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Dendrimers and supramolecular chemistry continue to fascinate researchers due to the endless unrevealed potential of their combination. This study investigates the self-assembly process of a series of hydrophobic triazolylferrocenyl dendrimers in aqueous medium. Deep investigation through NMR spectroscopy, absorption UV-vis spectroscopy along with theoretical simulations demonstrates that the ferrocenyl moieties interact intramolecularly and intermolecularly driving the self-assembly process. Data obtained by DLS, NTA, SEM, TEM, and EF-TEM demonstrate that these dendrimers, in water, spontaneously self-assemble through a hierarchical process. The dendrimers first self-assemble into uniform nanovesicles, which in turn self-assemble into larger vesosomes. The resulting vesosomes emit green non-traditional intrinsic fluorescence, which is a property that emerged from the self-assembled architectures. The vesosomes are efficiently uptaken by cancer cells and induce significant cytotoxic activity against the cancer cell line MCF-7, up to the submicromolar concentration. Positive dendritic effects are identified in the fluorescence intensity and in the cytotoxic activity of the vesosomes, which follow the trend G0-9Fc < G1-27Fc < G2-81Fc. This work showcases the remarkable potential of combining the two dynamic fields of dendrimers and supramolecular chemistry, which resulted in green fluorescent vesosomes capable of performing the dual role of cell imaging and killing, with potential applications in nanotheranostics.
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Marine green algae produce sulfated polysaccharides with diverse structures and a wide range of biological activities. This study aimed to enhance the biotechnological potential of sulfated heterorhamnan (Gb1) from Gayralia brasiliensis by chemically modifying it for improved or new biological functions. Using controlled Smith Degradation (GBS) and O-alkylation with 3-chloropropylamine, we synthesized partially water-soluble amine derivatives. GBS modification increase sulfate groups (29.3 to 37.5 %) and α-l-rhamnose units (69.9 to 81.2 mol%), reducing xylose and glucose, compared to Gb1. The backbone featured predominantly 3- and 2-linked α-l-rhamnosyl and 2,3- linked α-l-rhamnosyl units as branching points. Infrared and NMR analyses confirmed the substitution of hydroxyl groups with aminoalkyl groups. The modified compounds, GBS-AHCs and GBS-AHK, exhibited altered anticoagulant properties. GBS-AHCs showed reduced effectiveness in the APTT assay, while GBS-AHK maintained a similar anticoagulant activity level to Gb1 and GBS. Increased nitrogen content and N-alkylation in GBS-AHCs compared to GBS-AHK may explain their structural differences. The chemical modification proposed did not enhance its anticoagulant activity, possibly due to the introduction of amino groups and a positive charge to the polymer. This characteristic presents new opportunities for investigating the potential of these polysaccharides in various biological applications, such as antimicrobial and antitumoral activities.
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Anticoagulantes , Chlorophyta , Mananos , Algas Marinas , Sulfatos , Anticoagulantes/farmacología , Anticoagulantes/química , Anticoagulantes/síntesis química , Chlorophyta/química , Algas Marinas/química , Sulfatos/química , Polisacáridos/química , Polisacáridos/farmacología , Polisacáridos/síntesis química , Humanos , Desoxiazúcares/química , Desoxiazúcares/farmacologíaRESUMEN
Food waste is a worldwide problem. One third of the food produced in the world is lost or wasted every year. Most of this waste takes place downstream of the supply chain due to consumer behavior. This issue is expected to increase in both developed and emerging economies. With the beginning of the COVID-19 pandemic, a range of challenges led to changes in consumer behavior. This study explores household food waste behavior during the COVID-19 pandemic through the lens of the Theory of Planned Behavior. The risk perception regarding the pandemic was integrated into a broader framework, which was analyzed by Structural Equation Modeling. The sample comprises the participation of 452 Brazilian individuals. The results show that all the predictors incorporated in the model were statistically significant. The intention of reducing household food waste during the pandemic was found to be the strongest predictor of food waste behavior. Additionally, the pandemic apparently influenced consumers' perceptions about the control they think they have over food waste. This research has theoretical and managerial implications. From a theoretical perspective, this study identifies key predictors of household food waste by considering a period of health crisis in an emerging country. From a managerial standpoint, this research may provide a learning experience for future similar scenarios. Results may also motivate consumers to look for ways to reduce, reuse and recycle food waste.
