1,505 research outputs found
Heme modulates smooth muscle cell proliferation and migration via NADPH oxidase: A counter-regulatory role for heme oxygenase system
AbstractAccumulation of vascular smooth muscle cells (VSMC) in response to inflammatory stimuli is a key event in atherogenesis, which commonly occurs in sinuous vessels with turbulent blood flow what leads to hemolysis and consequent free heme accumulation, a known pro-oxidant and pro-inflammatory molecule.In this work, we investigated the effects of free heme on VSMC, and the molecular mechanisms underlying this process.Free heme induces a concentration-dependent migration and proliferation of VSMC which depends on the production of reactive oxygen species (ROS) derived from NADPH oxidase (NADPHox) activity. Additionally, heme activates redox-sensitive proliferation-related signaling routes, such as Mitogen Activated Protein Kinase (MAPK) and NF-ÎșB, and induces Heme Oxygenase-1 (HO-1) expression. NADPHox-dependent proliferative effect of heme seems to be endogenously modulated by HO since the pretreatment of VSMC with HO inhibitors potentiates heme-induced proliferation and, in parallel, increases ROS production. These effects were no longer observed in the presence of heme metabolites, carbon monoxide and biliverdin.The data indicate that VSMC proliferation induced by heme is endogenously modulated by a critical counter-regulatory crosstalk between NADPHox and HO systems
Induction of a gloverin-like antimicrobial polypeptide in the sugarcane borer Diatraea saccharalis challenged by septic injury
Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) is an important pest for Brazilian sugarcane. In the present study, we detected two distinct spots in hemolymph from septic injured larvae (HDs1 and HDs2), which are separated by 2DE gel electrophoresis. Both spots were subjected to in-gel tryptic digestion and MALDI-TOF/TOF analysis, which revealed the sequence VFGTLGSDDSGLFGK present in both HDs1 and HDs2. This sequence had homology and 80% identity with specific Lepidoptera antimicrobial peptides called gloverins. Analyses using the ImageMaster 2D software showed pI 8.94 of the HDs1 spot, which is similar to that described to Hyalophora gloveri gloverin (pI 8.5). Moreover, the 14-kDa molecular mass of the spot HDs1 is compatible to that of gloverins isolated from the hemolymph of Trichoplusia ni, Helicoverpa armigera and H. gloveri. Antimicrobial assays with partially purified fractions containing the HDs1 and HDs2 polypeptides demonstrated activity against Escherichia coli. This is the first report of antimicrobial polypeptides in D. saccharalis, and the identification of these peptides may help in the generation of new strategies to control this pest
Efeito de espĂ©cies vegetais em bordadura em cebola sobre a densidade populacional de tripes e sirfĂdeos predadores.
Analisou-se a relação entre o efeito do plantio de diferentes espĂ©cies vegetais, em bordadura, na cultura da cebola, Allium cepa L, na incidĂȘncia de Thrips tabaci Lind. e sirfĂdeos predadores, Toxomerus spp. O experimento foi conduzido na Epagri, EE de Ituporanga, de agosto a dezembro de 1998. Os tratamentos foram cebola em monocultivo; cebola + trigo mourisco (Fagopyrum esculentum Moench); cebola + nabo forrageiro (Raphanus sativus L. var. oleiferus Metzg.); cebola + cenoura (Daucus carota L., cv. Nantes e cv. BrasĂlia); cebola + milho (Zea mays L.); cebola + rĂșcula
(Eruca sativa L.) + vegetação espontĂąnea. O plantio de diferentes espĂ©cies vegetais em bordadura nĂŁo provocou diferenças significativas na incidĂȘncia de tripes e sirfĂdeos predadores. A produtividade comercial de bulbos de cebola foi similar em sistema de monocultivo e diversificado, sugerindo ser possĂvel adotar tais sistemas sem perdas em rendimento
Root dentinal microcracks: a post-extraction experimental phenomenon?
Aim
To investigate the prevalence, location and pattern of preâexisting microcracks in nonâendodontically treated teeth from fresh cadavers. Microâcomputed tomography (microâCT) technology was used as the analytical tool enabling full screening of the root dentine with the teeth retained in their original alveolar socket.
