Switching Regulator Based on a Non-Inverting Step-Down/Up DC-DC Converter for Lithium-Ion Battery Applications.

A regulator based on a converter with step-down/up characteristics is discussed in this paper, which is suitable for processing energy from a lithium-ion battery pack, where the voltage fluctuates from above or below the nominal value. However, this regulator can also be used for applications such as unregulated line rectifiers and renewable energy sources, among others. The converter consists of a non-cascaded interconnection of boost and buck-boost converters such that part of the input energy is transferred directly to the output without reprocessing. Furthermore, it has a non-pulsating input current and a non-inverting output voltage, making it easier to feed the power to other devices. For control purposes, non-linear and linear converter models are derived. The transfer functions of the linear model are used to implement the regulator using a current-mode control scheme. Finally, experimental results for a nominal output voltage of 48 V at 500 W are obtained for the converter in open-loop and closed-loop tests.

Risk factors associated with diabetic neuropathy in Mexican patients.

INTRODUCTION: Diabetic neuropathy (DN) is one of the most common complications of type 2 diabetes (T2D) and is a leading cause of lower limb amputation. The aim of the present study was to evaluate the risk factors contributing to DN in Mexican patients through the comparison of T2D patients with and without DN. MATERIALS AND METHODS: This cross-sectional study consisted of 509 subjects from Mexico who were classified as with DN and without DN. DN was assessed according to Douleur Neuropathique 4 questionnaire. Logistic regression analysis was performed to analyze risk factors contributing to DN. RESULTS: The prevalence of DN in the studied population was 28.3%. The risk factors associated with DN were T2D duration (odds ratio [OR]: 2.51; 95% confidence interval [CI] 1.36-4.65), glycemic exposure index (OR: 1.82; 95% CI 1.01-3.64), low- and high-density lipoprotein levels (OR: 1.53; 95% CI 1.02-2.31), metformin treatment (OR: 2.08; 95% CI 1.11-3.91), diabetic retinopathy (OR: 1.65; 95% CI 1.07-2.54), and smoking (OR: 1.51; 95% CI 1.00-2.26). CONCLUSIONS: Therefore, the early identification of risk factors for DN development in Mexican population would allow implementing personalized strategies to improve the overall T2D patients' quality of life and reduce healthcare costs in our country.

ANTECEDENTES: La neuropatía diabética (ND) es una de las complicaciones más comunes de la diabetes tipo 2 (DT2). ­. OBJETIVO: Investigar los factores de riesgo que contribuyen al desarrollo de ND en población mexicana con DT2, comparando pacientes diabéticos con y sin ND. MÉTODO: Estudio transversal con 509 pacientes mexicanos con DT2, clasificados en dos grupos, con y sin ND. La ND fue diagnosticada con el cuestionario DN4. La identificación de los factores de riesgo de ND se realizó mediante un análisis de regresión logística. RESULTADOS: La prevalencia de ND en la población de estudio fue del 28.3%. Los factores de riesgo asociados a ND fueron la duración de la DT2 (odds ratio [OR]: 2.51; intervalo de confianza del 95% [IC 95%]: 1.36-4.65), el índice glucémico (OR: 1.82; IC 95%: 1.01-3.64), las concentraciones bajas de colesterol unido a lipoproteínas de alta densidad (OR: 1.53; IC 95%: 1.02-2.31), el tratamiento con metformina (OR: 2.08; IC 95%: 1.11-3.91), la retinopatía diabética (OR: 1.65; IC 95%: 1.07-2.54) y el tabaquismo (OR: 1.51; IC 95%: 1.00-2.26). CONCLUSIONES: La identificación temprana de los factores de riesgo para el desarrollo de ND en población mexicana permitirá implementar estrategias personalizadas para mejorar la calidad de vida de los pacientes con DT2 y disminuir el gasto del sector salud originado por esta complicación.

A functional ABCA1 gene variant is associated with low HDL-cholesterol levels and shows evidence of positive selection in Native Americans.

It has been suggested that the higher susceptibility of Hispanics to metabolic disease is related to their Native American heritage. A frequent cholesterol transporter ABCA1 (ATP-binding cassette transporter A1) gene variant (R230C, rs9282541) apparently exclusive to Native American individuals was associated with low high-density lipoprotein cholesterol (HDL-C) levels, obesity and type 2 diabetes in Mexican Mestizos. We performed a more extensive analysis of this variant in 4405 Native Americans and 863 individuals from other ethnic groups to investigate genetic evidence of positive selection, to assess its functional effect in vitro and to explore associations with HDL-C levels and other metabolic traits. The C230 allele was found in 29 of 36 Native American groups, but not in European, Asian or African individuals. C230 was observed on a single haplotype, and C230-bearing chromosomes showed longer relative haplotype extension compared with other haplotypes in the Americas. Additionally, single-nucleotide polymorphism data from the Human Genome Diversity Panel Native American populations were enriched in significant integrated haplotype score values in the region upstream of the ABCA1 gene. Cells expressing the C230 allele showed a 27% cholesterol efflux reduction (P< 0.001), confirming this variant has a functional effect in vitro. Moreover, the C230 allele was associated with lower HDL-C levels (P = 1.77 x 10(-11)) and with higher body mass index (P = 0.0001) in the combined analysis of Native American populations. This is the first report of a common functional variant exclusive to Native American and descent populations, which is a major determinant of HDL-C levels and may have contributed to the adaptive evolution of Native American populations.