SARS-CoV-2 in Mexico: An Association Among Geography, Comorbidities, and Vitamin D Deficiency.

Objective: The aim of this study was to determine the association among temperature, relative humidity, latitude, vitamin D content and comorbidities in the spread of SAR-CoV-2 in Mexico in 2 different waves. Methods: The data on SARS-CoV-2 infections and comorbidities were obtained from the Mexican entities with the highest number of positive cases and deaths in the 2 waves that have most damaged the population. Results: Low temperature, high relative humidity, vitamin D deficiency and high percentage of comorbidities were factors that correlated with a high spread of SARS-CoV-2. Interestingly, 73.8% of the population had one of the most common comorbidities that favor the spread of the virus. Conclusion: The high percentage of comorbidities and the deficient concentration of vitamin D were determining factors in the high number of infections and deaths in Mexico. Furthermore, weather conditions could contribute to and alert to the spread of SARS-CoV-2.

Evaluation of the metrological reliability of a graduated cylinder from experimental data from an in-situ calibration.

This work presents the data experimentally collected in a chemical laboratory for the calibration of a graduated cylinder. There are several factors that can influence the volume measurement using this type of instrument and, consequently, its metrological reliability, for example: the internal geometry, the environmental conditions (ambient temperature, atmospheric pressure and relative humidity), the acceleration of gravity, the density of the air, among others. For the data collection it was necessary to use a glass liquid thermometer (Range: 0-10 °C), a digital thermohygrometer (Range: 0-100 °C and 0-99%RH) and a digital barometer (Range: 0-9999 mbar). Additionally, an analytical scale (Range: 0-220 g) was used for mass measurement. From the measurements obtained, it was possible to determine the in-situ air density and the buoyancy factor that influences the mass measurement. The data, rigorously obtained, present a potential use to determine the metrological reliability of a graduated cylinder for laboratory use and, additionally, contribute to perform a metrological validation of alternative methods for the calibration of graduated cylinder.

Recuperación cardiovascular durante ejercicio intermitente en pacientes con hipertensión y diabetes tipo 2 altamente adherentes / Cardiovascular recovery during intermittent exercise in highly-adherent partic pants with hypertension and type 2 diabetes mellitus

Background: Despite the evidence supporting metabolic benefits of high intensity interval exercise (HIIT), there is little information about the cardiovascular response to this type of exercise in patients with type 2 diabetes (T2D) and hypertension (HTA). Aim: To analyze the changes in heart rate at rest, at the onset and at the end of each interval of training, after twelve weeks of a HIIT program in T2D and HTA patients. Material and Methods: Twenty-three participants with T2D and HTA (20 women) participated in a controlled HIIT program. Fourteen participants attended 90% of more session of exercise and were considered as adherent. Adherent and non-adherent participants had similar body mass index (BMI), and blood pressure. A “1x2x10” (work: rest-time: intervals) HIIT exercise protocol was used both as a test and as training method during twelve weeks. The initial and finishing heart rate (HR) of each of the ten intervals before and after the intervention were measured. Results: After twelve weeks of HIIT intervention, adherent participants had a significant reduction in the heart rate at the onset of exercise, and during intervals 4, 5, 8 and 10. A reduction in the final heart rate was observed during intervals 8 and 10. In the same participants the greatest magnitude of reduction, at the onset or end of exercise was approximately 10 beats/min. No significant changes in BMI, resting heart rate and blood pressure were observed. Conclusions: A HIIT program reduces the cardiovascular effort to a given work-load and improves cardiovascular recovery after exercise.

[Cardiovascular recovery during intermittent exercise in highly-adherent partic pants with hypertension and type 2 diabetes mellitus]. / Recuperación cardiovascular durante ejercicio intermitente en pacientes con hipertensión y diabetes tipo 2 altamente adherentes.

