A short-term n-3 DPA supplementation study in humans

Purpose Despite the detailed knowledge of the absorption and incorporation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into plasma lipids and red blood cells (RBC) in humans, very little is known about docosapentaenoic acid (DPA, 22:5 n-3). The aim of this study was to investigate the uptake and incorporation of pure DPA and EPA into human plasma and RBC lipids.

Methods Ten female participants received 8 g of pure DPA or pure EPA in randomized crossover double-blinded manner over a 7-day period. The placebo treatment was olive oil. Blood samples were collected at days zero, four and seven, following which the plasma and RBC were separated and used for the analysis of fatty acids.

Results Supplementation with DPA significantly increased the proportions of DPA in the plasma phospholipids (PL) (by twofold) and triacylglycerol (TAG) fractions (by 2.3-fold, day 4). DPA supplementation also significantly increased the proportions of EPA in TAG (by 3.1-fold, day 4) and cholesterol ester (CE) fractions (by 2.0-fold, day 7) and of DHA in TAG fraction (by 3.1-fold, day 4). DPA proportions in RBC PL did not change following supplementation. Supplementation with EPA significantly increased the proportion of EPA in the plasma CE and PL fractions, (both by 2.7-fold, day 4 and day 7) and in the RBC PL (by 1.9-fold, day 4 and day 7). EPA supplementation did not alter the proportions of DPA or DHA in any lipid fraction. These results showed that within day 4 of supplementation, DPA and EPA demonstrated different and specific incorporation patterns.

Conclusion The results of this short-term study suggest that DPA may act as a reservoir of the major long-chain n-3 fatty acids (LC n-3 PUFA) in humans.

Skeletal muscle fat metabolism after exercise in humans: influence of fat availability

The mechanisms facilitating increased skeletal muscle fat oxidation following prolonged, strenuous exercise remain poorly defined. The aim of this study was to examine the influence of plasma free fatty acid (FFA) availability on intramuscular malonyl-CoA concentration and the regulation of whole-body fat metabolism during a 6-h postexercise recovery period. Eight endurance-trained men performed three trials, consisting of 1.5 h high-intensity and exhaustive exercise, followed by infusion of saline, saline + nicotinic acid (NA; low FFA), or Intralipid and heparin [high FFA (HFA)]. Muscle biopsies were obtained at the end of exercise (0 h) and at 3 and 6 h in recovery. Ingestion of NA suppressed the postexercise plasma FFA concentration throughout recovery (P < 0.01), except at 4 h. The alteration of the availability of plasma FFA during recovery induced a significant increase in whole-body fat oxidation during the 6-h period for HFA (52.2 ± 4.8 g) relative to NA (38.4 ± 3.1 g; P < 0.05); however, this response was unrelated to changes in skeletal muscle malonyl-CoA and acetyl-CoA carboxylase (ACC)β phosphorylation, suggesting mechanisms other than phosphorylation-mediated changes in ACC activity may have a role in regulating fat metabolism in human skeletal muscle during postexercise recovery. Despite marked changes in plasma FFA availability, no significant changes in intramuscular triglyceride concentrations were detected. These data suggest that the regulation of postexercise skeletal muscle fat oxidation in humans involves factors other than the 5′AMP-activated protein kinase-ACCβ-malonyl-CoA signaling pathway, although malonyl-CoA-mediated regulation cannot be excluded completely in the acute recovery period.

Measuring oral fatty acid thresholds, fat perception, fatty food liking, and papillae density in humans

Oral chemoreception of fatty acids and the association with diet and fatty food preferences may enable the identification of mechanisms involved with the development of obesity and why dietary changes may be difficult for many individuals.

