Use of a rhodamine-based chelator in a microfluidic paper-based analytical device for the in-situ copper quantification in natural waters.

This work describes the development of a microfluidic paper-based analytical device (µPAD) for the determination of copper in fresh and marine waters. A functionalized rhodamine-based chelator was synthesized and used as a chromogenic reagent, forming a highly intense pink complex with the analyte. The aim was to create a paper device that offers optimal performance and provides in-situ, rapid and cost-effective analysis in line with World Health Organization guidelines. The influence on the determination of several physical and chemical parameters was evaluated aiming to achieve the best performance. Under optimised conditions, a linear correlation was established in the range of 0.05-0.50 mg L-1 of copper, with a limit of detection of 10 µg L-1. The accuracy of the proposed method was assessed by comparing the results obtained with the developed µPAD and the results obtained with Inductively Coupled Plasma measurements (RE < 10 %). Recovery studies were also performed using different types of water samples with no need for any prior sample pre-treatment: tap, well, river and seawater. The average recovery percentage of 101 % (RSD = 4.3 %) was obtained, a clear indication of no multiplicative matrix interferences.

Microfluidic Paper-Based Device Incorporated with Silica Nanoparticles for Iodide Quantification in Marine Source Dietary Supplements.

Iodine is an essential micronutrient for humans due to its fundamental role in the biosynthesis of thyroid hormones. As a key parameter to assess health conditions, iodine intake needs to be monitored to ascertain and prevent iodine deficiency. Iodine is available from various food sources (such as seaweed, fish, and seafood, among others) and dietary supplements (multivitamins or mineral supplements). In this work, a microfluidic paper-based analytical device (µPAD) to quantify iodide in seaweed and dietary supplements is described. The developed µPAD is a small microfluidic device that emerges as quite relevant in terms of its analytical capacity. The quantification of iodide is based on the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by hydrogen peroxide in the presence of iodine, which acts as the catalyst to produce the blue form of TMB. Additionally, powder silica was used to intensify and uniformize the colour of the obtained product. Following optimization, the developed µPAD enabled iodide quantification within the range of 10-100 µM, with a detection limit of 3 µM, and was successfully applied to seaweeds and dietary supplements. The device represents a valuable tool for point-of-care analysis, can be used by untrained personnel at home, and is easily disposable, low-cost, and user-friendly.

Assessment of collagen content in fish skin - development of a flow analysis method for hydroxyproline determination.

This work describes the development of a flow injection method to determine hydroxyproline (HYP), one of collagen's most abundant amino acids. Collagen is a protein with several applications and high nutritional value. Evaluating the feasibility of using collagen from fish skin over its mammalian source is essential. The determination of HYP requires the pre-treatment and hydrolysis of the fish skin to break down collagen into its amino acids, and the HYP value quantified relates to the collagen content. The determination was based on the HYP oxidation with permanganate in an alkaline medium and the consequent decrease of colour intensity registered. Under optimal conditions, the developed method enables the determination of the HYP within the dynamic range of 23.8 to 500 mg L-1, with a limit of detection (LOD) of 2.6 mg L-1 and a limit of quantification (LOQ) of 23.8 mg L-1. Different samples were processed, and the digests were analysed by the proposed method and with the conventional procedure with good correlation (relative error < 7%). Moreover, the analyte quantification is performed faster, simpler, and more accurately, with less toxic solutions. The reproducibility of the developed method was also evaluated by calculating the relative standard deviation of the calibration curve slope (RSD < 1%).

Síndrome de Klippel-Trenaunay-Weber. Presentación de un caso y revisión de la literatura

El síndrome de Klippel-Trenaunay-Weber es una malformación vascular congénita poco frecuente. Está caracterizada por una triada de manifestaciones clínicas que comprende una malformación vascular venular, linfática y venosa, junto con hipertrofia esquelética; aumento de tejidos blandos de uno o más miembros; y la presencia de fistulas arteriovenosas. Se presenta el caso de una niña de 5 años de edad, a quien se le confirmó por hallazgos clínicos e imagenológicos un síndrome de Klippel-Trenaunay-Weber. Esta es una enfermedad rara, poco frecuente, con un patrón de herencia genética no bien definido, que necesita de un manejo multidisciplinario. El tratamiento de elección es el clínico sintomático, enfocado a evitar la discapacidad, mejorar la capacidad funcional, calidad de vida y prevenir complicaciones. Se presenta el caso por lo poco frecuente del padecimiento para mostrar su seguimiento y además con fines docentes.

