Investigation of charged polymer influence on green fluorescent protein thermal stability

Methods of stabilization and formulation of proteins are important in both biopharmaceutical and biocatalysis industries. Polymers are often used as modifiers of characteristics of biological macromolecules to improve the biochemical activity and stability of proteins or drug bioavailability. Green fluorescent protein (GFP) shows remarkable structural stability and high fluorescence; its stability can be directly related to its fluorescence output, among other characteristics. GFP is stable under increasing temperatures, and its thermal denaturation is highly reproducible. Relative thermal stability was undertaken by incubation of GFP at varying temperatures and GFP fluorescence was used as a reporter for unfolding. At 80 degrees C, DEAE-dextran did not have any effect on GFP fluorescence, indicating that it does not confer stability.

Monitoring the authenticity of Brazilian UHT milk: A chemometric approach

In this work, chemometric methods are reported as potential tools for monitoring the authenticity of Brazilian ultra-high temperature (UHT) milk processed in industrial plants located in different regions of the country. A total of 100 samples were submitted to the qualitative analysis of adulterants such as starch, chlorine, formal. hydrogen peroxide and urine. Except for starch, all the samples reported, at least, the presence of one adulterant. The use of chemometric methodologies such as the Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) enabled the verification of the occurrence of certain adulterations in specific regions. The proposed multivariate approaches may allow the sanitary agency authorities to optimise materials, human and financial resources, as they associate the occurrence of adulterations to the geographical location of the industrial plants. (c) 2010 Elsevier Ltd. All rights reserved.

Application of thermal sums concept to estimate the time to harvest new banana hybrids for export

Application of the thermal sum concept was developed to determine the optimal harvesting stage of new banana hybrids to be grown for export. It was tested on two triploid hybrid bananas, FlhorBan 916 (F916) and FlhorBan 918 (F918), created by CIRAD`s banana breeding programme, using two different approaches. The first approach was used with F916 and involved calculating the base temperature of bunches sampled at two sites at the ripening stage, and then determining the thermal sum at which the stage of maturity would be identical to that of the control Cavendish export banana. The second approach was used to assess the harvest stage of F918 and involved calculating the two thermal parameters directly, but using more plants and a longer period. Using the linear regression model, the estimated thermal parameters were a thermal sum of 680 degree-days (dd) at a base temperature of 17.0 degrees C for cv. F916, and 970 dd at 13.9 degrees C for cv. F918. This easy-to-use method provides quick and reliable calculations of the two thermal parameters required at a specific harvesting stage for a given banana variety in tropical climate conditions. Determining these two values is an essential step for gaining insight into the agronomic features of a new variety and its potential for export. (C) 2011 Elsevier B.V. All rights reserved.

Thermal properties and release of Lippia sidoides essential oil from gum arabic/maltodextrin microparticles

Microencapsulation of Lippia sidoides essential oil was carried out by spray drying. Blends of maltodextrin and gum arabic were used as carrier. Spray dried microparticles were characterized using conventional (thermogravimetry, evolved gas analysis) and combined (thermogravimetry-mass spectrometry analysis) thermal analysis techniques in order to evaluate the abilities of carriers with different compositions in retaining and in releasing the core vs. dynamic heating. Thermal analysis was useful to evaluate the physico-chemical interactions between the core and carriers and to determine the protective effect of the carriers on the evaporation of essential oil.

Thermal Characteristics of Polybia scutellaris Nests (Hymenoptera: Vespidae) Using Computational Fluid Dynamics: A Possible Adaptation to Tropical Climates

Polybia scutellaris constructs huge nests characterized by numerous spinal projections on the surface. We investigated the thermal characteristics of P scutellaris nests in order to determine whether their nest temperature is homeothermically maintained and whether the spines play a role in the thermoregulation of the nests. In order to examine these hypotheses, we measured the nest temperature in a active nest and in an abandoned nest. The temperature in the active nest was almost stable at 27 degrees C, whereas that of the abandoned nest varied with changes in the ambient temperature, suggesting that nest temperature was maintained by the thermogenesis of colony individuals. In order to predict the thermal properties of the spines, a numerical simulation was employed. To construct a 3D-model of a P scutellaris nest, the nest architecture was simplified into an outer envelope and the surface spines, for both of which the initial temperature was set at 27 degrees C. The physical properties of the simulated nest were regarded to be those of wood since the nest of this species is constructed from plant materials. When the model was exposed to cool air (12 degrees C), the temperature was lower in the models with more spines. On the other hand, when the nest was heated (42 degrees C), the temperature increase was smaller in models with more spines. It is suggested that the spines act as a heat radiator, not as an insulator, against the changes in ambient temperature.

