Oxytocin promotes bone formation during the alveolar healing process in old acyclic female rats

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Immunohistochemical detection of estrogen receptor beta in alveolar bone cells of estradiol-treated female rats: possible direct action of estrogen on osteoclast life span

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Antiulcerogenic action of ethanolic extract of the resin from Virola surinamensis Warb. (Myristicaceae)

Ethnopharmacological relevance: Virola surinamensis (Myristicaceae), popularly known as mucuiba, ucuuba or ucuuba do igapo is a large tree that grows abundantly in Varzea forest and on river banks in the Brazilian states of Amazonas and Tocantins. The resin obtained by cuts on the stem bark is a reputed folk remedy in its natural form for the treatment of ulcer, gastritis inflammation and cancer.Aim of the study: The present work evaluated the pharmacological activity of the resin obtained from bark of V surinamensis as antiulcerogenic in experimental in vivo model in order to observe whether its traditional use is justified.Materials and methods: The preventive action of ethanolic extract of V surinamensis was evaluated in experimental in vivo models in rodents that simulated this disease in human gastric mucosa.Results: Oral administration of acidified ethanol solution produced severe hemorrhagic lesions in glandular mucosa with ulcerative lesion of 50 +/- 11.5 mm. In animals pretreated with V surinamensis (500 mg/kg, p.o.) a significant inhibition of mucosal injury of 2.40 +/- 0.56 mm (95% inhibition) was detected. The V. surinamensis, at the same dose, also reduced significantly (p < 0.05) the formation of gastric lesions induced by indomethacin (39%), stress (45%) and by pylorus ligature in mice (31%) when compared to animals treated with vehicle. The extract from V surinamensis exerts gastroprotective action only when this extract contacts gastric mucosa (oral route) with. increased pH values and reduced H(+) concentration of gastric contents. The ethanolic extract of V surinamensis resin was analyzed by TLC and spectrometric methods (NMR and ES-MS) and the main constituent of this extract was epicatechin.Conclusions: We suggest that the epicatechin present in V surinamensis resin may be among active principles responsible for the antiulcer activity shown by the tested resin but their used suggest carefulness because toxicological symptoms mentioned by population. (C) Published by Elsevier B.V.

New Insight into the Mechanism of Action of Wasp Mastoparan Peptides: Lytic Activity and Clustering Observed with Giant Vesicles

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Mixing, demixing, and structure formation in a binary dipolar Bose-Einstein condensate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mechanism of micronuclei formation in polyploidizated cells of Allium cepa exposed to trifluralin herbicide

The trifluralin is an agent that promotes a cellular damage due to its direct action on the microtubules. This action leads to a decontrol in the cellular division, bringing about polyploid cells. In this work, we show the evidences that the exceeding genetical material of theses polyploidizated cells tends to be eliminated from the nucleus in the form of micronucleus. Our analyses prove this fact, both by the presence of a number of cells carrying micronucleus, and by the evidences of the elimination of the exceeding material itself, after exposition of the Allium cepa root tips tested with several concentration of trifluralin herbicide. It was noticed that the residual concentration induced a number of polyploid cells, micronuclei and mini cells. Inferences about the implications of the elimination of genetic material from micronuclei, such as cell viability and apoptosis, are also presented. (c) 2007 Elsevier B.V. All rights reserved.

Dissociation and electrooxidation of primaquine diphosphate as an approach to the study of anti-chagas prodrugs mechanism of action

This paper describes the voltammetric behavior of primaquine as a previous support to the further understanding of the delivery and action mechanisms of its respective synthesized prodrugs. There are few papers describing the drug behavior and most of the time no correlation between oxidation process and pH is done. Our results showed that primaquine oxidation is a one-step reaction involving two electrons with the charge transfer process being strongly pH-dependent in acid medium and pH-independent in a weak basic medium, with the neutral form being easily oxidized.This leads to the conclusion that quinoline nitrogen ring neutralization is a determinant step to the formation of the oxidized primaquine form. The existence of a relationship between the primaquine dissociation equilibrium and its electrooxidation process is shown.This work points the importance of voltammetric methodology as a tool for further studies on quantitative relationship studies between chemical structure and biological activity (QSAR) for electroactive drugs. (C) 2000 Elsevier B.V. S.A. All rights reserved.