BACKGROUND: Despite the evidence supporting metabolic benefits of high intensity interval exercise (HIIT), there is little information about the cardiovascular response to this type of exercise in patients with type 2 diabetes (T2D) and hypertension (HTA). AIM: To analyze the changes in heart rate at rest, at the onset and at the end of each interval of training, after twelve weeks of a HIIT program in T2D and HTA patients. MATERIAL AND METHODS: Twenty-three participants with T2D and HTA (20 women) participated in a controlled HIIT program. Fourteen participants attended 90% of more session of exercise and were considered as adherent. Adherent and non-adherent participants had similar body mass index (BMI), and blood pressure. A “1x2x10” (work: rest-time: intervals) HIIT exercise protocol was used both as a test and as training method during twelve weeks. The initial and finishing heart rate (HR) of each of the ten intervals before and after the intervention were measured. RESULTS: After twelve weeks of HIIT intervention, adherent participants had a significant reduction in the heart rate at the onset of exercise, and during intervals 4, 5, 8 and 10. A reduction in the final heart rate was observed during intervals 8 and 10. In the same participants the greatest magnitude of reduction, at the onset or end of exercise was approximately 10 beats/min. No significant changes in BMI, resting heart rate and blood pressure were observed. CONCLUSIONS: A HIIT program reduces the cardiovascular effort to a given work-load and improves cardiovascular recovery after exercise.

Resistencia a la fractura de dientes debilitados radicularmente rehabilitados con diferentes materiales / Fracture resistance of weak teeth with compromised roots rehabilitated with different materials

Resumen Introducción y objetivo: La preservación y restauración de dientes debilitados radicularmente se ha considerado como un procedimiento poco predecible debido a que existen factores que predisponen al fracaso. Esta condición se presenta frecuentemente y una alternativa para su rehabilitación es reforzar la superficie radicular para mejorar la estabilidad y retención del retenedor. El objetivo de este estudio fue evaluar la resistencia a la fractura de dientes debilitados radicularmente reconstruidos con ionómero de vidrio en combinación con diferentes retenedores comparados con raíces debilitadas sin refuerzo radicular. Materiales y métodos: 60 premolares uniradiculares con similares características fueron seleccionados y divididos aleatoriamente en 6 grupos, 30 dientes fueron internamente debilitados a 1mm y posteriormente reforzados con ionómero de vidrio. Los especímenes fueron sometidos a carga compresiva en una maquina de ensayos universal Instrom con una angulación de 45°. Posteriormente se identificaron los sitios de fractura con ayuda de una lupa 4X de lente convergente a una distancia de 25 cm. Resultados: Resultados indicaron diferencias estadísticamente significativas en relación a la condición radicular (P<0.05), demostrando que dientes con refuerzo radicular no mejora considerablemente la resistencia a la fractura. Conclusión: La conservación de la estructura dentaria es más importante que el tipo de refuerzo con materiales dentales. Las características físicas y químicas de los ionómeros permiten su empleo en zonas de socavado, sin aumentar la resistencia compresiva final de la estructura dentaria, brindando únicamente estabilidad del retenedor.

Abstract Introduction and objective: The preservation and restoration of weak teeth with compromised roots has been considered to be a slightly predictable procedure because there are factors that predispose to failure. This condition appears frequently, and an alternative to rehabilitation is to reinforce the radicular surface in order to improve the stability and retention of the retainer. The objective of this study was to evaluate the resistance to fracture of teeth with debilitated roots and reconstructed with glass ionomer combined with different retainers and compared with teeth with weakened roots without reconstruction. Materials and methods: 60 uniradicular premolars with similar characteristics were selected and divided randomly into 6 groups, 30 teeth were internally debilitated to 1mm and later reinforced with glass ionomer. The samples were submitted to a compressive load on an Instrom Universal Testing Machine with 45°angulation. Afterwards, fracture sites in each of the samples were identified using a magnifier 4X converging lens at a distance of 25 cm. Results: Statistically significant differences were observed regarding the root condition (P <0.05), demonstrating that teeth with root reinforcement did not improve significantly their resistance to fracture. Conclusion: The conservation of tooth structure is most important than the type of reinforcement with dental materials. The physical and chemical characteristics of the ionomers allow they can be used in undermined areas without increasing ultimate compressive strength of tooth structure, providing only stability of the retainer.