Cooperation between interleukin-5 and the chemokine eotaxin to induce eosinophil accumulation in vivo.

Experiments were designed to study the effect of systemically administered IL-5 on local eosinophil accumulation induced by the intradermal injection of the chemokine eotaxin in the guinea pig. Intravenous interleukin-5 (IL-5) stimulated a rapid and dramatic increase in the numbers of accumulating eosinophils induced by i.d.-injected eotaxin and, for comparison, leukotriene B4. The numbers of locally accumulating eosinophils correlated directly with a rapid increase in circulating eosinophils: circulating eosinophil numbers were 13-fold higher 1 h after intravenous IL-5 (18.3 pmol/kg). This increase in circulating cells corresponded with a reduction in the number of displaceable eosinophils recovered after flushing out the femur bone marrow cavity. Intradermal IL-5, at the doses tested, did not induce significant eosinophil accumulation. We propose that these experiments simulate important early features of the tissue response to local allergen exposure in a sensitized individual, with eosinophil chemoattractant chemokines having an important local role in eosinophil recruitment from blood microvessels, and IL-5 facilitating this process by acting remotely as a hormone to stimulate the release into the circulation of a rapidly mobilizable pool of bone marrow eosinophils. This action of IL-5 would be complementary to the other established activities of IL-5 that operate over a longer time course

Eotaxin: a potent eosinophil chemoattractant cytokine detected in a guinea pig model of allergic airways inflammation.

Eosinophil accumulation is a prominent feature of allergic inflammatory reactions, such as those occurring in the lung of the allergic asthmatic, but the endogenous chemoattractants involved have not been identified. We have investigated this in an established model of allergic inflammation, using in vivo systems both to generate and assay relevant activity. Bronchoalveolar lavage (BAL) fluid was taken from sensitized guinea pigs at intervals after aerosol challenge with ovalbumin. BAL fluid was injected intradermally in unsensitized assay guinea pigs and the accumulation of intravenously injected 111In-eosinophils was measured. Activity was detected at 30 min after allergen challenge, peaking from 3 to 6 h and declining to low levels by 24 h. 3-h BAL fluid was purified using high performance liquid chromatography techniques in conjunction with the skin assay. Microsequencing revealed a novel protein from the C-C branch of the platelet factor 4 superfamily of chemotactic cytokines. The protein, eotaxin, exhibits homology of 53% with human MCP-1, 44% with guinea pig MCP-1, 31% with human MIP-1α, and 26% with human RANTES. Laser desorption time of flight mass analysis gave four different signals (8.15, 8.38, 8.81, and 9.03 kD), probably reflecting differential O-glycosylation. Eotaxin was highly potent, inducing substantial 111In-eosinophil accumulation at a 1-2-pmol dose in the skin, but did not induce significant 111In-neutrophil accumulation. Eotaxin was a potent stimulator of both guinea pig and human eosinophils in vitro. Human recombinant RANTES, MIP-1α, and MCP-1 were all inactive in inducing 111In-eosinophil accumulation in guinea pig skin; however, evidence was obtained that eotaxin shares a binding site with RANTES on guinea pig eosinophils. This is the first description of a potent eosinophil chemoattractant cytokine generated in vivo and suggests the possibility that similar molecules may be important in the human asthmatic lung

Determination of urban volatile organic compound emission ratios and comparison with an emissions database

During the NEAQS-ITCT2k4 campaign in New England, anthropogenic VOCs and CO were measured downwind from New York City and Boston. The emission ratios of VOCs relative to CO and acetylene were calculated using a method in which the ratio of a VOC with acetylene is plotted versus the photochemical age. The intercept at the photochemical age of zero gives the emission ratio. The so determined emission ratios were compared to other measurement sets, including data from the same location in 2002, canister samples collected inside New York City and Boston, aircraft measurements from Los Angeles in 2002, and the average urban composition of 39 U.S. cities. All the measurements generally agree within a factor of two. The measured emission ratios also agree for most compounds within a factor of two with vehicle exhaust data indicating that a major source of VOCs in urban areas is automobiles. A comparison with an anthropogenic emission database shows less agreement. Especially large discrepancies were found for the C2-C4 alkanes and most oxygenated species. As an example, the database overestimated toluene by almost a factor of three, which caused an air quality forecast model (WRF-CHEM) using this database to overpredict the toluene mixing ratio by a factor of 2.5 as well. On the other hand, the overall reactivity of the measured species and the reactivity of the same compounds in the emission database were found to agree within 30%. Copyright 2007 by the American Geophysical Union

