Increased peri-ductal collagen micro-organization may contribute to raised mammographic density

BACKGROUND: High mammographic density is a therapeutically modifiable risk factor for breast cancer. Although mammographic density is correlated with the relative abundance of collagen-rich fibroglandular tissue, the causative mechanisms, associated structural remodelling and mechanical consequences remain poorly defined. In this study we have developed a new collaborative bedside-to-bench workflow to determine the relationship between mammographic density, collagen abundance and alignment, tissue stiffness and the expression of extracellular matrix organising proteins. METHODS: Mammographic density was assessed in 22 post-menopausal women (aged 54–66 y). A radiologist and a pathologist identified and excised regions of elevated non-cancerous X-ray density prior to laboratory characterization. Collagen abundance was determined by both Masson’s trichrome and Picrosirius red staining (which enhances collagen birefringence when viewed under polarised light). The structural specificity of these collagen visualisation methods was determined by comparing the relative birefringence and ultrastructure (visualised by atomic force microscopy) of unaligned collagen I fibrils in reconstituted gels with the highly aligned collagen fibrils in rat tail tendon. Localised collagen fibril organisation and stiffness was also evaluated in tissue sections by atomic force microscopy/spectroscopy and the abundance of key extracellular proteins was assessed using mass spectrometry. RESULTS: Mammographic density was positively correlated with the abundance of aligned periductal fibrils rather than with the abundance of amorphous collagen. Compared with matched tissue resected from the breasts of low mammographic density patients, the highly birefringent tissue in mammographically dense breasts was both significantly stiffer and characterised by large (>80 μm long) fibrillar collagen bundles. Subsequent proteomic analyses not only confirmed the absence of collagen fibrosis in high mammographic density tissue, but additionally identified the up-regulation of periostin and collagen XVI (regulators of collagen fibril structure and architecture) as potential mediators of localised mechanical stiffness. CONCLUSIONS: These preliminary data suggest that remodelling, and hence stiffening, of the existing stromal collagen microarchitecture promotes high mammographic density within the breast. In turn, this aberrant mechanical environment may trigger neoplasia-associated mechanotransduction pathways within the epithelial cell population. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13058-015-0664-2) contains supplementary material, which is available to authorized users

Percepção de professores de odontologia no processo de ensino-aprendizagem Perceptions of dentistry teachers in the teaching and learning process

Há necessidade de se pesquisar a formação didático-pedagógica do professor universitário e a qualidade da educação superior em decorrência das demandas da sociedade em mudança e da implantação das diretrizes curriculares nacionais. Analisa-se a percepção de docentes do curso de graduação em odontologia da Universidade Estadual de Londrina a respeito do papel do professor no processo ensino-aprendizagem. Adotou-se a abordagem qualitativa e a entrevista semiestruturada para a geração de dados. O estudo revelou que o professor tem um papel fundamental no processo de ensino-aprendizagem, sendo considerado responsável pela transmissão do conhecimento. As estratégias de ensino-aprendizagem se baseiam em exposições orais. Grande parte dos professores só teve formação didático-pedagógica nos cursos de mestrado e/ou doutorado, que não capacitam suficientemente os docentes para o exercício do magistério. A maioria dos professores não possui formação específica em educação. Conclui-se que há uma necessidade de rever tanto a formação quanto a atualização didático-pedagógica do professor universitário para que se possa buscar uma formação generalista, humanista, crítica e reflexiva do estudante.<br>The didactic-pedagogical training of the university professor and of the quality of higher education must be revised due to the demands of the dynamic society and to the implementation of national curricular guidelines. Within this context, it was analyzed the perceptions of dentistry undergraduate of Universidade Estadual de Londrina teachers about the role of the teacher in the teaching and learning process. A qualitative research was carried out and data were collected through semi-structured interviews. Results showed that the teacher plays an essential role in the teaching and learning process, being the sole provider of knowledge. Teaching and learning strategies are based on oral transmission. Most part of the teachers got their didactic-pedagogical education from postgraduate Courses (Master's and/or PhD), that do not qualify teachers adequately for their teaching career. The teachers are not formally prepared for their teaching careers. In conclusion, findings from this study must be revised both regarding the training and the didactic-pedagogical upgrading in search of a general, humanist, critical and reflexive formation of the student

Global Distribution, Composition and Abundance of Marine Litter

Marine debris is commonly observed everywhere in the oceans. Litter enters the seas from both land-based sources, from ships and other installations at sea, from point and diffuse sources, and can travel long distances before being stranded. Plastics typically constitute the most important part of marine litter sometimes accounting for up to 100 % of floating litter. On beaches, most studies have demonstrated densities in the 1 item m−2 range except for very high concentrations because of local conditions, after typhoons or flooding events. Floating marine debris ranges from 0 to beyond 600 items km−2. On the sea bed, the abundance of plastic debris is very dependent on location, with densities ranging from 0 to >7700 items km−2, mainly in coastal areas. Recent studies have demonstrated that pollution of microplastics, particles <5 mm, has spread at the surface of oceans, in the water column and in sediments, even in the deep sea. Concentrations at the water surface ranged from thousands to hundred thousands of particles km−2. Fluxes vary widely with factors such as proximity of urban activities, shore and coastal uses, wind and ocean currents. These enable the presence of accumulation areas in oceanic convergence zones and on the seafloor, notably in coastal canyons. Temporal trends are not clear with evidences for increases, decreases or without changes, depending on locations and environmental conditions. In terms of distribution and quantities, proper global estimations based on standardized approaches are still needed before considering efficient management and reduction measures