Tipos funcionais de plantas em pastagem natural na depressão central - RS.

O presente estudo foi conduzido na Estação Experimental Agronômica da Faculdade de Agronomia da Universidade Federal do Rio Grande do Sul em uma área de três hectares de campo natural, durante o período de dezembro/2002 a outubro 2003, com os objetivos de identificar e caracterizar a freqüência de ocorrência dos tipos funcionais de plantas (TFs) que foram obtidos a partir da descrição de atributos morfológicos, e caracterizar o comportamento alimentar de bovinos. Para a medição dos atributos, foram marcadas 30 unidades amostrais permanentes compostas de cinco quadros contíguos de 0,20 m x 0,20 m cada. Os resultados mostraram em relação à descrição da comunidade um subconjunto ótimo dos atributos propagação vegetativa, especializações morfológicas de defesa da lâmina foliar, biomassa da parte aérea, altura máxima da última folha expandida e porcentagem de biomassa acima da altura onde ocorre a maior concentração de biomassa fotossintetizante, os quais definiram cinco TFs em relação a inclinação do terreno e o pastejo. O tempo de pastejo aumentou à medida que aumentaram os dias de ocupação da área e que diminuiu a disponibilidade de forragem e altura das plantas. A análise dos resultados mostrou a possibilidade de se obter informações para o monitoramento da comunidade vegetal que visem potencializar a produção do agroecossistema

PEGylated and poloxamer-modified chitosan nanoparticles incorporating a lysine-based surfactant for pH-triggered doxorubicin release

The growing demand for efficient chemotherapy in many cancers requires novel approaches in target-delivery technologies. Nanomaterials with pH-responsive behavior appear to have potential ability to selectively release the encapsulated molecules by sensing the acidic tumor microenvironment or the low pH found in endosomes. Likewise, polyethylene glycol (PEG)- and poloxamer-modified nanocarriers have been gaining attention regarding their potential to improve the effectiveness of cancer therapy. In this context, DOX-loaded pH-responsive nanoparticles (NPs) modified with PEG or poloxamer were prepared and the effects of these modifiers were evaluated on the overall characteristics of these nanostructures. Chitosan and tripolyphosphate were selected to form NPs by the interaction of oppositely charged compounds. A pH-sensitive lysine-based amphiphile (77KS) was used as a bioactive adjuvant. The strong dependence of 77KS ionization with pH makes this compound an interesting candidate to be used for the design of pH-sensitive devices. The physicochemical characterization of all NPs has been performed, and it was shown that the presence of 77KS clearly promotes a pH-triggered DOX release. Accelerated and continuous release patterns of DOX from CS-NPs under acidic conditions were observed regardless of the presence of PEG or poloxamer. Moreover, photodegradation studies have indicated that the lyophilization of NPs improved DOX stability under UVA radiation. Finally, cytotoxicity experiments have shown the ability of DOX-loaded CS-NPs to kill HeLa tumor cells. Hence, the overall results suggest that these pH-responsive CS-NPs are highly potent delivery systems to target tumor and intracellular environments, rendering them promising DOX carrier systems for cancer therapy

Determination of Methotrexate in pH-Sensitive Chitosan Nanoparticles by Validated RP-LC and UV Spectrophotometric Methods

