Una propuesta para la enseñanza y el aprendizaje de los sistemas de numeración

En este artículo se exponen algunas reflexiones sobre la enseñanza y el aprendizaje de las matemáticas escolares de grado sexto. Dichas reflexiones se refieren específicamente a la experiencia vivida al planear, diseñar y desarrollar una unidad temática sobre los sistemas de numeración, para estudiantes de grado sexto del colegio

Pseudomonas deceptionensis sp. nov., a psychrotolerant bacterium from the Antarctic

During the taxonomic investigation of cold-adapted bacteria from samples collected in theAntarctic area of the South Shetland Islands, one Gram-reaction-negative, psychrotolerant,aerobic bacterium, designated strain M1T, was isolated from marine sediment collected onDeception Island. The organism was rod-shaped, catalase- and oxidase-positive and motile bymeans of a polar flagellum. This psychrotolerant strain grew at temperatures ranging from"46Cto 346C. Phylogenetic studies based on 16S rRNA gene sequences confirmed that Antarcticisolate M1Twas a member of the genusPseudomonasand was located in thePseudomonas fragicluster. 16S rRNA gene sequence similarity values were.98% between 13 type strainsbelonging to thePseudomonas fluorescenslineage. However, phylogenetic analysis ofrpoDgene sequences showed that strain M1Texhibited high sequence similarity only with respect toPseudomonas psycrophila(97.42%) andP. fragi(96.40%) and DNA-DNA hybridizationexperiments between the Antarctic isolate M1Tand the type strains of these two closely relatedspecies revealed relatedness values of 58 and 57%, respectively. Several phenotypiccharacteristics, together with the results of polar lipid and cellular fatty acid analyses, were used todifferentiate strain M1Tfrom related pseudomonads. Based on the evidence of this polyphasictaxonomic study, strain M1Trepresents a novel species, for which the namePseudomonasdeceptionensissp. nov. is proposed. The type strain is M1T(5LMG 25555T5CECT 7677T)

Effect of drill speed on the strain distribution during drilling of bovine and human bones

Drilling is an operation commonly required in orthopaedic surgery for insertion of screws and internal fixation of bone fractures. Induced damage is one of the undesired effects of drilling mainly due to the use of inadequate drilling parameters. During the recent years, scientists have been trying to describe the relationship between drilling parameters and bone injury. However, no studies have examined the level of strain generated in the bone during the drilling process. This paper focuses on the analysis of different drill speeds during drilling of fresh bovine femora and human cadaveric tibiae. The main contribution of this work is to determine how differences in applied drill speeds affect the strain of cortical tissue near the drilling site and the drill bit temperature. Strains were measured in ex-vivo material during the osteotomy preparation with three drill speeds (520, 900 and 1370 r.p.m.). Additionally, a thermographic camera was used to measure the drill bit temperature. As the drilling operations are blind in nature with unknown depth, the osteotomies were performed using a drill press machine without control of the feed rate or depth. Drill bit geometry was kept constant with 4 mm of diameter, point angle 120⁰ and helix angle 30⁰. The tests were conducted at room temperature without applying cooling at the drilling zone. Bone strains near to the drilling sites were recorded with high accuracy using linear strain gages mounted around the diaphyseal cortex. It was noted that the bone strain and drill bit temperature increased with an increasing drill speed. Human and bovine bone samples presented significantly different levels of strain and temperature. Both strain and temperature were higher when drilling bovine femora than when drilling human cadaveric tibiae

Biologic Therapy for Moderate to Severe Psoriasis. Real-World Follow-up of Patients Who Initiated Biologic Therapy at Least 10 Years Ago

