Hydrogels based on galactomannan and κ-carrageenan containing immobilized biomolecules for in vivo thermal-burn wound treatment.

Hydrogels based on natural polysaccharides have demonstrated efficacy in epithelial recovery from cutaneous burn wounds. Here, we prepared a double-network hydrogel consisting of galactomannan (from Cassia grandis seeds) and κ-carrageenan (commercially sourced), cross-linked with CaCl2, as a matrix for immobilizing lactoferrin and/or Cramoll, aiming at its applicability as dressings for second-degree burn wounds. The formulations obtained [H - hydrogel, HL - hydrogel + lactoferrin, HC - hydrogel + Cramoll and HLC - hydrogel + lactoferrin + Cramoll] were analyzed rheologically as well as in terms of their stability (pH, color, microbial contamination) for 90 days. The burn was created with an aluminum bar (97 ± 3 °C) in the dorsal region of Wistar rats and subsequently treated with hydrogels (H, HL, HC, HLC) and control saline solution (S). The burn was monitored for 3, 7 and 14 days to evaluate the efficacy of the hydrogels in promoting wound healing. The hydrogels did not reveal significant pH or microbiological changes; there was an increase in brightness and a reduction in opacity for H. The rheological analysis confirmed the gel-like viscoelastic signature of the systems without substantial modification of the basic rheological characteristics, however HLC proved to be more rigid, due to rheological synergy when combining protein biomolecules. Macroscopic analyses confirmed centripetal healing with wound contraction: S < H < HC < HL < HLC. Histopathological analyses showed that hydrogel-treated groups reduced inflammation, tissue necrosis and fibrosis, while promoting re-epithelialization with focal acanthosis, especially in HLC due to a positive synergistic effect, indicating its potential as a promising therapy in the repair of burns.

Detachment forces during parallel-plate gap separation mediated by a simple yield-stress fluid.

In this work we have monitored the multiple stages of the normal traction force response of a yield-stress fluid confined between two circular parallel plates that are separated at constant velocity. At narrow initial gaps, the air-fluid interface suffers from the Saffman-Taylor instability, confirmed by visual inspection of fingering patterns imprinted on the fluid. At larger initial gaps, the fluid preserves the initially imposed circular symmetry of the confining plates, indicating the absence of instability. Due to the system characteristics and experimental environment, the multiple traction force contributions occurred in cascade, permitting us to isolate the adhesion responses associated with viscosity, capillarity, and yield stress. Employing a standard Herschel-Bulkley model, we assessed the scaling of the traction force in multiple regimes-specifically, evaluating the dependencies of the fingering to yield-stress transitions.

Antifungal Nanoformulation for Biocontrol of Tomato Root and Crown Rot Caused by Fusarium oxysporum f. sp. radicis-lycopersici.

Tomatoes (Solanum lycopersicum L.) are the most cultivated and important vegetable crop in the world. These plants can wilt during crop growth due to fusarium wilt (fusariosis), a disease that damages tomato vascular systems. The Fusarium isolated and analyzed in this work correspond to Fusarium oxysporum f. sp. radicis-lycopersici. The isolates were molecularly identified, and analysis was done on the in vitro effects of the nanoemulsions (previously obtained from extracts of Chilean medicinal plants of the genera Psoralea and Escallonia) to inhibit mycelial and conidial germination of the isolates. Subsequently, the nanoemulsions were evaluated under greenhouse conditions for preventive control of fusariosis in the root and crown, with high levels of disease control observed using the highest concentrations of these nanoemulsions, at 250 and 500 ppm.

A Comparison of Immediate and Short-Term Defensive Responses to Phytophthora Species Infection in Both Susceptible and Resistant Walnut Rootstocks.

