High Extracellular Ca2+ Stimulates Ca2+-Activated Cl− Currents in Frog Parathyroid Cells through the Mediation of Arachidonic Acid Cascade

Elevation of extracellular Ca2+ concentration induces intracellular Ca2+ signaling in parathyroid cells. The response is due to stimulation of the phospholipase C/Ca2+ pathways, but the direct mechanism responsible for the rise of intracellular Ca2+ concentration has remained elusive. Here, we describe the electrophysiological property associated with intracellular Ca2+ signaling in frog parathyroid cells and show that Ca2+-activated Cl− channels are activated by intracellular Ca2+ increase through an inositol 1,4,5-trisphophate (IP3)-independent pathway. High extracellular Ca2+ induced an outwardly-rectifying conductance in a dose-dependent manner (EC50∼6 mM). The conductance was composed of an instantaneous time-independent component and a slowly activating time-dependent component and displayed a deactivating inward tail current. Extracellular Ca2+-induced and Ca2+ dialysis-induced currents reversed at the equilibrium potential of Cl− and were inhibited by niflumic acid (a specific blocker of Ca2+-activated Cl− channel). Gramicidin-perforated whole-cell recording displayed the shift of the reversal potential in extracellular Ca2+-induced current, suggesting the change of intracellular Cl− concentration in a few minutes. Extracellular Ca2+-induced currents displayed a moderate dependency on guanosine triphosphate (GTP). All blockers for phospholipase C, diacylglycerol (DAG) lipase, monoacylglycerol (MAG) lipase and lipoxygenase inhibited extracellular Ca2+-induced current. IP3 dialysis failed to induce conductance increase, but 2-arachidonoylglycerol (2-AG), arachidonic acid and 12S-hydroperoxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12(S)-HPETE) dialysis increased the conductance identical to extracellular Ca2+-induced conductance. These results indicate that high extracellular Ca2+ raises intracellular Ca2+ concentration through the DAG lipase/lipoxygenase pathway, resulting in the activation of Cl− conductance

Biochar: pyrogenic carbon for agricultural use: a critical review.

O biocarvão (biomassa carbonizada para uso agrícola) tem sido usado como condicionador do solo em todo o mundo, e essa tecnologia é de especial interesse para o Brasil, uma vez que tanto a ?inspiração?, que veio das Terras Pretas de Índios da Amazônia, como o fato de o Brasil ser o maior produtor mundial de carvão vegetal, com a geração de importante quantidade de resíduos na forma de finos de carvão e diversas biomassas residuais, principalmente da agroindústria, como bagaço de cana, resíduos das indústrias de madeira, papel e celulose, biocombustíveis, lodo de esgoto etc. Na última década, diversos estudos com biocarvão têm sido realizados e atualmente uma vasta literatura e excelentes revisões estão disponíveis. Objetivou-se aqui não fazer uma revisão bibliográfica exaustiva, mas sim uma revisão crítica para apontar alguns destaques na pesquisa sobre biochar. Para isso, foram selecionados alguns temaschave considerados críticos e relevantes e fez-se um ?condensado? da literatura pertinente, mais para orientar as pesquisas e tendências do que um mero olhar para o passad

The assimilation of western medicine into a semi-nomadic healthcare system: A case study of the indigenous Aeta Magbukún, Philippines

The Aeta Magbukún are a genetically and culturally distinct group of Indigenous people living in an isolated mountain forest in the municipality of Mariveles, in the province of Bataan, Philippines. This research aims to document some healthcare related information of the people, inform future decisions regarding maximising benefits of modern conveniences, and minimise negative consequences on their culture and health. Using an ethnographic approach, data were collated from a community health survey in combination with field notes from three of the co-authors while living with the Aetas. Despite major implications from rapid ecological and cultural changes, traditional ethnomedical systems continue to be revered as an essential healing practice, although they are increasingly used in conjunction with Western medicines and healthcare. At the Aeta village level, the changing socio-political influence among the kagun (traditional healer), the NGOs, and the Municipal Council in terms of healthcare provision is pivotal, as the kagun has chosen to integrate the Western medicine and healthcare services into their traditional healthcare system, without simply rejecting them. In turn, Western-style healthcare interventions have the potential to be carefully managed to integrate traditional Aeta Magbukún socio-political structures, healthcare, and cultural continuity. The cumulative influence of numerous other novel aspects to Aeta life (e.g., permanent housing, a highway through the village, literacy, cash economies, energy-dense foods, communication/entertainment devices, etc.) will place additional pressure on the traditional ethnomedical healthcare system. However, enabling the continuity of access to appropriate healthcare knowledge (both the transfer of knowledge from Western medicine to the Aeta Magbukún, and vice versa) can assist many cultures through the inherent stresses of increasingly rapid acculturation and development