[Abstract] Introduction: The aim of this study was to evaluate response and drug survival of biologic therapy in patients with moderate to severe plaque-type psoriasis who initiated biologic therapy at least 10 years ago, in a real-world setting. Methods: This was an observational retrospective follow-up study that included patients with moderate to severe plaque-type psoriasis who initiated biologic therapy between October 2006 and December 2009. Efficacy was expressed as the percentage of patients achieving a 50, 75 and 90% reduction from baseline in the Psoriasis Area and Severity Index (PASI 50, PASI 75, PASI 90, respectively) every 3 months during the first year of therapy and then every 12 months up to the end of follow-up or withdrawal from the study. Results: A total of 56 patients were included in the study, representing 140 treatment lines (median 2, range 1-8); of these patients, 53 were still receiving biologic therapy at the end of the study. The mean duration of biologic therapy was 140.4 (range 47.6-175.4) months. Etanercept was used in 98.2% of patients, followed by efalizumab (42.9%), adalimumab (41.1%), ustekinumab (33.9%) and infliximab (16.1%). Treatment lines were switched in 62.1% of treatments: 24.3% due to secondary failure, 20.7% due to primary failure and 3.6% due to side effects. No patient treated with anti-interleukins had to discontinue treatment due to side effects. Ustekinumab had the highest drug survival. Conclusions: This study in the real-world-setting shows maintenance of long-term efficacy and safety of biologic therapy in patients with moderate to severe plaque psoriasis in daily practice who initiated biologic therapy 10 years ago.The journal’s Rapid Service Fee was paid for by Fundación Profesor Novoa Santos (A Coruña. Spain

Glutaminase and MMP-9 downregulation in cortex and hippocampus of LPA1 receptor null mice correlate with altered dendritic spine plasticity

Lysophosphatidic acid (LPA) is an extracellular lipid mediator that regulates nervous system development and functions acting through G protein-coupled receptors (GPCRs). Here we explore the crosstalk between LPA1 receptor and glutamatergic transmission by examining expression of glutaminase (GA) isoforms in different brain areas isolated from wild-type (WT) and KOLPA1 mice. Silencing of LPA1 receptor induced a severe down-regulation of Gls-encoded long glutaminase protein variant (KGA) (glutaminase gene encoding the kidney-type isoforms, GLS) protein expression in several brain regions, particularly in brain cortex and hippocampus. Immunohistochemical assessment of protein levels for the second type of glutaminase (GA) isoform, glutaminase gene encoding the liver-type isoforms (GLS2), did not detect substantial differences with regard to WT animals. The regional mRNA levels of GLS were determined by real time RT-PCR and did not show significant variations, except for prefrontal and motor cortex values which clearly diminished in KO mice. Total GA activity was also significantly reduced in prefrontal and motor cortex, but remained essentially unchanged in the hippocampus and rest of brain regions examined, suggesting activation of genetic compensatory mechanisms and/or post-translational modifications to compensate for KGA protein deficit. Remarkably, Golgi staining of hippocampal regions showed an altered morphology of glutamatergic pyramidal cells dendritic spines towards a less mature filopodia-like phenotype, as compared with WT littermates. This structural change correlated with a strong decrease of active matrix-metalloproteinase (MMP) 9 in cerebral cortex and hippocampus of KOLPA1 mice. Taken together, these results demonstrate that LPA signaling through LPA1 influence expression of the main isoenzyme of glutamate biosynthesis with strong repercussions on dendritic spines maturation, which may partially explain the cognitive and learning defects previously reported for this colony of KOLPA1 mice

Early diarrhoea under sorafenib as a marker to consider the early migration to second-line drugs

Background: Despite atezolizumab and bevacizumab (A + B) is currently the first-line treatment for hepatocellular carcinoma (HCC) patients, some patients will not be adequate for this combination. In the setting of sorafenib some adverse events have been proposed as prognostic factors. Objective: To characterize the early diarrhoea development as prognostic factor in 344 HCC patients. Methods: The development of early diarrhoea in sorafenib treatment defined as patients who developed diarrhoea and needed dose modification within the first 60 days of treatment (e-diarrhoea) and 3-grouping variables were analysed: Patients with e-diarrhoea, patients who developed diarrhoea after the first 60 days of treatment (L-diarrhoea) and patients that never developed diarrhoea (never diarrhoea). Results: The median overall survival in sorafenib treated patients was significantly different across groups (6.8 months for e-diarrhoea, 26.7 months for L-diarrhoea and 13.3 months for never-diarrhoea). The emergence of e-diarrhoea was associated with poor outcomes (hazard ratio [HR] 1.84 [95%CI 1.15-2.95]), while there was no increased/decreased risk of dismal evolution in patients with L-diarrhoea (HR 0.66 [95%CI 0.42-1.03]). Conclusion: The emergence of e-diarrhoea in HCC patients treated with sorafenib is an early predictor of dismal evolution under this therapy. Thus, prompt identification of these non-responders may be useful for an early switch to second-line therapies

