Air-Sea Exchange of Legacy POPs in the North Sea Based on Results of Fate and Transport, and Shelf-Sea Hydrodynamic Ocean Models

The air-sea exchange of two legacy persistent organic pollutants (POPs), γ-HCH and PCB 153, in the North Sea, is presented and discussed using results of regional fate and transport and shelf-sea hydrodynamic ocean models for the period 1996–2005. Air-sea exchange occurs through gas exchange (deposition and volatilization), wet deposition and dry deposition. Atmospheric concentrations are interpolated into the model domain from results of the EMEP MSC-East multi-compartmental model (Gusev et al, 2009). The North Sea is net depositional for γ-HCH, and is dominated by gas deposition with notable seasonal variability and a downward trend over the 10 year period. Volatilization rates of γ-HCH are generally a factor of 2–3 less than gas deposition in winter, spring and summer but greater in autumn when the North Sea is net volatilizational. A downward trend in fugacity ratios is found, since gas deposition is decreasing faster than volatilization. The North Sea is net volatilizational for PCB 153, with highest rates of volatilization to deposition found in the areas surrounding polluted British and continental river sources. Large quantities of PCB 153 entering through rivers lead to very high local rates of volatilization.

A disappearing act performed by magnesium: the nucleotide exchange mechanism of Ran GTPase by Quantum mechanics/Molecular mechanics studies

The Ran GTPase protein is a guanine nucleotide-binding protein (GNBP) with an acknowledged profile in cancer onset, progression and metastases. The complex mechanism adopted by GNBPs in exchanging GDP for GTP is an intriguing process and crucial for Ran viability. The successful completion of the process is a fundamental aspect of propagating downstream signalling events. QM/MM molecular dynamics simulations were employed in this study to provide a deeper mechanistic understanding of the initiation of nucleotide exchange in Ran. Results indicate significant disruption of the metal-binding site upon interaction with RCC1 (the Ran guanine nucleotide exchange factor), overall culminating in the prominent shift of the divalent magnesium ion. The observed ion drifting is reasoned to occur as a consequence of the complex formation between Ran and RCC1 and is postulated to be a critical factor in the exchange process adopted by Ran. This is the first report to observe and detail such intricate dynamics for a protein in Ras superfamily.

Ischemic preconditioning before lower limb ischemia-reperfusion protects against acute lung injury

Objective: Prolonged limb ischemia followed by reperfusion (I/R) is associated with a systemic inflammatory response syndrome and remote acute lung injury. Ischemic preconditioning (IPC), achieved with repeated brief periods of I/R before the prolonged ischemic period, has been shown to protect skeletal muscle against ischemic injury. The aim of this study was to ascertain whether IPC of the limb before I/R injury also attenuates systemic inflammation and acute lung injury in a fully resuscitated porcine model of hind limb I/R. Methods: This prospective, randomized, controlled, experimental animal study was performed in a university-based animal research facility with 18 male Landrace pigs that weighed from 30 to 35 kg. Anesthetized ventilated swine were randomized (n = 6 per group) to three groups: sham-operated control group, I/R group (2 hours of bilateral hind limb ischemia and 2.5 hours of reperfusion), and IPC group (three cycles of 5 minutes of ischemia/5 minutes of reperfusion immediately preceding I/R). Plasma was separated and stored at -70° C for later determination of plasma tumor necrosis factor-a and interleukin-6 with bioassay as markers of systemic inflammation. Circulating phagocytic cell priming was assessed with a whole blood chemiluminescence assay. Lung tissue wet-to-dry weight ratio and myeloperoxidase concentration were markers of edema and neutrophil sequestration, respectively. The alveolar-arterial oxygen gradient and pulmonary artery pressure were indices of lung function. Results: In a porcine model, bilateral hind limb (I/R) injury significantly increased plasma interleukin-6 concentrations, circulating phagocytic cell priming, and pulmonary leukosequestration, edema, and impaired gas exchange. Conversely, pigs treated with IPC before the onset of the ischemic period had significantly reduced interleukin-6 levels, circulating phagocytic cell priming, and experienced significantly less pulmonary edema, leukosequestration, and respiratory failure. Conclusion: Lower limb IPC protects against systemic inflammation and acute lung injury in lower limb I/R injury.

