Mecanismes cel·lulars en la curació de ferides a Hirudo medicinalis

S'estudia la histologia normal de la paret corporal d'Hirudo medicinalis i els canvis morfogenètics que es donen durant el procés de cicatrització de ferides per incisió, cauterització i nitrat de plata. El procés de curació de ferides a Hirudo medicinalis consta d'una fase de formació d'un tap cel·lular, el pseudoblastema, d'un procés de reepitelització i de la formació d'un teixit cicatricial, com en els altres hirudinis estudiats (Myers, 1935; LeGore i Sparks, 1971; Cornec, 1984). Hem observat també el fenomen de la contracció de la ferida que permet l'acostament dels marges de la ferida. Formació i evolució del pseudoblastema El pseudoblastema, a diferència d'altres espècies estudiades, està format per un sol tipus cel·lular: les cèl·lules vasocentrals, provinents del teixit vasofibrós, una especialització del teixit connectiu. Aquestes cèl·lules estan capacitades per realitzar les diferents funcions que en espècies rincobdèl·lides realitzen diferents tipus cel·lulars. En concret: taponament de la ferida a través de la formació del pseudoblastema, fagocitosi dels teixits necrosats i regeneració, almenys d'una part, de la matriu connectiva cicatricial. També són responsables de la contracció de la ferida. Les cèl·lules vasocentrals en el seu estadi de repòs es troben en el teixit vasofibrós formant agrupacions coherents, però sense mostrar unions intercel·lulars especialitzades visibles en ME. La coherència del grup queda assegurada per les interdigitacions entre les cèl·lules vasocentrals i probablement per unions tipus adherens o especialitzades. Les unions amb la matriu són de tipus adherens. Aquestes cèl·lules vasocentrals presenten feixos de filaments d'actina força conspicus. En produir-se una ferida les cèl·lules vasocentrals s'activen, desconnecten les unions intercel·lulars i amb la matriu i migren cap a la zona afectada, on s'acumulen. El pseudoblastema actua com un tap cel·lular que funciona de forma eficient per tancar la ferida en un plaç de temps relativament curt. El pseudoblastema forma un teixit coherent amb unions intercel·lulars tipus adherens, caracteritzades per material electrodens en la cara intracitoplasmàtica, feixos de filaments d'actina que hi convergeixen i espais intercel·lulars petits, de 17-20 mm, atravessats per petites fibril·les. Un cop finalitzat el procés de reepitelització, es produeix una contracció de la ferida. Es produeix per la retracció del pseudoblastema cap a l'interior de l'animal. El pseudoblastema disminueix la seva amplària i arrossega els teixits contigus provocant un tancament. La força motriu que provoca la retracció i l'arrossegament dels teixits vindria donada per la presència dels filaments d'actina a les cèl·lules del pseudoblastema, els quals durant aquesta fase es tornen mes conspicus. La presència d'unions intercel·lulars especialitzades característiques de la fase de contracció, està relacionada amb la transmissió de la força de tensió. Aquestes unions connecten els feixos de filaments d'actina de les cèl·lules amb la matriu o d'una cèl·lula a altre a través d'espais intercel·lulars força amples en els que s'observa material electrodens. Reepitelització L'epitelització s'inicia quan el pseudoblastema està consolidat i segueix el mateix patró que la reepitelització de ferides en epitelis monoestratificats de vertebrats (Stem i DePalma, 1983, és a dir, per migració de tota la capa per sobre del substrat, segons l'anomenat model de lliscament. Les glàndules unicel·lulars mucoses del tegument degeneren abans de produir-se la migració epitelial i posteriorment, un cop consolidat l'epiteli a sobre de la ferida, es diferencien a partir de les cèl·lules epitelials. Durant l'epitelització es produeixen canvis importants en el citosquelet i les unions basals de les cèl·lules epitelials. En canvi, el complex d'unió lateral es manté durant tot el procés. En iniciar-se la migració els tonofilaments es desconnecten dels hemidesmosomes cuticulars i dèrmics i es reagrupen al voltant del nucli, a la vegada que els hemidesmosomes dèrmics es desconnecten de la làmina basal. Un cop acabada la migració, les cèl·lules epitelials estableixen unions basals amb les cèl·lules del pseudoblastema. Aquestes unions no són hemidesmosomes sinó que presenten el mateix aspecte que les unions intercel·lulars del pseudoblastema. Els hemidesmosomes no es tornen a formar fins que les cèl·lules epitelials han restablert la membrana basal. La regeneració de la membrana basal no s'inicia fins que no s'ha començat a regenerar matriu connectiva a la zona cicatricial. Regeneració de la cicatriu Al mateix temps que es dona el fenomen de contracció, s'observa regeneració de la matriu connectiva entre les cèl·lules del pseudoblastema. Aquestes cèl·lules són responsables almenys del recobriment fibrós que presenten en aquest estadi, durant el qual mostren sàculs del reticle endoplasmàtic rugós molt dilatats, característics de cèl·lules que secreten constituents de la matriu. A més, s'observa infiltració de matriu connectiva i processos citoplasmàtics dels fibròcits en els marges del pseudoblastema. En la matriu del teixit connectiu normal s'observen fibres que estan constituïdes per un còrtex de fibril·les col·làgenes organitzades al voltant dels processos citoplasmàtics dels fibròcits. Les fibres del teixit connectiu peridigestiu, d'uns 1,2-1,9 mm de diàmetre, presenten el còrtex prim, amb les fibril·les organitzades paral·lelament a l'eix de la fibra. En canvi, les fibres de la dermis i teixit connectiu intramuscular, d'uns 2,5-7,1 mm de diàmetre, tenen el còrtex gruixut, amb fibril·les que s'organitzen paral·lelament en la zona proximal a la medul·la i de forma desorganitzada en la part més distal. Als 8 mesos la cicatriu encara és detectable. La matriu cicatricial presenta fibres connectives del tipus prim i força material fibril·lar desorganitzat disposat laxament. S'observa colonització per part de fibròcits, cromatòfors, petites fibres musculars i nervis.