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Here we provide the 'Global Spectrum of Plant Form and Function Dataset', containing species mean values for six vascular plant traits. Together, these traits -plant height, stem specific density, leaf area, leaf mass per area, leaf nitrogen content per dry mass, and diaspore (seed or spore) mass - define the primary axes of variation in plant form and function. The dataset is based on ca. 1 million trait records received via the TRY database (representing ca. 2,500 original publications) and additional unpublished data. It provides 92,159 species mean values for the six traits, covering 46,047 species. The data are complemented by higher-level taxonomic classification and six categorical traits (woodiness, growth form, succulence, adaptation to terrestrial or aquatic habitats, nutrition type and leaf type). Data quality management is based on a probabilistic approach combined with comprehensive validation against expert knowledge and external information. Intense data acquisition and thorough quality control produced the largest and, to our knowledge, most accurate compilation of empirically observed vascular plant species mean traits to date.
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Anticoagulantes , Rapaces , Rodenticidas , Animales , Anticoagulantes/toxicidad , Argentina , Chile , Rodenticidas/toxicidad , Pruebas de ToxicidadRESUMEN
Dendronized gold nanoparticles (AuNPs) were synthesized bearing charged peripheral groups. Two novel AB3-type dendrons were synthesized with a thiol group at the focal point followed by their attachment to AuNPs. Dendrons were designed to have nine charged peripheral groups (carboxyl or amine), glycol solubilizing, units and one thiol moiety at the focal point. Both dendrons and all intermediates were synthesized in high yields and characterized by nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). The amine- and carboxyl-terminated dendrons were used to functionalize gold nanoparticles (AuNPs) previously stabilized with citrate. The nanoparticles' diameters and their colloidal stability were investigated using dynamic light scattering (DLS). The size and morphology of the dendronized AuNPs were evaluated by scanning electron microscopy (SEM), which revealed individual particles with no aggregation after replacement of citrate by the dendrons, in agreement with the DLS data. The absorption spectroscopy reveals a prominent plasmonic band at 560 nm for all AuNPs. The zeta potential further confirmed the expected charged structures of the dendronized AuNPs. Considering all the physical-chemical properties of the charged dendronized AuNPs developed in this work, these AuNPs might be used as a weapon against multi-drug resistant bacterial infections.
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Three-dimensional printing (3DP) has recently gained importance in the medical industry, especially in surgical specialties. It uses different techniques and materials based on patients' needs, which allows bioprofessionals to design and develop unique pieces using medical imaging provided by computed tomography (CT) and magnetic resonance imaging (MRI). Therefore, the Department of Biology and Medicine and the Department of Physics and Engineering, at the Bioastronautics and Space Mechatronics Research Group, have managed and supervised an international cooperation study, in order to present a general review of the innovative surgical applications, focused on anatomical systems, such as the nervous and craniofacial system, cardiovascular system, digestive system, genitourinary system, and musculoskeletal system. Finally, the integration with augmented, mixed, virtual reality is analyzed to show the advantages of personalized treatments, taking into account the improvements for preoperative, intraoperative planning, and medical training. Also, this article explores the creation of devices and tools for space surgery to get better outcomes under changing gravity conditions.
