Usually, if percutaneous absorption tests are conducted in accordance with OECD Guideline 428, in vitro determination is accepted by mainly regulatory agencies. In this paper, we focus on the lack of ...comparability of the results regarding the permeation parameter/flow rate, although it is widely discussed in the literature. This work sought to evaluate the absorption of caffeine using Franz-type diffusion cell with porcine ear skin samples, varying the storage duration and the way to handle them. Metrological tools were used for caffeine quantification such as certified reference material candidate, calibrated instruments, and validated methodology. Our results corroborate with the recommendation that membranes should be freshly prepared or frozen for short periods. Samples frozen for approximately one year should not be used because they present high cutaneous absorption. The results obtained for the absorption rate (J) are comparable to the results obtained by previous studies using similar experimental conditions. The evidence of the barrier characteristic promoted by the stratum corneum and the effect promoted by the storage time is shown through J = 6.25 ± 0.48 μg/cm2/h. We demonstrated the importance of metrological tools to guarantee reproducibility and comparability of the results between different laboratories.
•Metrology is the science which provide important tools for decision making.•Metrological tools are certified reference material, calibrated instruments and validated methodology.•The method is reliable and reproducible in terms of cutaneous absorption, when performed carefully using metrological tools.•This work aims to raise the critical sense regarding the demonstration of reproducibility among scientific works.
In embryogenesis, coronary blood vessels are formed by vasculogenesis from epicardium-derived progenitors. Subsequently, growing or regenerating myocardium increases its vasculature by angiogenesis, ...forming new vessels from the pre-existing ones. Recently, cell therapies for myocardium ischemia that used different protocols have given promising results, using either extra-cardiac blood vessel cell progenitors or stimulating the cardiac angiogenesis. We have questioned whether cardiomyocytes could sustain both vasculogenesis and angiogenesis. We used a 3D culture model of tissue-like spheroids in co-cultures of cardiomyocytes supplemented either with endothelial cells or with bone marrow-derived mesenchymal stroma cells. Murine foetal cardiomyocytes introduced into non-adherent U-wells formed 3D contractile structures. They were coupled by gap junctions. Cardiomyocytes segregated inside the 3D structure into clumps separated by connective tissue septa, rich in fibronectin. Three vascular endothelial growth factor isoforms were produced (VEGF 120, 164 and 188). When co-cultured with human umbilical cord endothelial cells, vascular structures were produced in fibronectin-rich external layer and in radial septa, followed by angiogenic sprouting into the cardiomyocyte microtissue. Presence of vascular structures led to the maintenance of long-term survival and contractile capacity of cardiac microtissues. Conversely, bone marrow mesenchymal cells formed isolated cell aggregates, which progressively expressed the endothelial markers von Willebrand's antigen and CD31. They proceeded to typical vasculogenesis forming new blood vessels organised in radial pattern. Our results indicate that the in vitro 3D model of cardiomyocyte spheroids provides the two basic elements for formation of new blood vessels: fibronectin and VEGF. Within the myocardial environment, endothelial and mesenchymal cells can proceed to formation of new blood vessels either through angiogenesis or vasculogenesis, respectively.
Nanometrology - challenges for health regulation Damasceno, Jailton Carreteiro; Ribeiro, Ana R.; Balottin, Luciene B. L. ...
Vigilância Sanitária em Debate,
11/2013, Letnik:
1, Številka:
4
Journal Article
Odprti dostop
The relationship between metrology, nanotechnology and nanoscience and sanitary regulation is discussed from the point of view of its importance and the interrelationship between the themes for the ...development of products and services involving nanotech-nology. The discussion involves the main techniques for measuring dimensional, chemical and biological properties of materials, and presents some of the challenges for the future. Issues such as processes of standardization and regulation in Europe, U.S. and Brazil are also addressed, providing an overview of how these processes are related to sanitary regulation.
Nanometrologia – desafios para a regulação sanitária Damasceno, Jailton Carreteiro; Ribeiro, Ana R.; Balottin, Luciene B. L. ...
Vigilância Sanitária em Debate,
11/2013, Letnik:
1, Številka:
4
Journal Article
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