The AcrAB-TolC efflux system of Salmonella enterica serovar Typhimurium plays a role in pathogenesis

The ability of an isogenic set of mutants of Salmonella enterica serovar Typhimurium L354 (SL1344) with defined deletions in genes encoding components of tripartite efflux pumps, including acrB, acrD, acrF and tolC, to colonize chickens was determined in competition with L354. In addition, the ability of L354 and each mutant to adhere to, and invade, human embryonic intestine cells and mouse monocyte macrophages was determined in vitro. The tolC and acrB knockout mutants were hyper-susceptible to a range of antibiotics, dyes and detergents; the tolC mutant was also more susceptible to acid pH and bile and grew more slowly than L354. Complementation of either gene ablated the phenotype. The tolC mutant poorly adhered to both cell types in vitro and was unable to invade macrophages. The acrB mutant adhered, but did not invade macrophages. In vivo, both the acrB mutant and the tolC mutant colonized poorly and did not persist in the avian gut, whereas the acrD and acrF mutant colonized and persisted as well as L354. These data indicate that the AcrAB-TolC system is important for the colonization of chickens by S. Typhimurium and that this system has a role in mediating adherence and uptake into target host cells.

Efeito da adição do poli(etileno acrilato de metila) (ema) e da fibra de linter de algodão nas propriedades do poli(tereftalato de etileno) reciclado (petrec)