Clonal rootstocks are one alternative used by the walnut industry to control damage caused by Phytophthora species, traditionally using plants grafted on susceptible Juglans regia rootstock. Vlach, VX211, and RX1 are clonal rootstocks with a degree of resistance to Phytophthora species. The resistance to pathogens in these rootstocks depends on the resistance mechanisms activated by the presence of the pathogen and subsequent development of responses in the host. In this work, we analyzed how plants of J. regia, Vlach, VX211, and RX1 responded to inoculation with Phytophthora cinnamomi or Phytophthora citrophthora isolates obtained from diseased English walnut plants from Chilean orchards. After inoculation, plants of Vlach, VX211, and RX1 showed canopy and root damage indexes that did not differ from noninoculated control plants. In contrast, plants of J. regia, which is susceptible to P. cinnamomi and P. citrophthora, died after inoculation. Vlach, VX211, and RX1 plants inoculated with P. cinnamomi or P. citrophthora showed greater root weight and volume and greater root growth rates than their respective controls. These results suggest that short-term carbohydrate dynamics may be related to the defense mechanisms of plants; they are immediately activated after inoculation through the production of phenolic compounds, which support the further growth and development of roots in walnut clonal rootstocks. To our knowledge, this is the first study that comprehensively characterizes vegetative and radicular growth and the dynamics of sugars and phenols in response to infection with P. cinnamomi or P. citrophthora in walnut rootstocks.

Solvent self-diffusion dependence on the swelling degree of a hydrogel.

This article describes high-field nuclear magnetic resonance experiments using pulsed gradient spin echo methods to investigate water mobility inside homogeneously swollen polyacrylamide hydrogel beads. The NMR data permitted determining the solvent self-diffusion coefficient dependence on either the swelling time or the polymer volume fraction. The sensitivity to the structure of the hydrogel network could be tuned to a certain extent via controlling the diffusion probing time. Relaxation measurements have helped substantiate a theoretical description for these self-diffusion dependencies based upon a fast-exchange two-site model. A tortuosity-porosity dependence is extracted from the model and then compared to other known tortuosity regimes. The diffusion dependence on the degree of swelling obtained here corroborates the existence of a gel swelling-front observed during inhomogeneous solvent imbibition experiments. Finally, we stress that the NMR experimental results reported here are of great value on performing theoretical modeling of gel swelling via solvent imbibition.

Patterns in Saccharomyces cerevisiae yeast colonies via magnetic resonance imaging.

We report the use of high-resolution magnetic resonance imaging methods to observe pattern formation in colonies of Saccharomyces cerevisiae. Our results indicate substantial signal loss localized in specific regions of the colony rendering useful imaging contrast. This imaging contrast is recognizable as being due to discontinuities in magnetic susceptibility (χ) between different spatial regions. At the microscopic pixel level, the local variations in the magnetic susceptibility (Δχ) induce a loss in the NMR signal, which was quantified via T2 and T2* maps, permitting estimation of Δχ values for different regions of the colony. Interestingly the typical petal/wrinkling patterns present in the colony have a high degree of correlation with the estimated susceptibility distribution. We conclude that the presence of magnetic susceptibility inclusions, together with their spatial arrangement within the colony, may be a potential cause of the susceptibility distribution and therefore the contrast observed on the images.

Investigating a galactomannan gel obtained from Cassia grandis seeds as immobilizing matrix for Cramoll lectin.

Characterization, with emphasis on the rheological properties, of Cassia grandis seeds galactomannan gel containing immobilized Cramoll 1-4 is presented. The gels, with and without immobilized Cramoll 1-4, were evaluated along time by rheometry, pH, color, microbial contamination and lectin hemagglutinating activity (HA). Rheological determinations confirmed the gels to be very stable up to 30 days with variations occurring after this period. Rheological data also showed that the gel/Cramoll 1-4 immobilizing matrix loses its elastic modulus substantially after 60 days. Both gels presented no microbial contamination as well as a pH close to neutral. Colorimetric parameters demonstrated the gels transparency with occasional yellowness. The opacity of the galactomannan gel did not change significantly along the study; the same did not occur for the gel with immobilized Cramoll 1-4 as a statistically significant reduction of its opacity was observed. In what concerns immobilized Cramoll 1-4 HA, up to 90% of its initial HA was maintained after 20 days, with a decrease to 60% after 60 days. These results combined with the thickening and stabilizing characteristics of the galactomannan gel make this gel a promising immobilizing matrix for Cramoll 1-4 that can be further exploited for clinical and cosmetic applications.

