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ABSTRACT Purpose: This study aimed to analyze variations in intraoperative corneal thickness during corneal cross-linking in patients with keratoconus and to investigate its possible correlation with presurgical maximal keratometry (Kmax) and pachymetry. Methods: This was a prospective case series. We used a method similar to the Dresden protocol, with the application of hydroxypropyl methylcellulose 0.1% hypo-osmolar riboflavin in corneas between 330 and 400 µm after epithelium removal. Corneal thickness was measured using portable calipers before and immediately after epithelium removal, and 30 and 60 min after the procedure. Results: The 30 patients in this study were followed up for one year. A statistically significant difference was observed in pachymetry values during the intraoperative period (p<0.0001) and an increase of 3.05 µm (95%C1: 0.56-5.54) for each diopter was seen after epithelium removal (p0.019). We found an average Kmax difference of —2.12 D between men and women (p0.013). One year after treatment, there was a statistically significant reduction in pachymetry (p<0.0001) and Kmax (p0.0170) values. Conclusions: A significant increase in pachymetry measurements was seen during the procedure, and most patients showed a regression in Kmax and pachymetry values one year after surgery.

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BACKGROUND AND OBJECTIVES: The storage temperature of immunohaematological reagents generally ranges from 2 to 8°C, and they should be utilised at room temperature. This study aimed to analyse the stability of immunohaematological reagents used in ABO and RhD typing. METHODS: The evaluation encompassed the potency, specificity, and integrity of anti-A, anti-B, anti-D, RhD control sera, and A1 and B red blood cells (RBC) reagents after long (8 h) and short (4 h) daily periods of exposure to room temperature (20-24°C), 5 days a week for 4 weeks. Additionally, the A1 and B RBC reagents were exposed daily for 11 h and 30 min at room temperature, including 30 more minutes at room temperature with simultaneous homogenisation through equipment. For the control, an aliquot of each reagent was constantly stored at refrigeration temperature, while another was exposed to room temperature for 12 h daily. Tests conducted included reaction intensity, titration, and avidity for antisera, reaction intensity, free haemoglobin determination, and electrical conductivity for the RBC reagents. RESULTS: The antisera maintained the reaction intensity. The titre and avidity of the antisera satisfied the minimum Brazilian requirements after different exposure periods. A higher free haemoglobin concentration was noted in the RBC reagents subjected to room temperature and simultaneous homogenisation, although this did not affect the potency and specificity. The electrical conductivity average of the RBC reagent remained consistent. CONCLUSION: The findings indicate that the immunohaematological reagents from a specific manufacturer are stable under the tested temperature, ensuring the quality of the results under these conditions.

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This study aimed to evaluate the effect of n-propyl gallate as pre-treatment for resin-dentin bond strength. The dentin pre-treatments evaluated included propyl gallate of concentrations 0.1% (w/v), 1.0% (w/v), and 10.0% (w/v), as well as glutaraldehyde 5.0% (v/v), and distilled water as a control treatment. Dentin specimens were prepared for Fourier Transformed Infrared Spectroscopy (FT-IR) (n = 3/pre-treatment). Pre-treatments were actively applied to dentin blocks before performing the adhesive procedure to composite resin. Microtensile bond strength to dentin (µTBS) (n = 8/pre-treatment) was determined after 24 h and 6 months of storage. Data were submitted to a two-way ANOVA, followed by Tukey's post hoc test. As for FT-IR, propyl gallate 1%-treated specimens presented higher water, carbonate, collagen, and amide absorbance rates compared to other tested groups, while specimens pre-treated with glutaraldehyde and distilled water presented similar absorbance curves. Regarding µTBS, all concentrations of propyl gallate resulted in statistically significant higher bond strength values than distilled water at 24 h. After 6 months of storage, propyl gallate 0.1% was the only group that maintained µTBS over time. Propyl gallate 0.1% might be a suitable dentinal pre-treatment due to being able to present chemical bonds with demineralized dentin and providing resin-dentin bond stability after 6 months of storage.