Klippel-Trenaunay-Weber syndrome is a rare congenital vascular malformation. Its characterized by a triad of clinical manifestations that includes venular, lymphatic, and venous vascular malformation, together with skeletal hypertrophy, soft tissue enlargement of one or more limbs, and presence of arteriovenous fistulas. We present the case of a 5-year-old girl who was confirmed by clinical and imaging findings to have Klippel-Trenaunay-Weber syndrome. This is a rare, infrequent disease with a not well-defined genetic inheritance pattern that requires multidisciplinary management. The treatment of choice is the symptomatic clinic, focused on avoiding disability, improving functional capacity, quality of life and preventing complications. The case is presented due to the infrequent nature of this condition to show its follow-up and also for teaching purpose

Peripheral Visual Information Halves Attentional Choice Biases.

A growing body of research has shown that simple choices involve the construction and comparison of values at the time of decision. These processes are modulated by attention in a way that leaves decision makers susceptible to attentional biases. Here, we studied the role of peripheral visual information on the choice process and on attentional choice biases. We used an eye-tracking experiment in which participants (N = 50 adults) made binary choices between food items that were displayed in marked screen "shelves" in two conditions: (a) where both items were displayed, and (b) where items were displayed only when participants fixated within their shelves. We found that removing the nonfixated option approximately doubled the size of the attentional biases. The results show that peripheral visual information is crucial in facilitating good decisions and suggest that individuals might be influenceable by settings in which only one item is shown at a time, such as e-commerce.

Combining microfluidic paper-based platform and metal-organic frameworks in a single device for phenolic content assessment in fruits.

A microfluidic paper-based device (µPAD) has been combined with metal-organic frameworks (MOFs) for total phenolic compounds (TPC) quantification in fruit samples for the first time. The performance of the µPAD, based upon the vertical flow approach, was enhanced in order to determine the TPC content with high accuracy in fruit samples. The method was based on the traditional Folin-Ciocalteu Index using gallic acid or oenotannin as reference phenolic compounds. This novel design and construction of the device are in agreement with the principles of Green Chemistry avoiding wax technology (lower toxicity). The analytical parameters that affect the colorimetric method (using digital imaging of the colored zone) performance were optimized including design, sample volume, and MOF amount. Then, the analytical features of the developed method were investigated such as dynamic range (1.6-30 mg L-1), limit of detection (0.5 mg L-1), and precision (RSD < 9%). Besides, the in-field analysis is achievable with a color stability up to 6 h after the loading process of the sample and storage stability for at least 15 days without performance losses (under vacuum at - 20 °C). Furthermore, the MOF ZIF-8@paper was characterized to study its composition and the successful combination. The feasibility of the proposed method was demonstrated by determining the TPC in 5 fruit samples using oenotannin as reference solute. The accuracy was validated by comparison of the data with the results obtained with the recommended protocol proposed by the International Organisation of Vine and Wine (OIV).

Non-transferrin-bound iron determination in blood serum using microsequential injection solid phase spectrometry- proof of concept.

Non-transferrin-bound iron (NTBI) is a group of circulating toxic iron forms, which occur in iron overload or health conditions with dysregulation of iron metabolism. NTBI is responsible for increased oxidative stress and tissue iron loading. Despite its relevance as a biochemical marker in several diseases, a standardized assay is still lacking. Several methods were developed to quantify NTBI, but results show high inter-method and even inter-laboratory variability. Thus, the development of a consistent NTBI assay is a major goal in the management of iron overload and related clinical conditions. In this work, a micro sequential injection lab-on-valve (µSI-LOV) method in a solid phase spectrophotometry (SPS) mode was developed for the quantification of NTBI, using a bidentate 3,4-hydroxypyridinone (3,4-HPO) ligand anchored to sepharose beads as a chromogenic reagent. To attain SPS, the functionalized beads were packed into a column in the flow cell, and the analyte, NTBI retained as iron (III), formed a colored complex at the beads while eliminating the sample matrix. The dynamic concentration range was 1.62-7.16 µmol L-1 of iron (III), with a limit of detection of 0.49 µmol L-1 and a limit of quantification of 1.62 µmol L-1. The proposed µSI-LOV-SPS method is a contribution to the development of an automatic method for the quantification of the NTBI in serum samples.