Prevalência de acidentes de trabalho em Dourados-MS ocorridos no período de 2012 a 2014 / Work accidents prevalence in Dourados-MS occurred in the period 2012-2014

No Brasil os acidentes de trabalho representam sérios problemas de saúde pública com aproximadamente 25% de lesões por causas externas atendidas nos serviços de urgências e emergências. Os trabalhadores adoecem e morrem por causas relacionadas ao trabalho em decorrência direta das atividades profissionais exercidas e das indiretas por doenças relacionadas com o trabalho. Objetivo: Descrever o perfil epidemiológico de todos os trabalhadores acometidos por acidentes de trabalhos assistidos pelos serviços de saúde públicos do Sistema Único de Saúde (SUS) e privados, notificantes do Sistema de Informação de Agravos de Notificação (SINAN) de Dourados-MS, no período de 2012 a 2014. Materiais e Métodos: Estudo transversal pautado na consulta do sistema de informação do banco de dados do SINAN, entre 2012 e 2014. Resultados: Em Dourados, no período considerado, foram notificados 262 casos de agravos e doenças relacionadas ao trabalho, sendo: acidentes graves (n=60/22,9%); acidentes biológicos (n=167/63,8%); intoxicações exógenas (n=4/1,5%); LER/DORT (n=29/11%); transtornos mentais (n=2/0,8%). Predominaram os acidentes e doenças entre trabalhadoras (68,7%). Houve predomínio de acidentes na faixa etária dos 28 aos 37 anos (29%). Conclusão: Prevaleceram os acidentes biológicos, entre mulheres, no período pesquisado. A avaliação epidemiológica dos agravos à saúde e acidentes envolvendo os trabalhadores é fundamental para o desenvolvimento das políticas públicas voltadas a esse grupo, contudo é necessário o aperfeiçoamento do sistema de informação, das ações de promoção, prevenção, controle e reabilitação do trabalhador.

In Brazil, industrial accidents pose serious public health problem with approximately 25% of injuries from external causes in the emergency care services. Workers get sick and die from causes related to work as a direct result of the exercised professional activities and indirect related diseases work. Objective: To describe the epidemiological profile of all affected workers work accidents assisted by the public health services of the Unified Health System (SUS) and private notifying the Notifiable Diseases Information System (SINAN) in Dourados-MS, period from 2012 to 2014. Materials and Methods: cross-sectional study guided by the consultation in the information system of the SINAN database between 2012 and 2014. Results: in Dourados, in the period considered, were reported 262 cases of injuries and illnesses related to work, as follows: serious accidents (n = 60 / 22.9%); biological accidents (n = 167 / 63.8%); exogenous intoxication (n = 4 / 1.5%); RSI / MSDs (n = 29/11%); mental disorders (n = 2 / 0.8%). Predominated accidents and diseases among workers (68.7%). There was a predominance of accidents in the age group of 28 to 37 years (29%). Conclusion: Prevailed biological accidents among women, in the period surveyed. Epidemiological evaluation of health hazards and accidents involving workers is key to the development of public policies aimed at this group, however it is necessary to improve the information system of promotion, prevention, control and rehabilitation of the worker.

Development and characterization of a new hydrogel based on galactomannan and κ-carrageenan.

A new hydrogel based on two natural polysaccharides was prepared in aqueous medium with 1.7% (w/v) galactomannan (from Cassia grandis seeds) and different concentrations of κ-carrageenan (0.3, 0.4 and 0.5%w/v), CaCl2 (0.0, 0.1 and 0.2M) and pH (5.0, 5.5 and 6.0), using a full factorial design based on rheological parameters. The best formulation was obtained with 1.7% (w/v) galactomannan and 0.5% (w/v) κ-carrageenan, containing 0.2M CaCl2 at pH 5.0. Nuclear magnetic resonance and scanning electron microscopy where used in order to characterize the hydrogel formulation. A shelf life study was carried out with this formulation along 90 days-period of storage at 4 °C, evaluating pH, color, microbial contamination and rheology. This hydrogel showed no significant changes in pH, no microbial contamination and became more translucent along the aging. Analyses by nuclear magnetic resonance and rheology showed a larger organization of the polysaccharides in the hydrogel matrix. The results demonstrated that this hydrogel was stable with possible applications in medical and cosmetic fields.

Development and characterization of hydrogels based on natural polysaccharides: policaju and chitosan.