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ABSTRACT Purpose: This study aimed to examine the effects of unilateral corneal collagen cross-linking treatment on visual acuity and the topographic findings of the fellow untreated eye of patients who had bilateral progressive keratoconus. Methods: Patients with progressive keratoconus who underwent cross-linking treatment were screened retrospectively. A total of 188 untreated eyes of 188 patients whose eyes were treated unilaterally with either standard or accelerated cross-linking and refused cross-linking procedure for the fellow eye were included. Visual acuity and topographic findings of the fellow untreated eyes were obtained preoperatively and postoperatively at the 1st, 3rd, 6th, 12th, 24th, 30th, and 36th months. Results: The change over time of variables examined was similar in the untreated eyes of patients who received standard and accelerated cross-linking methods (p>0.05). At the 12th month, 136 (95.8%) untreated eyes were stable according to progression criteria. Only 4 (8%) eyes were progressive at the 24th month. No progression was observed in any of the 16 patients with a 36-month follow up. Conclusions: The results showed that the fellow untreated eyes of patients with bilateral progressive keratoconus did not have significant progression rates after unilateral cross-linking treatment.

RESUMO Objetivo: Examinar os efeitos do tratamento de reticulação unilateral do colágeno corneano na acuidade visual e os achados topográficos em olhos não tratados de pacientes com ceratocone progressivo bilateral. Métodos: Foram rastreados retrospectivamente pacientes com ceratocone progressivo submetidos a tratamento de reticulação. Foram incluídos no estudo 188 olhos não tratados de 188 pacientes tratado unilateralmente com reticulação padrão ou acelerada e que recusaram o procedimento de reticulação no outro olho. A acuidade visual e os achados topográficos dos olhos não tratados foram obtidos no pré- e pós-operatório no 1º, 3º, 6º, 12º, 24º, 30º e 36º mês. Resultados: As alterações ao longo do tempo foram semelhantes para as variáveis examinadas nos olhos não tratados de pacientes tratados com métodos de reticulação padrão e acelerado (p>0,05). No 12º mês, 136 olhos não tratados (95,8%) estavam estáveis, de acordo com os critérios de progressão. Apenas quatro olhos (8%) mostraram progressão no 24º mês. Nenhuma progressão foi observada nos 16 pacientes que tiveram um acompanhamento de 36 meses. Conclusões: O estudo mostrou que os olhos não tratados de pacientes com ceratocone progressivo bilateral não apresentaram taxas de progressão significativas após o tratamento unilateral com reticulação.

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Introducción: Estimar la calidad de cualquier instrumento evaluativo escrito, es requisito esencial no solo en su proceso de construcción, sino también en la obtención de información para la toma correcta de decisiones. Objetivo: Evaluar la calidad del examen parcial de la asignatura Sangre y Sistema Nervioso, disciplina Bases Biológicas de la Estomatología, carrera Estomatología. Métodos: Estudio observacional analítico y transversal, en 27 exámenes correspondientes al examen parcial de la asignatura Sangre y Sistema Nervioso, disciplina Bases Biológicas de la Estomatología, carrera de Estomatología, Universidad de Ciencias Médicas de Santiago de Cuba, curso 2022. Se analizó la correspondencia del fondo de tiempo y la cantidad de ítems explorados en el examen, se calcularon índices de dificultad y de discriminación de incisos y preguntas, coeficiente de discriminación biserial puntual y de consistencia interna. Resultados: Existió correspondencia adecuada entre el fondo de tiempo asignado a los contenidos de las temáticas y la cantidad de ítems explorados en el examen. Predominaron los reactivos con índice de dificultad media y buen poder de discriminación. La consistencia interna de las preguntas y del examen general se evaluó de excelente. Conclusiones: La calidad del examen parcial aplicado en la asignatura Sangre y Sistema Nervioso de la disciplina Bases Biológicas de la Estomatología, carrera de Estomatología, Universidad de Ciencias Médicas de Santiago de Cuba, curso 2022, es adecuada.