The development of new materials to fill the demand of technological advances is a challenge for many researchers around the world. Strategies such as making blends and composites are promising alternatives to produce materials with different properties from those found in conventional polymers. The objective of this study is to evaluate the effect of adding the copolymer poly(ethylene methyl acrylate) (EMA) and cotton linter fibers (LB) on the properties of recycled poly(ethylene terephthalate) (PETrec) by the development of PETrec/EMA blend and PETrec/EMA/LB blend composite. In order to improve the properties of these materials were added as compatibilizers: Ethylene - methyl acrylate - glycidyl methacrylate terpolymer (EMA-GMA) and maleic anhydride grafted polyethylene (PE-g-MA). The samples were produced using a single screw extruder and then injection molded. The obtained materials were characterized by thermogravimetry (TG), melt flow index (MFI) mensurements, torque rheometry, pycnometry to determinate the density, tensile testing and scanning electron microscopy (SEM). The rheological results showed that the addition of the EMA copolymer increased the viscosity of the blend and LB reduces the viscosity of the blend composite. SEM analysis of the binary blend showed poor interfacial adhesion between the PETrec matrix and the EMA dispersed phase, as well as the blend composite of PETrec/EMA/LB also observed low adhesion with the LB fiber. The tensile tests showed that the increase of EMA percentage decreased the tensile strength and the Young s modulus, also lower EMA percentage samples had increased the elongation at break. The blend composite showed an increase in the tensile strength and in the Young`s modulus, and a decrease in the elongation at break. The blend formulations with lower EMA percentages showed better mechanical properties that agree with the particle size analysis which showed that these formulations presented a smaller diameter of the dispersed phase. The blend composite mechanical tests showed that this material is stronger and stiffer than the blend PETrec/EMA, whose properties have been reduced due to the presence of EMA rubbery phase. The use of EMA-GMA was effective in reducing the particle size of the EMA dispersed phase in the PETrec/EMA blend and PE-g-MA showed evidences of reaction with LB and physical mixture with the EMA

Analysis of the four wave mixing effect (FWM) in a dispersion decreasing fiber (DDF) for a WDM system

We did a numerical investigation of the propagation of short light pulses in the region of 1.55 mu m and the conversion efficiency (CE) for the four wave mixing generation (FWM) of ordinary and dispersion decreasing fibers for use in wavelength division multiplexing (WDM) systems, Our simulations studies three different profiles, linear, hyperbolic. and constant, One conclude that for all the profiles there is decrease of the conversion efficiency with the increase in the channel separation. The hyperbolic profile present a higher efficiency of around 1000 above in magnitude compared with the others profiles at 0.2 nm of channel separation. We calculate the conversion efficiency versus the fiber length for the three profiles. The conversion efficiency for the hyperbolic profile is higher when compared to the constant and linear profiles. The other interesting point of the hyperbolic profile is that the increase of the CE in the beginning of the fiber does not show my oscillation in the CE value (log eta), which was observed for the constant and linear profiles. For all the profiles there is an increase of the conversion efficiency with the increase of the pump power. The compression factor C-i for the generated FWM signal at omega(3) was measured along the DDF's and the constant profile fibers. One can conclude that with the use of decreasing dispersion profile (DDF) fibers one can have a control of the (CE) conversion efficiency and the compression factor of the four wave mixing (FWM) generation in WDM systems. (c) 2005 Elsevier B.V. All rights reserved.

Avaliação macroscópica, microscópica e histomorfométrica do tecido cicatricial pós-cirúrgico de eqüinos submetidos a duas técnicas de neurectomia digital

Avaliou-se macro e microscopicamente o tecido cicatricial pós-operatório de eqüinos submetidos a duas técnicas de neurectomia digital: guilhotina (TG) e stripping (TS). Decorridos 14 meses das cirurgias, foram colhidas 32 amostras de tecido cicatricial em quatro éguas, que tiveram os membros submetidos a ambas as técnicas. À macroscopia, verificaram-se as dimensões da cicatriz do coto proximal e a distância entre os cotos proximal e distal. À microscopia, foi quantificada a proporção de tecido nervoso regenerado por meio de histomorfometria. Não houve diferença nas dimensões do tecido cicatricial, contudo a distância entre cotos foi 5,6 vezes maior na TS (P<0,001). Histologicamente, observou-se a presença de tecido conjuntivo frouxo e denso, macrófagos e fibras nervosas delgadas em ambas as técnicas cirúrgicas. Estruturas nodulares, compostas por fascículos nervosos, foram visualizadas em 56,2% (9/16) das amostras colhidas em nervos submetidos à TS. As porcentagens médias de tecido nervoso no tecido cicatricial foram de 0,31% na TG e 2,6% na TS (P<0,001). Concluiu-se que o retorno à sensibilidade nervosa deve demorar mais a ocorrer após a TS, devido à maior distância entre cotos. A maior proporção de tecido nervoso sugere que essa técnica favorece a regeneração nervosa.