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Impresión Tridimensional , Realidad Virtual , Humanos , Imagen por Resonancia Magnética , Tomografía Computarizada por Rayos X , Sistema UrogenitalRESUMEN
In this contribution to the subfamily Pseudophyllinae in the Neotropics, we focus on reviewing the status of the genus Dasyscelidius and its three species. After this revision, the genus remains monotypic, including only Dasyscelidius atrifrons (type species), adjusting the diagnosis, limiting it to the characteristics of the only known species for the genus. D. atrifrons, is recorded for the Bogot Savanna, previously in its original description its locality was only Colombia, without additional data on this species in other later contributions. Dasyscelidius brasiliensis is placed into the new genus Pepumiri n. gen., which is similar to Pleminia, including only Pepumiri brasiliensis n. comb., from the middle and highland plateaus of the Brazilian Cerrado. Dasyscelidius minimus is designated as nomen dubium, since the only type specimen is lost, and its original description or later data are very poor and do not allow a good identification. Finally, this contribution contributes to the differentiation between brachypterous taxa of the tribes Pleminiini and Platyphyllini, which in several cases may be similar and difficult to place in each tribe.
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Ortópteros , Distribución Animal , AnimalesRESUMEN
In the synthesis of metallic nanoparticles in microemulsions, we hypothesized that the particle size is controlled by the reaction rate and not by the microemulsion size. Thus, the changes observed in the particle sizes as reaction conditions, such as concentrations, temperatures, the type of surfactant used, etc., are varied which should not be correlated directly to the modification of these conditions but indirectly to the changes they produce in the reaction rates. In this work, the microemulsions were formulated with benzene and water as continuous and dispersed phases, respectively, using n-dodecyltrimethylammonium bromide (DTAB) and n-octanol as the surfactant and cosurfactant. Using time-resolved UV-vis spectroscopy, we measured the reaction rates in the production of palladium (Pd) nanoparticles inside the microemulsions at different reactant concentrations and temperatures, keeping all the other parameters constant. The measured reaction rates were then correlated with the particle sizes measured by transmission electron microscopy (TEM). We found that the nanoparticle size increases linearly as the reaction rate increases, independently of the actual reactant concentration or temperature. We proposed a simple model for the observed kinetics where the reaction rate is controlled mainly by the diffusion of the reducing agent. With this model, we predicted that the particle size should depend indirectly, via the reaction kinetics, on the micelle radius, the water volume and the total microemulsion volume. Some of these predictions were indeed observed and reported in the literature.
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The synthesis and characterisation of new dyes based on indolizines bearing catechol groups in their structure is presented. The preparation was carried out through a simple three component one-pot reaction promoted by CuNPs/C, between pyridine-2-carbaldehyde, an aromatic alkyne and a tetrahydroisoquinoline (THIQ) functionalized with catechol groups. The products were isolated in 30%-34% yield, which was considered more than acceptable considering that the catechol hydroxyl groups were not protected prior to reaction. In view of the colour developed by the products and their response to the acidic and basic conditions of the medium, product 3aa was studied by UV-Vis and NMR spectroscopies at different pH values. We concluded that product 3aa suffered two deprotonations at pKa of 4.4 and 9.5, giving three species in a pH range between 2-12, with colours varying from light red to deep orange. The reversibility of the process observed for 3aa at different pH values, together with its changes in colour, make this new family of products attractive candidates to use them as pH indicators.
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The ABCG2 transporter plays a pivotal role in multidrug resistance, however, no clinical trial using specific ABCG2 inhibitors have been successful. Although ABC transporters actively extrude a wide variety of substrates, photodynamic therapeutic agents with porphyrinic scaffolds are exclusively transported by ABCG2. In this work, we describe for the first time a porphyrin derivative (4B) inhibitor of ABCG2 and capable to overcome multidrug resistance in vitro. The inhibition was time-dependent and 4B was not itself transported by ABCG2. Independently of the substrate, the porphyrin 4B showed an IC50 value of 1.6 µM and a mixed type of inhibition. This compound inhibited the ATPase activity and increased the binding of the conformational-sensitive antibody 5D3. A thermostability assay confirmed allosteric protein changes triggered by the porphyrin. Long-timescale molecular dynamics simulations revealed a different behavior between the ABCG2 porphyrinic substrate pheophorbide a and the porphyrin 4B. Pheophorbide a was able to bind in three different protein sites but 4B showed one binding conformation with a strong ionic interaction with GLU446. The inhibition was selective toward ABCG2, since no inhibition was observed for P-glycoprotein and MRP1. Finally, this compound successfully chemosensitized cells that overexpress ABCG2. These findings reinforce that substrates may be a privileged source of chemical scaffolds for identification of new inhibitors of multidrug resistance-linked ABC transporters.