Introduction: To estimate the quality of any written evaluative instrument is an essential requirement not only in its construction process, but also in obtaining information for correct decision making. Objective: To evaluate the quality of the partial test from Blood and Nervous System subject in Biological Bases of Dentistry discipline, Dentistry career. Methods: Analytical and cross-sectional observational study, in 27 tests corresponding to the partial test of Blood and Nervous System subject, Biological Bases of Dentistry discipline, Dentistry career, Santiago de Cuba Medical Sciences University, course 2022. The correspondence from the background of time and the number of items explored in the test were analyzed, indices of difficulty and discrimination of items and questions, punctual biserial discrimination coefficient and internal consistency were calculated. Results: There was an adequate correspondence between the amount of time assigned to the contents of the themes and the number of items explored in the test. Items with a medium difficulty index and good discrimination power prevailed. The internal consistency of the questions and general test was evaluated as excellent. Conclusions: The quality of the partial test from Blood and Nervous System subject, Biological Bases of Dentistry discipline, Dentistry career, Santiago de Cuba Medical Sciences University, course 2022, is adequate.

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There is a need to define mine tailings in a clear, precise, multidisciplinary, transdisciplinary, and holistic manner, considering not only geotechnical and hydraulic concepts but also integrating environmental and geochemical aspects with implications for the sustainability of mining. This article corresponds to an independent study that answers questions concerning the definition of mine tailings and the socio-environmental risks linked with mine tailings chemical composition by examining the practical experience of industrial-scale copper and gold mining projects in Chile and Peru. Definitions of concepts and analysis of key aspects in the responsible management of mine tailings, such as characterization of metallic-metalloid components, non-metallic components, metallurgical reagents, and risk identification, among others, are presented. Implications of potential environmental impacts from the generation of acid rock drainage (ARD) in mine tailings are discussed. Finally, the article concludes that mine tailings are potentially toxic to both communities and the environment, and cannot be considered as inert and innocuous materials; thus, mine tailings require safe, controlled, and responsible management with the application of the most high management standards, use of the best available technologies (BATs), use of best applicable practices (BAPs), and implementation of the best environmental practices (BEPs) to avoid risk and potential socio-environmental impact due to accidents or failure of tailings storage facilities (TSFs).

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The propargyl group is a highly versatile moiety whose introduction into small-molecule building blocks opens up new synthetic pathways for further elaboration. The last decade has witnessed remarkable progress in both the synthesis of propargylation agents and their application in the synthesis and functionalization of more elaborate/complex building blocks and intermediates. The goal of this review is to highlight these exciting advances and to underscore their impact.

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Introducción: Dentro de los grandes desafíos que la formación universitaria en el sector salud enfrenta hoy, está el implementar y validar instrumentos de evaluación efectivos. Objetivo: Evaluar la calidad de la prueba parcial del curso propio Bases morfofuncionales de las principales diátesis hemorrágicas en Estomatología, de la Facultad de Estomatología, Universidad de Ciencias Médicas de Santiago de Cuba, curso 2022. Método: Estudio observacional analítico y transversal, en 30 exámenes correspondientes a la prueba parcial del curso propio Bases morfofuncionales de las principales diátesis hemorrágicas en Estomatología, plan de estudio E, carrera de Estomatología, Facultad de Estomatología, Universidad de Ciencias Médicas de Santiago de Cuba, curso 2022. Se analizó la correspondencia del fondo de tiempo y la cantidad de ítems explorados en el examen, se calcularon índices de dificultad y de discriminación de incisos y preguntas, coeficiente de discriminación biserial puntual y de consistencia interna. Resultados: Existió correspondencia adecuada entre el fondo de tiempo asignado a los contenidos de las temáticas y la cantidad de ítems explorados en el examen. Predominaron los reactivos con índice de dificultad media y buen poder de discriminación. La consistencia interna de las preguntas de modo individual fue excelente, pero la del examen en general fue baja. Conclusiones: La calidad del examen parcial del curso propio Bases morfofuncionales de las principales diátesis hemorrágicas en Estomatología, aplicado en la Facultad de Estomatología, Universidad de Ciencias Médicas de Santiago de Cuba, curso 2022, fue poco adecuada.