The development of hydrogels based on natural polysaccharides was investigated by preparing mixtures of policaju/chitosan at weight ratios of 1:4 and 2:3. Utilizing dynamic light scattering (DLS) techniques for these mixtures, an increase on the hydrodynamic particle radius was observed varying their pH from 3.0 to 12.0. Furthermore, a reduction of ζ-potential was also observed for the same pH interval. Following rounds of drying/hydration cycles at a specific pH value, hydrogel matrices were formed. The pore size distribution of these formed hydrogels was examined using scanning electron microscopy. Further FT-IR analyses confirmed a physical interaction between the polysaccharides policaju and chitosan. Swelling experiments revealed water uptake values, after 24h of immersion in water, close to 270% for 1:4, and 320% for 2:3 hydrogels. Finally, rheological measurements were then conducted in order to confirm hydrogel viscoelastic features. These results indicate a promising road to biomaterials fabrication and biomedical applications.

Characterization and rheological study of the galactomannan extracted from seeds of Cassia grandis.

Galactomannan extracted from seeds of Cassia grandis with 0.1M NaCl, followed by ethanol precipitation, presented a yield of 36 ± 8%. The polysaccharide has a constant mannose/galactose ratio (2.44:1). Methylation analysis, one and two dimensional NMR spectroscopy confirmed that the polysaccharide has a central core composed of 4-linked ß-mannose units, with branches of galactose, linked to the carbohydrate core through α(1-6) linkage. The amorphous nature of the galactomannan was confirmed by X-ray diffraction. Rheological characterization exhibited Newtonian plateaus followed by shear-thinning zones characteristic of polymer solutions up to 1.5% (w/v) and above this value the system exhibited yield stress associated with a weak gel. Adjusting stress-strain curves confirmed a 1.6% (w/v) as the galactomannan concentration value for the sol-gel transition. These results indicate that the galactomannan extracted from C. grandis seeds presents rheological characteristics suitable for applications in pharmaceutical, biomedical, cosmetic and food industries.

Free-evolution kinetics in a high-swelling polymeric hydrogel.

We employ nuclear magnetic resonance microimaging to study the kinetics of a high-swelling ionic polymer gel. This includes the time evolution of the sphere diameter and also the evolution of the swollen-unswollen boundary. The experimental results for spherical ionic polyacrylamide gels are compared with the predictions of a nonlinear poroelastic theory by numerically solving the equations for the evolution.

Nuclear magnetic resonance signal dynamics of liquids in the presence of distant dipolar fields, revisited.

The description of the nuclear magnetic resonance magnetization dynamics in the presence of long-range dipolar interactions, which is based upon approximate solutions of Bloch-Torrey equations including the effect of a distant dipolar field, has been revisited. New experiments show that approximate analytic solutions have a broader regime of validity as well as dependencies on pulse-sequence parameters that seem to have been overlooked. In order to explain these experimental results, we developed a new method consisting of calculating the magnetization via an iterative formalism where both diffusion and distant dipolar field contributions are treated as integral operators incorporated into the Bloch-Torrey equations. The solution can be organized as a perturbative series, whereby access to higher order terms allows one to set better boundaries on validity regimes for analytic first-order approximations. Finally, the method legitimizes the use of simple analytic first-order approximations under less demanding experimental conditions, it predicts new pulse-sequence parameter dependencies for the range of validity, and clarifies weak points in previous calculations.

Assessing signal enhancement in distant dipolar field-based sequences.

The possibility of improving the signal-to-noise efficiency of NMR signal refocused by long-range dipolar interactions has been discussed recently [R.T. Branca, G. Galiana, W.S. Warren, Signal enhancement in CRAZED experiments, J. Magn. Reson. 187 (2007) 38-43]. For systems where T(1)>>T(2), by including an extra radio-frequency pulse in a standard CRAZED sequence, it is possible to increase the available signal by exploiting its sensitivity to T(1) relaxation. Here, we use analytical calculations to investigate the source of this improved signal and determine the maximum enhancement provided by the method.

Evaluation of azinphos-methyl resistance and activity of detoxifying enzymes in codling moth (Lepidoptera: Tortricidae) from central Chile.