Nanotechnology-based drug delivery systems are in constant development and, therefore, it is of great importance to have rapid, efficient and accurate analytical methodology to quantify the encapsulated drugs. Here, simple and fast methods, by reversed-phase liquid chromatography (RP-LC) and UV spectrophotometry, were developed and validated for the determination of methotrexate (MTX) in pH-sensitive chitosan nanoparticles (CS-NPs). NPs were prepared using a modified ionotropic complexation process, in which was included a surfactant derived from Nα,Nε-dioctanoyl lysine with an inorganic sodium counterion. The RP-LC method was carried out on a Waters XBridgeTM C18 column (250 mm x 4.6 mm I.D., 5μm), with mobile phase consisted of potassium phosphate buffer (0.05 M, pH 3.2): acetonitrile (86:14, v/v), and UV detection set at 303 nm. The analyses of MTX content by the UV method were also accomplished at 303 nm, using 0.1 M sodium hydroxide as diluent. The measurements were linearly correlated with concentration for both methods in the 1 - 30 μg/mL range (r > 0.9999). The specificity tests showed that there was no interference of the NP components on the quantitative analyses. Precision (repeatability and intermediate precision) was demonstrated by a relative standard deviation lower than 1.5%, whereas the accuracy was assessed by the recovery of MTX from sample matrices, given mean value of ~99%. The proposed methods were applied for the analyses of MTX in different batches of NPs, and the results showed non-significant differences (p > 0.05) between the values obtained with both methodologies. Moreover, the RP-LC method was successfully used to determine the drug entrapment efficiency, and to quantify MTX during in vitro release assays and photolytic degradation studies. In conclusion, the validated methods are suitable to assay MTX in pH-sensitive CS-NPs without any interference from the polymer or surfactant

Nanoparticles incorporating pH-responsive surfactants as a viable approach to improve the intracellular drug delivery

The pH-responsive delivery systems have brought newadvances in the field of functional nanodevices and might allow more accurate and controllable delivery of specific cargoes, which is expected to result in promising applications in different clinical therapies. Here we describe a family of chitosan TPP (tripolyphosphate) nanoparticles (NPs) for intracellular drug delivery, which were designed using two pH-sensitive amino acid-based surfactants fromthe family Nα,Nε-dioctanoyl lysine as bioactive compounds. Lowand mediummolecularweight chitosan (LMW-CS and MMW-CS, respectively) were used for NP preparation, and it was observed that the size distribution for NPs with LMW-CS were smaller (~168 nm) than that for NPs prepared with MMW-CS (~310 nm). Hemolysis assay demonstrated the pH-dependent biomembrane disruptional capability of the constructed NPs. The nanostructures incorporating the surfactants cause negligible membrane permeabilization at pH 7.4. However, at acidic pH, prevailing in endosomes, membrane-destabilizing activity in an erythrocyte lysis assay became evident. When pH decreased to 6.6 and 5.4, hemolytic capability of chitosan NPs increased along with the raise of concentration. Furthermore, studies with cell culture showed that these pH-responsive NPs displayed low cytotoxic effects against 3T3 fibroblasts. The influence of chitosan molecular weight, chitosan to TPP weight ratio, nanoparticle size and nature of the surfactant counterion on the membrane-disruptive properties of nanoparticleswas discussed in detail. Altogether, the results achieved here showed that by inserting the lysine-based amphiphiles into chitosan NPs, pH-sensitive membranolytic and potentially endosomolytic nanocarriers were developed, which, therefore, demonstrated ideal feasibility for intracellular drug delivery

Discriminação de áreas de pastagens plantadas por meio de séries temporais EVI-2.

Técnicas envolvendo a análise multitemporal vêm sendo amplamente empregadas em estudos com imagens de sensores ópticos. Alguns alvos possuem comportamento dinâmico no que diz respeito à resposta espectral no decorrer do tempo, como a paisagem agrícola, pastagens e a cobertura vegetal.O objetivo deste trabalho é avaliar o potencial de séries temporais EVI-2 (Enhanced Vegetation-2) para discriminar áreas de pastagens plantadas de áreas naturais, incluindo áreas com pastagens naturais.A área de estudo está localizada na região do município de Aquidauana (MS), entre as coordenadas 19º 24´e 19º 58´de latitude sul e 55º 43´ e 55 02´de longitude oeste. As estações do ano, chuvosa e seca, foram definidas a partir dos dados de precipitação mensal acumulada da estação pluviométrica de Taboco (20º 04? 13??S e 55º 38? 43??O). Os perfis temporais de EVI-2 foram derivados de imagens TM\Landsat de 2008 a 2011. A discriminação das classes analisadas foi avaliada por meio do teste não paramétrico Kruskal-Wallis ANOVA e apresentado por meio de dendrogramas.Os resultados indicaram que em ambas as estações a discriminação das áreas de pastagens das áreas de vegetação natural analisadas foi possível. Em 66% e 80% das imagens de EVI-2 as áreas de pastagens plantadas foram discriminadas nas estações chuvosa e seca, respectivamente

