Fluidized or not fluidized? Biophysical characterization of biohybrid lipid/protein/polymer liposomes and their interaction with tetracaine.

BACKGROUND: Nanomedicine and the pharmaceutical industry demand the investigation of new biomaterials to improve drug therapies. Combinations of lipids, proteins, and polymers represent innovative platforms for drug delivery. However, little is known about the interactions between such compounds and this knowledge is key to prepare successful drug delivery systems. METHODS: Biophysical properties of biohybrid vesicles (BhVs) composed of phospholipids, proteins, and amphiphilic block copolymers, assembled without using organic solvents, were investigated by differential scanning calorimetry and dynamic light scattering. We studied four biohybrid systems; two of them included the effect of incorporating tetracaine. Thermal changes of phospholipids and proteins when interacting with the amphiphilic block copolymers and tetracaine were analyzed. RESULTS: Lysozyme and the copolymers adsorb onto the lipid bilayer modifying the phase transition temperature, enthalpy change, and cooperativity. Dynamic light scattering investigations revealed relevant changes in the size and zeta potential of the BhVs. Interestingly, tetracaine, a membrane-active drug, can fluidize or rigidize BhVs. CONCLUSIONS: We conclude that positively charged regions of lysozyme are necessary to incorporate the block copolymer chains into the lipid membrane, turning the bilayer into a more rigid system. Electrostatic properties and the hydrophilic-lipophilic balance are determinant for the stability of biohybrid membranes. GENERAL SIGNIFICANCE: This investigation provides fundamental information associated with the performance of biohybrid drug delivery systems and can be of practical significance for designing more efficient drug nanocarriers.

On the evolution of the exclusion zone produced by hydrophilic surfaces: A contracted description.

After exciting scientific debates about its nature, the development of the exclusion zone, a region near hydrophilic surfaces from which charged colloidal particles are strongly expelled, has been finally traced back to the diffusiophoresis produced by unbalanced ion gradients. This was done by numerically solving the coupled Poisson equation for electrostatics, the two stationary Stokes equations for low Reynolds numbers in incompressible fluids, and the Nernst-Planck equation for mass transport. Recently, it has also been claimed that the leading mechanism behind the diffusiophoretic phenomenon is electrophoresis [Esplandiu et al., Soft Matter 16, 3717 (2020)]. In this paper, we analyze the evolution of the exclusion zone based on a one-component interaction model at the Langevin equation level, which leads to simple analytical expressions instead of the complex numerical scheme of previous works, yet being consistent with it. We manage to reproduce the evolution of the exclusion zone width and the mean-square displacements of colloidal particles we measure near Nafion, a perfluorinated polymer membrane material, along with all characteristic time regimes, in a unified way. Our findings are also strongly supported by complementary experiments using two parallel planar conductors kept at a fixed voltage, mimicking the hydrophilic surfaces, and some computer simulations.

Video-tracking and high-speed bright field microscopy allow the determination of swimming and cardiac effects of D. magna exposed to local anaesthetics.

Local anaesthetics are among the most used drugs in clinical practice, but once they are released to the environment, the effects on the aquatic fauna remain uncertain. This study evaluates, for the first time, the impact of tetracaine, lidocaine and bupivacaine on the survival rate and physiological effects of cladocera Daphnia magna. Video-tracking and image processing allowed us to obtain changes in behaviour parameters like swimming average velocity and mean square displacement. We found that tetracaine shows the most severe effect. A high-speed microscopy system was also used to determine the response of D. magna heart to these drugs. Our results show that tetracaine presents dose-dependent area reduction during all cardiac cycle, while bupivacaine and lidocaine did not present significative effects on heart size. The tested drugs, at environmental high concentrations, altered behaviour, heart function and survival of D. magna.

Características de pacientes ingresados a la unidad de cuidado intensivo neonatal en la Clínica Universidad de La Sabana / Features of patients hospitalized to the newborn intensive care at Clínica Universidad de La Sabana

Introducción: Es pertinente conocer las características de los pacientes que ingresan a las unidades de cuidado intensivo neonatal para que las acciones en salud respondan a sus necesidades particulares. Objetivo: Caracterizar los pacientes que ingresaron a la Unidad de Cuidado Intensivo Neonatal (UCIN) de la Clínica de la Universidad de La Sabana de enero a diciembre del 2012. Materiales y Métodos: estudio retrospectivo con n=206 neonatos que ingresaron a la UCIN de la Clínica Universidad de La Sabana en el 2012, se revisaron las historias clínicas de los pacientes ingresados para identificar sus características, se calcularon frecuencias relativas y absolutas; y para las variables cuantitativas se describieron medidas de tendencia central y dispersión. Resultados: el 56,3% eran hombres, el promedio de edad gestacional de 36,5 semanas (SD 3,3 semanas), el peso promedio fue de 2625,9 g (SD 757,5 g). La mediana de los días de estancia fue de 4 (IQR: 2 a 9). El principal diagnóstico fue ictericia neonatal en (21,8%), el 22% de los pacientes requirieron ventilación mecánica (VM). La media de la edad gestacional y del peso en pacientes con requerimientos de VM fue de 32.7 semanas (SD: 3,7 semanas) y 1883 g (SD: 779 g) respectivamente, comparado con 37,6 semanas (SD: 2,2 semanas) y 2840 g (SD: 601 g) en los que no requirieron VM. Conclusiones: características como bajo peso al nacer, edad gestacional temprana y el uso de surfactante, se asociaron con el requerimiento de VM, adicionalmente la mortalidad calculada fue del 2,8%.