Bactericidal/permeability-increasing protein attenuates systemic inflammation and acute lung injury in porcine lower limb ischemia-reperfusion injury.

OBJECTIVE: To investigate the role of recombinant bactericidal/permeability-increasing protein (rBPI21) in the attenuation of the sepsis syndrome and acute lung injury associated with lower limb ischemia-reperfusion (I/R) injury. SUMMARY BACKGROUND DATA: Gut-derived endotoxin has been implicated in the conversion of the sterile inflammatory response to a lethal sepsis syndrome after lower torso I/R injury. rBPI21 is a novel antiendotoxin therapy with proven benefit in sepsis. METHODS: Anesthetized ventilated swine underwent midline laparotomy and bilateral external iliac artery occlusion for 2 hours followed by 2.5 hours of reperfusion. Two groups (n = 6 per group) were randomized to receive, by intravenous infusion over 30 minutes, at the start of reperfusion, either thaumatin, a control-protein preparation, at 2 mg/kg body weight, or rBPI21 at 2 mg/kg body weight. A control group (n = 6) underwent laparotomy without further treatment and was administered thaumatin at 2 mg/kg body weight after 2 hours of anesthesia. Blood from a carotid artery cannula was taken every half-hour for arterial blood gas analysis. Plasma was separated and stored at -70 degrees C for later determination of plasma tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 by bioassay, and IL-8 by enzyme-linked immunosorbent assay (ELISA), as a markers of systemic inflammation. Plasma endotoxin concentration was measured using ELISA. Lung tissue wet-to-dry weight ratio and myeloperoxidase concentration were used as markers of edema and neutrophil sequestration, respectively. Bronchoalveolar lavage protein concentration was measured by the bicinclinoic acid method as a measure of capillary-alveolar protein leak. The alveolar-arterial gradient was measured; a large gradient indicated impaired oxygen transport and hence lung injury. RESULTS: Bilateral hind limb I/R injury increased significantly intestinal mucosal acidosis, intestinal permeability, portal endotoxemia, plasma IL-6 concentrations, circulating phagocytic cell priming and pulmonary leukosequestration, edema, capillary-alveolar protein leak, and impaired gas exchange. Conversely, pigs treated with rBPI21 2 mg/kg at the onset of reperfusion had significantly reduced intestinal mucosal acidosis, portal endotoxin concentrations, and circulating phagocytic cell priming and had significantly less pulmonary edema, leukosequestration, and respiratory failure. CONCLUSIONS: Endotoxin transmigration across a hyperpermeable gut barrier, phagocytic cell priming, and cytokinemia are key events of I/R injury, sepsis, and pulmonary dysfunction. This study shows that rBPI21 ameliorates these adverse effects and may provide a novel therapeutic approach for prevention of I/R-associated sepsis syndrome.

Cyclin G associated kinase interacts with interleukin 12 receptor beta2 and suppresses interleukin 12 induced IFN-gamma production.

BACKGROUND: Although severe encephalopathy has been proposed as a possible contraindication to the use of noninvasive positive-pressure ventilation (NPPV), increasing clinical reports showed it was effective in patients with impaired consciousness and even coma secondary to acute respiratory failure, especially hypercapnic acute respiratory failure (HARF). To further evaluate the effectiveness and safety of NPPV for severe hypercapnic encephalopathy, a prospective case-control study was conducted at a university respiratory intensive care unit (RICU) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) during the past 3 years. METHODS: Forty-three of 68 consecutive AECOPD patients requiring ventilatory support for HARF were divided into 2 groups, which were carefully matched for age, sex, COPD course, tobacco use and previous hospitalization history, according to the severity of encephalopathy, 22 patients with Glasgow coma scale (GCS) <10 served as group A and 21 with GCS = 10 as group B. RESULTS: Compared with group B, group A had a higher level of baseline arterial partial CO2 pressure ((102 +/- 27) mmHg vs (74 +/- 17) mmHg, P <0.01), lower levels of GCS (7.5 +/- 1.9 vs 12.2 +/- 1.8, P <0.01), arterial pH value (7.18 +/- 0.06 vs 7.28 +/- 0.07, P <0.01) and partial O(2) pressure/fraction of inspired O(2) ratio (168 +/- 39 vs 189 +/- 33, P <0.05). The NPPV success rate and hospital mortality were 73% (16/22) and 14% (3/22) respectively in group A, which were comparable to those in group B (68% (15/21) and 14% (3/21) respectively, all P > 0.05), but group A needed an average of 7 cm H2O higher of maximal pressure support during NPPV, and 4, 4 and 7 days longer of NPPV time, RICU stay and hospital stay respectively than group B (P <0.05 or P <0.01). NPPV therapy failed in 12 patients (6 in each group) because of excessive airway secretions (7 patients), hemodynamic instability (2), worsening of dyspnea and deterioration of gas exchange (2), and gastric content aspiration (1). CONCLUSIONS: Selected patients with severe hypercapnic encephalopathy secondary to HARF can be treated as effectively and safely with NPPV as awake patients with HARF due to AECOPD; a trial of NPPV should be instituted to reduce the need of endotracheal intubation in patients with severe hypercapnic encephalopathy who are otherwise good candidates for NPPV due to AECOPD.