Real-time monitoring and kinetic parameter estimation of the affinity interaction of jArtinM and rArtinM with peroxidase glycoprotein by the electrogravimetric technique

ArtinM is a D-mannose binding lectin that has been arousing increasing interest because of its biomedical properties, especially those involving the stimulation of Th1 immune response, which confers protection against intracellular pathogens The potential pharmaceutical applications of ArtinM have motivated the production of its recombinant form (rArtinM) so that it is important to compare the sugar-binding properties of jArtinM and rArtinM in order to take better advantage of the potential applications of the recombinant lectin. In this work, a biosensor framework based on a Quartz Crystal Microbalance was established with the purpose of making a comparative study of the activity of native and recombinant ArtinM protein The QCM transducer was strategically functionalized to use a simple model of protein binding kinetics. This approach allowed for the determination of the binding/dissociation kinetics rate and affinity equilibrium constant of both forms of ArtinM with horseradish peroxidase glycoprotein (HRP), a N-glycosylated protein that contains the trimannoside Man alpha 1-3[Man alpha 1-6]Man, which is a known ligand for jArtinM (Jeyaprakash et al, 2004). Monitoring of the real-time binding of rArtinM shows that it was able to bind HRP, leading to an analytical curve similar to that of jArtinM, with statistically equivalent kinetic rates and affinity equilibrium constants for both forms of ArtinM The lower reactivity of rArtinM with HRP than jArtinM was considered to be due to a difference in the number of Carbohydrate Recognition Domains (CRDs) per molecule of each lectin form rather than to a difference in the energy of binding per CRD of each lectin form. (C) 2010 Elsevier B V. All rights reserved

Thermal Characteristics of the Mud Nests of the Social Wasp Polybia spinifex (Hymenoptera; Vespidae)

The thermal characteristics of mud nests of Polybia spinifex were investigated by measuring internal and surface temperatures of the nests. The nests had a layer of mud envelope and consisted of mud with fine sand particles. The envelope had a vertically long slit-like entrance hole. The mud nests had high thermal conductivities (0.51-0.67 W/(m degrees C)) comparable to brick, rather than insulation materials of wasps` nests such as paper and wood. It was revealed that the long entrance radiated more heat from the thereto-image. The rate of thermal radiation (emissivity) of the nest surface was 0.80, and the value was similar to that of sand. The internal temperatures of the nests were high from top (T(n1), temperature difference between ambient temperature (T(a)) was 10 degrees C) to bottom (T(n3), difference, 5 degrees C) at noon. On the other hand, the temperature distributions were reversed during the night. Temperature T(n1) was lower by 1 degrees C than T(a), possibly from nightly dew on the top surface, whereas, at the middle point (T(n2),) and T(n3), temperatures were higher by 1 degrees C compared to T(a). Temperature fluctuations (ranges between maximum and minimum temperature) at T(n2) and T(n3) were similar to that of T(a), whereas the values at T(n1) and T(s) were higher than that of T(a).

Pt-RuO(2) electrodes prepared by thermal decomposition of polymeric precursors as catalysts for direct methanol fuel cell applications

The electrocatalytic activity of Pt and RuO(2) mixed electrodes of different compositions towards methanol oxidation was investigated. The catalysts were prepared by thermal decomposition of polymeric precursors and characterized by energy dispersive X-ray, scanning electronic microscopy, X-ray diffraction and cyclic voltammetry. This preparation method allowed obtaining uniform films with controlled stoichiometry and high surface area. Cyclic voltammetry experiments in the presence of methanol showed that mixed electrodes decreased the potential peak of methanol oxidation by approximately 100 mV (RHE) when compared to the electrode containing only Pt. In addition, voltammetric experiments indicated that the Pt(0.6)Ru(0.4)O(y) electrode led to higher oxidation current densities at lower potentials. Chronoamperometry experiments confirmed the contribution of RuO(2) to the catalytic activity as well as the better performance of the Pt(0.6)Ru(0.4)O(y) electrode composition. Formic acid and CO(2) were identified as being the reaction products formed in the electrolysis performed at 400 and 600 mV. The relative formation of CO(2) was favored in the electrolysis performed at 400 mV (RHE) with the Pt(0.6)Ru(0.4)O(y) electrode. The presence of RuO(2) in Pt-Ru-based electrodes is important for improving the catalytic activity towards methanol electrooxidation. Moreover, the thermal decomposition of polymeric precursors seems to be a promising route for the production of catalysts applicable to DMFC. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

Quantification of carbamazepine, carbamazepine-10,11-epoxide, phenytoin and phenobarbital in plasma samples by stir bar-sorptive extraction and liquid chromatography