Nomogram-based prediction of survival in patients with advanced oesophagogastric adenocarcinoma receiving first-line chemotherapy: a multicenter prospective study in the era of trastuzumab

Background: To develop and validate a nomogram and web-based calculator to predict overall survival (OS) in Caucasian-advanced oesophagogastric adenocarcinoma (AOA) patients undergoing first-line combination chemotherapy. Methods: Nine hundred twenty-four AOA patients treated at 28 Spanish teaching hospitals from January 2008 to September 2014 were used as derivation cohort. The result of an adjusted-Cox proportional hazards regression was represented as a nomogram and web-based calculator. The model was validated in 502 prospectively recruited patients treated between October 2014 and December 2016. Harrell's c-index was used to evaluate discrimination. Results: The nomogram includes seven predictors associated with OS: HER2-positive tumours treated with trastuzumab, Eastern Cooperative Oncology Group performance status, number of metastatic sites, bone metastases, ascites, histological grade, and neutrophil-to-lymphocyte ratio. Median OS was 5.8 (95% confidence interval (CI), 4.5–6.6), 9.4 (95% CI, 8.5–10.6), and 14 months (95% CI, 11.8–16) for high-, intermediate-, and low-risk groups, respectively (P<0.001), in the derivation set and 4.6 (95% CI, 3.3–8.1), 12.7 (95% CI, 11.3–14.3), and 18.3 months (95% CI, 14.6–24.2) for high-, intermediate-, and low-risk groups, respectively (P<0.001), in the validation set. The nomogram is well-calibrated and reveals acceptable discriminatory capacity, with optimism-corrected c-indices of 0.618 (95% CI, 0.591–0.631) and 0.673 (95% CI, 0.636–0.709) in derivation and validation groups, respectively. The AGAMENON nomogram outperformed the Royal Marsden Hospital (c-index=0.583; P=0.00046) and Japan Clinical Oncology Group prognostic indices (c-index=0.611; P=0.03351). Conclusions: We developed and validated a straightforward model to predict survival in Caucasian AOA patients initiating first-line polychemotherapy. This model can contribute to inform clinical decision-making and optimise clinical trial design

El diseño de las instituciones en el Estado Sandinista (1979-1982): la revolución como fuente de derecho

While the institutions of the new revolutionary state were emerging in Nicaragua, an element which would remain constant throughout the 1980s was taking shape: the pre-eminence of the executive power and the loss of the initial support of the Sandinista National Liberation Front (FSLN). At the same time, the understanding between Nicaragua and the US, which was already complicated within the context of the Cold War, worsened during this period. This paper aims to elucidate the various factors which caused the imbalance in the distribution of powers within Sandinista institutions.A medida que se iban perfilando en Nicaragua las instituciones del nuevo Estado revolucionario, se fue consolidando una constante que permanecería toda la década de 1980: la preeminencia del poder ejecutivo sobre los demás y la pérdida de los grandes apoyos iniciales del Frente Sandinista de Liberación Nacional (FSLN). Asimismo, el entendimiento entre Nicaragua y EE.UU., ya difícil en el contexto de la Guerra Fría, empeoró durante este período. El presente trabajo pretende dilucidar los diversos factores que generaron el desequilibrio de poderes del diseño institucional sandinista

Correlations of mutations in katG, oxyR-ahpC and inhA genes and in vitro susceptibility in Mycobacterium tuberculosis clinical strains segregated by spoligotype families from tuberculosis prevalent countries in South America

