Plasma response to fish oil in the elderly

Little information is available concerning whether incorporation of dietary omega-3 fatty acids into plasma lipids changes during healthy aging. Elderly (74 ± 4 years old) and young (24 ± 2 years old) adults were given a fish oil supplement for 3 weeks that provided 680 mg/day of docosahexaenoic acid and 320 mg/day of eicosapentaenoic acid, followed by a 2 week wash-out period. Compliance was monitored by spiking the capsules with carbon-13 glucose, the excretion of which was measured in breath CO2. In response to the supplement, plasma docosahexaenoic acid rose 42% more in the elderly but eicosapentaenoic responded similarly in both groups. Despite raising docosahexaenoic acid intake by five to tenfold, the supplement did not raise plasma free docosahexaenoic acid (% or mg/dL) in either group. We conclude that healthy aging is accompanied by subtle but significant changes in DHA incorporation into plasma lipids

Circadian Integration of Glutamatergic Signals by Little SAAS in Novel Suprachiasmatic Circuits

Neuropeptides are critical integrative elements within the central circadian clock in the suprachiasmatic nucleus (SCN), where they mediate both cell-to-cell synchronization and phase adjustments that cause light entrainment. Forward peptidomics identified little SAAS, derived from the proSAAS prohormone, among novel SCN peptides, but its role in the SCN is poorly understood.Little SAAS localization and co-expression with established SCN neuropeptides were evaluated by immunohistochemistry using highly specific antisera and stereological analysis. Functional context was assessed relative to c-FOS induction in light-stimulated animals and on neuronal circadian rhythms in glutamate-stimulated brain slices. We found that little SAAS-expressing neurons comprise the third most abundant neuropeptidergic class (16.4%) with unusual functional circuit contexts. Little SAAS is localized within the densely retinorecipient central SCN of both rat and mouse, but not the retinohypothalamic tract (RHT). Some little SAAS colocalizes with vasoactive intestinal polypeptide (VIP) or gastrin-releasing peptide (GRP), known mediators of light signals, but not arginine vasopressin (AVP). Nearly 50% of little SAAS neurons express c-FOS in response to light exposure in early night. Blockade of signals that relay light information, via NMDA receptors or VIP- and GRP-cognate receptors, has no effect on phase delays of circadian rhythms induced by little SAAS.Little SAAS relays signals downstream of light/glutamatergic signaling from eye to SCN, and independent of VIP and GRP action. These findings suggest that little SAAS forms a third SCN neuropeptidergic system, processing light information and activating phase-shifts within novel circuits of the central circadian clock

Dictator Games: A Meta Study

Over the last 25 years, more than a hundred dictator game experiments have been published. This meta study summarizes the evidence. Exploiting the fact that most experiments had to fix parameters they did not intend to test, the meta study explores a rich set of control variables for multivariate analysis. It shows that Tobit models (assuming that dictators would even want to take money) and hurdle models (assuming that the decision to give a positive amount is separate from the choice of amount, conditional on giving) outperform mere meta-regression and OLS

Hematopoietic progenitor cells regulate their niche microenvironment through a novel mechanism of cell-cell communication

Cellular communication within a larger microenvironment is critical for a number of physiological processes. Within the bone marrow niche, direct cell communication between hematopoietic progenitor cells (HPCs) and osteoblasts provides essential cues for their proliferation and survival. While contact-dependent communication between HPCs and osteoblasts is known to be critical, the molecular pathways that govern this interaction are largely unclear. Moreover, the downstream events occurring at the HPC/osteoblast contact site remain uncharacterized, despite their major role in signaling and remodeling within the niche microenvironment. Using live cell imaging approaches, we found that intercellular transfer is a novel mode of cell communication within the bone marrow niche microenvironment. HPCs made prolonged contact with the osteoblast surface via a specialized membrane domain enriched in prominin 1, CD63 and rhodamine PE. At the contact site, portions of the HPC specialized domain containing these molecules were taken up by the osteoblast and internalized into long-lived, SARA-positive, signaling endosomes. This resulted in the down-regulation of Smad signaling by the osteoblasts and a subsequent increase in the production of stromal-derived factor-1 (SDF-1), a chemokine responsible for HPC homing to bone marrow. These findings identify a novel mechanism involving intercellular transfer to signaling endosomes for targeted regulation of signaling and remodeling events within the osteoblastic niche microenvironment