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Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2/antagonistas & inhibidores , Adenosina Trifosfatasas/antagonistas & inhibidores , Inhibidores Enzimáticos/farmacología , Proteínas de Neoplasias/antagonistas & inhibidores , Porfirinas/farmacología , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2/química , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2/metabolismo , Adenosina Trifosfatasas/química , Adenosina Trifosfatasas/metabolismo , Línea Celular Tumoral , Evaluación Preclínica de Medicamentos , Resistencia a Múltiples Medicamentos/efectos de los fármacos , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/metabolismo , Células HEK293 , Humanos , Irinotecán/farmacología , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Estructura Molecular , Proteínas de Neoplasias/química , Proteínas de Neoplasias/metabolismo , Porfirinas/química , Porfirinas/metabolismo , Unión Proteica , Conformación Proteica/efectos de los fármacosRESUMEN
A water-soluble sulfated heterorhamnan (Gb1) was isolated from the green seaweed Gayralia brasiliensis and purified by ultrafiltration, yielding a homogeneous polysaccharide (Gb1r). Both fractions contained rhamnose, xylose, galacturonic and glucuronic acids, galactose, and glucose. Chemical and spectroscopic methods allowed the determination of Gb1 and Gb1r chemical structure. Their backbones were constituted by 3-, 2-, and 2,3-linked rhamnosyl units (1:0.49:0.13 and 1:0.58:0.17, respectively), which are unsulfated (13.5 and 14.6%), disulfated (16.6 and 17.8%) or monosulfated at C-2 (8 and 8.6%) and C-4 (24.5 and 23.4%). Gb1 was oversulfated giving rise to Gb1-OS, which presented ~2.5-fold higher content of disulfated rhamnosyl units than Gb1, as determined by methylation analyses and NMR spectroscopy. Gb1 and Gb1-OS potently reduced the viability of U87MG human glioblastoma cells. Gb1 caused cell cycle arrest in the G1 phase, increased annexin V-stained cells, and no DNA fragmentation, while Gb1-OS increased the percentage of cells in the S and G2 phases and the levels of fragmented DNA and cells double-stained with annexin V/propidium iodide, suggesting an apoptosis mechanism. The results suggest that the different effects of Gb1 and Gb1-OS were related to differences in the sulfate content and position of these groups along the polysaccharide chains.
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Antineoplásicos/farmacología , Neoplasias Encefálicas/tratamiento farmacológico , Glioma/tratamiento farmacológico , Mananos/farmacología , Algas Marinas , Sulfatos/farmacología , Antineoplásicos/aislamiento & purificación , Neoplasias Encefálicas/patología , Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Glioma/patología , Humanos , Mananos/aislamiento & purificación , Estructura Molecular , Algas Marinas/química , Relación Estructura-Actividad , Sulfatos/aislamiento & purificaciónRESUMEN
In this paper, the biologically inert agarose was selectively modified at C6 of ß-d-Galp units to produce an amino derivative with antibacterial property. The synthetic route involved the preparation of tosyl and azido agarose intermediates. All the polysaccharide derivatives were characterized by mono- and bidimensional 1H and 13C NMR and FT-IR analysis. A water-soluble amino polymer (Mw = 39,000 g mol-1, DSamino = 0.50) was produced by partial acid hydrolysis showing bactericidal and bacteriostatic activity against P. aeruginosa (ATCC 9027), S. aureus (ATCC 6538), and E. coli (ATCC 25922), with MIC values lower than 2.5 mg mL-1 and MBC values ranging from 2.5 to 5.0 mg mL-1.