Endurance training in obese humans improves glucose tolerance and mitochondrial fatty acid oxidation and alters muscle lipid content

Muscle fatty acid (FA) metabolism is impaired in obesity and insulin resistance, reflected by reduced rates of FA oxidation and accumulation of lipids. It has been suggested that interventions that increase FA oxidation may enhance insulin action by reducing these lipid pools. Here, we examined the effect of endurance training on rates of mitochondrial FA oxidation, the activity of carnitine palmitoyltransferase I (CPT I), and the lipid content in muscle of obese individuals and related these to measures of glucose tolerance. Nine obese subjects completed 8 wk of moderate-intensity endurance training, and muscle biopsies were obtained before and after training. Training significantly improved glucose tolerance, with a reduction in the area under the curve for glucose (P< 0.05) and insulin (P = 0.01) during an oral glucose tolerance test. CPT I activity increased 250% (P = 0.001) with training and became less sensitive to inhibition by malonyl-CoA. This was associated with an increase in mitochondrial FA oxidation (+120%, P < 0.001). Training had no effect on muscle triacylglycerol content; however, there was a trend for training to reduce both the total diacylglcyerol (DAG) content (−15%, P = 0.06) and the saturated DAG-FA species (−27%, P = 0.06). Training reduced both total ceramide content (−42%, P = 0.01) and the saturated ceramide species (−32%, P < 0.05). These findings suggest that the improved capacity for mitochondrial FA uptake and oxidation leads not only to a reduction in muscle lipid content but also a to change in the saturation status of lipids, which may, at least in part, provide a mechanism for the enhanced insulin action observed with endurance training in obese individuals.

Attacks on humans by Australian Magpies (Cracticus tibicen): Territoriality, brood-defence or testosterone?

Attacks on humans by Australian Magpies (Cracticus tibicen) are a significant human-wildlife conflict in Australia, especially in suburban environments. Remarkably little is known about the phenomenon. In this study, we explored three common hypotheses - territoriality, brood-defence and testosterone - as potential and non-exclusive explanations for aggression directed at people by Magpies living in suburban areas of Brisbane, south-eastern Queensland. The response of 10 pairs of aggressive Magpies to natural levels of human intrusion was compared with that of 10 non-aggressive pairs. Behavioural observations strongly supported the contention that attacks on humans resemble brood-defence and did not support an association with territoriality. The study also found no support for the suggestion that testosterone levels correlated with aggressiveness towards humans: male testosterone peaked immediately before laying and was significantly lower during the maximum period of attacks directed at people. Moreover, there were no differences in the testosterone levels of aggressive and non-aggressive male Magpies. The pattern of testosterone production over a breeding cycle closely resembled that of many other songbirds and appeared not to influence Magpie attacks on humans. © Royal Australasian Ornithologists Union 2010.

An ecology of religiosity: re-emphasizing relationships between humans and nonhumans

A growing anthropological literature on how various groups of people relate with nonhuman Others has questioned the universality of the conceptual binary between Nature and Culture and, particularly, the usefulness of the concept of 'Nature' to an understanding of human - nonhuman relationships. In light of this, what then becomes of ecology? In particular, can we retain the crucial ecological notions of system and form while bypassing 'Nature'? Drawing on Gregory Bateson's ecology of mind, I suggest that this is possible as long as we focus on processes and relationships. Moreover, the kinds of processes and relationships that more clearly highlight this endeavor are those that are informed by religious thoughts and actions. I offer the term 'an ecology of religiosity' to outline how an overall focus on relationships may dissolve a priori distinctions between Nature and Culture while foregrounding the context in which relationships reshape themselves through religious forms.

The height of approaching humans does not affect flight-initiation distance

Capsule Responses of animals to anthropogenic disturbances are often quantified using flight-initiation distance, the distance at which an animal flees a stimulus such as a person. We showed that the height of 20 researchers, selected to represent a diversity of heights, did not affect estimates of flight-initiation distance of Black Swans Cygnus atratus, suggesting that the height of humans used to test hypotheses of flight-initiation distances is not a confounding variable.

The double sensor-a non-invasive device to continuously monitor core temperature in humans on earth and in space

The objective of our study was to establish whether rectal temperature recordings in humans could be replaced by a non-invasive skin temperature sensor combined with a heat flux sensor (Double Sensor) located at the forehead to monitor core body temperature changes due to circadian rhythms. Rectal and Double Sensor data were collected continuously for 24h in seven men undertaking strict head-down tilt bed-rest. Individual differences between the two techniques varied between -0.72 and +0.55 degrees C. Nonetheless, when temperature data were approximated by cosinor analysis in order to compare circadian rhythm profiles between methods, it was observed that there were no significant differences between mesor, amplitude, and acrophase (P>0.310). It was therefore concluded that the Double Sensor technology is presently not accurate enough for performing single individual core body temperature measurements under resting conditions at normal ambient room temperature. Yet, it seems to be a valid, non-invasive alternative for monitoring circadian rhythm profiles.

