Solvent-free formation of cyclodextrin-based pseudopolyrotaxanes of polyethylene glycol: kinetic and structural aspects

Pseudopolyrotaxanes (PPRs) are supramolecular structures consisting of macrocycles able to thread on a linear polymer chain in a reversible, non-covalent way, often referred to in the literature as "molecular necklaces". While the synthesis and reaction mechanisms of these structures in solution have been widely described, their solvent-free production has received little attention, despite the advantages that this route may offer. We propose in this work a kinetic mechanism that describes the PPR formation in the solid phase as a process occurring in two consecutive stages. This mechanism has been used to investigate the spontaneous formation of a PPR that occurs when grinding alpha-Cyclodextrin (alpha-CD) with polyethylene glycol (PEG). In the threading stage, the inclusion of the polymer and subsequent release of the water molecules lodged in the cavity of the macrocycle cause vibrational changes that are reflected in the time-dependence of the FTIR-ATR spectra, while the further assembly of PPRs to form crystals produces characteristic reflections in the XRD patterns, due to the channel-like arrangement of CDs, that can be used to track the formation of the adduct in crystalline form. The effects that working variables have on the kinetics of the reaction, such as temperature, feed ratio, molar mass of the polymer and the introduction of an amorphous block in the polymer structure, have been investigated. The rate constants of the threading step increase with the temperature and the activation energy of the process increases at lower proportions of CD to PEG. This is attributed to the lower degree of covering of the polymer chain with CDs that reduces the hydrogen-bonding driven stabilization between adjacent macrocycles. The formation of crystalline PPR, which takes place slowly at room temperature, is markedly promoted at higher temperatures, with lower proportions of CD favoring both the formation and the growth of the crystals. The molar mass of the polymer does not modify the typical channel-like arrangement of packed PPRs but the conversion into crystalline PPR diminishes when using PEG1000 instead of PEG400. At a microscopic level, the crystals arrange into lamellar structures, in the order of hundreds of nm, embedded in an amorphous-like matrix. The introduction of a polypropylene oxide block in the structure of the polymer (Pluronic L62) renders poorer yields and a considerable loss of crystallinity of the product of the reaction. The methodology here proposed can be applied to the general case of inclusion complexes of CDs with drugs in the solid phase, or to multicomponent systems that contain polymers as excipients in pharmaceutical formulations along with CDs

Exploration of cannabis use and polygenic risk scores on the psychotic symptom progression of a FEP cohort

Cannabis use is highly prevalent in first-episode psychosis (FEP) and plays a critical role in its onset and prognosis, but the genetic underpinnings promoting both conditions are poorly understood. Current treatment strategies for cannabis cessation in FEP are clearly inefficacious. Here, we aimed to characterize the association between cannabis-related polygenic risk scores (PRS) on cannabis use and clinical course after a FEP. A cohort of 249 FEP individuals were evaluated during 12 months. Symptom severity was measured with the Positive and Negative Severity Scale and cannabis use with the EuropASI scale. Individual PRS for lifetime cannabis initiation (PRSCI) and cannabis use disorder (PRSCUD) were constructed. Current cannabis use was associated with increased positive symptoms. Cannabis initiation at younger ages conditioned the 12-month symptom progression. FEP patients with higher cannabis PRSCUD reported increased baseline cannabis use. PRSCI was associated with the course of negative and general symptomatology over follow-up. Cannabis use and symptom progression after a FEP were modulated by cannabis PRS, suggesting that lifetime initiation and use disorders may have partially independent genetic factors. These exploratory results may be the first step to identify those FEP patients more vulnerable to cannabis use and worse outcomes to ultimately develop tailored treatments

Contamination level and spatial distribution of heavy metals in water and sediments of El Guájaro Reservoir, Colombia

Heavy metals have become a subject of special concern worldwide, mainly due to high persistence in the environment, toxicity, biogeochemical recycling and ecological risk. Therefore, the objective of this investigation was to analyze the spatial–temporal distribution of heavy metals in water and sediments to determine the environmental status of El Guájaro Reservoir, where such studies have not been developed. Two measurement campaigns (dry and wet period) were carried out and eight sampling stations were selected. A comparison of water and sediment quality parameters with existing national and international regulations was done. Also, heavy metal distribution maps were generated, and the geoaccumulation index was calculated to identify sources and sediments contamination level. Based on the obtained results, agriculture and mining activities are the main causes of the reservoir contamination. This metals levels could be a potential risk for the aquatic life and the populations that are supplied from this water body

Current and Future Niche of North and Central American Sand Flies (Diptera: Psychodidae) in Climate Change Scenarios

