Dificultades y alternativas en la resolución de problemas matemáticos

Si aceptamos como premisa que la educación primaria es esencialmente formativa más que informativa, el propósito del maestro en la materia de matemáticas será en consecuencia, despertar en los alumnos el interés para buscar y amplificar diferentes alternativas en la resolución de problemas, desarrollando su capacidad para que con mente abierta aborden diferentes niveles de complejidad, y evitando la memorización que, por difícil y rutinaria, genera en el alumno apatía y enemistad con las matemáticas. Movidas por esta inquietud, realizamos un diagnostico entre profesores y alumnos de quinto grado, acerca de las dificultades más frecuentes asociadas a la resolución de problemas matemáticos, y se elaboraron algunas alternativas didácticas a dichas dificultades que hemos venido implementando, con resultados tan positivos que consideramos conveniente compartir esta experiencia con otros colegas, pues creemos que puede servir de apoyo en su práctica docente

De novo Development of Heart Valve Calcification in Incident Peritoneal Dialysis Patients

Background and AimsCardiac valve calcification (VC) is a frequent complication in chronic kidney disease and is considered a risk factor for all-cause and cardiovascular mortality. However, little is known about the pathophysiology mechanisms that originate it and the factors associated with its development. We undertook this study to analyze the frequency and factors related to de novo development of mitral valve calcification (MVC) and aortic valve calcifications (AVC) in incident peritoneal dialysis (PD) patients.MethodsA prospective cohort of 124 incident PD patients was studied. Demographic and clinical data were recorded and blood assayed at baseline and after 1 year of follow-up for calcium, phosphorus, glucose, urea, creatinine, cholesterol, triglycerides by spectrophotometry assay; high-sensitivity C-reactive protein (CRP) by immunoturbidimetric ultrasensitive assay, intact parathormone (iPTH) and osteocalcin by electrochemiluminescence, fetuin-A and osteoprotegerin by EDI-ELISA. Valve calcification was evaluated by M-mode bidimensional echocardiogram.ResultsSixty eight percent of patients were male, ages 43 ± 13 years; 51% were diabetic with 1.4 ± 1 months on PD. After 12.3 ± 1 months, 57 patients (46%) developed VC: AVC in 33 (57.8%), MVC in 15 (26.3%) and 9 (15.8%) patients in both valves. There was no correlation between AVC and MCV. In univariate logistic regression analysis, age, diabetes and elevated concentrations of OPG, iPTH and CRP were risk factors for development MVC. In multivariate analysis, only iPTH remained an independent risk factor as was also the case in AVC.ConclusionsAge, diabetes, osteoprotegerin, parathormone and C-reactive protein are risk factors related to de novo development of MVC and iPTH for AVC in incident dialysis patients

Hypervirulent Klebsiella pneumoniae serotype K1 clinical isolates form robust biofilms at the air-liquid interface

The prevalence of a new hypervirulent and hypermucoviscous K. pneumoniae phenotype (Hmv) is increasing worldwide, mainly linked to serotypes K1 and K2. Since capsular thickness can directly affect the capability to form biofilms, we aimed to evaluate the association between the Hmv phenotype with adhesion and biofilm formation in a collection of clinical K. pneumoniae isolates. We selected 38 Hmv clinical isolates [15 serotype K1; 9 serotype K2; 3 non-K1/K2 (rmpA+); 11 non-K1/K2 (rmpA-)] and 7 non-Hmv clinical isolates. The Hmv phenotype was assessed through the mucoviscosity test. Serum resistance was determined by bacterial viability tests in pooled human serum. Adhesion was evaluated with the Biofilm Ring Test®, and biofilm formation was identified by crystal violet staining (Solid-Liquid, SLI-biofilm) or visual examination (Air-Liquid, ALI-biofilm). This study linked for the first time the formation of robust ALI-biofilm plugs by K. pneumoniae to the capsular serotype K1, a group of hypervirulent strains which are generally highly susceptible to the antimicrobial agents. Among all the studied isolates, the capsular serotype K1 presented lower initial adhesion despite having the adhesins mrkD and fimH but higher ALI-biofilm formation than isolates with other capsular serotypes (K2 or non-K1/K2). This structure might confer increased resistance to a group of hypervirulent K. pneumoniae serotype K1

PROPUESTA DIDÁCTICA DE UN APPLET PARA SIMULAR LA RESPUESTA DE UN SISTEMA MASA RESORTE FORZADO CON AMORTIGUAMIENTO, CON EL APOYO DE SOFTWARE GEOGEBRA.