Introduction: One of the challenges facing universities of health sciences today is the implementation and validation of effective tools for evaluation. Objective: To evaluate the quality of the partial exams of an in-house course in Morphofunctional bases of the most common hemorrhagic diathesis in Stomatology, Facultad de Estomatología, Universidad de Ciencias Médicas de Santiago de Cuba, course 2022. Method: An analytical and transversal observational study was carried out. For the study, it was selected 30 of the partial exams implemented in the in-house Morphofunctional bases of the most common hemorrhagic diathesis in Stomatology course, type (E) course syllabus, Stomatology career, Facultad de Estomatología, Universidad de Ciencias Médicas de Santiago de Cuba, course 2022. Correspondence between scheduled time and the number of items used in the test was assessed, and also, difficulty index and discrimination index for items and questions, point-biserial item discrimination coefficient and internal consistency coefficient were calculated. Results: There was an adequate correspondence between the time scheduled for the topics and the number of items used in the exam. Items with a moderate difficulty index and high degree of discrimination index predominated. The internal consistency of the individual questions was excellent, but the exam in general was low. Conclusions: The quality of the partial exam of the in-house course Morphofunctional bases of the main hemorrhagic diathesis treated in Stomatology, giving in the Faculty of Stomatology, University of Medical Sciences of Santiago de Cuba, course 2022, was inadequate.

Introdução: Entre os grandes desafios que a educação universitária na área da saúde enfrenta hoje, está a implementação e validação de instrumentos de avaliação eficazes. Objetivo: Avaliar a qualidade do teste parcial do curso Bases morfofuncionais da diátese hemorrágica principal em Estomatologia, da Facultad de Estomatología de la Universidad de Ciencias Médicas de Santiago de Cuba, curso 2022. Método: Estudo observacional analítico e transversal, em 30 exames correspondentes à prova parcial do próprio curso Bases morfofuncionais da diátese hemorrágica principal em Estomatologia, plano de estudos E, carreira de Estomatologia de la Universidad de Ciencias Médicas de Santiago de Cuba, curso 2022. A correspondência do analisou-se o fundo de tempo e o número de itens explorados no exame, calcularam-se índices de dificuldade e discriminação de subseções e questões, coeficiente de discriminação bisserial pontual e consistência interna. Resultados: Houve correspondência adequada entre o tempo destinado aos conteúdos dos temas e o número de itens explorados no exame. Predominaram os itens com índice de dificuldade médio e bom poder de discriminação. A consistência interna das questões individuais foi excelente, mas a do exame como um todo foi baixa. Conclusões: A qualidade do exame parcial das Bases Morfofuncionais da diátese hemorrágica principal do curso de Estomatologia, aplicado na Facultad de Estomatología de la Universidad de Ciencias Médicas de Santiago de Cuba, curso 2022, não foi adequada.

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In a previous study, we reported the identification and synthesis of a male-specific sex pheromone component of the stink bug, Pellaea stictica, as the alcohol 2,4,8,13-tetramethyltetradecan-1-ol (1). To establish the correlation between the stereochemistry of the pheromone and its bioactivity, it first was necessary to determine its absolute configuration. For this purpose, a series of syntheses were designed to: (a) furnish a mixture of all possible stereoisomers; (b) a narrowed down group of diastereomers, and (c) one specific enantiomer. A crucial step in the syntheses involved a coupling reaction between two key intermediates: a phosphonium salt and an aldehyde, through a Wittig olefination. Nuclear magnetic resonance data of a mixture of the synthetic pheromone diastereomers and further comparison of GC retention times with that of the natural product by gas chromatography suggested that the methyl branches at C2 and C4 were in a syn relationship, reducing the possibilities to only four of the eight possible stereoisomers. Employing GC analysis, chiral derivatization reagents and synthetic (8R)-2,4-syn-1 it was possible to confirm the configuration of the methyl branch at C8 as R, reducing the number of possible stereoisomers to two. After enantioselective synthesis of (2R,4R,8R)-1, the absolute configurations of all methyl branches of the natural compound were confirmed as R, fully identifying the male-produced sex pheromone of P. stictica as (2R,4R,8R)-2,4,8,13-tetramethyltetradecan-1-ol.