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Staphylococcus aureus , Antibacterianos , Escherichia coli , Pruebas de Sensibilidad Microbiana , SefarosaRESUMEN
In this study we described the synthesis of a hybrid polysaccharide harboring moieties of ulvan and kappa-carrabiose. Alkylamines (1,3-diaminopropane and 1,6-diaminohexane) were selectively inserted into ß-D-GlcAp and α-L-IdoAp units in the ulvan structure via an amide bond formation producing ulvan-amide derivatives F-DAP (N% = 1.77; Mw = 208 kg mol-1) and F-DAH (N% = 1.77; Mw = 202 kg mol-1), which were reacted with kappa-carrabiose via reductive amination to produce hybrid ulvan-kappa-carrabiose polysaccharides F-DAP-Kb (N% = 1.56; Mw = 206 kg mol-1) and F-DAH-Kb (N% = 1.16; Mw = 200 kg mol-1). All the ulvan derivatives were characterized by 1H and 13C NMR spectroscopy and did not show cytotoxicity against human dermal fibroblasts (HDFa) at the concentrations of 25, 100, and 500 µg mL-1, neither anticoagulant properties at the range of 10-150 µg mL-1. Therefore, the ulvan-amide derivatives and the hybrid ulvan-kappa-carrabiose polysaccharides showed good biocompatibility in vitro, presenting as worthy candidates for tailoring scaffolds for biomedical applications.
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Anticoagulantes/farmacología , Carragenina/farmacología , Polisacáridos/farmacología , Anticoagulantes/síntesis química , Anticoagulantes/toxicidad , Carragenina/síntesis química , Carragenina/toxicidad , Fibroblastos/efectos de los fármacos , Humanos , Tiempo de Tromboplastina Parcial , Polisacáridos/síntesis química , Polisacáridos/toxicidadRESUMEN
Background: A high-throughput method using inductively coupled plasma mass spectrometry (ICP-MS) was developed and validated for the quantitative analysis of antimony in human plasma and peripheral blood mononuclear cells from patients with cutaneous leishmaniasis undergoing treatment with meglumine antimoniate. Materials & methods: Antimony was digested in clinical samples with 1% tetramethylammonium hydroxide/1% EDTA and indium was used as internal standard. Accuracy, precision and stability were evaluated. Conclusion: Taking the lower limit of quantitation to be the lowest validation concentration with precision and accuracy within 20%, the current assay was successfully validated from 25 to 10000 ng/ml for antimony in human plasma and peripheral blood mononuclear cells. This protocol will serve as a baseline for future analytical designs, aiming to provide a reference method to allow inter-study comparisons.
Lay abstract Cutaneous leishmaniasis is a disease caused by single-cell parasites in the genus Leishmania which results in painful skin ulcers and is spread by insect bites. Drugs containing antimony are the mainstay therapy for cutaneous leishmaniasis, but if and how the amount of these compounds in the cells can affect the success of the treatment, remains unknown. Validated methods to reliably measure these amounts in human cells are limited. Here we have developed a validated method that allows quantifying antimony in human plasma and peripheral blood cells from patients undergoing antileishmanial treatment. This protocol will serve as a baseline for future studies aiming to understand how antimonials work to treat leishmaniasis infections and how this therapy can be improved.
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Antimonio/química , Antiprotozoarios/farmacocinética , Antimoniato de Meglumina/farmacocinética , Antimonio/sangre , Antiprotozoarios/sangre , Antiprotozoarios/química , Humanos , Leishmania/efectos de los fármacos , Espectrometría de Masas , Antimoniato de Meglumina/sangre , Antimoniato de Meglumina/química , Estructura Molecular , Pruebas de Sensibilidad ParasitariaRESUMEN
In this article, we describe the semi-synthesis of N-alkyl-kappa-carrageenan derivatives and their antibacterial activity against Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 8739), and Pseudomonas aeruginosa (ATCC 9027). Kappa-carrageenan was submitted to partial acid hydrolysis promoting the selective cleavage of α-glycosidic bonds involving 3,6-anhydro-α-D-Galp units, giving rise to reducing low-molecular weight polysaccharide fragments, which were reacted with alkylamines of varying chain lengths by reductive amination. The carrageenan derivatives were characterized by HPSEC-MALLS-RID and 1D and 2D 1H and 13C NMR spectroscopy. The antibacterial activity of N-alkyl-kappa-carrageenan derivatives was compared with N-alkyl-(1-deoxylactitol-1-yl)-amines using a microdilution test, which indicated that inhibitory activity was dependent on the degree of substitution by hydrophobic groups at the polysaccharide structure. Comparing the effect of different N-alkyl chains, those with longer chains showed higher activity.