Background Mutations associated with resistance to rifampin or streptomycin have been reported for W/Beijing and Latin American Mediterranean (LAM) strain families of Mycobacterium tuberculosis. A few studies with limited sample sizes have separately evaluated mutations in katG, ahpC and inhA genes that are associated with isoniazid (INH) resistance. Increasing prevalence of INH resistance, especially in high tuberculosis (TB) prevalent countries is worsening the burden of TB control programs, since similar transmission rates are noted for INH susceptible and resistant M. tuberculosis strains. Results We, therefore, conducted a comprehensive evaluation of INH resistant M. tuberculosis strains (n = 224) from three South American countries with high burden of drug resistant TB to characterize mutations in katG, ahpC and inhA gene loci and correlate with minimal inhibitory concentrations (MIC) levels and spoligotype strain family. Mutations in katG were observed in 181 (80.8%) of the isolates of which 178 (98.3%) was contributed by the katG S315T mutation. Additional mutations seen included oxyR-ahpC; inhA regulatory region and inhA structural gene. The S315T katG mutation was significantly more likely to be associated with MIC for INH ≥2 μg/mL. The S315T katG mutation was also more frequent in Haarlem family strains than LAM (n = 81) and T strain families. Conclusion Our data suggests that genetic screening for the S315T katG mutation may provide rapid information for anti-TB regimen selection, epidemiological monitoring of INH resistance and, possibly, to track transmission of INH resistant strains.Fil: Dalla Costa, Elis R. State Foundation for Production and Research in Health (FEPPS); Brasil.Fil: Ribeiro, Marta O. State Foundation for Production and Research in Health (FEPPS); Brasil.Fil: Silva, Márcia S. N. State Foundation for Production and Research in Health (FEPPS); Brasil.Fil: Arnold, Liane S. State Foundation for Production and Research in Health (FEPPS); Brasil.Fil: Rostirolla, Diana C. State Foundation for Production and Research in Health (FEPPS); Brasil.Fil: Cafrune, Patricia I. State Foundation for Production and Research in Health (FEPPS); Brasil.Fil: Espinoza, Roger C. Blufstein Clinic Laboratory; Perú.Fil: Palaci, Moises. Federal University of Espírito Santo; Brasil.Fil: Telles, Maria A. Adolfo Lutz Institute; Brasil.Fil: Ritacco, Viviana. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Servicio de Micobacterias; Argentina.Fil: Suffys, Philip N. Oswaldo Cruz Institute; Brasil.Fil: Lopes, Maria L. Evandro Chagas Institute; Brasil.Fil: Campelo, Creuza L. LACEN Ceará; BrasilFil: Miranda, Silvana S. Federal University of Minas Gerais; Brasil.Fil: Kremer, Kristin. National Institute for Public Healthand the Environment (RIVM). Mycobacteria Reference Unit (CIb-LIS); Países Bajos.Fil: Almeida da Silva, Pedro E. Federal Foundation of Rio Grande; Brasil.Fil: de Souza Fonseca, Leila. Federal University of Rio de Janeiro. Tuberculosis Academic Program; Brasil.Fil: Ho, John L. Cornell University; Estados Unidos.Fil: Kritski, Afrânio L. Federal University of Rio de Janeiro. Tuberculosis Academic Program; Brasil.Fil: Rossetti, María L. R. State Foundation for Production and Research in Health (FEPPS); Brasil

Riesgos y oportunidades asociados a la conservación de los polinizadores y a la gestión de los servicios de polinización en América Latina

