Continuous monitoring reveals multiple controls on ecosystem metabolism in a suburban stream

1. Primary production and respiration in streams, collectively referred to as stream ecosystem metabolism, are fundamental processes that determine trophic structure, biomass and nutrient cycling. Few studies have used high‐frequency measurements of gross primary production (GPP) and ecosystem respiration (ER) over extended periods to characterise the factors that control stream ecosystem metabolism at hourly, daily, seasonal and annual scales. 2. We measured ecosystem metabolism at 5‐min intervals for 23 months in Shepherd Creek, a small suburban stream in Cincinnati, Ohio (U.S.A.). 3. Daily GPP was best predicted by a model containing light and its synergistic interaction with water temperature. Water temperature alone was not significantly related to daily GPP, rather high temperatures enhanced the capacity of autotrophs to use available light. 4. The relationship between GPP and light was further explored using photosynthesis–irradiance curves (P–I curves). Light saturation of GPP was evident throughout the winter and spring and the P–I curve frequently exhibited strong counterclockwise hysteresis. Hysteresis occurred when water temperatures were greater in the afternoon than in the morning, although light was similar, further suggesting that light availability interacts synergistically with water temperature. 5. Storm flows strongly depressed GPP in the spring while desiccation arrested aquatic GPP and ER in late summer and autumn. 6. Ecosystem respiration was best predicted by GPP, water temperature and the rate of water exchange between the surface channel and transient storage zones. We estimate that c. 70% of newly fixed carbon was immediately respired by autotrophs and closely associated heterotrophs. 7. Interannual, seasonal, daily and hourly variability in ecosystem metabolism was attributable to a combination of light availability, water temperature, storm flow dynamics and desiccation. Human activities affect all these factors in urban and suburban streams, suggesting stream ecosystem processes are likely to respond in complex ways to changing land use and climate

A randomized, placebo-controlled trial of late Na current inhibition (ranolazine) in coronary microvascular dysfunction (CMD): impact on angina and myocardial perfusion reserve.

AimsThe mechanistic basis of the symptoms and signs of myocardial ischaemia in patients without obstructive coronary artery disease (CAD) and evidence of coronary microvascular dysfunction (CMD) is unclear. The aim of this study was to mechanistically test short-term late sodium current inhibition (ranolazine) in such subjects on angina, myocardial perfusion reserve index, and diastolic filling.Materials and resultsRandomized, double-blind, placebo-controlled, crossover, mechanistic trial in subjects with evidence of CMD [invasive coronary reactivity testing or non-invasive cardiac magnetic resonance imaging myocardial perfusion reserve index (MPRI)]. Short-term oral ranolazine 500-1000 mg twice daily for 2 weeks vs. placebo. Angina measured by Seattle Angina Questionnaire (SAQ) and SAQ-7 (co-primaries), diary angina (secondary), stress MPRI, diastolic filling, quality of life (QoL). Of 128 (96% women) subjects, no treatment differences in the outcomes were observed. Peak heart rate was lower during pharmacological stress during ranolazine (-3.55 b.p.m., P < 0.001). The change in SAQ-7 directly correlated with the change in MPRI (correlation 0.25, P = 0.005). The change in MPRI predicted the change in SAQ QoL, adjusted for body mass index (BMI), prior myocardial infarction, and site (P = 0.0032). Low coronary flow reserve (CFR <2.5) subjects improved MPRI (P < 0.0137), SAQ angina frequency (P = 0.027), and SAQ-7 (P = 0.041).ConclusionsIn this mechanistic trial among symptomatic subjects, no obstructive CAD, short-term late sodium current inhibition was not generally effective for SAQ angina. Angina and myocardial perfusion reserve changes were related, supporting the notion that strategies to improve ischaemia should be tested in these subjects.Trial registrationclinicaltrials.gov Identifier: NCT01342029

Aryl Hydrocarbon Hydroxylase, Epoxide Hydrolase, and Benzo[a]pyrene Metabolism in Human Epidermis: Comparative Studies in Normal Subjects and Patients with Psoriasis

