Aminopeptidase-N modulation assists lean mass anabolism during refuelling in the white-throated sparrow.

Songbirds meet the extreme metabolic demands of migration by burning both stored fat and protein. However, catabolizing these endogenous tissues for energy leads to organ atrophy, and reductions in gastrointestinal tissue can be as great as 50% of the pre-flight mass. Remarkably, during stopover refuelling birds quickly regain digestive mass and performance. Aminopeptidase-N (APN) is a brush-border enzyme responsible for late-stage protein digestion and may critically assist tissue reconstruction during the stopover, thus compensating for reduced gut size. We hypothesized that birds recovering from a fast would differentially upregulate APN activity relative to disaccharidases to rapidly process and assimilate dietary protein into lean mass. We fasted 23 wild-caught migratory white-throated sparrows (Zonotrichia albicollis) for 48 h to mimic mass reductions experienced during migratory flight and measured intestinal APN activity before the fast, immediately after the fast, and during recovery at 24 h and 48 h post-fast. Total fat mass, lean mass and basal metabolic rate were measured daily. We show that fasted birds maintain APN activity through the fast, despite a 30% reduction in intestine mass, but during refuelling, APN activity increases nearly twofold over pre-fasted individuals. This suggests that dynamically regulating APN may be necessary for rapid protein reconstruction during the stopover.

Developing a Stopover-CORT hypothesis: Corticosterone predicts body composition and refueling rate in Gray Catbirds during migratory stopover.

Migratory flight is energetically challenging, requiring alternating phases of fuel catabolism and fuel accumulation, accompanied by dramatic changes in body composition and behavior. Baseline corticosterone (CORT; the primary glucocorticoid in birds) is thought to underlie transitions between fuel catabolism during flight, fuel deposition during stopover, and the initiation of migratory flight. However, studies of CORT on stopover physiology and behavior remain disparate efforts, lacking the cohesion of a general hypothesis. Here we develop a Stopover-CORT hypothesis formalizing the relationships among CORT, body condition, and refueling rate in migratory birds. First we expect body mass to increase with triglycerides (TRIG) as birds refuel. Second, based on a synthesis of previous literature, we predict a U-shaped CORT curve over the course of stopover, postulating that elevated CORT at arrival is reactive, responding to poor body condition, while CORT elevation before departure is preparative, driving changes in behavior and body condition. We tested these predictions in Gray Catbirds (Dumetella carolinensis) following a trans-Gulf flight during spring migration. We found baseline CORT was negatively correlated with body condition and TRIG, corresponding with our predictions for arriving and refueling-but not departing-birds. It is possible catbirds undergo regional habitat translocations rather than complete the entire stopover phase at our study site. We propose the Stopover-CORT hypothesis as a useful predictive framework for future studies of the mechanistic basis of stopover physiology. By studying the regulation of stopover refueling and departure, we may better understand physiological limitations to overall migration rate and improve assessments of habitat quality for refueling birds.

A protocol for distilling animal body water from biological samples and measuring oxygen and hydrogen stable isotopes via cavity ring-down spectroscopy.

The application of stable isotope analysis (SIA) to the fields of ecology and animal biology has rapidly expanded over the past three decades, particularly with regards to water analysis. SIA now provides the opportunity to monitor migration patterns, examine food webs, and assess habitat changes in current and past study systems. While carbon and nitrogen SIA of biological samples have become common, analyses of oxygen or hydrogen are used more sparingly despite their promising utility for tracing water sources and animal metabolism. Common ecological applications of oxygen or hydrogen SIA require injecting enriched isotope tracers. As such, methods for processing and analyzing biological samples are tailored for enriched tracer techniques, which require lower precision than other techniques given the large signal-to-noise ratio of the data. However, instrumentation advancements are creating new opportunities to expand the applications of high-throughput oxygen and hydrogen SIA. To support these applications, we update methods to distill and measure water derived from biological samples with consistent precision equal to, or better than, ± 0.1 ‰ for δ17O, ± 0.3 ‰ for δ18O, ± 1 ‰ for δ2H, ± 2 ‰ for d-excess, and ± 15 per meg for Δ17O.

Progressive Disruption of Sphingosine-1-Phosphate Receptor 1 Correlates with Blood-Brain Barrier Leakage in A Rat Model of Chronic Hypoxic Hypoperfusion.

Endothelial dysfunction and blood-brain barrier (BBB) leakage have been suggested as a fundamental role in the development of cerebral small vessel disease (SVD) pathology. However, the molecular and cellular mechanisms that link cerebral hypoxic hypoperfusion and BBB disruption remain elusive. Sphingosine-1-phosphate (S1P) regulates the BBB integrity by binding to its receptor isoform 1 (S1PR1) on endothelial cells. This study tested the hypothesis that hypoxic hypoperfusion triggers capillary endothelial S1PR1 disruption, which compromises BBB integrity and leads to SVD-related neuropathological changes, using a chronic hypoxic hypoperfusion model with BBB dysfunction. Spontaneously hypertensive rat stroke-prone underwent unilateral carotid artery occlusion (UCAO) followed by a Japanese permissive diet (JPD) for up to 9 weeks. Selective S1PR1 agonist SEW2871 was used to activate S1PR1. Significant progressive reduction of S1PR1 was detected in rat brains from 4 to 9 weeks following UCAO/JPD onset, which was also detected in cerebral vasculature in human SVD. S1PR1 activation by SEW2871 significantly reduced lesions in both white and grey matter and ameliorated cerebral blood flow. SEW2871 reversed the loss of endothelial S1PR1 and tight junction proteins, and significantly attenuated UCAO/JPD induced accumulation of neuronal phosphorylated tau. This protective role of SEW2871 is associated with promotion of Akt phosphorylation and inhibition of S1PR2/Erk1/2 activation. Our data suggest S1PR1 signalling as a potential molecular mechanistic basis that links hypoxic hypoperfusion with BBB damage in the neuropathological cascades in SVD. The reversal of BBB disruption through pharmacological intervention of S1PR1 signalling likely reveals a novel therapeutic target for SVD.

Short flap rhytidectomy and fractional CO2 laser rejuvenation of the aging face.

BACKGROUND: There is currently a high demand for a concurrent system of skin rejuvenation accompanying rhtidectomy. CO2 laser treatment prior to surgical ablative reduction has produced promising results, but the adjunct service of laser treatment at the time of surgery has never been reviewed. OBJECTIVES: Determine the effects of concurrent treatment of rhytides and evidence of aging in the skin with surgical correction followed by fractional CO2 laser application. METHODS: During study time from September 2008 to February 2009 treat patients who have underwent short flap rhytidectomy to the Lutronic eCO2™ fractional laser using the patented "Controlled Chaos Technology." RESULTS: Complications included 2.3% herpes simplex outbreak, 4% persistent erythema past 2 weeks, four cases of prolonged edema to 5 days, one case of impetigo, and no evidence of dyspigmentation. Patient satisfaction data demonstrated no refunds at 12 months. CONCLUSIONS: Combination fractional laser resurfacing with short flap, high-Superficial muscular aponeurotic system rhytidectomy is a safe procedure with excellent patient satisfaction and clinical outcomes.