Advances in chitosan and chitosan derivatives for biomedical applications in tissue engineering: An updated review.

In recent years, chitosan (CS) has received much attention as a functional biopolymer for various applications, especially in the biomedical field. It is a natural polysaccharide created by the chemical deacetylation of chitin (CT) that is nontoxic, biocompatible, and biodegradable. This natural polymer is difficult to process; however, chemical modification of the CS backbone allows improved use of functional derivatives. CS and its derivatives are used to prepare hydrogels, membranes, scaffolds, fibers, foams, and sponges, primarily for regenerative medicine. Tissue engineering (TE), currently one of the fastest-growing fields in the life sciences, primarily aims to restore or replace lost or damaged organs and tissues using supports that, combined with cells and biomolecules, generate new tissue. In this sense, the growing interest in the application of biomaterials based on CS and some of its derivatives is justifiable. This review aims to summarize the most important recent advances in developing biomaterials based on CS and its derivatives and to study their synthesis, characterization, and applications in the biomedical field, especially in the TE area.

Evaluation of the usefulness of vitamin D as a predictor of mortality in patients with COVID-19.

INTRODUCTION: One of the functions of vitamin D is to regulate respiratory epithelium inflammatory response; therefore, deficiency of this vitamin in the context of COVID-19 could constitute a predictive biomarker of the disease outcome. OBJECTIVE: To evaluate the usefulness of vitamin D for predicting mortality in patients with COVID-19. METHODS: Observational, retrospective study in which 154 patients diagnosed with COVID-19 were included, out of whom 111 survived and 43 died. Vitamin D concentration was determined in all of them. RESULTS: A log-rank p-value < 0.032 was obtained for survival when vitamin D concentration was used as a categorical variable (≤ 20 ng/mL and > 20 ng/mL). On Cox proportional analysis, age and vitamin D concentration were shown to be risk factors associated with mortality in patients with COVID-19 (age: HR = 1.036, 95% CI = 1.016-1.058, p < 0.001; vitamin D: HR (≤ 20 ng/mL and > 20 ng/mL) = 0.478, 95% CI = 0.237-0.966, p < 0.040). CONCLUSION: Age and vitamin D concentration were predictive factors for mortality in COVID-19-infected patients.

INTRODUCCIÓN: Una de las funciones de la vitamina D es regular la respuesta inflamatoria del epitelio respiratorio; por ello, la deficiencia de esa vitamina en el contexto de COVID-19 podría constituir un biomarcador preditivo del desenlace de COVID-19. OBJETIVO: Evaluar la utilidad de la vitamina D para predecir la mortalidad en pacientes con COVID-19. MÉTODOS: Estudio observacional y retrospectivo en el que se incluyeron 154 pacientes con diagnóstico de COVID-19, de los cuales 111 sobrevivieron y 43 fallecieron. En todos se determinó la concentración de vitamina D. RESULTADOS: Se obtuvo un valor log-rank de p < 0.032 para la supervivencia al utilizar la concentración de vitamina D como variable categórica (≤ 20 ng/mL y > 20 ng/mL). Mediante análisis proporcional de Cox se encontró que la edad y concentración de vitamina D mostraron ser factores de riesgo asociados a la mortalidad en pacientes con COVID-19 (edad: HR = 1.036, IC 95 % = 1.016-1.058, p < 0.001; vitamina D: HR ≤ 20 ng/mL y > 20 ng/mL = 0.478, IC 95 % = 0.237-0.966, p < 0.040). CONCLUSIÓN: La edad y la concentración de vitamina D constituyeron factores predictivos de mortalidad en pacientes infectados por COVID-19.

