Melatonin reduces the severity of experimental amoebiasis

<p>Abstract</p> <p>Background</p> <p>Melatonin has immunomodulatory effects but very little is known about its influence in protozoan infections, such as <it>Entamoeba histolytica</it>, which causes amoebiasis, a disease with significant morbidity and mortality. In this study, we evaluated the effects of exogenous melatonin interference in experimental amoebiasis and on interactions between human blood cells and <it>E. histolytica </it>trophozoites.</p> <p>Methods</p> <p>The effect of melatonin was investigated in models of experimental amoebiasis in hamsters and rats by evaluating the area of necrosis induced by <it>E. histolytica</it>. The activity of melatonin on the interactions between leukocytes and amoebae was determined by examining leukophagocytosis. For <it>in vitro </it>tests, polymorphonuclear and mononuclear human blood leucocytes were incubated with <it>E. histolytica </it>trophozoites.</p> <p>Results</p> <p>The areas of amoebic necrosis were significantly reduced in animals treated with melatonin. Melatonin treatment increased leukophagocytosis but was associated with a greater number of dead amoebae.</p> <p>Conclusions</p> <p>These results suggest that melatonin may play a beneficial role in the control of amoebic lesions, raising the possibility that this drug may be used as an adjuvant in anti-amoebic therapy.</p

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Effect of temperature on bond behavior of externally bonded FRP laminates with mechanical end anchorage

The use of mechanical anchorage systems can delay or avoid premature failure of reinforced concrete (RC) structures with externally-bonded fiber-reinforced polymer (EB-FRP) laminates. This work reports the results of an experimental program aimed at studying the bond behavior of a metallic anchorage plate, typically used for pre-stressed EB-FRP systems. The overall experimental program comprised 17 concrete prisms with carbon fiber reinforced polymer (CFRP) laminates externally bonded to the concrete with mechanical anchorage at the end and where different levels of normal stress were applied. Direct shear tests were carried out using two configurations: (i) the steady-state tests, where the laminate was pulled out from the block with increasing force and constant temperature (20 ºC, 60 ºC and 80 ºC); (ii) and the transient tests, where the laminate was pulled out with constant force (0.36%, 0.45% and 0.54% of strain) and the temperature was gradually increased. Experimental results showed that the ultimate capacity of the mechanical anchorage can decrease by 44-59% depending on the temperature and level of normal stress.This work was supported by FEDER funds through the Operational Program for Competitiveness Factors – COMPETE and National Funds through FCT (Portuguese Foundation for Science and Technology) under the project FRPLongDur POCI-01-0145- FEDER-016900 (FCT PTDC/ECM-EST/1282/2014) and partly financed by the project POCI544 01-0145-FEDER-007633. The first author wishes also to acknowledge the grant SFRH/BD/98309/2013 provided by FCT. The second author acknowledges the Spanish Government (Ministerio de Educación, Cultura y Deporte) for the grant José Castillejo ref. CAS16/00288. Finally, the authors also like to thank all the companies that have been involved supporting and contributing for the development of this study, mainly: the S&P Clever Reinforcement Ibérica Lda. company for providing the laminates, the epoxy adhesive and metallic anchorage plates; the Hilti Portugal-Produtos e Serviços, Lda. company for providing the chemical bond agent to fix the anchor bolts; and the Tecnipor-Gomes & Taveira Lda company for producing the concrete blocks

Super-poissonian photon statistics and correlations between pump and probe fields in Electromagnetically Induced Transparency

We have measured the photon statistics of pump and probe beams after interaction with Rb atoms in a situation of Electromagnetically Induced Transparency. Both fields present super-poissonian statistics and their intensities become correlated, in good qualitative agreement with theoretical predictions in which both fields are treated quantum-mechanically. The intensity correlations measured are a first step towards the observation of entanglement between the fields.Comment: 4 pages, two-column, 4 figures, first submitted to PRL on Aug. 6, 200