals, with low acidity. The main objective of this work was to evaluate the influence of factors such as banana weight and extraction time during a hot aqueous extraction process on the total soluble solids content of banana. The extract is to be used by the food and beverage industries. The experiments were performed with 105 mL of water, considering the moisture of the ripe banana (65%). Total sugar concentrations were obtained in a beer analyzer and the result expressed in degrees Plato (°P, which is the weight of the extract or the sugar equivalent in 100 g solution at 20 °C), aiming at facilitating the use of these results by the beverage industries. After previous studies of characterization of the fruit and of ripening performance, a 22 full-factorial star design was carried out, and a model was developed to describe the behavior of the dependent variable (total soluble solids) as a function of the factors (banana weight and extraction time), indicating as optimum conditions for extraction 38.5 g of banana at 39.7 min.Gabinete de Relações Internacionais da Ciência e do Ensino Superior (GRICES), Portugal.Fundação de Amparo à Pesquisa do Estado de São Paulo (Fapesp), Brasil.Coordenação para Aperfeiçoamento do Ensino Superior (CAPES), Brasil.Fundação para a Ciência e Tecnologia (FCT), Portugal

A preliminary analysis of the wear pathways of sliding contacts on temporomandibular joint total joint replacement prostheses

In the last years, several materials and design have been assessed in an attempt to improve the mechanical performance of temporomandibular joint total joint replacement (TMJ TJR) prostheses. However, the wear of the TMJ TJR condyle to the polymer-based fossa component during loading and sliding movements. That promotes the release of debris and risks of toxicity to the surrounding tissues. The purpose of this study was to perform a narrative literature review on the wear of TMJ TJR sliding contacts and potential toxicity of metallic debris to the patients. Previous studies reported a significant deterioration of the sliding contact surfaces of TMJ TJR prostheses. Material loss as a result of wear can cause a TMJ TJR condyle/fossa mismatch and the modification of the contact pressure and chewing loading. As a further consequence of wear, metal particles are released to the surrounding tissues with a high risk of local tissue and systemic toxicity through the bloodstream. The presence of particles induces the stimulation of inflammatory reactions depending on the concentration and size of debris. Thus, CoCr-based condyle release metallic ions and sub-micron particles that can be engulfed by macrophages or internalized by other tissue cells. The wear and material loss of TMJ TJR could be decreased by design optimization and novel materials with low friction and contact pressure. That consequently decrease the amount of metallic ions and particles to the surrounding tissues, preventing peri-prosthetic inflammatory reactions.This study was supported by FCT-Portugal (UID/EEA/04436/2013, NORTE-01-0145- FEDER-000018—HAMaBICo, POCI-01-0145-FEDER-031035_LaserMULTICER), SFRH/BPD/123769/ 2016 and CNPq-Brazil (CNPq/UNIVERSAL/421229/2018-7)