Introduction: It is relevant to know the characteristics of patients who enter to neonatal intensive care units in order to learn how to respond to their specific conditions and which health actions can be applied for their particular needs. Objective: The aim of this study is describe patients admitted at Clinica Universidad de La Sabana (Neonatal Intensive Care -NIC) from January to December 2012. Materials and Methods: Retrospective study with n=206 neonates admitted to the NIC at Clinica Universidad de La Sabana in 2012, medical records of patients admitted were reviewed to identify its characteristics, as well absolute and relative frequencies were calculated. In terms of quantitative variables, they were measured with central tendency and dispersion. Results: 56.3% of patients were men, the average gestational age was 36.5 weeks (SD 3.3 weeks), the average weight was 2625 gr (SD 757.5 gr). The median days of stay was 4 (IQR:2-9). The main diagnosis was neonatal icterus (21.8%); 22% of patient's required mechanical ventilation (MV). The mean gestational age and weight in patients with VM requirements was 32.7 weeks (SD: 3.7 weeks) and 1883 gr (SD: 779 gr) respectively. Contrasted with the gestational age and weight of newborns that not requiring VM was 37.6 weeks (SD 2.2 weeks) and 2840 gr (SD: 601 gr). Conclusions: Low birth weight, early gestational age and the use of surfactant, were associated with the requirement of VM, and the mortality found was 2.8% for the whole cohort.

[Microbiologic and molecular diagnostic of cariogenic bacteria in pregnant women from the Araucania Region of Chile]. / Diagnóstico microbiológico y molecular de bacterias cariogénicas en mujeres embarazadas de la Región de La Araucanía, Chile.

Dental caries is a transmissible infectious disease in which Streptococcus mutans is a principal protagonist. Although it is widely believed that pregnancy is harmful to teeth, the effect of pregnancy on the development of caries is not clear. Considering this situation, the aim of the present study was to evaluate the levels of infection and to differentiate bacterial species with cariogenic potential in pregnant women from the Araucania region in Chile, by bacteriological and molecular analysis. In this work, we evaluated 51 pregnant women aged 15 to 40 years. The results show that 100% of women are infected by mutans streptococci Group, and 70.6% exhibited high levels of infection (> 500.000 cfu/mL). The molecular analysis shows that Streptococcus mutans and Streptococcus sobrinus frequencies were 92.1% and 1.9%, respectively. In conclusion, our data suggest that pregnant women are a high risk group for caries development.

Diagnóstico microbiológico y molecular de bacterias cariogénicas en mujeres embarazadas de la Región de La Araucanía, Chile / Microbiologic and molecular diagnostic of cariogenic bacteria in pregnant women from the Araucania Region of Chile

Dental caries is a transmissible infectious disease in which Streptococcus mutans is a principal protagonist. Although it is widely believed that pregnancy is harmful to teeth, the effect of pregnancy on the development of caries is not clear. Considering this situation, the aim of the present study was to evaluate the levels of infection and to differentiate bacterial species with cariogenic potential in pregnant women from the Araucania region in Chile, by bacteriological and molecular analysis. In this work, we evaluated 51 pregnant women aged 15 to 40 years. The results show that 100 percent of women are infected by mutans streptococci Group, and 70.6 percent exhibited high levels of infection (> 500.000 cfu/mL). The molecular analysis shows that Streptococcus mutans and Streptococcus sobrinus frequencies were 92.1 percent and 1.9 percent, respectively. In conclusion, our data suggest that pregnant women are a high risk group for caries development.

La caries dental es una enfermedad infecciosa, en la cual Streptococcus del grupo mutans, son los principales protagonistas. Aunque está ampliamente difundida la creencia de que el embarazo es perjudicial para la salud dental, el real efecto de esta condición sobre el desarrollo de caries aún no está claro. Considerando esta situación, el objetivo de nuestro trabajo fue evaluar los niveles de infección en mujeres embarazadas de la Región de La Araucanía (Chile) y diferenciar especies bacterianas con potencial cariogénico, de aquellas sin este potencial, mediante análisis bacteriológico y molecular. En el presente estudio fueron evaluadas 51 mujeres gestantes con edades que fluctuaron entre 15 y 40 años. Los resultados muestran que 100 por ciento) de las mujeres se encuentran infectadas por Streptococcus del grupo mutans, de las cuales 10,6 por ciento muestra un riesgo elevado de desarrollar caries (>500.000 ufc/ml). El análisis molecular mostró que las frecuencias de Streptococcus mutans y Streptococcus sobrinus fueron 92,1 por ciento y 1,9 por ciento, respectivamente. En conclusión, nuestros datos sugieren que las mujeres embarazadas son un grupo de alto riesgo para el desarrollo de caries dental.