Superparamagnetic Poly (3-hydroxybutyrate-co-3 hydroxyvalerate) (PHBV) nanoparticles for biomedical applications

Indexación: ScieloBackground: The progress in material science and the recent advances in biodegradable/biocompatible polymers and magnetic iron oxide nanoparticles have led to develop innovative diagnostic and therapeutic strategies for diseases based on multifunctional nanoparticles, which include contrast medium for magnetic resonance imaging, agent for hyperthermia and nanocarriers for targeted drug delivery. The aim of this work is to synthesize and characterize superparamagnetic iron oxide (magnetite), and to encapsulate them into poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles for biomedical applications. Results: The magnetite nanoparticles were confirmed by X-ray diffraction and exhibited a size of 22.3 ± 8.8 nm measured by transmission electron microscopy (TEM). Polymeric PHBV nanoparticles loaded with magnetite (MgNPs) were analyzed using dynamic light scattering and showed a size of 258.6 ± 35.7 nm and a negative zeta potential (-10.8 ± 3.5 mV). The TEM examination of MgNPs exhibited a spherical core-shell structure and the magnetic measurements showed in both, non-encapsulated magnetite and MgNPs, a superparamagnetic performance. Finally, the in vitro studies about the magnetic retention of MgNPs in a segment of small intestine of rats showed an active accumulation in the region of the magnetic field. Conclusions: The results obtained make the MgNPs suitable as potential magnetic resonance imaging contrast agents, also promoting hyperthermia and even as potential nanocarriers for site-specific transport and delivery of drugs. Keywords: hyperthermia, magnetic resonance image (MRI), magnetite, PHBV, polymeric nanoparticles.http://ref.scielo.org/cxt57

Comparative voltammetric and FTIRRAS study on the electro-oxidation of thiourea and methyl-thioureas on platinum in aqueous acid solutions

A comparative voltammetric and spectroscopic study on thiourea, methylthiourea, 1,3 dimethylthiourea and tetramethylthiourea electro-oxidation is presented. The investigation was performed at platinum electrodes in aqueous acid solutions in the potential range between 0.05 and 1.6 V (versus SHE). The electro-oxidation of thioureas starts at ca. 0.55 V and it involves at least two reaction stages irrespective of their nature. The first electro-oxidation stage occurs in the range 0.55–0.9 V and involves the formation of a soluble disulphide derivative influenced by the blockage of the electrode surface. The second electro-oxidation stage occurs in the range 0.9–1.6 V and it involves a complex electrochemical process yielding products such as carbon dioxide, sulphate ions, CN- and CO-containing species. The second electro-oxidation stage is likely mediated by the oxygen-containing layer that is produced electrochemically on platinum in that range of potential. The gradual depletion of thioureas and the progressive formation of soluble products in the thin solution layer in contact with the electrode are followed through changes in the band intensities of IR spectra. From the correlation between voltammetric and spectroscopic data a description of global reactions involving the electro-oxidation of thioureas to soluble products in both potential ranges is presented. The proposed reaction pathways are consistent with the participation of different adsorbates as was reported earlier for thioureas on platinum.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Regularity analysis of nocturnal oximetry recordings to assist in the diagnosis of sleep apnoea syndrome

The relationship between sleep apnoea–hypopnoea syndrome (SAHS) severity and the regularity of nocturnal oxygen saturation (SaO2) recordings was analysed. Three different methods were proposed to quantify regularity: approximate entropy (AEn), sample entropy (SEn) and kernel entropy (KEn). A total of 240 subjects suspected of suffering from SAHS took part in the study. They were randomly divided into a training set (96 subjects) and a test set (144 subjects) for the adjustment and assessment of the proposed methods, respectively. According to the measurements provided by AEn, SEn and KEn, higher irregularity of oximetry signals is associated with SAHS-positive patients. Receiver operating characteristic (ROC) and Pearson correlation analyses showed that KEn was the most reliable predictor of SAHS. It provided an area under the ROC curve of 0.91 in two-class classification of subjects as SAHS-negative or SAHS-positive. Moreover, KEn measurements from oximetry data exhibited a linear dependence on the apnoea–hypopnoea index, as shown by a correlation coefficient of 0.87. Therefore, these measurements could be used for the development of simplified diagnostic techniques in order to reduce the demand for polysomnographies. Furthermore, KEn represents a convincing alternative to AEn and SEn for the diagnostic analysis of noisy biomedical signals

Prophylactic Activated Recombinant Factor VII in Liver Resection and Liver Transplantation: Systematic Review and Meta-Analysis