Proyecto de investigación y tesis. Guía para su elaboración

La investigación final que deben realizar los residentes para culminar la especialización es el instrumento creado en el proceso formativo de posgrado, para que aprenda y aplique los aspectos básicos de la metodología de la investigación médica. Este trabajo tiene como objetivo brindar una guía de consulta a estudiantes y docentes, sobre la estructura y presentación de los proyectos de investigación e informe final de los trabajos de terminación de la especialidad. Para ello se realizó una búsqueda bibliográfica para la recopilación y clasificación de la bibliografía actualizada. Se brindan consideraciones de cómo elaborar el proyecto de investigación y el informe final y se especifica la información que deben tener ambos documentos. Se exponen elementos fundamentales sobre la estructura y presentación de los proyectos de investigación e informe final que podrán ser utilizados como guía de consulta para estudiantes y docentes.

The final research that residents must carry out to complete the specialization is the instrument created in the postgraduate training process, so that they learn and apply the basic aspects of medical research methodology. This work aims to provide a reference guide for students and teachers, on the structure and presentation of research projects and final report of completion of the specialty. For this, a bibliographic search was carried out for the compilation and classification of the updated bibliography. Considerations of how to prepare the research project and the final report are provided, and the information that both documents must have is specified. Fundamental elements on the structure and presentation of research projects and final report that can be used as a reference guide for students and teachers are exposed.

La esquizofrenia: una mirada desde la ciencia, la tecnología y la sociedad

RESUMEN La esquizofrenia es probablemente el trastorno más enigmático y trágico que tratan los psiquiatras, y quizás, el más devastador. Se manifiesta en la juventud, por lo que los pacientes esquizofrénicos normalmente viven muchos años después del inicio de la enfermedad y continúan padeciendo sus efectos sin poder llevar una vida completamente normal. Se realizó una revisión bibliográfica para la cual se emplearon los recursos disponibles en Infomed, específicamente en las bases de datos EBSCO, SCIELO y libros de textos de autores cubanos y extranjeros. Se aplicó el método analítico-sintético y se revisaron 18 artículos científicos. Se expusieron los elementos que abordan el desarrollo histórico- cultural de la esquizofrenia desde la perspectiva de la ciencia, la tecnología y la sociedad. Se realizó esta revisión con el objetivo de contribuir al conocimiento sobre el desarrollo histórico cultural de la esquizofrenia, teniendo en cuenta las teorías que ha desarrollado el hombre a través de la ciencia para explicar la aparición de la enfermedad y la importancia de los factores sociales en la aparición, evolución y rehabilitación de este padecimiento.

ABSTRACT Schizophrenia is probably the most enigmatic and tragic disorder that psychiatrists treat, and perhaps the most devastating. It manifests itself in youth, so schizophrenic patients usually live many years after the onset of the disease and continue to suffer from its effects without being able to lead a completely normal life. A bibliographic review was carried out using the resources available in Infomed, specifically in the EBSCO and SCIELO databases and textbooks by Cuban and foreign authors. The analytical-synthetic method was applied and 18 scientific articles were reviewed. The elements that address the historical-cultural development of schizophrenia from the perspective of science, technology and society were exposed. This review was carried out with the aim of contributing to the knowledge about the historical cultural development of schizophrenia, taking into account the theories that man has developed through science to explain the appearance of the disease and the importance of social factors in the appearance, evolution and rehabilitation of this condition.