ResumenSe presenta una propuesta didáctica de una aplicación de las ecuaciones diferenciales de orden superior, para el diseño y simulación de la respuesta de un sistema masa resorte, modelado con el apoyo de un applet, el cual se elaboró con el software GeoGebra. El applet se usa para simular la respuesta de  una masa suspendida en un resorte, a la cual se le aplica una fuerza externa, que puede ser del tipo: constante, senoidal o cosenoidal, bajo el esquema de un sistema que se encuentra amortiguado. Se hace el análisis de la respuesta  para cada uno de los tres tipos de función forzante mencionados, considerando los tres casos de la respuesta transitoria asociada: sistema sobreamortiguado, críticamente amortiguado y subamortiguado. El uso del software tiene la ventaja de que puede ser uno de los soportes del  proceso  enseñanza - aprendizaje en la asignatura de ecuaciones diferenciales en Ingeniería.Palabra(s) Clave(s): Ecuaciones Diferenciales, sistema masa resorte amortiguado, función forzante y  GeoGebra. AbstractWe present a didactic proposal of an application of the differential equations of higher order, for the design and simulation of the response of a mass spring system, modeled with the support of an applet, which was elaborated with GeoGebra software. The applet is used to simulate the response of a mass suspended in a spring, to which is applied an external force, that can be of the type: constant, sinusoidal or cosenoidal, under the scheme of a system that is damped. The analysis of the response is performed for each of the three types of forcing function mentioned, considering the three cases of the associated transient response: overdamped, critically damped and underdamped system. The use of software has the advantage that it can be one of the supports of the teaching - learning process in the subject of differential equations in Engineering.Keywords: Differential Equations, damped spring mass system, GeoGebra

Assessment of trimethoprim-sulfamethoxazole susceptibility testing methods for fastidious Haemophilus spp.

Objectives: To compare the determinants of trimethoprim-sulfamethoxazole resistance with established susceptibility values for fastidious Haemophilus spp., to provide recommendations for optimal trimethoprim-sulfamethoxazole measurement. Methods: We collected 50 strains each of Haemophilus influenzae and Haemophilus parainfluenzae at Bellvitge University Hospital. Trimethoprim-sulfamethoxazole susceptibility was tested by microdilution, E-test and disc diffusion using both Mueller-Hinton fastidious (MH-F) medium and Haemophilus test medium (HTM) following EUCAST and CLSI criteria, respectively. Mutations in folA, folP and additional determinants of resistance were identified in whole-genome-sequenced isolates. Results: Strains presented generally higher rates of trimethoprim-sulfamethoxazole resistance when grown on HTM than on MH-F, independent of the methodology used (average MIC 2.6-fold higher in H. influenzae and 1.2-fold higher in H. parainfluenzae). The main resistance-related determinants were as follows: I95L and F154S/V in folA; 3- and 15-bp insertions and substitutions in folP; acquisition of sul genes; and FolA overproduction potentially linked to mutations in -35 and -10 promoter motifs. Of note, 2 of 19 H. influenzae strains (10.5%) and 9 of 33 H. parainfluenzae strains (27.3%) with mutations and assigned as resistant by microdilution were inaccurately considered susceptible by disc diffusion. This misinterpretation was resolved by raising the clinical resistance breakpoint of the EUCAST guidelines to ≤30 mm. Conclusions: Given the routine use of disc diffusion, a significant number of strains could potentially be miscategorized as susceptible to trimethoprim-sulfamethoxazole despite having resistance-related mutations. A simple modification to the current clinical resistance breakpoint given by the EUCAST guideline for MH-F ensures correct interpretation and correlation with the reference standard method of microdilution