Intraoperative blood loss is a frequent complication of hepatic resection and orthotopic liver transplantation. Recombinant activated coagulation factor VII (rFVIIa) is a coagulation protein that induces hemostasis by directly activating factor X. There is no clear information about the prophylactic value of rFVIIa in hepatobiliary surgery, specifically in liver resection and orthotopic liver transplantation. The aim of this study was to assess the effect of rFVIIa prophylaxis to prevent mortality and bleeding resulting from hepatobiliary surgery.Relevant randomized trials were identified by searching The Cochrane Central Register of Controlled Trials in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index. Randomized clinical trials comparing different rFVIIa prophylactic schemas against placebo or no intervention to prevent bleeding in hepatobiliary surgery were included. Adults undergoing liver resection, partial hepatectomy, or orthotopic liver transplantation were included. Dichotomous data were analyzed calculating odds ratios (ORs) and 95% confidence intervals (CIs). Continuous data were analyzed calculating mean differences (MD) and 95% CIs.Four randomized controlled trials were included. There were no significant differences between rFVIIa and placebo for mortality (OR 0.96; 95% CI 0.35-2.62), red blood cell units (MD 0.32; 95% CI -0.08-0.72) or adverse events (OR 1.55; 95% CI 0.97-2.49).The available information is limited, precluding the ability to draw conclusions regarding bleeding prophylaxis in hepatobiliary surgery using rFVIIa. Although an apparent lack of effect was observed in all outcomes studied, further research is needed

An endemic new species of Andean lizard of the genus Liolaemus from southern Peru (Iguania: Liolaemidae) and its phylogenetic position

Integrative evidence of several external morphological characters and molecular phylogeneticanalyses of mitochondrial DNA (12S, cyt-b) are used to place a new species of Andean lizard of the genus Liolaemus (Iguania: Liolaemidae) in the Liolaemus montanus group and as sister group of the clade formed by L. signifer. The new species is characterized by a unique combination of morphometric characteristics, scalation, and color pattern. The L. montanus group now contains seventeen species in southern Peru, distributed along the eastern and western slopes of the Andes.Utilizamos evidencia integradora de varios caracteres morfológicos externos y análisis filogenéticos moleculares de ADN mitocondrial (12S, cyt-b) que ubican una nueva especie del género Liolaemus (Iguania: Liolaemidae) en el grupo de Liolaemus montanus y como grupo hermano del clado formado por L. signifer. La nueva especie se caracteriza por una combinación única de patrón morfométrico, escamación y color. El grupo montanus del género Liolaemus en Perú contiene diecisiete especies, distribuidas a lo largo de la vertiente oriental y occidental de los Andes en el sur del paísFil: Chaparro, Juan C.. Museo de Biodiversidad del Perú; PerúFil: Quiroz, Aaron. Universidad Nacional de San Agustín. Facultad de Ciencias Biológicas. Departamento Académico de Biología. Museo de Historia Natural; PerúFil: Mamani, Luis. Universidad Nacional de San Antonio Abad del Cusco; PerúFil: Gutiérrez, Roberto C.. Universidad Nacional de San Agustín. Facultad de Ciencias Biológicas. Departamento Académico de Biología. Museo de Historia Natural; PerúFil: Condorí, Peter. Universidad Nacional de San Antonio Abad del Cusco; PerúFil: de la Riva, Ignacio. Consejo Superior de Investigaciones Científicas; EspañaFil: Herrera Juárez, Gabriela. niversidad Nacional de San Agustín de Arequipa; PerúFil: Cerdeña José. Universidad Nacional de San Agustín. Facultad de Ciencias Biológicas. Departamento Académico de Biología. Museo de Historia Natural; PerúFil: Arapa, Laura Andrea. Universidad Nacional de San Agustín. Facultad de Ciencias Biológicas. Departamento Académico de Biología. Museo de Historia Natural; PerúFil: Abdala, Cristian Simón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentin

Multiscale entropy analysis of unattended oximetric recordings to assist in the screening of paediatric sleep apnoea at home