Muscular Dystrophy in Dogs: Does the Crossing of Breeds Influence Disease Phenotype?

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

Influência da umidade nas propriedades mecânicas dos compósitos poliméricos híbridos (sisal/ vidro)

This study aims to evaluate the mechanical properties of polymer matrix composites reinforced with sisal fabric bidirectional tissue (Agave sisalana,) and E-glass fibers, containing the following configuration: a polymer matrix hybrid composite (Polyester Resin orthophalic) reinforced with three (3) layers of glass fibers and alternating-2 (two) layers of bidirectional sisal fabric, and finally a composite of polymer matrix reinforced with five (5) layers of glass fiber mat-type E. For this purpose as first step, the preparation of by sisal, since they are not on the market. The composites were made by manual lamination (Hand lay-up) and evaluated for tensile properties and three point bending both in the dry, and wet conditions aswele as immersed in oil. Macroscopic and microscopic characteristics of the materialsweve awalysed, after the completion of the mechanical tests. After the studies, it was proven that the sisal fiber decreases the tensile stiffness of the material above 50% for both situations studied the tensile strength of the material decreases by approximately 40% for the cases mentioned, and when compared to the specific strength stiffness values drop to 14.6% and 29.02% respectively for the dry state only. Constants for bending the values were are to approximately 50% to 25% for strength and stiffness of the material for the cases dry, wet and immersed in oil. Under the influence of tension fluids do not interfere in the stiffness of the material for the bending tests, the same does not occur with the resistance, and these values are modified only in the cases stiffness and flexural strength

Envelhecimento ambiental em compósitos poliméricos à base de tecidos de reforços híbridos

The utilization of synthetic fibers for plastic reinforcement is more and more frequent and this growing interest requires that their mechanic behavior under the most variable conditions of structural applications be known. The use of such materials in the open and exposed to the elements is one of them. In this case, it becomes extremely necessary to study their mechanical properties (strength, stiffness) and the mechanism of fracture by which the environment aging them out. In order to do that, the material must be submitted to hot steam and ultraviolet radiation exposure cycles, according to periods of time determined by the norms. This study proposal deals with the investigation of accelerated environmental aging in two laminated polymeric composites reinforced by hybrid woven made up of synthetic fibers. The configurations of the laminated composites are defined as: one laminate reinforced with hybrid woven of glass fibers/E and Kevlar fibers/49 (LHVK) and the other laminate is reinforced with hybrid tissue of glass fibers/E and of carbon fibers AS4 (LHVC). The woven are plane and bidirectional. Both laminates are impregnated with a thermofix resin called Derakane 470-300 Epoxy Vinyl-Ester and they form a total of four layers. The laminates were industrially manufactured and were made through the process of hand-lay-up. Comparative analyses were carried out between their mechanical properties by submitting specimen to uniaxial loading tractions and three-point flexion. The specimen were tested both from their original state, that is, without being environmentally aging out, and after environmental aging. This last state was reached by using the environmental aging chamber

Estudo da produção de pectinase por fermentação em estado sólido utilizando pedúnculo de caju como substrato