Vitamin C and E supplementation prevents some of the cellular adaptations to endurance-training in humans

BACKGROUND: It is clear that reactive oxygen species (ROS) produced during skeletal muscle contraction have a regulatory role in skeletal muscle adaptation to endurance exercise. However, there is much controversy in the literature regarding whether attenuation of ROS by antioxidant supplementation can prevent these cellular adaptations. Therefore, the aim of this study was to determine whether vitamin C and E supplementation attenuates performance and cellular adaptations following acute endurance exercise and endurance training. METHODS: A double-blinded, placebo-controlled randomized control trial was conducted in eleven healthy young males. Participants were matched for peak oxygen consumption (VO2peak) and randomly allocated to placebo or antioxidant (vitamin C (2×500mg/day) and E (400IU/day)) groups. Following a four-week supplement loading period, participants completed acute exercise (10×4min cycling at 90% VO2peak, 2min active recovery). Vastus lateralis muscle samples were collected pre-, immediately-post- and 3h-post-exercise. Participants then completed four weeks of training (3 days/week) using the aforementioned exercise protocol while continuing supplementation. Following exercise training, participants again completed an acute exercise bout with muscle biopsies. RESULTS: Acute exercise tended to increase skeletal muscle oxidative stress as measured by oxidized glutathione (GSSG) (P=0.058) and F2-isoprostanes (P=0.056), with no significant effect of supplementation. Acute exercise significantly increased mRNA levels of peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), mitochondrial transcription factor A (TFAM) and PGC related coactivator (PRC), with no effect of supplementation. Following endurance training, supplementation did not prevent significantly increased VO2peak, skeletal muscle levels of citrate synthase activity or mRNA or protein abundance of cytochrome oxidase subunit 4 (COX IV) (P<0.05). However, following training, vitamin C and E supplementation significantly attenuated increased skeletal muscle superoxide dismutase (SOD) activity and protein abundance of SOD2 and TFAM. CONCLUSION: Following acute exercise, supplementation with vitamin C and E did not attenuate skeletal muscle oxidative stress or increased gene expression of mitochondrial biogenesis markers. However, supplementation attenuated some (SOD, TFAM) of the increased skeletal muscle adaptations following training in healthy young men.

Dogs can detect scat samples more efficiently than humans: an experiment in a continuous Atlantic Forest remnant

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Scintigraphic validation of AC Biosusceptometry to study the gastric motor activity and the intragastric distribution of food in humans

Abnormal intragastric distribution of food (IDF) and a phasic contractility in the proximal stomach have been related to dyspeptic symptoms. Thus, the behaviour of the stomach and the proximal region, in particular, continues to attract attention and demand for reliable and comfortable techniques. The aims of this study were to employ AC Biosus-ceptometry (ACB) and scintigraphy to evaluate IDF and gastric motor activity in humans. Fifteen healthy volunteers ingested 60 mL of yogurt containing 2 mCi of Tc-99m and 4 g of ferrite. Each volunteer had gastric motility and IDF evaluated twice on separate days; on one occasion by ACB and another by scintigraphy. Digital signal processing was performed in MatLab (Mathworks Inc., Natick, MA, USA). Results were expressed as mean +/- SD. Similar results of distal accumulation time (P < 0.001) were obtained for scintigraphy (6.93 +/- 3.25 min) and for ACB (7.04 +/- 3.65 min). Fast Fourier Transform revealed two dominant frequencies (P > 0.9). Besides the well-know frequency of 3 cpm, our results showed identical frequencies in proximal stomach recordings (P < 0.001) for scintigraphic (1.01 +/- 0.01 cpm) and ACB (0.98 +/- 0.06 cpm). In summary, our data showed that scintigraphy and ACB are promising techniques to evaluate several aspects of gastric motility. Moreover, ACB is non-invasive, radiation-free and deserves the same importance as conventional methods for this kind of analysis.