Balancing personal maintenance with parental investment in a chick-rearing seabird: physiological indicators change with foraging conditions.

Seabird parents use a conservative breeding strategy that favours long-term survival over intensive parental investment, particularly under harsh conditions. Here, we examine whether variation in several physiological indicators reflects the balance between parental investment and survival in common murres (Uria aalge) under a wide range of foraging conditions. Blood samples were taken from adults during mid-chick rearing from 2007 to 2014 and analysed for corticosterone (CORT, stress hormone), beta-hydroxybutyrate (BUTY, lipid metabolism reflecting ongoing mass loss), and haematocrit (reflecting blood oxygen capacity). These measures, plus body mass, were related to three levels of food availability (good, intermediate, and poor years) for capelin, the main forage fish for murres in this colony. Adult body mass and chick-feeding rates were higher in good years than in poor years and heavier murres were more likely to fledge a chick than lighter birds. Contrary to prediction, BUTY levels were higher in good years than in intermediate and poor years. Murres lose body mass just after their chicks hatch and these results for BUTY suggest that mass loss may be delayed in good years. CORT levels were higher in intermediate years than in good or poor years. Higher CORT levels in intermediate years may reflect the necessity of increasing foraging effort, whereas extra effort is not needed in good years and it is unlikely to increase foraging success in poor years. Haematocrit levels were higher in poor years than in good years, a difference that may reflect either their poorer condition or increased diving requirements when food is less available. Our long-term data set provided insight into how decisions about resource allocation under different foraging conditions are relating to physiological indicators, a relationship that is relevant to understanding how seabirds may respond to changes in marine ecosystems as ocean temperatures continue to rise.

Attenuation of ciclosporin-induced nephrotoxicity by dietary supplementation of seal oil in Sprague-Dawley rats.

Fish oil, rich in omega-3 (n-3) polyunsaturated fatty acids (PUFAs), has been reported to attenuate nephrotoxicity induced by ciclosporin (cyclosporine A). Harp seal oil is a rich source of n-3 PUFAs. This study investigated the ability of dietary seal oil to reduce nephrotoxicity caused by ciclosporin. Sprague-Dawley rats were maintained on a standard diet (with sunflower oil as lipid, SFO) or a diet enriched with seal oil (with 85% seal oil and 15% sunflower oil as lipid, SO) for four weeks before and four weeks after intravenous administration of ciclosporin (15 mg kg(-1) daily). Kidney function was assessed by measuring blood urea nitrogen, creatinine clearance, urinary N-acetyl-1-beta-D-glucosaminidase, 6-keto-prostaglandin F(1alpha), thromboxane B(2) and malondialdehyde. Systolic blood pressure (SBP) was monitored. Ciclosporin concentrations in blood were measured using liquid chromatographytandem mass spectrometry (LC-MS/MS). The fatty acid compositions of the diets and erythrocyte membranes were analysed by gas chromatography (GC). The results showed that nephrotoxicity was induced by ciclosporin in rats maintained on both SO and SFO diets. However, rats fed on SO diet endured less toxicity than those on SFO diet. The n-3 and n-6 PUFAs in the erythrocyte membrane of rats maintained on SO diet were found to be 10.79% and 11.93%, while those in rats maintained on SFO diet were found to be 1.67% and 22.71%, respectively. In conclusion, dietary supplementation of seal oil was found to reduce ciclosporin-induced nephrotoxicity in rats.

Maternal dietary fat intake during gestation and lactation alters tissue fatty acid composition in the adult offspring of C57Bl/6 mice.

We investigated the effects of maternal dietary fat intake during gestation and lactation on the tissue fatty acid composition of the adult offspring. Female C57Bl/6 mice were fed high fat diets enriched with lard or safflower oil or chow during mating, gestation and lactation. The offspring obtained from each group of mothers were continued on diets rich in lard, safflower oil or chow post-weaning until 11 weeks of age. Livers and hearts were collected for fatty acid analysis. A maternal diet rich in safflower oil was associated with enrichment of hepatic tissue with n-3 polyunsaturated fatty acids in the offspring fed chow post-weaning compared to the offspring fed chow throughout. However, a continuous exposure to a safflower oil- as well as lard-rich diet during the pre- and post-weaning time periods was associated with reduced content of docosahexaenoic acid in both liver and heart tissues compared to the offspring fed chow throughout. In conclusion, this study demonstrated lasting effects of maternal dietary fat intake, as well as an interaction between pre- and post-weaning diets, on the tissue fatty composition in adult offspring.