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Objetivou-se comparar os teores dos nutrientes do capim Andropogon gayanus obtidos no equipamento NIRS com os valores obtidos por análises de via úmida, para identificar se os modelos globais de calibração do equipamento NIRS são adequados para predizer a composição químico-bromatológica. As análises de via seca no NIRS foram executadas no Laboratório de Bromatologia e Nutrição Animal (Laban), pertencente à Faculdade de Medicina Veterinária (Famev) da Universidade Federal de Uberlândia (UFU), enquanto as análises de via úmida foram realizadas no Laboratório de Química Analítica de Plantas da Embrapa Cerrados, localizado em Brasília-DF. As amostras utilizadas foram de capim Andropogon gayanus, cultivar Planaltina, as quais, após corte de 20cm acima do solo, foram secas e moídas no tamanho de 1mm. Após a moagem, foram analisadas por via úmida para os teores de matéria seca (MS), matéria mineral (MM), proteína bruta (PB), fibra insolúvel em detergente neutro (FDN) e fibra insolúvel em detergente ácido (FDA), segundo metodologias propostas por Detmann et al. (2012). As amostras moídas foram colocadas em cubetas próprias do equipamento e escaneadas em espectrômetro de refletância no infravermelho próximo (NIRS) NIR, modelo Spectra Star 2600 XT series of Near Infrared Analyzers (Unity Scientific®), em duplicata. Para obtenção dos teores de MS, MM, PB, FDN e FDA, empregaram-se modelos de calibração do próprio equipamento NIRS, utilizando-se a curva de calibração própria do equipamento. As médias dos teores de MS, MM, PB, FDN e FDA obtidas pelas análises de bancada (via úmida) e pelo uso do equipamento NIRS foram comparadas pelo teste T (dados pareados), ao nível de 5% de probabilidade, empregando-se o delineamento em blocos ao acaso. Houve diferença significativa nos nutrientes preditos pelo NIRS e analisados por via úmida (P≤0,05). O NIRS superestimou os teores de matéria seca e matéria mineral, mas subestimou os teores de FDN, FDA e PB. Esse resultado mostra que, quando do uso de modelos globais de calibração, esse equipamento não é capaz de predizer corretamente a composição químico-bromatológica de forrageiras de clima tropical.

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Chemical derivatization for improving selectivity and/or sensitivity is a common practice in analytical chemistry. It is particularly attractive in flow analysis in view of its highly reproducible reagent addition(s) and controlled timing. Then, measurements without attaining the steady state, kinetic discrimination, exploitation of unstable reagents and/or products, as well as strategies compliant with Green Analytical Chemistry, have been efficiently exploited. Flow-based chemical derivatization has been accomplished by different approaches, most involving flow and manifold programming. Solid-phase reagents, novel strategies for sample insertion and reagent addition, as well as to increase sample residence time have been also exploited. However, the required alterations in flow rates and/or manifold geometry may lead to spurious signals (e.g., Schlieren effect) resulting in distorted peaks and a noisy/drifty baseline. These anomalies can be circumvented by a proper flow system design. In this review, these aspects are critically discussed mostly in relation to spectrophotometric and luminometric detection.

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Several low molecular weight naphthoquinones are very useful in organic synthesis. These compounds have given rise to thousands of other naphthoquinones that have been tested against various microorganisms and pharmacological targets, including being used in the preparation of several drugs that are on the pharmaceutical market. Among these naphthoquinones, the series of compounds prepared from 1,2-naphthoquinone-4-sulfonic acid salts (ß-NQS) stands out. In addition to being used in organic synthesis, they are excellent analytical derivatization reagents to spectrophotometrically determine drugs containing primary and secondary amino groups. This review summarizes the literature involving ß-NQS.

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Peptide synthesis is an area with a wide field of application, from biomedicine to nanotechnology, that offers the option of simultaneously synthesizing a large number of sequences for the purpose of preliminary screening, which is a powerful tool. Nevertheless, standard protocols generate large volumes of solvent waste. Here, we present a protocol for the multiple Fmoc solid-phase peptide synthesis in tea bags, where reagent recycling steps are included. Fifty-two peptides with wide amino acid composition and seven to twenty amino acid residues in length were synthesized in less than three weeks. A clustering analysis was performed, grouping the peptides by physicochemical features. Although a relationship between the overall yield and the physicochemical features of the sequences was not established, the process showed good performance despite sequence diversity. The recycling system allowed to reduce N, N-dimethylformamide usage by 25-30% and reduce the deprotection reagent usage by 50%. This protocol has been optimized for the simultaneous synthesis of a large number of peptide sequences. Additionally, a reagent recycling system was included in the procedure, which turns the process into a framework of circular economy, without affecting the quality of the products obtained.