Elementos traza introducidos con aguas residuales a suelos agrícolas se acumulan en las fracciones estables - Trace elements added to agricultural soils with wastewater are accumulated in stable fractions

El objetivo de este trabajo fue analizar la distribución de los elementos traza (ET) en las fracciones del suelo, en función de los años de riego y su relación con la biodisponibilidad para maíz en el distrito de riego 003, de Tula, Hidalgo. Se muestrearon cuatros zonas con 27, 35, 52 y 102 años de riego, con agua residual, cultivadas con maíz. También se recolectó material vegetal en tres parcelas por cada zona. Se cuantificaron los elementos traza totales, extractables, en la fracciones del suelo y en el material vegetal. La concentración de cadmio total fue mayor a las que se consideran normales en el suelo. Los elementos traza se encuentran en mayor porcentaje en los carbonatos (8% - 31%) y la fracción residual (21% - 72%), con excepción del cobre, que además se asocia con la fracción orgánica (33% - 41%). En tejido vegetal se encontraron concentraciones de zinc (2 – 14 mg kg-1), níquel (0.58 – 1.1 mg kg-1) y plomo (27 – 33 mg kg-1), más altas de las normales, lo que se relacionó al factor de bioconcentración. El manejo del suelo y la concentración de elementos traza determina su biodisponibilidad en suelos áridos

A genome-wide association study follow-up suggests a possible role for PPARG in systemic sclerosis susceptibility

Introduction: A recent genome-wide association study (GWAS) comprising a French cohort of systemic sclerosis (SSc) reported several non-HLA single-nucleotide polymorphisms (SNPs) showing a nominal association in the discovery phase. We aimed to identify previously overlooked susceptibility variants by using a follow-up strategy.<p></p> Methods: Sixty-six non-HLA SNPs showing a P value <10-4 in the discovery phase of the French SSc GWAS were analyzed in the first step of this study, performing a meta-analysis that combined data from the two published SSc GWASs. A total of 2,921 SSc patients and 6,963 healthy controls were included in this first phase. Two SNPs, PPARG rs310746 and CHRNA9 rs6832151, were selected for genotyping in the replication cohort (1,068 SSc patients and 6,762 healthy controls) based on the results of the first step. Genotyping was performed by using TaqMan SNP genotyping assays. Results: We observed nominal associations for both PPARG rs310746 (PMH = 1.90 × 10-6, OR, 1.28) and CHRNA9 rs6832151 (PMH = 4.30 × 10-6, OR, 1.17) genetic variants with SSc in the first step of our study. In the replication phase, we observed a trend of association for PPARG rs310746 (P value = 0.066; OR, 1.17). The combined overall Mantel-Haenszel meta-analysis of all the cohorts included in the present study revealed that PPARG rs310746 remained associated with SSc with a nominal non-genome-wide significant P value (PMH = 5.00 × 10-7; OR, 1.25). No evidence of association was observed for CHRNA9 rs6832151 either in the replication phase or in the overall pooled analysis.<p></p> Conclusion: Our results suggest a role of PPARG gene in the development of SSc

Films of chitosan and chitosan-oligosaccharide neutralized and thermally treated: Effects on its antibacterial and other activities

The present study focuses on the effects of heat and neutralization treatments on solubility, water vapour permeability and antimicrobial activity of chitosan (Ch) and chitosan/chitooligosaccharide (ChO)-based films. ChO films showed stronger antimicrobial activity against Escherichia coli, Bacillus cereus, Staphylococcus aureus, Serratia liquefaciens and Lactobacillus plantarum than Ch films, indicating that this effect is attributed to the presence of chitooligosaccharides (COS) in the films. Heat and neutralization treatments decreased significantly the solubility of chitosan films and gave rise to a sharp loss in their antimicrobial activity. The incorporation of COS in chitosan films increased the inhibitory effect against the studied microorganisms without affecting significantly the water vapour permeability of the films. Thus, it is possible to get a more insoluble chitosan film with high antimicrobial activity by means of incorporation of COS combined with heat or neutralization treatments.MINECO, project (MAT2010-21621-C02-01

Development and Characterization of a Semi-Solid Dosage Form of Meglumine Antimoniate for Topical Treatment of Cutaneous Leishmaniasis.