Aviation turbulence: dynamics, forecasting, and response to climate change

Atmospheric turbulence is a major hazard in the aviation industry and can cause injuries to passengers and crew. Understanding the physical and dynamical generation mechanisms of turbulence aids with the development of new forecasting algorithms and, therefore, reduces the impact that it has on the aviation industry. The scope of this paper is to review the dynamics of aviation turbulence, its response to climate change, and current forecasting methods at the cruising altitude of aircraft. Aviation-affecting turbulence comes from three main sources: vertical wind shear instabilities, convection, and mountain waves. Understanding these features helps researchers to develop better turbulence diagnostics. Recent research suggests that turbulence will increase in frequency and strength with climate change, and therefore, turbulence forecasting may become more important in the future. The current methods of forecasting are unable to predict every turbulence event, and research is ongoing to find the best solution to this problem by combining turbulence predictors and using ensemble forecasts to increase skill. The skill of operational turbulence forecasts has increased steadily over recent decades, mirroring improvements in our understanding. However, more work is needed—ideally in collaboration with the aviation industry—to improve observations and increase forecast skill, to help maintain and enhance aviation safety standards in the future

The incidence and clinical burden of respiratory syncytial virus disease identified through hospital outpatient presentations in Kenyan children

There is little information that describe the burden of respiratory syncytial virus (RSV) associated disease in the tropical African outpatient setting. Methods We studied a systematic sample of children aged <5 years presenting to a rural district hospital in Kenya with acute respiratory infection (ARI) between May 2002 and April 2004. We collected clinical data and screened nasal wash samples for RSV antigen by immunofluorescence. We used a linked demographic surveillance system to estimate disease incidence. Results Among 2143 children tested, 166 (8%) were RSV positive (6% among children with upper respiratory tract infection and 12% among children with lower respiratory tract infection (LRTI). RSV was more likely in LRTI than URTI (p<0.001). 51% of RSV cases were aged 1 year or over. RSV cases represented 3.4% of hospital outpatient presentations. Relative to RSV negative cases, RSV positive cases were more likely to have crackles (RR = 1.63; 95% CI 1.34–1.97), nasal flaring (RR = 2.66; 95% CI 1.40–5.04), in-drawing (RR = 2.24; 95% CI 1.47–3.40), fast breathing for age (RR = 1.34; 95% CI 1.03–1.75) and fever (RR = 1.54; 95% CI 1.33–1.80). The estimated incidence of RSV-ARI and RSV-LRTI, per 100,000 child years, among those aged <5 years was 767 and 283, respectively. Conclusion The burden of childhood RSV-associated URTI and LRTI presenting to outpatients in this setting is considerable. The clinical features of cases associated with an RSV infection were more severe than cases without an RSV diagnosis

Assessing the Effects of Banana Pingers as a Bycatch Mitigation Device for Harbour Porpoises (Phocoena phocoena)

This is the final version. Available on open access from Frontiers Media via the DOI in this recordData Availability Statement: The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation, to any qualified researcher.Bycatch is a significant cause of population declines of marine megafauna globally. While numerous bycatch mitigation strategies exist, acoustic alarms, or pingers, are the most widely adopted strategy for small cetaceans. Although pingers have been shown to be an effective measure for numerous species, there are some concerns about their long-term use. Bycatch is recognized as a persistent problem in waters around Cornwall, United Kingdom, where several cetacean species are resident, with harbour porpoises (Phocoena phocoena) being the most-commonly sighted. In this study, we assessed the effects of a Banana Pinger (Fishtek Marine Limited) on harbour porpoises in Cornwall between August 2012 and March 2013. Two passive acoustic loggers (C-PODs; Chelonia Limited) were deployed 100 m apart to record cetacean activity during cycles of active and inactive pinger periods. Harbour porpoises were 37% less likely to be detected at the C-POD near the pinger when the pinger was active, while they were only 9% less likely to be detected 100 m further away. The effect of the pinger was constant over the study period at both C-PODs despite the temporal variation in harbour porpoise detections. In addition, we found no evidence of reduced pinger effect with changing environmental conditions. Furthermore, harbour porpoise detections at the C-POD near the pinger did not depend on the time elapsed since the pinger turned off, with harbour porpoises returning to the ensonified area with no delay. Together these results suggest that (1) harbour porpoises did not habituate to the pinger over an 8-month period, (2) the pinger effect is very localized, and (3) pinger use did not lead to harbour porpoise displacement over the study period, suggesting an absence of long-term behavioral effects. We suggest that the deployment of pingers on fishing nets would likely reduce net-porpoise interactions, thereby mitigating bycatch of harbour porpoises and potentially other cetacean species. As the small-scale fishery dominates in United Kingdom waters, there is an acute need for cost-effective mitigation strategies with concurrent monitoring to be implemented rapidly in order to address the problem of harbour porpoise, and more generally, cetacean bycatch.Whale and Dolphin ConservationFishtek Marine Limite