La depresión en pacientes con diagnóstico de diabetes mellitus tipo 2

RESUMEN Fundamento: durante la evolución de la diabetes mellitus pueden aparecer complicaciones crónicas que afectan la esperanza y la calidad de vida relacionadas con la salud por lo que se perjudica la salud física y mental de los pacientes. Objetivo: determinar el comportamiento de la depresión en pacientes con diagnóstico de diabetes mellitus del consultorio médico de la familia #21 del municipio Rodas provincia Cienfuegos. Métodos: se realizó un estudio descriptivo de corte transversal, en el período de mayo de 2020 a mayo de 2021, el universo y la muestra estuvieron en correspondencia con los 36 pacientes diabéticos dispensarizados en el consultorio, a los que se les aplicó una encuesta y el Inventario de Depresión Rasgo-Estado. Se estudiaron las variables: edad, sexo, tipo de tratamiento, síntomas de depresión, complicaciones y nivel de depresión. El análisis y procesamiento de la información se hizo mediante el paquete estadístico SPSS versión 15 para Windows, los resultados se expresaron en números y porcientos. Resultados: predominó el sexo femenino en un 58,3 %, el grupo etáreo más representado fue el de 48-57 (50 %). Predominó el grupo de pacientes que consumen hipoglicemiantes orales (55 %). Hubo prevalencia de los pacientes con depresión (72,2 %), siendo más frecuente los que reciben tratamiento con hipoglicemiantes orales (47,2) y existió una elevada incidencia en el sexo femenino (41,6 %). Predominaron los pacientes con complicaciones renales (19,4 %) y cardiovasculares (16,6 %). El 75 % de los pacientes presentaron depresión baja. Conclusiones: en el estudio predominó el sexo femenino y el grupo etáreo de 48-57 años. Existió una prevalencia elevada de las complicaciones asociadas a la aparición de depresión y el consumo de hipoglicemiantes orales. Más de la mitad de los pacientes estudiados presentaron síntomas manifiestos de depresión. Prevalecieron los pacientes que presentaron depresión baja.

ABSTRACT Background: during the evolution of diabetes mellitus, chronic complications may appear that affect life expectancy and health-related quality of life, thus harming the physical and mental health of patients. Objective: to determine the behavior of depression in patients diagnosed with diabetes mellitus of the Family Medical Office #21 of the Rodas municipality, Cienfuegos province. Methods: a descriptive cross-sectional study was carried out, in the period from May 2020 to May 2021, the universe and the sample were in correspondence with the 36 diabetic patients dispensed in the office, to whom a survey was applied and the Adult Depression Test. The variables were studied: age, sex, type of treatment, symptoms of depression, complications, level of depression. The analysis and processing of the information was done using the statistical package SPSS version 15 for Windows, the results were expressed in numbers and percentages. Results: predominance of the female sex in 58.3 %, the most represented age group is that of 48-57 (50 %). The group of patients consuming oral hypoglycemic drugs (55 %) predominated. There was a prevalence of patients with depression (72.2 %), being more frequent those receiving treatment with oral hypoglycemic agents (47.2) and there was a high incidence in females (41.6 %). Patients with renal (19.4 %) and cardiovascular (16.6 %) complications predominated. 75 % of the patients presented low depression. Conclusions: the female sex and the age group of 48-57 predominated in the study. There was a high prevalence of complications associated with the appearance of depression and the consumption of oral hypoglycemic agents. More than half of the patients studied presented manifest symptoms of depression. Patients who presented low depression prevailed.

Design of a microfluidic paper-based device for the quantification of phenolic compounds in wine samples.

In this work, the design and development of a microfluidic paper-based device (µPAD) for the quantification of total phenolic compounds (TPC) in wines is described. The developed µPAD was based upon the vertical flow concept and the colour reaction used was the known Folin-Ciocalteu reaction using gallic acid as reference phenolic compound. After studying operational parameters, namely type of paper, reagents and sample volume, a dynamic range of 5-50 mg L-1 was obtained with a limit of detection of 1.2 mg L-1. The described device proved to have good precision (relative standard deviation < 5%) and no significant interferences were observed from known compounds present in wines. Furthermore, the stability of the colour product and of the device itself were assessed; the µPAD was stable for 30 days (in the dark at room temperature) and it could be scanned up to 8 h after sample introduction. The developed µPAD pose as a simple method for TPC quantification and was successfully applied to several wine samples including sparkling and table wines with two different approaches: i) using gallic acid as reference compound with standard addition; and ii) using taniraisin with external calibration. The accuracy of the proposed µPAD method was assessed by comparison with the reference spectrophotometric method according to the International Organisation of Vine and Wine (OIV) recommendations.