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The detailed study of graphene oxide (GO) synthesis by changing the graphite/oxidizing reagents mass ratios (mG/mROxi), provided GO nanosheets production with good yield, structural quality, and process savings. Three initial samples containing different amounts of graphite (3.0 g, 4.5 g, and 6.0 g) were produced using a bench reactor under strictly controlled conditions to guarantee the process reproducibility. The produced samples were analyzed by Raman spectroscopy, atomic force microscopy (AFM), x-ray diffraction (XDR), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetry (TGA) techniques. The results showed that the major GO product comprised of nanosheets containing between 1-5 layers, with lateral size up to 1.8 µm. Therefore, it was possible to produce different batches of graphene oxide with desirable physicochemical characteristics, keeping the amount of oxidizing reagent unchanged. The use of different proportions (mG/mROxi) is an important strategy that provides to produce GO nanostructures with high structural quality and scale-up, which can be well adapted in medium-sized bench reactor.

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The bond strength and nature of a set of 32 Togni-like reagents have been investigated at the M062X/def2-TZVP(D) level of theory in acetonitrile described with the SMD continuum solvent model, to rationalize the main factors responsible for their thermodynamic stability in different conformations, and trifluoromethylation capabilities. For the assessment of bond strength, we utilized local stretching force constants and associated bond strength orders, complemented with local features of the electron density to access the nature of the bonds. Bond dissociation energies varied from 31.6 to 79.9 kcal/mol depending on the polarizing power of the ligand trans to CF3 . Based on the analysis of the Laplacian of the density, we propose that the charge-shift bond character plays an important role in the stability of the molecules studied, especially for those containing I-O bonds. New insights on the trans influence and on possible ways to fine-tune the stability of these reagents are provided.

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ABSTRACT Purpose: Keratoconus presents certain specificities in pediatric patients compared with adults. The greatest challenge is because the disease is typically more severe and progresses faster in children. This retrospective study aimed to report crosslinking procedure in patients under 18 years of age and their follow-up for at least 24 months after the procedure. Methods: Overall, 12 eyes from 10 patients were studied and data, such as visual acuity with and without correction, maximum keratometry, corneal thickness, foveal thickness, and endothelial microscopy, were assessed at both preoperative and postoperative visits. Corneal crosslinking was performed in all patients. Results: A tendency toward reduced Kmax and improved Corrected Distance Visual Acuity at all postoperative moments. Only one of the 12 eyes exhibited increased Kmax of more than 1 D during a time frame longer than 12 months. Regarding pachymetry, a tendency for corneal thinning was observed in the first four months after surgery. Conclusion: Encouraging results were obtained regarding the stabilization of the disease, progression, and procedural safety, corroborating to other authors' findings. The significance of early diagnosis and short-term follow-up were highlighted.

RESUMO Objetivo: O ceratocone na população pediátrica apresenta algumas particularidades em relação à população adulta. O maior desafio é devido à doença ser geralmente mais severa e rapidamente progressiva em crianças. Métodos: Este artigo utiliza uma análise retrospectiva para relatar o uso do crosslinking em jovens menores de 18 anos e sua evolução pelo menos 24 meses após o procedimento. Foram estudados 12 olhos de 10 pacientes, e dados como acuidade visual com e sem correção, ceratometria máxima, espessura corneana, espessura foveal e microscopia endotelial avaliados no pré e pós-operatórios. O crosslinking corneano foi realizado em todos os pacientes pelo mesmo cirurgião. Resultados: Observou-se uma tendência de redução do valor do Kmax e melhora da acuidade visual corrigida em todos os momentos de pós operatório. Com relação à paquimetria, observou-se afinamento corneano do ponto mais fino, nos primeiros quatro meses de pós-operatório. Conclusão: Resultados encorajadores foram obtidos com relação à estabilização da doença, progressão e segurança do procedimento, corroborando com as conclusões de outros autores. A importância do diagnóstico precoce e do acompanhamento a curto prazo do paciente deve ser destacada.