A sensitive and reproducible stir bar-sorptive extraction and high-performance liquid chromatography-UV detection (SBSE/HPLC-UV) method for therapeutic drug monitoring of carbamazepine, carbamazepine-10,11-epoxide, phenytoin and phenobarbital in plasma samples is described and compared with a liquid:liquid extraction (LLE/HPLC-UV) method. Important factors in the optimization of SBSE efficiency such as pH, extraction time and desorption conditions (solvents, mode magnetic stir, mode ultrasonic stir, time and number of steps) assured recoveries ranging from 72 to 86%, except for phenytoin (62%). Separation was obtained using a reverse phase C-18 column with UV detection (210 nm). The mobile phase consisted of water: acetonitrile (78:22, v/v). The SBSE/HPLC-UV method was linear over a working range of 0.08-40.0 mu g mL(-1) for carbamazepine, carbamazepine-10,11-epoxide and phenobarbital and 0.125-40.0 mu g mL(-1) for phenytoin, The intra-assay and inter-assay precision and accuracy were studied at three concentrations (1.0, 4.0 and 20.0 mu g mL(-1)). The intra-assay coefficients of variation (CVs) for all compounds were less than 8.8% and all inter-CVs were less than 10%. Limits of quantification were 0.08 mu g mL(-1) for carbamazepine, carbamazepine-10,11-epoxide and phenobarbital and 0.125 mu g mL(-1) for phenytoin. No interference of the drugs normally associated with antiepileptic drugs was observed. Based on figures of merit results, the SBSE/HPLC-UV proved adequate for antiepileptic drugs analyses from therapeutic levels. This method was successfully applied to the analysis of real samples and was as effective as the LLE/HPLC-UV method. (c) 2008 Elsevier B.V. All rights reserved.

Characterization and voltammetric behavior of Pt(y)Mo(z)O(x)/C electrodes prepared by the thermal decomposition of polymeric precursors

Carbon-supported catalysts containing platinum and molybdenum oxide are prepared by thermal decomposition of polymeric precursors. The Pt(y)Mo(z)O(x)/C materials are characterized by energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction. The catalysts present a well-controlled stoichiometry and nanometric particles. Molybdenum is present mainly as the MoO(3) orthorhombic structure, and no Pt alloys are detected. The voltammetric behavior of the electrodes is investigated; a correlation with literature results for PtMo/C catalysts prepared by other methods is established. The formation of soluble species and the aging effect are discussed. (C) 2009 Elsevier B.V. All rights reserved.

Potential of Amaranthus cruentus BRS Alegria in the production of flour, starch and protein concentrate: chemical, thermal and rheological characterization

BACKGROUND: Amaranth is a little-known culture in Brazilian agriculture. Amaranthus cruentus BRS Alegria was the first cultivar recommended by Embrapa for the soil of the Brazilian scrubland. In order to evaluate the potential of this species in the production of flour, starch and protein concentrates, the latter products were obtained from A. cruentus BRS Alegria seeds, characterized and compared with the products obtained from the A. caudatus species cultivated in its soil of origin. RESULTS: The seeds of A. cruentus BRS Alegria furnished high-purity starch and flour with significant content of starch, proteins, and lipids. The starch and flour of this species presented higher gelatinization temperatures and formed stronger gels upon cooling compared with those obtained from the A. caudatus species. This is due to their greater amylose content and a difference in the composition of the more important fatty acids, such as stearic, oleic and linoleic acids, which indicates that they have greater heat stability. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and differential scanning calorimetry revealed the presence of albumins, globulins, glutelins and prolamins in the protein concentrate, which was obtained as a byproduct of starch production. CONCLUSION: Amaranthus cruentus BRS Alegria has potential application in the production of flour, starch and protein concentrates, with interesting characteristics for use as food ingredients. (C) 2010 Society of Chemical Industry

Rifampicin determination in plasma by stir bar-sorptive extraction and liquid chromatography

A sensitive and reproducible stir bar-sorptive extraction and high performance liquid chromatography-UV detection (SBSE/HPLC-UV) method for therapeutic drug monitoring of rifampicin in plasma samples is described and compared with a liquid:liquid extraction (LLE/HPLC-UV) method. This miniaturized method can result in faster analysis, higher sample throughput, lower solvent consumption and less workload per sample while maintaining or even improving sensitivity. Important factors in the optimization of SBSE efficiency such as pH, temperature, extraction time and desorption conditions (solvents, mode magnetic stir, mode ultrasonic stir, time and number of steps) were optimized recoveries ranging from 75 to 80%. Separation was obtained using a reverse phase C(8) column with UV detection (254 nm). The mobile phase consisted of methanol:0.25 N sodium acetate buffer, pH 5.0 (58:42, v/v). The SBSE/HPLC-UV method was linear over a working range of 0.125-50.0 mu g mL(-1). The intra-assay and inter-assay precision and accuracy were studied at three concentrations (1.25, 6.25 and 25.0 mu g mL(-1)). The intra-assay coefficients of variation (CVs) for all compounds were less than 10% and all inter-CVs were less than 10%. Limits of quantification were 0.125 mu g mL(-1). Stability studies showed rifampicin was stable in plasma for 12 h after thawing; the samples were also stable for 24 h after preparation. Based on the figures of merit results, the SBSE/HPLC-UV proved to be adequate to the rifampicin analyses from therapeutic to toxic levels. This method was successfully applied to the analysis of real samples and was as effective as the LLE/HPLC-UV method. (C) 2009 Elsevier B.V. All rights reserved.