Discriminação de pastagem plantada por meio da classificação supervisionada das séries multitemporais de EVI-2 na transição Pantanal-Cerrado.

Dada a alta demanda pela espacialização das áreas de pastagens plantadas e a eficiência da classificação supervisionada de séries temporais de EVI-2 derivadas de imagens de média resolução (De Paula, 2013), objetivou-se discriminar e gerar mapa de pastagens plantadas por meio da classificação supervisionada utilizando o classificador máxima verossimilhança (MaxVer) aplicado à séries temporais de EVI-2 derivadas de imagens de média resolução espacial

Reduction Of Blood Nitric Oxide Levels Is Associated With Clinical Improvement Of The Chronic Pelvic Pain Related To Endometriosis.

The objective of this prospective study was to determine the plasma levels of nitric oxide (NO) in women with chronic pelvic pain secondary to endometriosis (n=24) and abdominal myofascial pain syndrome (n=16). NO levels were measured in plasma collected before and 1 month after treatment. Pretreatment NO levels (μM) were lower in healthy volunteers (47.0±12.7) than in women with myofascial pain (64.2±5.0, P=0.01) or endometriosis (99.5±12.9, P<0.0001). After treatment, plasma NO levels were reduced only in the endometriosis group (99.5±12.9 vs 61.6±5.9, P=0.002). A correlation between reduction of pain intensity and reduction of NO level was observed in the endometriosis group [correlation = 0.67 (95%CI = 0.35 to 0.85), P<0.0001]. Reduction of NO levels was associated with an increase of pain threshold in this group [correlation = -0.53 (-0.78 to -0.14), P<0.0001]. NO levels appeared elevated in women with chronic pelvic pain diagnosed as secondary to endometriosis, and were directly associated with reduction in pain intensity and increase in pain threshold after treatment. Further studies are needed to investigate the role of NO in the pathophysiology of pain in women with endometriosis and its eventual association with central sensitization.0

Inclusion of a pH‑responsive amino acid‑based amphiphile in methotrexate‑loaded chitosan nanoparticles as a delivery strategy in cancer therapy

The encapsulation of antitumor drugs in nanosized systems with pH-sensitive behavior is a promising approach that may enhance the success of chemotherapy in many cancers. The nanocarrier dependence on pH might trigger an efficient delivery of the encapsulated drug both in the acidic extracellular environment of tumors and, especially, in the intracellular compartments through disruption of endosomal membrane. In this context, here we reported the preparation of chitosan-based nanoparticles encapsulating methotrexate as a model drug (MTX-CS-NPs), which comprises the incorporation of an amino acid-based amphiphile with pH-responsive properties (77KS) on the ionotropic complexation process. The presence of 77KS clearly gives a pH-sensitive behavior to NPs, which allowed accelerated release of MTX with decreasing pH as well as pH-dependent membrane-lytic activity. This latter performance demonstrates the potential of these NPs to facilitate cytosolic delivery of endocytosed materials. Outstandingly the cytotoxicity of MTX-loaded CS-NPs was higher than free drug to MCF-7 tumor cells and, to a lesser extent, to HeLa cells. Based on the overall results, MTX-CS-NPs modified with the pH-sensitive surfactant 77KS could be potentially useful as a carrier system for intracellular drug delivery and, thus, a promising targeting anticancer chemotherapeutic agent