Pectinolytic enzymes, or simply pectinases, are complex enzymes that degrade pectic polymers. They have many uses, such as fruit juice extraction and purification, textile fiber treatment and vegetal oil extraction. The aim of this work was to study the kinetics of pectinases production by solid-state fermentation, using dry cashew apple residue as substrate and the microorganism Aspergillus niger CCT 0916. The influence of the initial medium moisture and medium supplementation with a source of nitrogen and phosphorus was evaluated using the factorial experimental planning and response surface methodology. Ammonia sulphate and potassium phosphate were used as nitrogen and phosphorus source, respectively. The variables time of contact (T) and ratio volume solvent/fermented medium (RZ), in systems with and without agitation, were evaluated in order to study the best extraction condition of the produced enzyme. Washed and unwashed cashew apple residues were tested as the growth medium. The unwashed residue was obtained by drying the residue after the extraction of the juice, while the washed residue was obtained by water washing 5 times using the proportion of 1 kg pulp/2 liters of water. Samples were taken every 12 hours for moisture content, pH, protein, reducing sugars, polygalacturonase activity (PG) and viscosity reduction. The physical-chemical composition of the residues had different sugar and pectin levels. For the unwashed residue, the peak activity was reached with 40% of initial moisture content, 1% of nitrogen supplementation without phosphorus addition after 30 hours of process. These conditions led to 16 U/g of PG activity and 82% of viscosity reduction. The calculated models reached similar values to the experimental ones in the same process conditions: 15.55 U/g of PG and 79.57% of viscosity eduction. Similarly, the greatest enzyme production for washed residue was reached with 40% initial moisture content, 1% nitrogen supplementation without phosphorus addition after 22 hours of cultivation. In this condition it was obtained polygalacturonase activity of 9.84 U/g and viscosity reduction of 81.36%. These values are close to experimental values that were of 10.1 U/g and 81%, respectively. The conditions that led to the best PG activity results was the agitated one and the best extraction condition was obtained with 100 minutes of solvent/medium contact and RZ of 5 (mL/g)

Padrão de distribuição e caracterização morfológica de fibras serotonérgicas nos núcleos da linha Média/ intralaminares do tálamo do mocó (Kerodon rupestris)

The midline/intralaminar nuclei form a remarkable group of nuclei of the medial and dorsal thalamus. The midline nuclei, in rats, comprises the paratenial nuclei (PT), paraventricular (PV), intermediodorsal (IMD), reuniens (Re) and rhomboid (Rh). The intralaminar nuclei comprises the central medial (CM), paracentral (PC), central lateral (CL) and parafascicular (PF). Such nuclei have dense serotonergic innervation originating from the brainstem, especially from the so-called ascending activation system. These nuclei, in turn, send projections to various cortical and subcortical areas, specifically to limbic areas, which suggests the important role of this neurotransmitter in the limbic circuitry. The aim of this study was to characterize the distribution pattern and morphology of serotonin fibers in the nuclei of the midline and intralaminar thalamic of rocky cavy (Kerodon rupestris), a tipical rodent from brazilizan northeast. To reach this aim we used four rock cavies adults. Following the transcardially perfusion with paraformaldehyde and brain microtomy steps was performed immunohistochemistry for serotonin (5-HT), Nissl technique and subsequent achievement and image analysis to characterize the cytoarchitecture of these nuclei and the serotonergic fibers visualized. An analysis was made of Relative Optical Density (ROD) to semi-quantify the concentration of serotonin fibers in the areas of interest. Thus, we observed a cytoarchitectonic arrangement of these nuclei similar to that found in rats. In case of fibers distribution, those immunoreactive to 5-HT were presented in a higher concentration according as ROD in the midline nuclei relative to intralaminar; Re being the core which has a higher pixel value followed by the PV , Rh, IMD and PT. In intralaminar CL showed higher pixels, followed by nuclei CM, PC and PF. The serotonergic fibers were classified as number of varicosities and axon diameter, therefore find three types of fibers distributed through this nuclear complex: fibers rugous, granular and semi-granular. In PV fibers predominated rugous; in PT fibers predominated granular; IMD, CL and PF fibers were represented by semi-granular and Re, Rh, PC and CM fibers showed granular and semi-granular. Morphological characterization of serotonergic fibers and differences in density between the nuclei may suggest different patterns of synaptic organization of this neurotransmitter beyond confirming his large repertoire functional

CHEMICAL MODIFICATION EFFECT on THE MECHANICAL PROPERTIES of HIPS/COCONUT FIBER COMPOSITES

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sugarcane bagasse cellulose/HDPE composites obtained by extrusion

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evaluation of stitched fabric composite processed by RTM in quasi-static test

Stitched fabrics have been widely studied for potential application in aircraft structures since stitch yarns offer improvements in the out-of-plane mechanical properties and also can save time in the lay up process. The down side of stitch yarns came up in the manufacturing process of fabric in which defects introduced by the needle movement creating fiber-free-zones, fiber breakage and misalignment of fibers. The dry stitched carbon fabric preform has mainly been used in the Resin Transfer Molding (RTM) process which high fiber content is aimed, those defects influence negatively the injection behavior reducing the mechanical properties of final material. The purpose of this research work focused on testing in quasi-static mechanical mode (in-plane tension) of a monocomponent resin CYCOM (R) 890 RTM/carbon fiber anti-symmetric quadriaxial fabric stitched by PE 80Dtex yarn processed by RTM. The evaluation consisted in comparing the scatter of the quasi-static test with the attenuation of ultrasonic maps, which show the path of the resin and possible dry spots considering that interference of yarn in resin flow is detectable in ultrasonic measurement. Microscopic analysis was also considered for further evaluation in case of premature failure. (C) 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of ICM11

Caracterização do processo de gelificação de soluções quitosana utilizando reometria e espalhamento dinâmico da luz

Gels consist of soft materials with vast use in several activities, such as in pharmaceutical industry, food science, and coatings/textile applications. In order to obtain these materials, the process of gelification, that can be physical (based on physical interactions) and/or chemical (based on covalent crosslinking), has to be carried out. In this work we used dynamic light scattering (DLS) and rheometry to monitor the covalent gelification of chitosan solutions by glutaraldehyde. Intensity correlation function (ICF) data was obtained from DLS and the exponential stretched Kohrausch-William-Watts function (KWW) was fitted to them. The parameters of the KWW equation, β, Γ and C were evaluated. These methods were effective in clarifying the process of sol-gel transition, with the emergence of non-ergodicity, and determining the range of gelation observed in about 10-20 minutes. The dependence between apparent viscosity on reaction time was used to support the discussion proposed.

Conciliação entre modelos de mecanismos avançados de oxidação eletroquímica

Many pollutants dumped in waterways, such as dyes and pesticides, have become so ubiquitous that they represent a serious threat to human health. The electrochemical oxidation is presented as an alternative clean, efficient and economic degradation of wastewater containing organic compounds and a number of advantages of this technique is to just not make use of chemical reagents, since only electrical energy is consumed during the removal of pollutants organic. However, despite being a promising alternative, still needs some tweaking in order to obtain better efficiency in the elimination of persistent pollutants. Thus, this study sought a relationship between a recently discovered phenomenon that reflects the participation of dissolved oxygen in solution in the electrochemical oxidation process, as an anomaly, present a kinetic model that shows instantaneous current efficiency (ICE) above 100% limited by theory, manifested for some experiments with phenolic compounds with H2SO4 or HClO4 as supporting electrolyte with electrodes under anodic oxidation on boron doped diamond (BDD). Therefore it was necessary to reproduce the data ICE exposes the fault model, and thus the 2-naphthol was used as phenolic compound to be oxidised at concentrations of 9, 12 and 15 mmol L-1, and H2SO4 and HClO4 to 1 mol L-1 as a supporting electrolyte under a current density of 30 mA cm-2 in an electrochemical reactor for continuous flow disk configuration, and equipped with anodes DDB at room temperature (25 oC). Experiments were performed using N2 like as purge gas for eliminate oxygen dissolved in solution so that its influence in the system was studied. After exposure of the anomaly of the ICE model and investigation of its relationship with dissolved O2, the data could be treated, making it possible for confirmation. But not only that, the data obtained from eletranálise and spectroscopic analysis suggest the involvement of other strongly oxidizing species (O3 (ozone) and O radicals and O2 -), since the dissolved O2 can be consumed during the formation of new strong oxidizing species, not considered until now, something that needs to be investigated by more accurate methods that we may know a little more of this system. Currently the performance of the electrocatalytic process is established by a complex interaction between different parameters that can be optimized, so it is necessary to the implementation of theoretical models, which are the conceptual lens with which researchers see