Jarosite pseudomorph formation from arsenopyrite oxidation using Acidithiobacillus ferrooxidans

In this work, the oxidizing action of a native strain type A. ferrooxidans on a sulphide containing a predominance of arsenopyrite and pyrite has been evaluated. Incubation of the A. ferrooxidans strain in flasks containing 200 mL of T&K medium with the ore (particle size of 106 mu m) at pulp density 8% (w/v) at 35 degrees C on a rotary shaker at 200 rpm resulted in preferential oxidation of the arsenopyrite and the mobilization of 88% of the arsenic in 25 days. Mineralogical characterization of the residue after biooxidation was carried out with FTIR. XRD and SEM/XEDS techniques. An in situ oxidation of the arsenopyrite is suggested on the basis of the frequent appearance of jarosite pseudomorph replacing arsenopyrite, in which the transformations Fe(2+) -> Fe(3+), S(-2) -> S(+6) and As(-1) -> As(+3) -> As(+5) occur for the most part without formation of soluble intermediates, resulting in a type of jarosite that typically contains high concentrations of arsenic (type A-jarosite). However, during pyrite oxidation, dissolution of the constituent Fe and S predominates, which is evidenced by corrosion of pyrite particles with formation of pits, generating a type of jarosite with high quantities of K (type B-jarosite). Lastly, a third type of jarosite (type C-jarosite) also precipitated forming a thin film that covered the grains of pyrite principally. (C) 2010 Elsevier B.V. All rights reserved.

Laser 904 nm action on bone repair in rats with osteoporosis

The aim of the present study was to determine the action of AsGA laser irradiation on bone repair in the tibia of osteopenic rats. The animals were randomly divided into eight experimental groups according to the presence of ovarian hormone (sham group) or the absence of the hormone (OVX group), as well as being irradiated or non-irradiated. Low-level 904-nm laser (50 mJ/cm(2)) accelerated the repair process of osteopenic fractures, especially in the initial phase of bone regeneration.Introduction The development of new techniques to speed the process of bone repair has provided significant advances in the treatment of fractures. Some attention recently focused on the effects of biostimulation on bone.Methods Forty-eight adult rats were randomly divided into eight experimental groups (six animals in each group) according to the presence of ovarian hormone (sham group) or absence of the hormone (ovariectomized (OVX) group) as well as being irradiated or non-irradiated. For the application of low-level laser therapy, the animals were anesthetized with one third of the dose sufficient to immobilize the animal and irradiated with AsGa laser (904 nm, 50 mJ/cm(2) for 2s, point form and in contact). The control animals received the same type of manipulation as the irradiated animals, but with the laser turned off. Half of the animals were killed 7 days following the confection of the bone defect, and the other half were killed 21 days after the surgery. After complete demineralization, the tibias were cut cross-sectionally in the central region of the bone defect and embedded in paraffin blocks. The blocks were then cut in semi-seriated slices and stained with hematoxylin and eosin.Results There was new bone formation in the animals in the OVX group with laser treatment killed after 7 days (p<0.001). The lowest percentage of bone formation was observed in the OVX without laser killed after 7 days (p>0.05). All animals killed after 21 days exhibited linear closure of the lesion.Conclusion Low-level 904-nm laser (50 mJ/cm(2)) accelerated the repair process of osteopenic fractures, especially in the initial phase of bone regeneration.

Antioxidant action of Rosemary extract in soybean oil submitted to thermoxidation

This work was aimed at evaluating the antioxidant activity of rosemary extract added to soybean oil in thermoxidation conditions. Purified soybean oil, refined soybean oil and refined soybean oil containing 1,000 mg/kg rosemary extract were heated at 180°C. The oxidation of the samples was evaluated after 0, 2.5, 5, 7.5 and 10 hours of thermoxidation by means of oxidative stability determination, total polar compounds and conjugated dienes. The purified oil differed significantly from the refined oil, mainly in relation to oxidative stability due the removal of the natural antioxidants. Rosemary extract presented antioxidant effects at high temperatures. After 10 hours of heating, 1,000 mg/kg rosemary extract added to the refined soybean oil significantly increased the oil oxidative stability from 7.52 to 13.5 hours and decreased the formation of polymers and decomposing products measured through the polar rates from 17.35 to 7.99%. The build up of primary oxidation products gauged through diene rates also decreased from 1.61 to 0.80%. Rosemary extract could be recommended as an alternative antioxidant.

The Mode of Action of Recombinant Mycobacterium tuberculosis Shikimate Kinase: Kinetics and Thermodynamics Analyses

Tuberculosis remains as one of the main cause of mortality worldwide due to a single infectious agent, Mycobacterium tuberculosis. The aroK-encoded M. tuberculosis Shikimate Kinase (MtSK), shown to be essential for survival of bacilli, catalyzes the phosphoryl transfer from ATP to the carbon-3 hydroxyl group of shikimate (SKH), yielding shikimate-3-phosphate and ADP. Here we present purification to homogeneity, and oligomeric state determination of recombinant MtSK. Biochemical and biophysical data suggest that the chemical reaction catalyzed by monomeric MtSK follows a rapid-equilibrium random order of substrate binding, and ordered product release. Isothermal titration calorimetry (ITC) for binding of ligands to MtSK provided thermodynamic signatures of non-covalent interactions to each process. A comparison of steady-state kinetics parameters and equilibrium dissociation constant value determined by ITC showed that ATP binding does not increase the affinity of MtSK for SKH. We suggest that MtSK would more appropriately be described as an aroL-encoded type II shikimate kinase. Our manuscript also gives thermodynamic description of SKH binding to MtSK and data for the number of protons exchanged during this bimolecular interaction. The negative value for the change in constant pressure heat capacity (ΔCp) and molecular homology model building suggest a pronounced contribution of desolvation of non-polar groups upon binary complex formation. Thermodynamic parameters were deconvoluted into hydrophobic and vibrational contributions upon MtSK:SKH binary complex formation. Data for the number of protons exchanged during this bimolecular interaction are interpreted in light of a structural model to try to propose the likely amino acid side chains that are the proton donors to bulk solvent following MtSK:SKH complex formation. © 2013 Rosado et al.