Methodology
As a pilot study and to validate the present method, a series of 4 highâresolution scans were performed on one boneâblock specimen with teeth collected postâmortem: (i) entire boneâblock including the teeth, (ii) second molar tooth extracted atraumatically from the boneâblock, (iii) extracted tooth dehydrated to induce dentinal defects and (iv) entire boneâblock following reinsertion of the extracted tooth into its matching alveolar socket. In the main study, fortyâtwo dentoalveolar maxillary and mandibular boneâblocks each containing 3â5 adjacent teeth (a total of 178 teeth) were collected postâmortem and scanned in a microâCT device. All crossâsection images of the 178 teeth (n = 65 530) were screened from the cementoenamel junction to the apex to identify the presence of dentinal defects.
Results
In the pilot study, the microcracks observable when the dehydrated tooth was outside the boneâblock remained detectable when the entire boneâblock plus reinserted tooth was scanned. This means that the screening process revealed the presence of the same microcracks in both experimental situations (the tooth outside and inside the maxillary boneâblock). From a total of 178 teeth in the boneâblocks removed from cadavers, 65 530 crossâsectional images were analysed and no dentinal microcracks were detected.
Conclusions
This in situ cadaveric model revealed the lack of preâexisting dentinal microcracks in nonâendodontically treated teeth. Thus, the finding of dentinal microcracks observed in previous crossâsectional images of stored extracted teeth is unsound and not valid. It should be assumed that microcracks observed in stored extracted teeth subjected to root canal procedures are a result of the extraction process and/or the postâextraction storage conditions. Therefore, as a consequence, the presence of such dentinal microcracks in stored extracted teeth â observable in crossâsectional images of the roots â should be referred to as experimental dentinal microcracks
Fusarium wilt incidence and common bean yield according to the preceding crop and the soil tillage system
The objective of this work was to evaluate the effects of preceding crops and tillage systems on the incidence of Fusarium wilt (Fusarium oxysporum f. sp. phaseoli) and common bean (Phaseolus vulgaris) yield. The cultivar BRS Valente was cultivated under centerâpivot irrigation in the winter seasons of 2003, 2004 and 2005, after several preceding crops established in the summer seasons. Preceding crops included the legumes Cajanus cajan (pigeon pea), Stylosanthes guianensis, and Crotalaria spectabilis; the grasses Pennisetum glaucum (millet), Sorghum bicolor (forage sorghum), Panicum maximum, and Urochloa brizantha; and a consortium of maize (Zea mays) and U. brizantha (Santa FĂ© system). Experiments followed a stripâplot design, with four replicates. Fusarium wilt incidence was higher in the noâtillage system. Higher disease incidences corresponded to lower bean yields in 2003 and 2004. Previous summer cropping with U. brizantha, U. brizantha + maize consortium, and millet showed the lowest disease incidence. Therefore, the choice of preceding crops must be taken into account for managing Fusarium wilt on irrigated common bean crops in the Brazilian Cerrado
Integrated reduction/oxidation reactions and sorption processes for Cr(VI) removal from aqueous solutions using Laminaria digitata macro-algae
The main goal of this work was the valorization of seaweed Laminaria digitata, after acid pre-treatment, for
the remediation of hexavalent chromium solutions. The Cr(VI) removal efficiency by the protonated biomass
was studied as a function of different parameters, such as contact time, pH, biomass and Cr(VI) concentration,
and temperature. Cr(VI) removal is based on a complex mechanism that includes a reduction of
Cr(VI) to Cr(III), through the oxidation of biomass at acidic medium, and further chemical binding of Cr(III)
to the negatively charged binding groups, mainly carboxylic groups. The optimum pH for chromium
removal, using protonated L. digitata algae, was 2.5. The maximum amount of Cr(VI) reduction by the algae
was around 2.1 mmol/g. The uptake capacity of Cr(III) by the oxidized biomass, after Cr(VI) reduction, was
higher than by the algae in its original form (protonated algae). Results suggest that the oxidation of the
biomass during Cr(VI) reduction, turns other active sites available for Cr(III) binding. Also, the Cr(III) binding
from a solution of reduced Cr(VI) was much lower than from a pure Cr(III) solution. The result suggests
the presence in solution of Cr(III) complexes with the organic matter released from the algae surface during
Cr(VI) reduction. The activation energy obtained for the Cr(VI) reduction by L. digitata was
45 ñ 20 kJ mol 1. A kinetic model based on the redox reaction between Cr(VI) species and organic compounds
from the biosorbent surface was able to fit well the hexavalent chromium concentration. Trivalent
chromium equilibrium biosorption was well described at different chromium concentrations, considering
the interaction between carboxylic groups present in the surface of the biomass and Cr(III) in solution
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