Resultados de trabajo del Programa Materno Infantil. Hospital Pediátrico Universitario de Cienfuegos, 2021 / Results of work of the maternal child program. University Pediatric Hospital of Cienfuegos, 2021

RESUMEN Fundamento: una estrategia fundamental para lograr resultados satisfactorios en la atención materno infantil fue la implementación del Programa Nacional de Atención Materno Infantil, cuyos resultados en el 2021 no fueron los esperados de cada año a nivel de país. Objetivo: describir los resultados de trabajo del Programa Materno Infantil en el Hospital Pediátrico Universitario de Cienfuegos en el año 2021. Métodos: estudio descriptivo, de corte transversal, realizado en el Hospital Pediátrico de Cienfuegos y que recoge los resultados integrales del Programa Materno Infantil en dicha institución. Se exponen todos los indicadores del programa. Se ofrece, además, una contextualización del escenario en el año 2021. Resultados: el escenario de enfrentamiento a la COVID-19 en Cienfuegos impactó durante el año 2021 en los resultados obtenidos por la institución; aumentaron las atenciones en cuerpo de guardia a 45 151 consultas, como principal motivo las enfermedades respiratorias agudas. La mortalidad hospitalaria se incrementó en seis fallecidos más con respecto al 2020, en correspondencia con la principal causa de atención en urgencias, seguidas de la sepsis. Se mantuvo la cabecera municipal como el principal emisor de pacientes y le siguieron en frecuencia Cumanayagua y Rodas como los municipios que mayor número de ingresos aportaron. El promedio de estadía hospitalaria fue de 4,3 días y la supervivencia general se comportó en un 96,8 %. Conclusiones: el colectivo de la institución continúa desarrollando la gestión clínica para alcanzar la calidad de los servicios hospitalarios óptimos para incidir, modificar y hacer sostenibles los indicadores con resultados desfavorables.

ABSTRACT Background: A fundamental strategy to achieve satisfactory results in maternal and child care was the implementation of the National Program for Maternal and Child Care (PAMI). The results of the PAMI in 2021 are not what is expected each year at the country level and it was not far from the reality of the Paquito Glez University Pediatric Hospital. Objective: Mention the results of the work of the Maternal and Child Program at the University Pediatric Hospital of Cienfuegos in the year 2021. Methods: descriptive, cross-sectional study, carried out at the Pediatric Hospital of Cienfuegos and which includes the comprehensive results of the Maternal and Child Program at said institution. All the indicators of the program are exposed. It also offers a contextualization of the scenario in the year 2021. Results: The scenario of confrontation with COVID-19 in Cienfuegos had an impact during the year 2021 on the results obtained by the institution, increasing care in the emergency room to 45,151 consultations, as the main reason for Acute Respiratory Diseases. Hospital mortality increases by six more deaths compared to 2020, responding to the main cause of emergency care followed by Sepsis. The municipal seat remains the main issuer of patients and is followed in frequency by Cumanayagua and Rodas, corresponding to the municipalities that contribute the greatest number of admissions. The average hospital stay was 4.3 and the general survival behaves in 96.8%. Conclusions: The group of the institution continues to develop clinical management to achieve the quality of optimal hospital services to influence, modify and make sustainable the indicators with unfavorable results.

A Robust Flow-Based System for the Spectrophotometric Determination of Cr(VI) in Recreational Waters.

A flow-based method for the spectrophotometric determination of chromium (VI) in recreational waters with different salinities was developed. Chromium can occur in the environment in different oxidation states with different related physiological properties. With regard to chromium, the speciation is particularly important, as the hexavalent chromium is considered to be carcinogenic. To achieve that purpose, the use of the diphenylcarbazide (DPC) selective colored reaction with the hexavalent chromium was the chosen strategy. The main objective was to develop a direct and simple spectrophotometric method that could cope with the analysis of different types of environmental waters, within different salinity ranges (fresh to marine waters). The potential interference of metal ions, that can usually be present in environmental waters, was assessed and no significant interferences were observed (<10%). For a complete Cr(VI) determination (three replicas) cycle, the corresponding reagents consumption was 75 µg of DPC, 9 mg of ethanol and 54 mg of sulfuric acid. Each cycle takes about 5 min, including the system clean-up. The limit of detection was 6.9 and 12.2 µg L−1 for waters with low and high salt content, respectively. The method was applied for the quantification of chromium (VI) in both fresh and marine water, and the results were in agreement with the reference procedure.

Sequential injection spectrophotometric method for screening bromate produced as an ozonation water disinfection by-product.

The aim of this work was the development of an automatic sequential injection analysis method to monitor the ozonation process for water disinfection. The determination was based on the reaction between bromate and o-dianisidine in the presence of bromide in acidic medium. The determination parameters were studied and adjusted to enable bromate quantification in the range 0.35-4.0 mg BrO3-/L with a limit of detection of 20 µg BrO3-/L. The choice of a sequential injection procedure enabled a minimal consumption of reagents and no need for sample pre-treatment. The developed sequential injection proved to be accurate with < 5% relative deviation when compared to ICP-MS and an average of 101% in recovery percentages studies. It was effectively applied to monitor an ozonation process enabling the follow-up of the process with real-time quantification of the bromate content.

Chip-Based Spectrofluorimetric Determination of Iodine in a Multi-Syringe Flow Platform with and without In-Line Digestion-Application to Salt, Pharmaceuticals, and Algae Samples.

In this work, a flow-based spectrofluorimetric method for iodine determination was developed. The system consisted of a miniaturized chip-based flow manifold for solutions handling and with integrated spectrofluorimetric detection. A multi-syringe module was used as a liquid driver. Iodide was quantified from its catalytic effect on the redox reaction between Ce(IV) and As(III), based on the Sandell-Kolthoff reaction. The method was applied for the determination of iodine in salt, pharmaceuticals, supplement pills, and seaweed samples without off-line pre-treatment. An in-line oxidation process, aided by UV radiation, was implemented to analyse some samples (supplement pills and seaweed samples) to eliminate interferences and release iodine from organo-iodine compounds. This feature, combined with the fluorometric reaction, makes this method simpler, faster, and more sensitive than the classic approach of the Sandell-Kolthoff reaction. The method allowed iodine to be determined within a range of 0.20-4.0 µmol L-1, with or without the in-line UV digestion, with a limit of detection of 0.028 µmol L-1 and 0.025 µmol L-1, respectively.

COVID-19-associated mucormycosis, diabetes and steroid therapy: Experience in a single centre in Western Mexico.

BACKGROUND: COVID-19-associated mucormycosis (CAM) has emerged as a challenging complication as the current pandemic has increased the population requiring treatment with corticosteroids. CAM has caused a massive outbreak in India, reported to be causing cases in Iran, Egypt and The Netherlands. OBJECTIVES: To describe CAM cases occurring in a single centre in Western Mexico. METHODS: Our group carried out a retrospective study from May 2020 to May 2021 to identify CAM cases in patients with previous COVID-19 diagnosis. RESULTS: Six CAM cases occurred in a single centre in Western Mexico during the study period, most of them with diabetes (n = 5/6) and all received corticosteroid therapy even when only three had severe COVID-19. After analysing local COVID-19 burden, it was estimated that in this region, CAM was 300 times more frequent among COVID individuals than the estimates for general population. CONCLUSION: Similar to large reports in India and other countries, CAM cases reported in this study were diagnosed in individuals with diabetes, hyperglycaemic status and with history of previous use of corticosteroids. Identifying these individuals at risk can help the early identification of CAM. In addition, strict glycaemic control and avoidance of unnecessary corticosteroid in non-severe COVID-19 cases could help in preventing this complicated fungal infection.

Sequential injection method for bi-parametric determination of iron and manganese in soil leachates.

The aim of this work was to develop a sequential injection (SI) method for the determination of the micronutrients iron and manganese, in soil leachates, as a tool to assess potential groundwater contamination. The described sequential injection method was based on the reaction of iron with chelator MRB12, a greener alternative chromogenic reagent, and the reaction of manganese with zincon, within a single manifold. The developed SI method enabled the determination of iron in the range 0.10-1.00 mg L-1, and manganese in the range 0.25-2.5 mg L-1 with a limit of detection of 0.08 mg L-1 for iron and 0.24 mg L-1 for manganese. The determination of both parameters was made in 6 minutes, in triplicate. The application to monitor laboratory scale soil core columns (LSSCs), as a simulation of the soil leaching process, proved its efficiency to assess potential contamination of ground waters. Iron and manganese contents were effectively analysed in two different scenarios to mimic the leaching process with rainwater and fertilizer.

Characterization of Oral Enterobacteriaceae Prevalence and Resistance Profile in Chronic Kidney Disease Patients Undergoing Peritoneal Dialysis.