Cutaneous leishmaniasis (CL) is treated with painful intralesional injections of meglumine antimoniate (MA).With the aim of developing an alternative topical treatment for CL, a gel-based formulation with 30% MA was prepared and its physicochemical properties, stability and rheological behavior were studied. The following were assessed: drug release on propylene hydrophilic membranes ex vivo human skin permeation, tolerance in healthy volunteers, cytotoxicity in three cell lines and anti-leishmanial activity against Leishmania infantum promastigotes and amastigotes. The MA gel formulation was found to have suitable pH, and good spreadability and stability. Low quantities of pentavalent antimony (SbV) were observed in release and permeation tests, whereas retention was high in both non-damaged and damaged skin (71,043.69 +/-10,641.57 and 10,728 +/-2254.61 microg/g/cm2 of SbV, respectively). The formulation did not have a toxic effect on the cell lines, and presented lower SbV IC50 values against amastigotes (15.76 +/- 4.81microg/mL) in comparison with the MA solution. The high amount of drug retained in the skin and the SbV IC50 values obtained suggest that this semi-solid dosage form has potential as an alternative treatment of CL

Effectiveness of an intervention for improving drug prescription in primary care patients with multimorbidity and polypharmacy:Study protocol of a cluster randomized clinical trial (Multi-PAP project)

This study was funded by the Fondo de Investigaciones Sanitarias ISCIII (Grant Numbers PI15/00276, PI15/00572, PI15/00996), REDISSEC (Project Numbers RD12/0001/0012, RD16/0001/0005), and the European Regional Development Fund ("A way to build Europe").Background: Multimorbidity is associated with negative effects both on people's health and on healthcare systems. A key problem linked to multimorbidity is polypharmacy, which in turn is associated with increased risk of partly preventable adverse effects, including mortality. The Ariadne principles describe a model of care based on a thorough assessment of diseases, treatments (and potential interactions), clinical status, context and preferences of patients with multimorbidity, with the aim of prioritizing and sharing realistic treatment goals that guide an individualized management. The aim of this study is to evaluate the effectiveness of a complex intervention that implements the Ariadne principles in a population of young-old patients with multimorbidity and polypharmacy. The intervention seeks to improve the appropriateness of prescribing in primary care (PC), as measured by the medication appropriateness index (MAI) score at 6 and 12months, as compared with usual care. Methods/Design: Design:pragmatic cluster randomized clinical trial. Unit of randomization: family physician (FP). Unit of analysis: patient. Scope: PC health centres in three autonomous communities: Aragon, Madrid, and Andalusia (Spain). Population: patients aged 65-74years with multimorbidity (≥3 chronic diseases) and polypharmacy (≥5 drugs prescribed in ≥3months). Sample size: n=400 (200 per study arm). Intervention: complex intervention based on the implementation of the Ariadne principles with two components: (1) FP training and (2) FP-patient interview. Outcomes: MAI score, health services use, quality of life (Euroqol 5D-5L), pharmacotherapy and adherence to treatment (Morisky-Green, Haynes-Sackett), and clinical and socio-demographic variables. Statistical analysis: primary outcome is the difference in MAI score between T0 and T1 and corresponding 95% confidence interval. Adjustment for confounding factors will be performed by multilevel analysis. All analyses will be carried out in accordance with the intention-to-treat principle. Discussion: It is essential to provide evidence concerning interventions on PC patients with polypharmacy and multimorbidity, conducted in the context of routine clinical practice, and involving young-old patients with significant potential for preventing negative health outcomes. Trial registration: Clinicaltrials.gov, NCT02866799Publisher PDFPeer reviewe