Dra. Mardones-Leiva, Lorena

The purpose of this study was to investigate healthy lifestyle behaviours across age categories in the older population in Chile. Data from 1390 older adults (≥60 years), in the 2009–2010 Chilean National Health Survey were analyzed. We derived the following age categories: 60–65, 66–70, 71–75, 76–80 and >80 years. The associations between age and compliance with healthy lifestyle behaviours (smoking, sitting time, physical activity, sleep duration and intake of salt, alcohol, fruit and vegetables) were investigated using logistic regression. The probability of meeting the guidelines for alcohol intake (OR trend: 1.35 [95% CI: 1.11; 1.64], p = 0.001) and smoking (OR trend: 1.23 [95% CI: 1.13; 1.33], p < 0.0001) increased with age, whereas spending <4 h per day sitting time or engaging in at least 150 min of physical activity per week or sleep on average between 7 and 9 h per day were less likely to be met with increasing age (OR trend: 0.77 [95% CI: 0.71; 0.83], p < 0.000; OR trend: 0.73 [95% CI: 0.67; 0.79], p < 0.0001, and OR trend: 0.89 [95% CI: 0.82; 0.96], p = 0.002, respectively). No significant trend across age categories was observed for fruit and vegetables, and salt intake. The probability of meeting at least 3 out of 7 healthy lifestyle behaviours across the age categories was also lower in older age categories compared to those aged 60 to 65 years. Overall, in older adults the probability of having the healthy lifestyle behaviours of physical activity, sitting time and sleeping behaviours was low but not for smoking or alcohol consumption. With an increasingly ageing population, these findings could inform stakeholders on which lifestyle behaviours could be targeted in the older adults and therefore which interventions should take place to promote healthy ageing.

La vitamina C es el antioxidante más conocido, debido a su asociación con la prevención del resfrío común. Esta vitamina también participa en la síntesis de colágeno y de catecolaminas, actuando como cofactor de hidrolasas. Se han evidenciado efectos benéficos del consumo de vitamina C en la prevención del cáncer, del envejecimiento y de enfermedades cardiovasculares y neurodegenerativas, debido a que estas patologías presentan un componente oxidativo en su origen y propagación. En particular, la acción anti-cancerígena de la vitamina C resulta ser bastante compleja de analizar, y ha sido debatida por décadas. Actualmente, se sabe que los niveles plasmáticos de esta vitamina son finamente regulados, alcanzando un valor cercano a 50 μM al consumir la dosis diaria recomendada (60 mg/día), gracias a su absorción intestinal y a su reabsorción renal. La administración de dosis mayores a 500 mg/día por vía oral permite alcanzar una concentración plasmática máxima de 150 μM 1 . La vitamina C ingerida es absorbida a nivel intestinal en su forma reducida (ascorbato, AA) por el co-transportador sodio-ascorbato (SVCT1), y en su forma oxidada (deshidroascorbato, DHA), por los transportadores facilitativos de glucosa (GLUT2 preferentemente). Por otro lado, la administración por vía endovenosa de dosis mayores a 0,4 g/kg permite alcanzar niveles plasmáticos estables cercanos a 1,5 mM, con un máximo de hasta 30 mM. Diversos estudios prospectivos observacionales revelaron que la suplementación con AA oral disminuye en 20% la mortalidad asociada al desarrollo de cáncer de mama y que mega-dosis de vitamina C endovenosa actúan como co-adyudantes en distintas terapias anti-cancerígenas (radioterapia, quimioterapia con carbioplatino o paclitaxel) y reducen el riesgo de progresión de cáncer de hígado posterior a hepatectomía parcial 2−3 . La administración de DHA también presentó efectividad como terapia complementaria en el caso del tratamiento con doxoribucina, metotrexato y cisplatino 2 . Lamentablemente, la mayoría de estos estudios clínicos carecieron de la rigurosidad requerida o involucraban un número muy pequeño de pacientes. Por otro lado, dado que estos estudios se realizaron sin conocer el mecanismo de acción de la vitamina C, no se monitoreó relación entre dosis, tiempo de aplicación y efectividad de la respuesta. Además, hay que considerar que algunos de estos agentes anti-cancerígenos son oxidantes, por lo que la vitamina C podría intervenir con su mecanismo de acción.

Differentiated mammary epithelial cells are responsible for milk synthesis during lactation, supporting early postnatal life in mammals. These cells are found in the terminal alveoli of a secretory epithelium, which is surrounded by myoepithelial cells and a stroma rich in fatty tissue. The aim of this study was to explore the cell-specific expression of the glucose transporter GLUT8 in mammary gland and evaluate its functionality for glucose transport, in order to confirm its role in lactose synthesis. Our histological results revealed that GLUT8 is expressed in adipocytes and the epithelial and myoepithelial cells in mammary gland, with a predominant intracellular granular pattern. Colocalization studies of endogenous and green fluorescent protein fused GLUT8 revealed their expressions in lysosome and Golgi, respectively, with Pearson's coefficient correlations of 0.82 ± 0.05 and 0.68 ± 0.16. Functional studies of dileucine to dialanine mutant of GLUT8 showed a fructose-sensitive 2-deoxy glucose uptake at a rate of 83.3 pmoles/(min∗106 cells), 7 folds over empty vector, with a 60 ± 4 and 72 ± 6% decline in 2-deoxy glucose in the presence of 20 and 50 mM fructose, respectively. We concluded that functional GLUT8 is expressed in mammary gland, localizing in mammary epithelial and myoepithelial cells, and adipocytes. In lactation, GLUT8 is expressed mainly in luminal epithelial cells, at the compartments of the endomembrane system. It is necessary to explore the physiological/pathological functions of GLUT8 in mammary gland, including its role in lactation.

The mammary gland increases energy requirements during pregnancy and lactation to support epithelial proliferation and milk nutrients synthesis. Lactose, the principal carbohydrate of the milk, is synthetized in the Golgi of mammary epithelial cells by lactose synthase from glucose and UPD galactose. We studied the temporal changes in the expression of GLUT1 and GLUT8 in mammary gland and their association with lactose synthesis and proliferation in BALB/c mice. Six groups were used: virgin, pregnant at 2 and 17 days, lactating at 2 and 10 days, and weaning at 2 days. Temporal expression of GLUT1 and GLUT8 transporters by qPCR, western blot and immunohistochemistry, and its association with lactalbumin, Ki67, and cytokeratin 18 within mammary tissue was studied, along with subcellular localization. GLUT1 and GLUT8 transporters increased their expression during mammary gland progression, reaching 20-fold increasing in GLUT1 mRNA at lactation (p < 0.05) and 2-fold at protein level for GLUT1 and GLUT8 (p < 0.05 and 0.01, respectively). The temporal expression pattern was shared with cytokeratin 18 and Ki67 (p < 0.01). Endogenous GLUT8 partially co-localized with 58 K protein and α-lactalbumin in mammary tissue and with Golgi membrane–associated protein 130 in isolated epithelial cells. The spatial-temporal synchrony between expression of GLUT8/GLUT1 and alveolar cell proliferation, and its localization in cis-Golgi associated to lactose synthase complex, suggest that both transporters are involved in glucose uptake into this organelle, supporting lactose synthesis.