Regular applications of insecticides have been the main management practice against codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae) in Chile. Organophosphates are the most widely used insecticides, and azinphos-methyl is an important element in spray programs. In particular, we evaluated diagnostic doses of azinphos-methyl on neonate and postdiapausing larvae from seven apple (Malus spp.) orchards. We also evaluated the activity of detoxifying enzymes, such as glutathione S-transferases (GSTs), cytochrome P450 polysubstrate monooxygenases (PSMOs), and esterases, which are likely to be involved in resistance to insecticides. Such responses were compared with an insecticide-susceptible strain that has been maintained in the laboratory for several years. Neonate larval mortality of field populations to azinphos-methyl was not significantly different from of the susceptible strain. In contrast, postdiapause larval mortality was significantly lower in the six analyzed populations than in the susceptible strain. The C. pomonella populations with reduced postdiapause mortality to azinphos-methyl also showed statistically higher GST activity. Finally, no significant differences were found in total esterase or PSMO activity between C. pomonella populations. Therefore, the observed reduction in postdiapause larval mortality to azinphos-methyl seems to be associated with an increase in GST activity.

Enhanced Overhauser contrast in proton-electron double-resonance imaging of the formation of an alginate hydrogel.

Proton-electron double-resonance imaging (PEDRI) was recently employed to monitor the process of formation of a calcium alginate hydrogel at a field of 16mT. Here, under the same experimental conditions, images obtained through this technique are compared to images obtained by conventional T(2)-weighted method. The results confirm that the image contrast obtained using PEDRI, thanks to the Overhauser effect, exhibits an improved sensitivity with respect to changes in water mobility as previously suggested in the literature. Furthermore, by increasing the echo time interval for the T(2)-weighted images, important features of the gelling dynamics obtained via PEDRI could not be reproduced.

Simultaneous measurement of D and T2 using the distant dipolar field.

The presence of long-range dipolar fields in liquids is known to introduce a non-linear term in the Bloch-Torrey equations which is responsible for many interesting effects in nuclear magnetic resonance as well as in magnetic resonance imaging. We show here, for the first time, that the diffusion coefficient D and the spin-spin relaxation time T2 can be obtained simultaneously from the time evolution profile of the long-range dipolar field refocused signal. In a COSY Revamped by Z-asymmetric Echo Detection sequence, the analytical first-order approximation solution of the Bloch-Torrey equations modified to include the effect of the distant dipolar field is used to demonstrate the technique in an experiment using doped water.

Distant-dipole field in liquids and diffusion: a perturbative approach.

A perturbative approach is employed to solve the Bloch-Torrey equations in the presence of distant-dipole fields in nuclear magnetic resonance. The procedure, although only carried out to first order in the perturbation parameter a=1/k2Dtaud, could, in principle, be generalized to higher orders. Here D is the diffusivity, taud the dipolar demagnetization time, and k is the wave vector of the spatial modulation of magnetization produced by the magnetic field gradient. The results are especially interesting for dilute binary mixtures consisting of molecular species with different diffusivities. In this case the calculated two-dimensional correlation spectroscopy revamped by asymmetric Z-gradient echo detection spectra are shown to be free from some inadequacies resulting from a simplistic application of standard approximations.

Intermolecular double-quantum coherences in two-dimensional spectra of binary mixtures in solution. The role of diffusion.

Proton NMR two-dimensional 2-D spectra of binary mixtures, obtained with the correlation spectroscopy revamped by asymmetric Z gradient echo detection pulse sequence, were employed to test various assumptions usually adopted to describe the role of diffusion in intermolecular double quantum coherences. When two molecular species, with significantly different diffusivities, are considered, the relative amplitudes of the peaks, and their widths, furnish a stringent test that unveils some inadequacies in standard approximations.

Low field intermolecular double-quantum coherence imaging via the Overhauser effect.

Intermolecular double-quantum coherence (i-DQC) signals in liquids are usually associated with high magnetic fields. We demonstrate that, in a magnetic field of only 16mT, i-DQC imaging of water protons is feasible thanks to the nuclear magnetization enhancement produced by the Overhauser effect. i-DQC images of a phantom containing an aqueous solution of a trityl free radical, with phase encoding in the DQC evolution period or in the acquisition period, are presented. Possible applications of low field i-MQC images are proposed.