High-level medium-chain triglyceride feeding and energy expenditure in normal-weight women.

The objective of this study was to assess how short-term feeding of high levels of dietary medium-chain triglyceride (MCT) affect energy expenditure and postprandial substrate oxidation rates in normal-weight, premenopausal women. Eight healthy women were fed both a MCT-rich and an isocaloric long-chain triglyceride (LCT)-rich diet for two 1-week periods separated by a minimum of 21 days. The energy intake in each diet was 45% carbohydrates, 40% fat, and 15% protein. The 2 diets had either 60.81% or 1.11% of total fat energy from MCT with the remaining fat energy intake from LCT. On days 1 and 7 of each diet, resting metabolic rate and postprandial energy expenditure (EE) were measured by indirect calorimetry with a ventilated hood. Results indicated on days 1 and 7, there were no significant differences between diets for resting metabolic rate or mean postprandial EE. On both days 1 and 7, fat oxidation for the MCT-rich diet was significantly greater (0.0001

Aerobic exercise, lipoproteins, and cardiovascular disease: benefits and possible risks.

Aerobic exercise has been shown to reduce the risk of cardiovascular disease (CVD). This reduction is proportional to the intensity of the exercise. The reduction in CVD risk is at least partially mediated by changes in circulating lipoproteins resulting from adaptive changes in enzymes involved in their metabolism. Specifically, aerobic exercise is associated with reductions in low density lipoprotein (LDL), total cholesterol and triacylglycerol (TAG), and increases in high density lipoprotein (HDL). Exposure to oxygen can oxidatively damage LDL. Oxidized LDL is a risk factor for atherosclerosis. Although aerobic exercise can cause oxidative damage, there are adaptive changes resulting from chronic exercise that result in lower rather than higher levels of oxidized LDL.

Milk from mothers of both premature and full-term infants provides better antioxidant protection than does infant formula.

We hypothesized that premature (PT) infants' mother's milk may provide antioxidant advantages compared with milk from mothers of full-term (FT) infants, and human milk may provide antioxidant properties not seen in infant formulas. We designed three experiments to test these hypotheses. Experiment 1 assessed resistance to oxidative stress of human milk and formulas designed for FT and PT infants. Experiment 2 determined differences in resistance to oxidative stress between milk from mothers of FT and PT infants, including analysis of catalase activity. Experiment 3 examined factors in human milk that may account for increased resistance to oxidative stress. In experiment 1, we induced physiologic oxidative stress in human milk (n = 5) and formula (n = 2) and measured ascorbate radical using electron paramagnetic resonance. Results indicated the following: 1) during oxidative stress, ascorbate may be spared in human milk compared with formula; 2) ascorbate radical production is more intense in formula compared with human milk, with or without oxidative stress; and 3) oxygen consumption in human milk is less than that in formula, with or without oxidative stress. In experiment 2, milk samples were collected from mothers of PT (n = 28) and FT (n = 17) infants at wk 1, 2, and 12 of lactation. No differences in oxygen consumption after oxidative stress appeared between PT and FT milk. Catalase levels in human milk increased with time. In experiment 3, addition of catalase, superoxide dismutase, and glutathione peroxidase to formulas (n = 4) increased resistance to oxidative stress. Denaturing endogenous enzymes did not decrease the ability of human milk to resist oxidative stress. Ferrous sulfate plus vitamin C added to human milk and formulas fortified with iron increased oxidative stress. Addition of iron chelators to formula reduced oxidative stress. In conclusion, human milk has better antioxidant protection than do formulas, perhaps because of the higher iron content of formulas. Milk from mothers of PT and FT infants has equal resistance to oxidative stress.