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Antibacterianos/farmacología , Carragenina/farmacología , Escherichia coli/efectos de los fármacos , Pseudomonas aeruginosa/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Antibacterianos/síntesis química , Antibacterianos/química , Conformación de Carbohidratos , Carragenina/síntesis química , Carragenina/química , Pruebas de Sensibilidad MicrobianaRESUMEN
The aim of the present work was to evaluate the effects of Thalassia testudinum hydroethanolic extract, its polyphenolic fraction and thalassiolin B on the activity of phase I metabolizing enzymes as well as their antimutagenic effects. Spectrofluorometric techniques were used to evaluate the effect of tested products on rat and human CYP1A and CYP2B activity. The antimutagenic effect of tested products was evaluated in benzo[a]pyrene (BP)-induced mutagenicity assay by an Ames test. Finally, the antimutagenic effect of Thalassia testudinum (100 mg/kg) was assessed in BP-induced mutagenesis in mice. The tested products significantly (p < 0.05) inhibit rat CYP1A1 activity, acting as mixed-type inhibitors of rat CYP1A1 (Ki = 54.16 ± 9.09 µg/mL, 5.96 ± 1.55 µg/mL and 3.05 ± 0.89 µg/mL, respectively). Inhibition of human CYP1A1 was also observed (Ki = 197.1 ± 63.40 µg/mL and 203.10 ± 17.29 µg/mL for the polyphenolic fraction and for thalassiolin B, respectively). In addition, the evaluated products significantly inhibit (p < 0.05) BP-induced mutagenicity in vitro. Furthermore, oral doses of Thalassia testudinum (100 mg/kg) significantly reduced (p < 0.05) the BP-induced micronuclei and oxidative damage, together with an increase of reduced glutathione, in mice. In summary, Thalassia testudinum metabolites exhibit antigenotoxic activity mediated, at least, by the inhibition of CYP1A1-mediated BP biotransformation, arresting the oxidative and mutagenic damage. Thus, the metabolites of T. testudinum may represent a potential source of chemopreventive compounds for the adjuvant therapy of cancer.
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Antimutagênicos/farmacología , Benzo(a)pireno/toxicidad , Citocromo P-450 CYP1A1/antagonistas & inhibidores , Inhibidores Enzimáticos del Citocromo P-450/farmacología , Flavonoides/farmacología , Hydrocharitaceae/metabolismo , Polifenoles/farmacología , Salmonella typhi/efectos de los fármacos , Activación Metabólica , Animales , Antimutagênicos/aislamiento & purificación , Benzo(a)pireno/metabolismo , Citocromo P-450 CYP1A1/metabolismo , Citocromo P-450 CYP1A2/metabolismo , Inhibidores del Citocromo P-450 CYP1A2/aislamiento & purificación , Inhibidores del Citocromo P-450 CYP1A2/farmacología , Inhibidores Enzimáticos del Citocromo P-450/aislamiento & purificación , Daño del ADN/efectos de los fármacos , Flavonoides/aislamiento & purificación , Humanos , Isoenzimas , Cinética , Micronúcleos con Defecto Cromosómico/inducido químicamente , Pruebas de Micronúcleos , Estrés Oxidativo/efectos de los fármacos , Polifenoles/aislamiento & purificación , Ratas , Salmonella typhi/genéticaRESUMEN
The production of a chitin-like exopolysaccharide (EPS) was optimized through experimental design methods, evaluating the influence of urea, phosphate, and glucose. Under optimized conditions, up to 1.51 g/L was produced and its physicochemical characteristics were evaluated by chromatography, NMR, and FTIR spectroscopy, and rheological techniques. The results showed a homogeneous EPS (Mw 4.9 × 105 g mol-1) composed of chitin, linear polymer of ß-(1â4)-linked N-acetyl-d-glucosamine residues. The acetylation degree as determined by 13C CP-MAS NMR spectroscopy was over 90 %. The EPS biological activities, such as antioxidant effect and antitumor properties, were evaluated. To the best of our knowledge, this is the first study on the production of a new alternative of extracellular chitin-like polysaccharide with promising bioactive properties from the filamentous fungus M. alpina.