Evaluación de la utilidad de la vitamina D como predictor de mortalidad en pacientes con COVID-19 / Evaluation of the usefulness of vitamin D as a predictor of mortality in patients with COVID-19

Resumen Introducción: Una de las funciones de la vitamina D es regular la respuesta inflamatoria del epitelio respiratorio; por ello, la deficiencia de esa vitamina en el contexto de COVID-19 podría constituir un biomarcador preditivo del desenlace de COVID-19. Objetivo: Evaluar la utilidad de la vitamina D para predecir la mortalidad en pacientes con COVID-19. Métodos: Estudio observacional y retrospectivo en el que se incluyeron 154 pacientes con diagnóstico de COVID-19, de los cuales 111 sobrevivieron y 43 fallecieron. En todos se determinó la concentración de vitamina D. Resultados: Se obtuvo un valor log-rank de p < 0.032 para la supervivencia al utilizar la concentración de vitamina D como variable categórica (≤ 20 ng/mL y > 20 ng/mL). Mediante análisis proporcional de Cox se encontró que la edad y concentración de vitamina D mostraron ser factores de riesgo asociados a la mortalidad en pacientes con COVID-19 (edad: HR = 1.036, IC 95 % = 1.016-1.058, p < 0.001; vitamina D: HR ≤ 20 ng/mL y > 20 ng/mL = 0.478, IC 95 % = 0.237-0.966, p < 0.040). Conclusión: La edad y la concentración de vitamina D constituyeron factores predictivos de mortalidad en pacientes infectados por COVID-19.

Abstract Introduction: One of the functions of vitamin D is to regulate respiratory epithelium inflammatory response; therefore, deficiency of this vitamin in the context of COVID-19 could constitute a predictive biomarker of the disease outcome. Objective: To evaluate the usefulness of vitamin D for predicting mortality in patients with COVID-19. Methods: Observational, retrospective study in which 154 patients diagnosed with COVID-19 were included, out of whom 111 survived and 43 died. Vitamin D concentration was determined in all of them. Results: A log-rank p-value < 0.032 was obtained for survival when vitamin D concentration was used as a categorical variable (≤ 20 ng/mL and > 20 ng/mL). On Cox proportional analysis, age and vitamin D concentration were shown to be risk factors associated with mortality in patients with COVID-19 (age: HR = 1.036, 95% CI = 1.016-1.058, p < 0.001; vitamin D: HR [≤ 20 ng/mL and > 20 ng/mL] = 0.478, 95% CI = 0.237-0.966, p < 0.040). Conclusion: Age and vitamin D concentration were predictive factors for mortality in COVID-19-infected patients.

Evaluation of the Stroke-Specific Quality-of-Life (SSQOL) Scale in Mexico: A Preliminary Approach.

OBJECTIVES: The prevalence of stroke survivors with incomplete recovery in society has been estimated at 460/100,000 people, and one third of them require help in at least one daily activity. Two thirds of all deaths related to stroke in the world occur in low- and middle-income countries. The objective of the present work was to assess the reliability and validity of the previously translated Spanish Stroke-Specific Quality-of-Life (SSQOL) version 2.0 scales in Mexican stroke survivors. METHODS: An observational and cross-sectional pilot study was conducted. Thirty-one patients who suffered stroke up to 1 year prior to the present study were included. Patients were interviewed twice in a 7-day period; other indexes and scales were applied. The reliability was assessed by using Cronbach's alpha (internal consistency) and test-retest by using Spearman's rho scores; the acceptability was evaluated by the floor and ceiling effects. RESULTS: Ceiling and floor effects were observed for fewer than 20% of the patients. The overall internal consistency of the questionnaire was greater than 0.7 (Cronbach's α), with only two domains (family roles and personality) having lower internal consistency values. The results displayed high test-retest reliability: all domains had Spearman's rho scores of over 0.8. The questionnaire has adequate construct validity. CONCLUSIONS: Our preliminary results showed that the psychometric properties (acceptability and reliability) of the Spanish SSQOL questionnaire are good, encouraging, and comparable to those of other similar studies. This study is the first approach to validate the Spanish version of the SSQOL questionnaire in Mexican stroke survivors.

High-performance liquid chromatographic assay for morphine in small plasma samples: application to pharmacokinetic studies in rats.