RBPI21 interacts with negative membranes endothermically promoting the formation of rigid multilamellar structures

rBPI21 belongs to the antimicrobial peptide and protein (AMP) family. It has high affinity for lipopolysaccharide (LPS), acting mainly against Gram-negative bacteria. This work intends to elucidate the mechanism of action of rBPI21 at the membrane level. Using isothermal titration calorimetry, we observed that rBPI21 interaction occurs only with negatively charged membranes (mimicking bacterial membranes) and is entropically driven. Differential scanning calorimetry shows that membrane interaction with rBPI21 is followed by an increase of rigidity on negatively charged membrane, which is corroborated by small angle X-ray scattering (SAXS). Additionally, SAXS data reveal that rBPI21 promotes the multilamellarization of negatively charged membranes. The results support the proposed model for rBPI21 action: first it may interact with LPS at the bacterial surface. This entropic interaction could cause the release of ions that maintain the packed structure of LPS, ensuring peptide penetration. Then, rBPI21 may interact with the negatively charged leaflets of the outer and inner membranes, promoting the interaction between the two bacterial membranes, ultimately leading to cell death. © 2013 Elsevier B.V.

Neurotoxic action of permethrin in Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) female ticks. Morphological and cytochemical evaluation of the central nervous system

Studies on the molecular bases of the neurotoxic action of acaricides are found in the literature; but there are no studies of this action on the nervous system of ticks at the cellular level. The present study describes the morphological and cytochemical changes in the synganglion of Rhipicephalus sanguineus semi-engorged females exposed to different concentrations of permethrin, a pyrethroid with recognized neurotoxic action. Permethrin induced the degeneration of the synganglion through a process of apoptosis involving autophagy, characterized by the condensation and margination of the chromatin, formation of blebs in the nuclear envelope and fragmentation of the nucleus, loss of shape of neural cells and integrity of cellular membrane, cytoplasmic shrinkage, and lower levels of acid phosphatase in the nervous tissue as the concentration of permethrin increased. This study provided further evidence of the neurotoxic action of permethrin, which impairs the metabolism of R. sanguineus nervous systems, and consequently the physiology of other systems, dependent on the neural control. These results provide cytochemical and histological confirmation of the neurotoxic action of permethrin, previously inferred from molecular and tick behavioral evidence. © 2013 Elsevier B.V.

Práticas discursivas e subjetivação docente: uma análise do discurso pedagógico sobre formação de professores no Curso de Pedagogia da UFPA

Dissertação que investiga e problematiza as práticas discursivas e os processos de constituição e subjetivação de sujeitos docentes envolvidos no discurso pedagógico sobre Formação de Professores no contexto do Movimento de Reestruturação Curricular do Curso de Pedagogia da UFPA, no período de 1992 a 2001. Parte das seguintes questões: Qual a proveniência do discurso pedagógico sobre formação de professores no interior do Movimento de Reestruturação Curricular do Curso de Pedagogia da Ufpa? Como este surge, para responder a que urgência histórica? Qual sua emergência? Que tipo docente, em particular, se deseja? Qual sua identidade? Que processos ou técnicas de subjetivação são postos em ação para a constituição desse particular sujeito docente? Quais técnicas de governança e práticas de si são postas em funcionamento para produzi-lo, fabricá-lo? O que se prescreve a esse docente, o que ele deve ser? Assume a pedagogia como poderosa tecnologia de subjetivação e produção de sujeitos docentes e para responder a tais questões toma a arqueogenealogia, bem como a análise enunciativa do acontecimento discursivo de perspectiva foucaultiana, como substrato e fio condutor teórico-metodológico e analítico. A análise se concentra em fontes documentais institucionais do referido movimento de reestruturação curricular e outros que se constituem como campo de presença, interrogando o discurso pedagógico, através de suas formas concretas de aparição, em sua materialidade, naquilo que produz, seus objetos discursivos, problematizando seu caráter produtivo de sujeitos. Como resultado, evidencia que a subjetividade docente no campo da pedagogia é continuamente produzida em uma cadeia entre práticas discursivas e não discursivas, e que dispositivos pedagógicos de produção de tais subjetividades, como o dispositivo de governamentalidade e o dispositivo de moralidade, se materializam em seus pressupostos teóricos, em suas proposições temáticas, prescrições didáticas, curriculares, avaliativas, enfim, em adjetivações e predicativos direcionados ao sujeito docente como objeto do discurso pedagógico.