Prior studies have shown that human skin possesses a cytochrome P-450-dependent microsomal enzyme that is capable of metabolizing drugs and polycyclic aromatic hydrocarbon (PAH) carcinogens. This study characterized benzo[a]pyrene (BP) metabolism in human epidermis of normal and psoriatic individuals. The basal level of the cytochrome P-450-dependent microsomal enzyme aryl hydrocarbon hydroxylase (AHH) and epoxide hydrolase (EH) were measured in freshly keratomed epidermis from 12 normal individuals and from uninvolved skin sites of 12 patients with psoriasis. The induction response of AHH following the in vitro addition of the PAH benz[A]anthracene (BA) was also assessed. The basal activity (mean ± SE) of AHH in normal epidermis was 62.1 ± 5.6 units (fmol 3-hydroxybenzo[a]pyrene, 3-OH-BP/min/mg protein) whereas the activity in uninvolved skin of psoriatic individuals was 62.9 ± 5.1 units (NS), Epoxide hydrolase activity was 25.1 ± 1.1 (pmol BP 4,5-diol/min/mg protein) units in normal epidermis and 24.8 ± 2.1 units in epidermis from patients with psoriasis (NS). Following addition of BA (100μM), in vitro, AHH activity in normal epidermis increased by a mean value of 165% whereas activity in nonlesional epidermis of psoriatic individuals increased 320%. Kinetic studies in normal epidermis revealed that the AHH reaction was linear up to 60 min and to 50 μg protein, had a pH optimum of 7.4, and the Km for BP was 0.62 MM. High-performance liquid chromatography (HPLC) confirmed that the pattern of metabolism of BP was quite similar in epidermal microsomes prepared from normal and psoriatic individuals, insofar as the formation of diols, phenols, and quinones was concerned. These studies indicate that human epidermis is capable of metabolizing BP and that there is no significant difference between normal individuals and patients with psoriasis insofar as basal AHH activity or total BP metabolism is concerned. Furthermore, the epidermal enzyme system in patients with psoriasis has a greater responsiveness to environmental PAH than does that of normal individuals

Trauma Simulation Training Increases Confidence Levels in Prehospital Personnel Performing Life-Saving Interventions in Trauma Patients

Introduction. Limited evidence is available on simulation training of prehospital care providers, specifically the use of tourniquets and needle decompression. This study focused on whether the confidence level of prehospital personnel performing these skills improved through simulation training. Methods. Prehospital personnel from Alachua County Fire Rescue were enrolled in the study over a 2-to 3-week period based on their availability. Two scenarios were presented to them: a motorcycle crash resulting in a leg amputation requiring a tourniquet and an intoxicated patient with a stab wound, who experienced tension pneumothorax requiring needle decompression. Crews were asked to rate their confidence levels before and after exposure to the scenarios. Timing of the simulation interventions was compared with actual scene times to determine applicability of simulation in measuring the efficiency of prehospital personnel. Results. Results were collected from 129 participants. Pre-and postexposure scores increased by a mean of 1.15 (SD 1.32; 95% CI, 0.88-1.42; < 0.001). Comparison of actual scene times with simulated scene times yielded a 1.39-fold difference (95% CI, 1.25-1.55) for Scenario 1 and 1.59 times longer for Scenario 2 (95% CI, 1.43-1.77). Conclusion. Simulation training improved prehospital care providers' confidence level in performing two life-saving procedures

Postcopulatory sexual selection

The female reproductive tract is where competition between the sperm of different males takes place, aided and abetted by the female herself. Intense postcopulatory sexual selection fosters inter-sexual conflict and drives rapid evolutionary change to generate a startling diversity of morphological, behavioural and physiological adaptations. We identify three main issues that should be resolved to advance our understanding of postcopulatory sexual selection. We need to determine the genetic basis of different male fertility traits and female traits that mediate sperm selection; identify the genes or genomic regions that control these traits; and establish the coevolutionary trajectory of sexes