Se realizó una revisión sobre el estado de conservación de los polinizadores y la polinización en América Latina (LA). Se presentan pautas para mejorar las oportunidades de conservación, considerando las amenazas a los polinizadores y las perspectivas desde el conocimiento tradicional y local. El análisis indica que diversas amenazas (e.g., agricultura a gran escala, deforestación, uso excesivo de agroquímicos) están vinculadas con la disminución de polinizadores, afectando la reproducción de las plantas nativas y los rendimientos de muchos cultivos. LA alberga la mayor diversidad de abejas en todo el mundo y una gran diversidad de polinizadores vertebrados (e.g., colibríes, aves de percha nectarívoras, murciélagos nectarívoros y otros mamíferos). Se proporcionan recomendaciones para proteger los polinizadores nativos y mejorar los servicios de polinización, las que podrían ser consideradas por los tomadores de decisiones y así promover la conservación biocultural. Por ejemplo, desarrollar instrumentos legales, políticas e incentivos para ayudar a los agricultores a mantener los hábitats naturales, para reemplazar o reducir el uso de agroquímicos y para promover las prácticas agroecológicas; perfeccionar las reglamentaciones sobre aplicación de agroquímicos para minimizar la exposición de los polinizadores a insecticidas y herbicidas; mejorar la comunicación pública del conocimiento sobre los polinizadores y la polinización para incentivar un cambio en las prácticas agrícolas hegemónicas y los patrones de consumo actuales; considerar otras éticas ambientales de las minorías étnicas para enfatizar la necesidad de promover una relación sostenible entre producción de alimentos y biodiversidad. Se necesita urgentemente una visión más amplia que combine las dimensiones sociales, ecológicas y culturales para una mejor toma de decisiones. Esta perspectiva socio-agroecológica holística es importante para conservar y gestionar los polinizadores a diferentes escalas espaciales y temporales, y para poder integrar los servicios de polinización con enfoques de gestión del territorio favorables a los polinizadores y con sistemas agrícolas diversificados.The conservation status of pollinators and pollination in Latin America (LA) is reviewed. The knowledge regarding native and managed pollinators (e.g., honeybee and stingless bees) and pollination services was synthetized, and the guidelines to improve the opportunities for conservation are provided, considering the threats to pollinators and the perspectives from traditional and local knowledge. The analysis indicates that diverse threats (e.g., large-scale agriculture, deforestation, overuse of agrochemicals) are linked with pollination and pollinator decline, which affect the reproduction of most native plants and the yields of many crops. LA harbours the highest bee diversity worldwide, with 26% of the total recorded species, and it is a biodiversity hotspot of vertebrate pollinators, including hummingbirds, perching birds, nectarivorous bats and other mammal pollinators. Specific recommendations to conserve native pollinators and to improve pollination services are provided, which could be considered by stakeholders and governments aiming to elaborate biocultural conservation. For example, introducing policies and legal responses for incentives to help farmers maintain natural habitats and forests, to replace or reduce agrochemicals and to improve diversified crop production with agroecological practices; refining agrochemical regulations to minimize the exposure of pollinators to insecticides and herbicides; improving knowledge and education on pollinators and pollination gives societies worldwide the opportunity to change current hegemonic agricultural practices and consumption patterns; integrating different land ethical views of ethnic minorities on a sustainable relationship between production and biodiversity. A wider view combining social, ecological, cultural dimensions may support better decision making. This holistic socio-agroecological perspective is urgently needed to conserve and manage pollinators at different spatial and temporal scales, and to integrate pollination services, pollinator-friendly habitat management approaches and diversified farming systems.Fil: Galetto, Leonardo. Universidad Nacional de Córdoba - CONICET. Instituto Multidisciplinario de Biología Vegetal (IMBIV)Fil: Aizen, Marcelo Adrian. Universidad Nacional del Comahue - CONICET. Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA)Fil: del Coro Arizmendi, María. Universidad Nacional Autónoma de México, Tlalnepantla, MéxicoFil: Magalhães Freitas, Breno. Universidade Federal do Ceará - Departamento de Zootecnia - Setor de Abelhas, Fortaleza, BrazilFil: Garibaldi, Lucas Alejandro. Universidad Nacional de Río Negro - CONICET. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural (IRNAD)Fil: Giannini, Tereza Cristina. Instituto Tecnológico Vale Desenvolvimento Sustentavel, Belem, BrazilFil: Lopes, Ariadna Valentina. Universidade Federal de Pernambuco - Departamento de Botánica, Recife, BrazilFil: Espírito Santo, Maria do. Universidade Estadual de Montes Claros - Departamento de Biologia Geral (CCBS), MG, BrasilFil: Nates Parra, Guiomar. Universidad Nacional de Colombia, Bogotá DC, ColombiaFil: Motta Maués, Márcia. Embrapa Amazônia Oriental - Laboratório de Entomologia, Belém, Pará, BrazilFil: Rodríguez, Jaime I.. Museo Nacional de Historia Natural de Bolivia, La Paz, BoliviaFil: Quezada Euán, José Javier Guadalupe. Universidad Autónoma de Yucatán - Departamento de Apicultura Tropical, Mérida, México (FMVZ)Fil: Viana, Blandina Felipe. Universidade Federal da Bahia, Salvador, Bahia, BrazilFil: Imperatriz Fonseca, Vera Lucia. Instituto Tecnológico Vale Desenvolvimento Sustentavel, Belem, Para, BrazilFil: Vandame, Rémy. El Colegio de la Frontera Sur, San Cristóbal de las Casas, Chiapas, Méxic