Dra. Mardones-Leiva, Lorena

The liver has an extraordinary regenerative capacity in response to partial hepatectomy (PHx), which develops with neither tissue inflammation response nor alterations in the whole organism. This process is highly coordinated and it has been associated with changes in glutathione (GSH) metabolism. However, there are no reports indicating ascorbic acid (AA) levels after partial hepatectomy. AA and GSH act integrally as an antioxidant system that protects cells and tissues from oxidative damage and imbalance observed in a variety of diseases that affect the liver. Although rat hepatocytes are able to synthesize AA and GSH, which are the providers of AA for the whole organism, they also acquire AA from extracellular sources through the sodiumcoupled ascorbic acid transporter-1 (SVCT1). Here, we show that hepatocytes from rat livers subjected to PHx increase their GSH and AA levels from 1 to 7 days post hepatectomy, whose peaks precede the peak in cellproliferation observed at 3 days post-hepatectomy. The increase in both antioxidants was associated with higher expression of the enzymes involved in their synthesis, such as the modifier subunit of enzyme glutamine cysteine ligase (GCLM), glutathione synthetase (GS), gulonolactonase (GLN) and gulonolactone oxidase (GULO). Importantly, rat hepatocytes, that normally exhibit kinetic evidence indicating only SVCT1-mediated transport of AA, lost more than 90% of their capacity to transport it at day 1 after PHx without evidence of recovery at day 7. This observation was in agreement with loss of SVCT1 protein expression, which was undetectable in hepatocytes as early as 2 h after PHx, with partial recovery at day 7, when the regenerated liver weight returns to normal. We conclude that after PHx, rat hepatocytes enhance their antioxidant capacity by increasing GSH and AA levels prior to the proliferative peak. GSH and AA are increased by de novo synthesis, however paradoxically hepatocytes from rat subjected to PHx also suppress their capacity to acquire AA from extracellular sources through SVCT1.

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.

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.