Phylogenomics of Leptospira santarosai, a prevalent pathogenic species in the Americas.

BACKGROUND: Leptospirosis is a complex zoonotic disease mostly caused by a group of eight pathogenic species (L. interrogans, L. borgpetersenii, L. kirschneri, L. mayottensis, L. noguchii, L. santarosai, L. weilii, L. alexanderi), with a wide spectrum of animal reservoirs and patient outcomes. Leptospira interrogans is considered as the leading causative agent of leptospirosis worldwide and it is the most studied species. However, the genomic features and phylogeography of other Leptospira pathogenic species remain to be determined. METHODOLOGY/PRINCIPAL FINDINGS: Here we investigated the genome diversity of the main pathogenic Leptospira species based on a collection of 914 genomes from strains isolated around the world. Genome analyses revealed species-specific genome size and GC content, and an open pangenome in the pathogenic species, except for L. mayottensis. Taking advantage of a new set of genomes of L. santarosai strains isolated from patients in Costa Rica, we took a closer look at this species. L. santarosai strains are largely distributed in America, including the Caribbean islands, with over 96% of the available genomes originating from this continent. Phylogenetic analysis showed high genetic diversity within L. santarosai, and the clonal groups identified by cgMLST were strongly associated with geographical areas. Serotype identification based on serogrouping and/or analysis of the O-antigen biosynthesis gene loci further confirmed the great diversity of strains within the species. CONCLUSIONS/SIGNIFICANCE: In conclusion, we report a comprehensive genome analysis of pathogenic Leptospira species with a focus on L. santarosai. Our study sheds new light onto the genomic diversity, evolutionary history, and epidemiology of leptospirosis in America and globally. Our findings also expand our knowledge of the genes driving O-antigen diversity. In addition, our work provides a framework for understanding the virulence and spread of L. santarosai and for improving its surveillance in both humans and animals.

Severe Rickettsia typhi Infections, Costa Rica.

Murine typhus is a febrile, fleaborne disease caused by infection with Rickettsia typhi bacteria. Cases can range from mild and nonspecific to fatal. We report 2 cases of murine typhus in Costa Rica, confirming the presence and circulation of R. typhi causing severe disease in the country.

Facilitadores y barreras percibidos en la práctica de la actividad física en adolescentes escolarizados en Piedecuesta (Santander), en 2016: análisis cualitativo / Perceived facilitators and barriers to physical activity in adolescents in Piedecuesta (Santander), in 2016: qualitative analysis / Facilitadores e barreiras evidentes na prática da atividade física nos adolescentes em idade escolar em Piedecuesta Santander, em 2016: Análise qualitativa

Resumen Objetivo: Describir la percepción que tienen adolescentes escolarizados entre 12 y 16 años, en Piedecuesta (Santander), en 2016, sobre los facilitadores y las barreras que influyen en la práctica de la actividad física. Metodología: Análisis cualitativo desde un enfoque fenomenológico, con la participación de 20 adolescentes escolarizados que, mediante entrevistas semiestructuradas y un grupo focal, conversaron sobre la práctica, los beneficios, los entornos y la influencia y la compañía en relación con la actividad física, para identificar barreras y facilitadores. Resultados: La práctica de la actividad física se limitaba a las clases de educación física en la mayoría de los casos. El compañero principal en la práctica extracurricular era el padre del mismo sexo. La actividad física representaba una oportunidad para el disfrute, mejorar la salud física y mental, así como la contextura corporal, y para romper con la rutina diaria. La falta de tiempo por compromisos académicos fue la razón principal para no realizar actividad física. Los lugares públicos no siempre estaban disponibles, a menudo no se consideraban seguros. En la escuela, el espacio y las instalaciones eran inadecuados, y el uso estaba restringido. Conclusiones: La escuela es un punto de convergencia importante para la práctica de la actividad física, lo que sugiere la necesidad de fortalecer el plan de estudios al respecto; este entorno es un facilitador potencial para aumentar el nivel de actividad física en adolescentes. También se percibe como barrera, dado que la práctica interfiere con las actividades académicas. Las mejoras en la seguridad y el atractivo estético en el entorno comunitario se visibilizan como un facilitador para promover la actividad física.

Abstract Objective: Describe the perception of adolescents aged between 12 and 16 years, in Piedecuesta (Santander), in 2016, about the facilitators and barriers that influence physical activity. Methodology: Qualitative analysis from a phenomenological approach, with the participation of 20 adolescents who talked about the practice, benefits, environments, influence and company in connection with physical activity , to identify barriers and facilitators, through semi-structured interviews and a focus group. Results: Physical activity was limited to physical education classes in most cases. The main companion in extracurricular physical activity was the parent of the same sex. Physical activity represented an opportunity for enjoyment, improvement of physical and mental health, as well as body composition, and to have a break in their daily routine. Lack of time due to academic commitments was the main reason for not doing physical activity. Public places were not always available and they were often not considered to be safe. Space and facilities at school were inadequate, and their use was restricted.. Conclusions: The school is an important point of convergence for doing physical activity, suggesting the need to strengthen the curriculum in this respect; this environment is a potential facilitator to increasing the level of physical activity in adolescents. It can also be seen as a barrier, given that the practice interferes with academic activities. Improvements in safety and aesthetic appeal in the surrounding community are seen as a facilitator to promoting physical activity.