Ecological niche models are useful tools to infer potential spatial and temporal distributions in vector species and to measure epidemiological risk for infectious diseases such as the Leishmaniases. The ecological niche of 28 North and Central American sand fly species, including those with epidemiological relevance, can be used to analyze the vector’s ecology and its association with transmission risk, and plan integrated regional vector surveillance and control programs. In this study, we model the environmental requirements of the principal North and Central American phlebotomine species and analyze three niche characteristics over future climate change scenarios: i) potential change in niche breadth, ii) direction and magnitude of niche centroid shifts, iii) shifts in elevation range. Niche identity between confirmed or incriminated Leishmania vector sand flies in Mexico, and human cases were analyzed. Niche models were constructed using sand fly occurrence datapoints from Canada, USA, Mexico, Guatemala and Belize. Nine non-correlated bioclimatic and four topographic data layers were used as niche components using GARP in OpenModeller. Both B2 and A2 climate change scenarios were used with two general circulation models for each scenario (CSIRO and HadCM3), for 2020, 2050 and 2080. There was an increase in niche breadth to 2080 in both scenarios for all species with the exception of Lutzomyia vexator. The principal direction of niche centroid displacement was to the northwest (64%), while the elevation range decreased greatest for tropical, and least for broad-range species. Lutzomyia cruciata is the only epidemiologically important species with high niche identity with that of Leishmania spp. in Mexico. Continued landscape modification in future climate change will provide an increased opportunity for the geographic expansion of NCA sand flys’ ENM and human exposure to vectors of Leishmaniases

Consensus on complementary feeding from the Latin American Society for Pediatric Gastroenterology, Hepatology and Nutrition: COCO 2023

Abstract Complementary feeding (CF) is defined as infant feeding that complements breastfeeding or, alternatively, breastfeeding with a breast milk substitute, and is a process that goes beyond simply providing guidance on what and how to introduce foods. The information provided by health professionals should be up-to-date and evidence-based. There are different guidelines or position papers at the international level, which, although most of the recommendations may be applicable, there are some others that require regionalization or adaptation to the conditions and reality of each area. The Nutrition working group of the Latin American Society of Pediatric Gastroenterology, Hepatology and Nutrition convened a group of experts, representatives from each of the countries that make up the society, with the objective of developing a consensus on CA, incorporating, when possible, local information that adapts to the reality of the region. The purpose of this document is to show the results of this work. Through Delphi methodology, a total of 34 statements or statements regarding relevant aspects of CA were evaluated, discussed and voted upon.Resumen La alimentación complementaria (AC) se define como la alimentación de los lactantes que complementa a la lactancia materna o en su defecto, a la lactancia con un sucedáneo de la leche materna, y es un proceso que va más allá de simplemente una guía sobre qué y cómo introducir los alimentos. La información brindada por parte de los profesionales de la salud debe ser actualizada y basada en evidencia. Existen diferentes guías o documentos de posición a nivel internacional, que, aunque la mayoría de las recomendaciones pueden ser aplicables, hay algunas otras que requieren una regionalización o adecuación a las condiciones y realidad de cada zona. El grupo de trabajo de Nutrición de la Sociedad Latinoamericana de Gastroenterología, Hepatología y Nutrición Pediátrica convocó a un grupo de expertos, representantes de cada uno de los países que conforman la sociedad, con el objetivo de desarrollar un consenso sobre la AC, que incorporó cuando así fue posible, información local que se adapte a la realidad de la región. El objetivo de este documento es mostrar los resultados de dicho trabajo. A través de metodología Delphi, se evaluaron, discutieron y votaron un total de 34 declaraciones o enunciados con respecto a aspectos relevantes de la AC

Sistemas de protección y detección de contagios en los pediatras de atención primaria en la epidemia por COVID-19

Introducción: durante la pandemia de COVID-19, el uso de equipos y dispositivos de protección por parte de los profesionales es fundamental para evitar la transmisión de la infección en el colectivo de sanitarios. Material y métodos: el Grupo Laboral-Profesional de la Asociación Española de Pediatría de Atención Primaria (AEPap) ha realizado una encuesta a los vocales autonómicos de la AEPap para conocer la disponibilidad que han tenido los pediatras de Atención Primaria (PAP) de sistemas de protección frente a la enfermedad, y las pruebas diagnósticas realizadas para el diagnóstico de los contagios de los PAP. Resultados: en marzo de 2020, solo en el 32% de las comunidades autónomas (CC. AA.), los pediatras tenían sistemas de protección adecuados. En abril ascendió al 70%. En todas las CC. AA. se han registrado casos de PAP enfermos, aunque es difícil cuantificar el número de afectados. De las que tenemos datos, sumando el número de pediatras enfermos conocido, más test de reacción en cadena de la polimerasa (PCR) positivo, los que han estado en aislamiento y los ingresados, la cifra asciende al 7,65% de la cifra total de PAP. Los test rápidos serológicos o PCR o ambos se han realizado en seis comunidades los últimos días de abril y en otras seis los primeros días de mayo. Entre las CC. AA. de las que hay información, Aragón es la única comunidad en la que no se ha realizado test. Se ha correlacionado la disponibilidad de los sistemas de protección y el gasto sanitario. Conclusiones: los sistemas de protección han sido insuficientes. Las CC. AA. con mayor gasto sanitario han contado más precozmente con sistemas de protección adecuados. Han resultado infectados PAP en todas las comunidades autónomas, especialmente en Madrid, Castilla y León y Comunidad Valenciana. La detección de profesionales afectos por la infección ha sido tardía

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

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