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Objetivo : Evaluar la relación entre el índice urémico (IU) y la función renal medida por el aclaramiento de creatinina (ClCr) en personas sanas y en pacientes con enfermedad renal crónica (ERC); asimismo, comparar con la función renal extrapolada según la creatinina sérica y la calculada por algunas fórmulas recomendadas en la literatura internacional. Material y métodos : Estudio transversal, de correlación, analítico y observacional. Se incluyeron pacientes atendidos de forma ambulatoria en el Hospital Cayetano Heredia, Lima, Perú entre junio del 2018 y junio del 2019. Se realizó correlación de Pearson entre el IU y el ClCr; para la comparación de las medias del IU, creatinina sérica y las fórmulas estandarizadas en función al ClCr estratificado se utilizó el test de ANOVA y el eta cuadrado. Resultados: El IU de la población fue 4,37 ± 4,99 mg/dl y presentó correlación lineal cuadrática estadísticamente significativa con el ClCr (r=-0,74, p=0,000). Asimismo, el IU y el Log IU mostraron un valor predictivo el ClCr superior a la creatinina sérica y a las diversas fórmulas recomendadas en la literatura. El IU presentó correlación significativa con el potasio sérico y su fracción excretoria de forma relevante en comparación con la creatinina sérica. Conclusiones: El IU es un indicador del estado metabólico y nutricional que refleja el ClCr con una precisión estadísticamente significativa en la persona sana y en el paciente con distintos grados de ERC. Además, traduce aspectos relevantes de la función tubular renal.

SUMMARY Objective : To evaluate the relationship between uremic index (UI) and renal function measured by creatinine clearance (CrCl) in persons with normal renal function and in those with chronic renal failure (CRF), as well as to compare the renal function extrapolated from serum creatinine and that calculated with equations internationally recommended. Methods : A cross sectional study was conducted including patients attended in outpatient clinics at Hospital Cayetano Heredia in Lima from June 2018 to June 2019. Pearson's correlation between UI and CrCl was calculated; comparison of means of UI, serum creatinine and standard equations was done by ANOVA and eta square. Results: the overall UI was 4.37 ± 4.99 mg/dl and correlated linearly with CrCl (r=-0.74, p=0.000). The UI and the log UI were significantly more predictive of CrCl than serum creatinine and the international equations used. The UI correlated significantly with serum potassium than serum creatinine. Conclusions : The UI is a good indicator of the metabolic and nutritional status in persons With normal renal function and with CRF and reflects more accurately the CrCl.

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RESUMEN Fundamento La pandemia actual por SARS-CoV-2 contabiliza más de un millón de contagios, y ha causado la muerte, hasta ahora, a más de 300 000 personas. Además, ha tenido un gran impacto psicológico en el contexto latinoamericano. Objetivo describir las características dinámicas de la salud mental en adultos peruanos durante la cuarentena por COVID-19. Métodos estudio descriptivo, que exploró las características dinámicas de manera gráfica, mediante un instrumento de salud mental aplicado (online) a 763 adultos peruanos. Se aplicó un análisis de red mediante los paquetes qgrap y el gráfico LASSO. Resultados se observaron mayores medidas de centralidad de red en los reactivos vinculados a síntomas negativos en la salud mental, como el reactivo 9 (sentimiento de infelicidad y depresión) y el 10 (pérdida de confianza); así como la mayor conexión positiva entre los reactivos 3 (toma de decisiones y confianza) y 4 (sentido de vida); y la mayor relación negativa entre los componentes 1 (concentración) y 5 (tensión y angustia). Conclusión los sujetos participantes en el estudio manifestaron fundamentalmente sentimientos de infelicidad, depresión y pérdida de confianza, entre otros síntomas negativos. El estudio de la repercusión de la pandemia COVID-19 en la salud mental, adquiere mayor precisión y fundamento científico al aplicarse métodos como el análisis de redes.

