Evaluation of the electrochemical response of Saccharomyces cerevisiae using screen-printed carbon electrodes (SPCE) modified with oxidized multi-walled carbon nanotubes dispersed in water - Nafion®.

The evaluation of the electrochemical determination of Saccharomyces cerevisiae was carried out using a screen-printed carbon electrode (SPCE) modified with Nafion-dispersed oxidized multi-walled carbon nanotubes (OMWCNT). The morphology was studied using scanning electron microscopy (SEM), showing a complete modification of the surface with the nanotubes and yeast interaction with them instead of the graphite surface. The redox couple Fe(CN)6 4-/Fe(CN)6 3- was used to determine the electroactive area, the heterogeneous transfer constant, and the Nafion® effect. Results showed increases in electroactive area and heterogeneous transfer constant of 146% and 20.4%, respectively, due to the presence of nanotubes. Studies of the Nafion® effect showed that the polymeric membrane affects the electroactive area but not the heterogeneous transfer constant. Studies of the scan rate effect show that yeast oxidation is an irreversible mixed control process. As the concentration and scan rate increased, the anodic potential shifted toward more anodic values. The relationship between yeast concentration and the anodic current density (current/electroactive area) of yeast showed a linear range between 0.61 and 7.69 g L-1, the limit of detection (LOD) and the limit of quantification (LOQ) were 0.17 g L-1, and 0.61 g L-1, respectively, and the sensibility obtained was 0.03 µA L g-1 mm-2. These results show that with the screen-printed carbon electrodes it is possible to improve the electrochemical determination of this microorganism, enhancing the analytical parameters and quantification, allowing greater portability and decreasing measurement times and associated waste.

Electrochemical determination of Saccharomyces cerevisiae sp using glassy carbon electrodes modified with oxidized multi-walled carbon nanotubes dispersed in water -Nafion®.

The electrochemical behavior of Saccharomyces cerevisiae sp was studied using a glassy carbon electrode (GCE) modified with Nafion-dispersed oxidized multi-walled carbon nanotubes (OMWCNT). The morphology was studied using scanning electron microscopy (SEM), showing that the yeast sticks to the carbon nanotube surface instead of the glassy carbon surface. The redox couple Fe(CN)6 4-/Fe(CN)6 3- was used to determine the electroactive area and the heterogeneous transfer constant, which increased 80.5% and 108% respectively by the presence of nanotubes. The studies of the pH effect showed that the anodic potential decreases at alkaline pH and that the highest current intensity occurs at a pH value of 7.00. Studies of the scan rate effect have shown that yeast oxidation is an irreversible mixed control process in which two electrons participate. The relationship between yeast concentration and the anodic current density was studied using different electrochemical techniques obtaining the best analytical parameters through chronoamperometry. The linear range was between 3.36 and 6.52 g L-1, the limit of detection (LOD) and the limit of quantification (LOQ) were 0.98 g L-1 and 3.36 g L-1 respectively, and the sensibility obtained was 0.086 µA L g-1 mm-2. These results show that the multi-walled carbon nanotubes in water and Nafion® allow obtaining an anodic signal corresponding to the yeast, which facilitates its quantification through electrochemical methodologies, favoring the reduction of analysis times and costs compared with other techniques.

Recomendaciones y consideraciones del Comité Vascular de la Asociación Colombiana de Neurología para el manejo del ataque cerebrovascular isquémico durante la pandemia por covid-19 / Considerations and recommendations from the Stroke Committee of the Colombian Neurological Association for the management of Acute Ischemic Stroke during the pandemic for COVID-19

RESUMEN PROPÓSITO: En marzo 11 del 2020 la Organización Mundial de la Salud declara la pandemia por Covid-19. El clínico se va enfrentar a pacientes con ataque cerebrovascular (ACV) y sospecha o presencia de la infección. Miembros participantes del comité vascular de la Asociación Colombiana de Neurología basados en la experticia y la literatura amplían las primeras recomendaciones en el manejo de los pacientes con ACV isquémico agudo durante la actual pandemia. MÉTODOS: Mediante reuniones virtuales y por consenso de los participantes se escogieron tres ejes de trabajo: Tamización para Covid-19, Medidas de bioseguridad y Aspectos relevantes del ACV isquémico en época de pandemia por Covid-19. Se desarrollaron los ejes por grupos de trabajo mediante la modalidad de pregunta-respuesta pretendiendo generar en cada una de ellas recomendaciones sobre el tema. La versión final del documento conto con la revisión y el aval de todos los participantes. RESULTADOS: El documento cuenta con tres secciones correspondientes a los ejes de trabajo. En el primer eje se responden 3 preguntas y se dan recomendaciones sobre la tamización de la infección por Covid-19 en ACV agudo. En el segundo se responden 8 preguntas y se dan recomendaciones sobre las medidas de bioseguridad en la atención de pacientes con ACV durante la pandemia. En el tercero se tratan 13 aspectos relevantes del ACV durante la pandemia, según criterio de los participantes, y se dan recomendaciones pertinentes. CONCLUSIÓN: Las recomendaciones son basadas en la literatura y consenso de los participantes para el cuidado de pacientes con ACV isquémico agudo con sospecha o infección por Covid-19. No pretenden reemplazar las guías o protocolos establecidos sino ampliar las primeras recomendaciones del comité y apoyar al clínico en la atención de pacientes con ACV isquémico durante la pandemia.

SUMMARY PURPOSE: The World Health Organization declared the COVID-19 pandemic on March 11th 2020. Clinicians will face patients with stroke and confirmed or suspected infection. Members of the Stroke Committee of the Colombian Neurological Association based on their expertise and literature review extend on the first recommendations on acute ischemic stroke management during the pandemic. METHODS: Through virtual meetings and by consensus of participants three topics were selected: COVID-19 screening, biosafety measures and relevant aspects of acute ischemic stroke care during the pandemic. A question and answer format was used to develop recommendations for each topic. RESULTS: The manuscript is divided into three sections. The first includes three questions and recommendations on screening for COVID-19 in stroke patients. The second includes 8 questions and recommendations on biosafety measures on stroke patients during the pandemic. The last section includes 13 relevant stroke topics during COVID-19 pandemic, as deemed by the authors, and their recommendations. CONCLUSIONS: Recommendations on stroke care and COVID-19 are based on literature review and expert consensus. The aim of the manuscript is to extend on the first recommendations forwarded by the Committee, not to replace current guidelines, and to support the clinician caring for stroke patients during the pandemic.

Guías para el manejo de las enfermedades más frecuentes del pelo / Guidelines for the management of most common diseases of the hair

Las enfermedades del pelo se hacen cada día más frecuentes en la consulta y el dermatólogo se ve enfrentado a su manejo. Esta guía pretende dar una serie de indicaciones para el enfoque clínico del paciente, y el manejo terapéutico, con base en los estudios clínicos y la experiencia de los autores. Se hace énfasis en las entidades más vistas en la consulta, como la alopecia areata, la alopecia en efluvio telógeno, las alopecias androgénicas femeninas y masculinas y las alopecias cicatriciales.