In order to perform a reliable pharmacokinetic study of morphine during subchronic treatment in rats, an easy, rapid, sensitive and selective analytical method was proposed and validated. The analyte and internal standard (naloxone) were extracted from plasma samples (100 microL) by a single solid-phase extraction method prior to reverse-phase high performance liquid chromatography (HPLC) along with electrochemical detection (ED). Standard calibration graphs were linear within a range of 3.5-1,000 ng/mL (r=0.999). The intra-day coefficients of variation (CV) were in the range of 5.8-8.5% at eight concentration levels (7-1,000 ng/mL) and the inter-day coefficient of variation ranged from 7.4 to 8.8%. The intra-day assay accuracy was in the range of -5-10% and the inter-day assay accuracy ranged from 3.0 to 9.3% of relative error (RE). The limit of quantification was 3.5 ng/mL using a plasma sample of 100 microL (15.8% of CV and 12.8% of RE). Plasma samples were stable for 2 months at -20 degrees C. This method was found to be suitable for pharmacokinetic studies in rats, after subcutaneous administration of morphine (5.6 mg/kg per day) in subchronic treatment for 6 and 12 days.

Amyotrophic lateral sclerosis in a secluded region in Mexico possibly related to lead toxicity / Esclerosis lateral amiotrofica posiblemente relacionada con intoxicación de plomo una area aislada de México

La esclerosis lateral amiotrófica (ELA) es un padecimiento con una distribución relativamente uniforme en el mundo. La relación entre la ELA y diversos factores ambientales tóxicos se ha documentado en múltiples estudios. Uno de los aspectos más relevantes para el estudio de dichos factores ambientales es el hallazgo de "brotes" de la enfermedad en sujetos cuyo único punto en común es compartir el mismo medio ambiente. El objetivo de éste estudio es investigar la presencia de un "brote" de ELA en la comunidad de Tetela del Río en Guerrero. Se realizó un cuestionario para recolectar posibles casos de la enfermedad así como factores de riesgo, además de mediciones de plomo en quince sujetos control de la comunidad. El cuestionario se aplicó casa por casa en la comunidad, se detectaron 5 posibles casos con disartria, disfagia y atrofia de las extremidades. Los niveles promedio de plomo en los controles fueron de 22.4 ug/dl, los cuales fueron significativamente mayores a los de una población control en Hidalgo (p<0.00001). En este estudio sólo se confirmó un caso definitivo de ELA, pero el testimonio de los pobladores de la comunidad apuntaron hacia otros 5 posibles casos. El estudio de los brotes de FLA provee de información muy valiosa para la detección de factores ambientales relacionados al desarrollo de la enfermedad, lo cual puede ayudar en la búsqueda de opciones terapéuticas.

Cambios en los niveles estriatales de glutamato y aspartato en un modelo de la corea de Huntington: prevención de la neurotoxicidad del ácido quinolínico por kinurenina y probenecid / Changes in the striatal levels of glutamate and aspartante in a Huntington chorea model: prevention of quinolinic acid induced neurotoxicity by kynurenine and probenecid

La kinurenina (KYN) es el metabolito precursor del antagonista de los receptores glutamatérgicos para N-metil-D-as-partato (NMDA), el ácido kinurénico (KYNA). Por su pate, el probenecid (PROB) bloquea la excreción del KYNA desde el fluido extracelular. El KYNA antagoniza la neurotoxicidad ácido quinolínico (QUIN), en el cerebro de mamíferos. En este trabajo evaluamos el efecto de la administración sistémica de KYN y del PROB por separado o en combinación, sobre el contenido estriatal de dos aminoácidos excitadores del sistema nervioso, los ácidos glutámico (Glu) y aspártico (Asp), después de la administración intraestriatal unilateral de QUIN (240 nmol/ml) a las ratas. Los contenidos estriales de Glu y Asp. Analizados por cromatografía de líquidos, se encontraron disminuidos en ratas lesionadas por QUIN al compararse contra valores control (-44 por ciento y -43 por ciento, respectivamente). Los cambios en las concentraciones de estos aminoácidos fueron parcial o totalmente prevenidos por la administración de los pretratamientos con KYN (150, 300 ó 450 mg/kg, i.p.) o PROB (100, 200 ó 300 mg/kg, i.p.) a las ratas 2 horas antes de la inyección del QUIN. La coadministración de ambos fármacos previno la pérdida estriatal de Glu y Asp mediada por QUIN. Por su parte, la administración de un conocido antagonista de los receptores para NMDA, la dizocilpina (MK-80 1, 10 mg/kg, i.p.) previno totalmente la disminución estriatal de ambos aminoácidos. Estos hallazgos sugieren un papel farmacológico de la KYN y del PROB como inductores del antagonismo del KYNA sobre los receptores para NMDA