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Antineoplásicos/farmacología , Antioxidantes/farmacología , Neoplasias de la Mama/tratamiento farmacológico , Quitina/química , Fermentación , Mortierella/metabolismo , Polisacáridos/farmacología , Antineoplásicos/química , Antioxidantes/química , Neoplasias de la Mama/patología , Femenino , Glucosa/metabolismo , Humanos , Polisacáridos/química , Polisacáridos/aislamiento & purificación , Células Tumorales CultivadasRESUMEN
Due to the recent rise in the use of lower-limb exoskeletons as an alternative for gait rehabilitation, gait phase detection has become an increasingly important feature in the control of these devices. In addition, highly functional, low-cost recovery devices are needed in developing countries, since limited budgets are allocated specifically for biomedical advances. To achieve this goal, this paper presents two gait phase partitioning algorithms that use motion data from a single inertial measurement unit (IMU) placed on the foot instep. For these data, sagittal angular velocity and linear acceleration signals were extracted from nine healthy subjects and nine pathological subjects. Pressure patterns from force sensitive resistors (FSR) instrumented on a custom insole were used as reference values. The performance of a threshold-based (TB) algorithm and a hidden Markov model (HMM) based algorithm, trained by means of subject-specific and standardized parameters approaches, were compared during treadmill walking tasks in terms of timing errors and the goodness index. The findings indicate that HMM outperforms TB for this hardware configuration. In addition, the HMM-based classifier trained by an intra-subject approach showed excellent reliability for the evaluation of mean time, i.e., its intra-class correlation coefficient (ICC) was greater than 0 . 75 . In conclusion, the HMM-based method proposed here can be implemented for gait phase recognition, such as to evaluate gait variability in patients and to control robotic orthoses for lower-limb rehabilitation.
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Algoritmos , Dispositivo Exoesqueleto , Pie/fisiología , Marcha/fisiología , Extremidad Inferior/fisiología , Monitoreo Fisiológico/métodos , Paresia/fisiopatología , Adulto , Anciano , Estudios de Casos y Controles , Femenino , Humanos , Aprendizaje Automático , Masculino , Cadenas de Markov , Persona de Mediana Edad , Monitoreo Fisiológico/instrumentación , Presión , Adulto JovenRESUMEN
In this paper, carrageenans having distinct sulfation patterns (κ-, ι-, ι/ν-, θ- and λ-carrageenans), were fully or partially oxidized at C-6 of the ß-d-Galp units using 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and trichloroisocyanuric acid (TCCA) in bicarbonate buffer. The modified carrageenans were characterized by mono- and bidimensional 1H and 13C NMR spectroscopy. The influence of the sulfate and carboxyl groups onto anticoagulant activity was evaluated using Activated Partial Thromboplastin Time (aPTT) in vitro assay. The results showed a synergic effect of the carboxyl groups on the anticoagulant activity, which was dependent on the regiochemistry of the sulfate groups in the polysaccharide backbone. Sulfate groups at C2 of the ß-d-GalAp units appeared to positively influence the anticoagulant effect in comparison to C4-sulfate samples. Also, the partially oxidized κ-carrageenan derivative (κLO) showed better anticoagulant effect than the fully oxidized carrageenan (κHO).