Two- and three-dimensional piezoelectric scaffolds for bone tissue engineering.

The incidence of bone disorders worldwide is increasing. For this reason, new and more effective strategies for bone repair are needed. The most common strategy used for cell regeneration relies in biochemical stimulation while biophysical stimulation using mechanical, and electrical cues is a promising, however, still under-investigated field. This work reports on the development of piezoelectric 2D and 3D porous scaffolds for bone tissue regeneration strategies. While the porous scaffolds mimic the bone's structure, the piezoelectric activity of the scaffolds mimics the bone mechano-electric microenvironment. The piezoelectric activity is related to the electroactive ß-phase of poly(vinylidene fluoride) (PVDF) in the scaffolds and was dynamically stimulated by cell culture in a custom-made mechanical bioreactor. These two factors combined provide an effective biomimetic environment for the proliferation of preosteoblasts. The electromechanically-responsive scaffolds are found to promote the enhancement of proliferation rate of MC3T3-E1 osteoblastic cells in about 20 % as well as an improved adhesion and proliferation over the materials, mainly when dynamically stimulated. These results prove that local piezoelectric effect, as the one existing in bone tissue, allows effective cell proliferation, which could be further translated in more efficient strategies for bone tissue regeneration.

Acute endocrine and nutritional co-regulation of the hepatic omy-miRNA-122b and the lipogenic gene fas in rainbow trout, Oncorhynchus mykiss.

Hepatic lipogenesis represents a crucial part of intermediary metabolism and is acutely regulated by endocrine factors and nutrients. The liver-specific and highly abundant microRNA-122 has emerged as a powerful regulator of lipogenesis in higher vertebrates, but little is known about its endocrine and nutritional regulation. In this study, we investigated the hypothesis that insulin regulates hepatic expression of omy-miRNA-122 isomiRNAs (omy-miRNA-122a and omy-miRNA-122b) by using in vivo and in vitro approaches. Since the hepatic insulin pathway and lipogenesis are acutely regulated by dietary macronutrient ratios in rainbow trout, we further investigated the effect of single meals with altered carbohydrate/protein ratio and lipid/protein ratio on the postprandial expression of omy-miRNA-122 isomiRNAs. Insulin acutely induced omy-miRNA-122b expression in vivo and in vitro. Conversely, a single meal with increased lipid to protein ratio acutely decreased expression of both omy-miRNA-122 isomiRNAs. As a direct proof of lipogenic effects of miRNA-122 is currently still lacking in fish, we investigated the correlated expression between omy-miRNA-122 isomiRNAs and the rate-limiting lipogenic gene fas, an indirect target gene of miRNA-122 in mammals. Our results show a significant positive correlation of omy-miRNA-122b and fas, consistent with a potential evolutionary conserved role for miRNA-122 in the regulation of postprandial lipogenesis in trout.

Avaliaçäo dos teores de dióxido de enxofre e da qualidade microbiológica de cogumelos em conserva / Evaluation of sulphur dioxide and microbiological quality of conserved mushrooms

Cogumelos säo alimentos bem apreciados e seu consumo tem aumentado substancialmente. Para estender a vida de prateleira a adiçäo de dióxido de enxofre ou sais de sulfitos que o produzam é usada por atuar como branqueador e conservador. A Resoluçäo n. 04/88 do Conselho Nacional de Saúde (CNS), do Ministério da Saúde permite a adiçäo de no máximo de 200 bactérias coliformes fecais por g säo requeridos na Resoluçäo 12/78 da Comissäo Nacional de Normas e Padröes para Alimentos do Ministério da Saúde. Com o propósito de avaliar os teores de sulfito, pH, e a qualidade microbiológica de cogumelos em conserva foram analisadas 108 amostras sendo 25 industrializadas, 36 provenientes de produtores da regiäo de Mogi das Cruzes e 47 lotes importados da China. O método utilizado para análise de dióxido de enxofre foi de Monier-Williams, cujo limite de detecçäo foi de 0,15 mg/kg e a recuperaçäo de 91 por cento. Os teores de dióxido de enxofre variaram de näo detectado a 1052 mg/kg sendo que 68 por centos das amostras industrializadas, 61 por cento das provenientes de produtores e 23 por cento dos lotes importados encontraram-se acima do limite permitido. O valor de pH variou de 2,60 a 5,35. Todas as amostras de cogumelos encontraram-se em acordo dos padröes microbiológicos. Os altos níveis de dióxido de enxofre encontrados evidenciam uma preocupaçäo de saúde pública. Os resultados microbiológicos sugerem que níveis baixos de dióxidos de enxofre säo suficientes na conservaçäo do produto, näo justificando as doses encontradas.(AU)

Mushrooms are well-liked food whose consumption has increased substantially. To extend its shelf life the addition of sulphur dioxide is necessary as it acts as a bleaching and preservative agent. Resolution 04/88 from the Brazilian Health Ministry National Commission of Rules and Standards for Foods allows the maximum of 50 mg/kg of sulphur dioxide. The absence of Salmonella in 25 gram samples and a maximum of 200 fecal coliforms per gram is also required in the Resolution 12/78 from the Brazilian Health Ministry National Commission of Rules and Standards for Foods. A total of 108 samples, 25 from stores and markets, 36 from mushroom producers and 47 imported lots from China were analysed for sulphite and pH levels, and were submitted to microbiological examination. The Monier-William method was used and its detection limit was 0.15 mg/kg and recovery of 91%. Levels of suphur dioxide varied from not detected to 1052 mg/kg. The samples showed levels above those permitted, from retailers, producers and imported lots, at 68, 61 and 23%, respectively. The pH levels varied from 2.60 to 5.35. All mushroom samples were acceptable in accordance with microbiological standards. The high levels of sulphur dioxide found are of concern to public health. The microbiological results show that low levels of sulphur dioxide are sufficient to preserve this product, not justifying the levels found. (AU)