ABSTRACT Background The current SARS-CoV-2 pandemic accounts for more than one million infections, and has caused the death, so far, more than 300,000 people. In addition, it has had a great psychological impact in the Latin American context. Objective to describe the dynamic characteristics of mental health in Peruvian adults during the COVID-19 quarantine. Methods descriptive study, which explored the dynamic characteristics graphically, using a mental health instrument applied (online) to 763 Peruvian adults. A network analysis was applied using the qgrap packages and the LASSO graph. Results higher network centrality measures were observed in the items related to negative symptoms in mental health, such as item 9 (feeling of unhappiness and depression) and item 10 (loss of confidence); as well as the greater positive connection between items 3 (decision making and trust) and 4 (meaning of life); and the highest negative relationship between components 1 (concentration) and 5 (tension and anguish). Conclusion the individuals participating in the study mainly manifested feelings of unhappiness, depression and loss of confidence, among other negative symptoms. The study of the impact of the COVID-19 pandemic on mental health acquires greater precision and scientific basis when applying methods such as network analysis.

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Natural rubber is an essential material, especially for plane and truck tyres but also for medical gloves. Asia ranks first in the production of natural rubber, of which the Hevea tree is currently the sole source. However, it is anticipated that this source alone will not be able to fulfill the growing demand. Guayule, a shrub native to northern Mexico and southern United States, may also contribute. This plant not only contains polyisoprene, but also resin, a mixture of lipids and terpenoids. This review summarizes various aspects of this plant, from the usage history, botanical description, geographical distribution and cultivation practices, down to polyisoprene and resin biosynthesis including their distribution within the plant and molecular composition. Finally, the main processes yielding dry rubber or latex are depicted, as well as the properties of the various extracts along with economic considerations. The aim is to provide a wide picture of current knowledge available about this promising crop, a good feedstock candidate for a multiple-product biorefinery.

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ABSTRACT Purpose: This study was performed to evaluate the outcomes of accelerated corneal cross-linking in keratoconic corneas with thinnest pachymetry values of <400 µm. Methods: The study included 28 eyes of 24 patients. The uncorrected and best-corrected visual acuities (logMAR), flattest and steepest keratometric readings, central corneal thickness at the thinnest point, corneal higher-order aberrations, and contrast sensitivity were assessed before and at 1, 3, 6, 12, and 24 months after corneal cross-linking. Result: The mean best-corrected visual acuity and contrast sensitivity increased (p=0.02, p=0.03, respectively), whereas the mean uncorrected visual acuity did not significantly differ (p>0.05) at 24 months after corneal cross-linking, compared with measurements before corneal cross-linking. Although the mean flattest keratometric reading showed no significant change (p=0.58), the mean steepest keratometric reading was reduced when compared with its value before corneal cross-linking (p=0.001). No change was observed in the mean central corneal thickness at the thinnest point at 24 months after corneal cross-linking, compared with its value before corneal cross-linking (p=0.12). Conclusion: Accelerated corneal cross-linking in keratoconic eyes with thin corneas could halt the progression of keratoconus in corneas thinner than 400 µm at 24 months after treatment.

RESUMO Objetivo: Este estudo foi realizado para avaliar os resultados do cross-linking corneano acelerado em córneas ceratocônicas com os valores mais baixos de paquimetria <400 µm. Métodos: O estudo incluiu 28 olhos de 24 pacientes. As acuidades visuais não corrigidas e melhor corrigidas (logMAR), leituras ceratométricas mais planas e íngremes, espessura corneana central no ponto mais fino, aberrações corneanas de mais alta ordem e a sensibilidade ao contraste foram avaliadas antes e em 1, 3, 6, 12 e 24 meses após a realização do do cross-linking. Resultados: A média da acuidade visual melhor corrigida e a sensibilidade ao contraste aumentaram (p=0,02, p=0,03, respectivamente), enquanto a média da acuidade visual não corrigida não diferiu significativamente (p>0,05) aos 24 meses após o cross-linking, comparada com medidas antes do procedimento. Embora a leitura da média da ceratometria mais plana não tenha apresentado alteração significativa (p=0,58), a leitura ceratométrica mais íngreme diminuiu quando comparada ao seu valor antes do cross-linking (p=0,001). Não foi observada alteração na média da espessura corneana central no ponto mais fino aos 24 meses após o cross-linking em comparação com seu valor antes do procedimento (p=0,12). Conclusão: O cross-linking corneano acelerado nos olhos ceratocônicos com córneas finas pode interromper a progressão do ceratocone nas córneas mais finas que 400 µm 24 meses após o tratamento.

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