Evaluation of the aquatic macroinvertebrate community as a tool for monitoring a reservoir in the Pitangui river basin, Parana, Brazil

Evaluation of the aquatic macroinvertebrate community as a tool for monitoring a reservoir in the Pitangui river basin, Parana, Brazil. Benthic and nektonic macroinvertebrates play an important role in the structure and function of aquatic ecosystems and their distribution is influenced by chemical features of the substrate, vegetation composition, and water depth. Knowledge on the fauna contributes to the assessment of water quality and development of biodiversity conservation activities. Different biotic factors affecting the invertebrate community were evaluated in the Alagados reservoir, the main water source of the city of Ponta Grossa, Parana. In five different sampling points, 18,473 specimens of aquatic or semiaquatic macroinvertebrates were collected, belonging to 46 taxa of the phylla Annelida (Hirudinea and Oligochaeta), Mollusca (Gastropoda), Platyhelminthes (Turbellaria), Nematoda and Arthropoda (Arachnida, Crustacea and Insecta). This community was composed mainly of predators (45.7% of the taxa sampled), collectors and/or filterers (23.9%), scrapers (15.2%), shredders (13.0%) and detritivores (2.2%). Diversity (H`) and evenness (J) indices were significantly low for the sites examined, and H` ranged between 0.3301 and 1.0396. Regarding tolerance of organisms to organic pollution, more sensitive taxa were very rare (Plecoptera) or unusual (Trichoptera and Ephemeroptera). Among the more resistant groups are Chironomidae and Hirudinea, both fairly common in the samples. This study corroborates the importance of bioindicators as a tool to assess water quality for human consumption and for the conservation of aquatic environments, integrating physical, chemical and biological factors in monitoring programs.

Home blood pressure monitoring in blood pressure control among haemodialysis patients: an open randomized clinical trial

Background. It is not known if the adjustment of antihypertensive therapy based on home blood pressure monitoring (HBPM) can improve blood pressure (BP) control among haemodialysis patients. Methods. This is an open randomized clinical trial. Hypertensive patients on haemodialysis were randomized to have the antihypertensive therapy adjusted based on predialysis BP measurements or HBPM. Before and after 6 months of follow-up, patients were submitted to ambulatory blood pressure monitoring (ABPM) for 24 h, HBPM during 1 week and echocardiogram. Results. A total of 34 and 31 patients completed the study in the HBPM and predialysis BP groups, respectively. At the end of study, the systolic (SBP) and diastolic (DBP) blood pressure during the interdialytic period measured by ABPM were significantly lower in the HBPM group in relation to the predialysis BP group (mean 24-h BP: 135 +/- 12 mmHg/76 +/- 7 mmHg versus 147 +/- 15 mmHg/79 +/- 8 mmHg; P < 0.05). In the HBPM analysis, the HBPM group showed a significant reduction only in SBP compared to the predialysis BP group (weekly mean: 144 +/- 21 mmHg versus 154 +/- 22 mmHg; P < 0.05). There were no differences between the HBPM and predialysis BP groups in relation to the left ventricular mass index at the end of the study (108 +/- 35 g/m(2) versus 110 +/- 33 g/m(2); P > 0.05). Conclusions. Decision making based on HBPM among haemodialysis patients has led to a better BP control during the interdialytic period in comparison with predialysis BP measurements. HBPM may be a useful adjuvant instrument for blood pressure control among haemodialysis patients.

INTRACRANIAL PRESSURE MONITORING IN CHILDREN WITH FULMINANT HEPATIC FAILURE

Introduction. We describe a series of 10 children with intracranial hypertension complicating fulminant hepatic failure submitted to intracranial pressure (ICP) monitoring for intensive care an transplantation management. Patients and methods. Information from pediatrics patients acute liver failure admitted to our hospital was collected in a standard protocol form. We analyzed data from 10 patients, medium age 5.2 years old. In this period we studied aspects as ICP transducer used, number of days with ICP monitoring and complications of ICP monitoring. Results. Hepatitis A was diagnosed in five patients and hepatitis B in two cases. The initial ICP were 2 to 24 mmHg in transducer Seven patients died, four due to intracranial hypertension, included the patient operated for subdural hematoma, and three with transplantation failure. Only, a case of hematoma was verified. Conclusions. The application of ICP monitoring allows intensive care for aggressive ICP management. It can be used in children without adaptations. [REV NEUROL 2009: 48: 134-6]