Chronic Kidney Disease (CKD) is a growing public-health concern worldwide. Patients exhibit compromised immunity and are more prone to infection than other populations. Therefore, oral colonization by clinically relevant members of the Enterobacteriaceae family, major agents of both nosocomial and dialysis-associated infections with frequent prevalence of antibiotic resistances, may constitute a serious risk. Thus, this study aimed to assess the occurrence of clinically relevant enterobacteria and their antibiotic resistance profiles in the oral cavity of CKD patients undergoing peritoneal dialysis (CKD-PD) and compare it to healthy controls. Saliva samples from all the participants were cultured on MacConkey Agar and evaluated regarding the levels of urea, ammonia, and pH. Bacterial isolates were identified and characterized for antibiotic resistance phenotype and genotype. The results showed that CKD-PD patients exhibited significantly higher salivary pH, urea, and ammonia levels than controls, that was accompanied by higher prevalence and diversity of oral enterobacteria. Out of all the species isolated, only the prevalence of Raoultella ornithinolytica varied significantly between groups, colonizing the oral cavity of approximately 30% of CKD-PD patients while absent from controls. Antibiotic resistance phenotyping revealed mostly putative intrinsic resistance phenotypes (to amoxicillin, ticarcillin, and cephalothin), and resistance to sulfamethoxazole (~43% of isolates) and streptomycin (~17%). However, all isolates were resistant to at least one of the antibiotics tested and multidrug resistance isolates were only found in CKD-PD group (31,6%). Mobile genetic elements and resistance genes were detected in isolates of the species Raoultella ornithinolytica, Klebsiella pneumoniae, Klebsiella oxytoca, Escherichia coli, and Enterobacter asburiae, mostly originated from CKD-PD patients. PD-related infection history revealed that Enterobacteriaceae were responsible for ~8% of peritonitis and ~ 16% of exit-site infections episodes in CKD-PD patients, although no association was found to oral enterobacteria colonization at the time of sampling. The results suggest that the CKD-induced alterations of the oral milieu might promote a dysbiosis of the commensal oral microbiome, namely the proliferation of clinically relevant Enterobacteriaceae potentially harboring acquired antibiotic resistance genes. This study highlights the importance of the oral cavity as a reservoir for pathobionts and antibiotic resistances in CKD patients undergoing peritoneal dialysis.

Design and Functionalization of a µPAD for the Enzymatic Determination of Nitrate in Urine.

In this work, the design of a microfluidic paper-based analytical device (µPAD) for the quantification of nitrate in urine samples was described. Nitrate monitoring is highly relevant due to its association to some diseases and health conditions. The nitrate determination was achieved by combining the selectivity of the nitrate reductase enzymatic reaction with the colorimetric detection of nitrite by the well-known Griess reagent. For the optimization of the nitrate determination µPAD, several variables associated with the design and construction of the device were studied. Furthermore, the interference of the urine matrix was evaluated, and stability studies were performed, under different conditions. The developed µPAD enabled us to obtain a limit of detection of 0.04 mM, a limit of quantification of 0.14 mM and a dynamic concentration range of 0.14-1.0 mM. The designed µPAD proved to be stable for 24 h when stored at room temperature in air or vacuum atmosphere, and 60 days when stored in vacuum at -20 °C. The accuracy of the nitrate µPAD measurements was confirmed by analyzing four certified samples (prepared in synthetic urine) and performing recovery studies using urine samples.

New microfluidic paper-based analytical device for iron determination in urine samples.

Iron is an important micronutrient involved in several mechanisms in the human body and can be an important biomarker. In this work, a simple and disposable microfluidic paper-based analytical device (µPAD) was developed for the quantification of iron in urine samples. The detection was based on the colorimetric reaction between iron(II) and bathophenanthroline and the reduction of iron(III) to iron(II) with hydroxylamine. The developed µPAD enabled iron determination in the range 0.07-1.2 mg/L, with a limit of detection of 20 µg/L and a limit of quantification of 65 µg/L, thus suitable for the expected values in human urine. Additionally, targeting urine samples, the potential interference of the samples color was overcome by incorporating a sample blank assessment for absorbance subtraction. Stability studies revealed that the device was stable for 15 days prior to usage and that the formed colored product was stable for scanning up to 3 h. The accuracy of the developed device was established by analyzing urine samples (#26) with the developed µPAD and with the atomic absorption spectrometry method; the relative deviation between the two sets of results was below 9.5%.