Producción CientíficaUntreated paediatric obstructive sleep apnoea syndrome (OSAS) can severely affect the development and quality of life of children. In-hospital polysomnography (PSG) is the gold standard for a definitive diagnosis though it is relatively unavailable and particularly intrusive. Nocturnal portable oximetry has emerged as a reliable technique for OSAS screening. Nevertheless, additional evidences are demanded. Our study is aimed at assessing the usefulness of multiscale entropy (MSE) to characterise oximetric recordings. We hypothesise that MSE could provide relevant information of blood oxygen saturation (SpO2) dynamics in the detection of childhood OSAS. In order to achieve this goal, a dataset composed of unattended SpO2 recordings from 50 children showing clinical suspicion of OSAS was analysed. SpO2 was parameterised by means of MSE and conventional oximetric indices. An optimum feature subset composed of five MSE-derived features and four conventional clinical indices were obtained using automated bidirectional stepwise feature selection. Logistic regression (LR) was used for classification. Our optimum LR model reached 83.5% accuracy (84.5% sensitivity and 83.0% specificity). Our results suggest that MSE provides relevant information from oximetry that is complementary to conventional approaches. Therefore, MSE may be useful to improve the diagnostic ability of unattended oximetry as a simplified screening test for childhood OSAS.Sociedad Española de Neumología y Cirugía Torácica (SEPAR) project 153/2015Junta de Castilla y León (Consejería de Educación) y el Fondo Europeo de Desarrollo Regional (FEDER), projects (RTC-2015-3446-1) y (TEC2014-53196-R)Ministerio de Economía y Competitividad (MINECO) y FEDER, y el proyecto POCTEP 0378_AD_EEGWA_2_P de la Comisión Europea. L.National Institutes of Health (NIH) grant 1R01HL130984-01Ministerio de Asuntos Económicos y Transformación Digital, grant IJCI-2014-2266

Description and phylogenetic relationships of a new species of Liolaemus (Iguania: Liolaemidae) and notes on the L. montanus group of Peru

A new lizard species of the Liolaemus montanus group endemic of the Andes western slope, Huaytará Province, Huancavelica, Peru is described. This new species of Liolaemus is of medium size (maximum SVL 70.1 mm) and is characterized by presenting a unique color standard in males, where several light-blue scales on the back and side of the body are prominent, and the abdomen is of an intense yellow. Also, the scales of the back and sides of the body are sub-imbricated, with a slight keel and its shape is rounded to triangular. While females, as well as males exhibit pre-cloacal pores. The combination of several states of morphological, morphometric and flake characters and their color standard clearly differentiate these new taxa of the other Liolaemus species, especially of the members of the L. montanus group described for the center and south of Peru. Also, in this study, we present a revision of the taxonomic status and distribution of species of the L. montanus group described or cited for Peru.Se describe una nueva especie de lagartija del grupo de Liolaemus montanus, endémico de la vertiente occidental de los Andes, en la provincia de Huaytará, departamento de Huancavelica, Perú. Esta nueva especie de Liolaemus, es de tamaño medio (máximo LHC 70,1 mm), se caracteriza por presentar un patrón de coloración único en los machos, donde numerosas escamas celestes se destacan sobre el dorso del cuerpo y el vientre es de color amarillo intenso. Además tiene las escamas del dorso y lados del cuerpo subimbricadas, con quilla leve y de forma redondeada a triangular. Tanto machos como hembras tienen poros precloacales. La combinación de varios estados de caracteres morfológicos, morfométricos, de escamación, y en el patrón de coloración, diferencian claramente este nuevo taxón de las demás especies de Liolaemus, especialmente de los integrantes del grupo de L. montanus descritos para el centro y sur del Perú. Asimismo, en este trabajo, presentamos una revisión del estado taxonómico y distribución de las especies del grupo de L. montanus descritas o citadas para Perú.Asociación Herpetológica Argentin

Comparative voltammetric and FTIRRAS study on the electro-oxidation of thiourea and methyl-thioureas on platinum in aqueous acid solutions

A comparative voltammetric and spectroscopic study on thiourea, methylthiourea, 1,3 dimethylthiourea and tetramethylthiourea electro-oxidation is presented. The investigation was performed at platinum electrodes in aqueous acid solutions in the potential range between 0.05 and 1.6 V (versus SHE). The electro-oxidation of thioureas starts at ca. 0.55 V and it involves at least two reaction stages irrespective of their nature. The first electro-oxidation stage occurs in the range 0.55–0.9 V and involves the formation of a soluble disulphide derivative influenced by the blockage of the electrode surface. The second electro-oxidation stage occurs in the range 0.9–1.6 V and it involves a complex electrochemical process yielding products such as carbon dioxide, sulphate ions, CN- and CO-containing species. The second electro-oxidation stage is likely mediated by the oxygen-containing layer that is produced electrochemically on platinum in that range of potential. The gradual depletion of thioureas and the progressive formation of soluble products in the thin solution layer in contact with the electrode are followed through changes in the band intensities of IR spectra. From the correlation between voltammetric and spectroscopic data a description of global reactions involving the electro-oxidation of thioureas to soluble products in both potential ranges is presented. The proposed reaction pathways are consistent with the participation of different adsorbates as was reported earlier for thioureas on platinum.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada