Three new cytotoxic cyclopeptides belonging to iturin class have been isolated from marine bacterium Bacillus sp. These three compounds have the cytotoxic activities. Their structures were determined based on chemical analysis and all kinds of spectroscopic techniques.
Purpose We present a systematic review of the recent literatures regarding the arthroscopic and open technique in fragment fixation for osteochondritis dissecans (OCD) of the humeral capitellum and an analysis of the subjective and objective outcomes between these two procedures. Methods PubMed and EMBASE were reviewed for suitable articles relating to fragment fixation for OCD, both open and arthroscopic. We included all studies reporting on the clinical outcomes of these two procedures that were published in the English language. Data extracted from each study included level of evidence, number of patients, surgical techniques, length of follow-up, clinical outcome measures including outcome scores, range of motion (ROM), return to sports, osseous union and complications. We analyzed each study to determine the primary outcome measurement.
Astrocytes play critical roles in neural circuit formation and function. Recent studies have revealed several secreted and contact-mediated signals from astrocytes which are essential for neurite outgrowth and synapse formation. However, the mechanisms underlying the regulation of dendritic branching by astrocytes remain elusive. Phospholipase D1 (PLD1), which catalyzes the hydrolysis of phosphatidylcholine (PC) to generate phosphatidic acid (PA) and choline, has been implicated in the regulation of neurite outgrowth. Here we showed that knockdown of PLD1 selectively in astrocytes reduced dendritic branching of neurons in neuron-glia mixed culture. Further studies from sandwich-like cocultures and astrocyte conditioned medium suggested that astrocyte PLD1 regulated dendritic branching through secreted signals. We later demonstrated that PA was the key mediator for astrocyte PLD1 to regulate dendritic branching. Moreover, PA itself was sufficient to promote dendritic branching of neurons. Lastly, we showed that PA could activate protein kinase A (PKA) in neurons and promote dendritic branching through PKA signaling. Taken together, our results demonstrate that astrocyte PLD1 and its lipid product PA are essential regulators of dendritic branching in neurons. These results may provide new insight into mechanisms underlying how astrocytes regulate dendrite growth of neurons.
Homogeneous PZT/Ag composites and compositionally graded PZT/Ag actuators were fabricated and evaluated in this work. The piezoelectric constant decreases gradually and the dielectric constant increases significantly with an increase in silver content of the PZT/Ag composites. The fracture toughness of the PZT/Ag composites is enhanced with addition of the silver powders. Based on the corresponding piezoelectric properties of the monolithic PZT/Ag composites, a graded material with symmetric silver compositions from 1 to 10 vol % then inversely to 1 vol % was successfully fabricated by conventional sintering. This study indicates that the PZT/Ag composites can be used to acting as bimorph actuator materials.
Lead-free piezoelectric ceramics have received more attention due to the environmental protection of the earth. Niobate ceramics such as NaNbO3 and KNbO3 have been studied as promising Pb-free piezoelectric ceramics, but their sintering densification is fairly difficult. In the present study, Spark Plasma Sintering (SPS) was applied to the sintering of Na0.5K0.5NbO3 ceramics, whose powder was synthesized by the conventional oxide mixing method. No loss of sodium and potassium were found in the SPS sintering process, by which the density of the K0.5Na0.5NbO3 solid solution ceramics was raised to 4.21g/cm3 (>93% of the theoretical density) at temperatures as low as 920°C. The crystal phase of the Na0.5K0.5NbO3 is an orthorhombic structure. The piezoelectric parameter (d33) of the K0.5Na0.5NbO3 ceramics reached 49 pC/N.
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