Visualized effect of oxidation on magnetic recording fidelity in pseudo-single-domain magnetite particles

Magnetite (​Fe3O4) is an important magnetic mineral to Earth scientists, as it carries the dominant magnetic signature in rocks, and the understanding of its magnetic recording fidelity provides a critical tool in the field of palaeomagnetism. However, reliable interpretation of the recording fidelity of ​Fe3O4 particles is greatly diminished over time by progressive oxidation to less magnetic iron oxides, such as maghemite (γ-Fe2O3), with consequent alteration of remanent magnetization potentially having important geological significance. Here we use the complementary techniques of environmental transmission electron microscopy and off-axis electron holography to induce and visualize the effects of oxidation on the magnetization of individual nanoscale ​Fe3O4 particles as they transform towards γ-Fe2O3. Magnetic induction maps demonstrate a change in both strength and direction of remanent magnetization within ​Fe3O4 particles in the size range dominant in rocks, confirming that oxidation can modify the original stored magnetic information

Increased shear in the North Atlantic upper-level jet stream over the past four decades

Earth’s equator-to-pole temperature gradient drives westerly mid-latitude jet streams through thermal wind balance. In the upper atmosphere, anthropogenic climate change is strengthening this meridional temperature gradient by cooling the polar lower stratosphere and warming the tropical upper troposphere acting to strengthen the upper-level jet stream. In contrast, in the lower atmosphere, Arctic amplification of global warming is weakening the meridional temperature gradient acting to weaken the upper-level jet stream. Therefore, trends in the speed of the upper-level jet stream represent a closely balanced tug-of-war between two competing effects at different altitudes. It is possible to isolate one of the competing effects by analysing the vertical shear—the change in wind speed with height—instead of the wind speed, but this approach has not previously been taken. Here we show that, although the zonal wind speed in the North Atlantic polar jet stream at 250 hectopascals has not changed since the start of the observational satellite era in 1979, the vertical shear has increased by 15 per cent (with a range of 11–17 per cent) according to three different reanalysis datasets. We further show that this trend is attributable to the thermal wind response to the enhanced upper-level meridional temperature gradient. Our results indicate that climate change may be having a larger impact on the North Atlantic jet stream than previously thought. The increased vertical shear is consistent with the intensification of shear-driven clear-air turbulence expected from climate change which will affect aviation in the busy transatlantic flight corridor by creating a more turbulent flying environment for aircraft. We conclude that the effects of climate change and variability on the upper-level jet stream are being partly obscured by the traditional focus on wind speed rather than wind shear

Change and Aging Senescence as an adaptation

Understanding why we age is a long-lived open problem in evolutionary biology. Aging is prejudicial to the individual and evolutionary forces should prevent it, but many species show signs of senescence as individuals age. Here, I will propose a model for aging based on assumptions that are compatible with evolutionary theory: i) competition is between individuals; ii) there is some degree of locality, so quite often competition will between parents and their progeny; iii) optimal conditions are not stationary, mutation helps each species to keep competitive. When conditions change, a senescent species can drive immortal competitors to extinction. This counter-intuitive result arises from the pruning caused by the death of elder individuals. When there is change and mutation, each generation is slightly better adapted to the new conditions, but some older individuals survive by random chance. Senescence can eliminate those from the genetic pool. Even though individual selection forces always win over group selection ones, it is not exactly the individual that is selected, but its lineage. While senescence damages the individuals and has an evolutionary cost, it has a benefit of its own. It allows each lineage to adapt faster to changing conditions. We age because the world changes.Comment: 19 pages, 4 figure