Resumo Objetivo: Descrever a percepção que os adolescentes entre 12 e 17 anos de Piedecuesta em Santander, tiveram em 2016 sobre os facilitadores e as barreiras que influenciaram na prática da atividade física. Metodologia: Análise qualitativa partindo de um foco fenomenológico, com a participação de 20 adolescentes em idade escolar que, através de entrevistas semiestruturadas e um grupo focal, conversaram sobre a prática, os benefícios, os entornos, a influência e o acompanhamento relacionados com a atividade física, para identificar barreiras e facilitadores. Resultados: Na maioria dos casos, a prática da atividade física limitava-se às aulas de educação física. O companheiro principal na prática extracurricular era o genitor ou genitora do mesmo sexo. A atividade física representava uma oportunidade para disfrutar, melhorar a saúde física e mental, além da estrutura corporal e para sair da rotina diária. A falta de tempo devido às responsabilidades escolares foi a principal razão para não realizarem atividade física. Os lugares públicos nem sempre estavam disponíveis e geralmente não são considerados seguros. Na escola, o espaço e as instalações eram inadequados e o uso estava restrito. Conclusões: A escola é um importante ponto de convergência para a prática da atividade física, o que determina a necessidade de fortalecer o currículo relacionado; esse ambiente é um facilitador potencial para aumentar o nível de atividade física nos adolescentes. Também se percebe como barreira, já que a prática interfere com as atividades escolares. As melhorias na segurança e um espaço comunitário mais atraente do ponto de vista estético são determinantes como facilitadores para a promoção da atividade física.

Binding of imidazole, 1-methylimidazole and 4-nitroimidazole to yeast cytochrome c peroxidase (CcP) and the distal histidine mutant, CcP(H52L).

Imidazole, 1-methylimidazole and 4-nitroimidazole bind to yeast cytochrome c peroxidase (yCcP) with apparent equilibrium dissociation constants (KD(app)) of 3.3±0.4, 0.85±0.11, and ~0.2M, respectively, at pH7. This is the weakest imidazole binding to a heme protein reported to date and it is about 120 times weaker than imidazole binding to metmyoglobin. Spectroscopic changes associated with imidazole and 1-methylimidazole binding to yCcP suggest partial ionization of bound imidazole to imidazolate. The pKa for ionization of bound imidazole is estimated to be 7.4±0.2, about 7 units lower than that of free imidazole and about 3 units lower than imidazole bound to metmyoglobin. Equilibrium binding of imidazole to CcP(H52L) is biphasic with low- and high-affinity phases having KD(app) values of 9.5±4.5 and 0.13±0.04M, respectively. CcP(H52L) binding of 1-methylimidazole is monophasic with an affinity similar to those of yCcP and rCcP. Binding of 1-methylimidazole to rCcP is associated with two kinetic phases, the initial binding complete within 10s, followed by a process that is consistent with 1-methylimidazole binding to a cavity created by movement of Trp-191 from the interior of the protein to the surface. Both the equilibrium binding and kinetics of 1-methylimidazole binding to yCcP are pH dependent. yCcP has a four-fold increase in 1-methylimidazole binding affinity on decreasing the pH from 7.5 to 4.0, an observation that is unique among the many studies on binding of imidazole and imidazole derivatives to heme proteins.

Kinetic and equilibrium studies of acrylonitrile binding to cytochrome c peroxidase and oxidation of acrylonitrile by cytochrome c peroxidase compound I.

Ferric heme proteins bind weakly basic ligands and the binding affinity is often pH dependent due to protonation of the ligand as well as the protein. In an effort to find a small, neutral ligand without significant acid/base properties to probe ligand binding reactions in ferric heme proteins we were led to consider the organonitriles. Although organonitriles are known to bind to transition metals, we have been unable to find any prior studies of nitrile binding to heme proteins. In this communication we report on the equilibrium and kinetic properties of acrylonitrile binding to cytochrome c peroxidase (CcP) as well as the oxidation of acrylonitrile by CcP compound I. Acrylonitrile binding to CcP is independent of pH between pH 4 and 8. The association and dissociation rate constants are 0.32±0.16 M(-1) s(-1) and 0.34±0.15 s(-1), respectively, and the independently measured equilibrium dissociation constant for the complex is 1.1±0.2 M. We have demonstrated for the first time that acrylonitrile can bind to a ferric heme protein. The binding mechanism appears to be a simple, one-step association of the ligand with the heme iron. We have also demonstrated that CcP can catalyze the oxidation of acrylonitrile, most likely to 2-cyanoethylene oxide in a "peroxygenase"-type reaction, with rates that are similar to rat liver microsomal cytochrome P450-catalyzed oxidation of acrylonitrile in the monooxygenase reaction. CcP compound I oxidizes acrylonitrile with a maximum turnover number of 0.61 min(-1) at pH 6.0.