Plasma dynamics in an inductively coupled magnetic neutral loop discharge

Magnetic neutral loop discharges (NLDs) can be operated at significantly lower pressures than conventional radio-frequency (rf) inductively coupled plasmas (ICPs). These low pressure conditions are favourable for technological applications, in particular anisotropic etching. An ICP–NLD has been designed providing excellent diagnostics access for detailed investigations of fundamental mechanisms. Spatially resolved Langmuir probe measurements have been performed in the plasma production region (NL region) as well as in the remote application region downstream from the NL region. Depending on the NL gradient two different operation modes have been observed exhibiting different opportunities for control of plasma uniformity. The efficient operation at comparatively low pressures results in ionization degrees exceeding 1%. In this regime neutral dynamics has to be considered and can influence neutral gas and process uniformity. Neutral gas depletion through elevated gas temperatures and high ionization rates have been quantified. At pressures above 0.1 Pa, gas heating is the dominant depletion mechanism. At lower pressures neutral gas is predominantly depleted through high ionization rates and rapid transport of ions by ambipolar diffusion along the magnetic field lines. Non-uniform profiles of the ionization rate can, therefore, result in localized neutral gas depletion and non-uniform processing. We have also investigated the electron dynamics within the radio-frequency cycle using phase resolved optical emission spectroscopy and Thomson scattering. In these measurements electron drift phenomena along the NL torus have been identified.

Referral to an Extracorporeal Membrane Oxygenation Center and Mortality Among Patients With Severe 2009 Influenza A(H1N1)

Context Extracorporeal membrane oxygenation (ECMO) can support gas exchange in patients with severe acute respiratory distress syndrome (ARDS), but its role has remained controversial. ECMO was used to treat patients with ARDS during the 2009 influenza A(H1N1) pandemic.

Teaching the physiology of adaptation to hypoxic stress with the aid of a classic paper on high altitude by Houston and Riley

Many pathological conditions exist where tissues exhibit hypoxia or low oxygen tension. Hypoxic hypoxia arises when there is a reduction in the amount of oxygen entering the blood and occurs in healthy people at high altitude. In 1946, research sponsored by the United States Navy led to the collection and subsequent publication of masses of data demonstrating the physiological consequences and adaptations of ascent to high altitude. This article describes how a figure from a 1947 paper from the American Physiological Society Legacy collection (Houston CS, Riley RL. Respiratory and circulatory changes during acclimatization to high altitude. Am J Physiol 149: 565-588) may be used to allow students to review their understanding of some of the generalized effects of hypoxia on the body. In particular, this figure summarizes some of the adaptive responses that take place in the oxygen transport system as a consequence of prolonged hypoxia.

Synchronous records of pCO2 and Δ14C suggest rapid, ocean-derived pCO2 fluctuations at the onset of Younger Dryas

Just before the onset of the Younger Dryas (YD) cold event, several stomatal proxy-based pCO2 records have shown a sharp increase in atmospheric CO2 concentration (pCO2) of between ca 50 and 100 ppm, followed by a rapid decrease of similar or even larger magnitude. Here we compare one of these records, a high-resolution pCO2 record from southern Sweden, with the IntCal13 record of radiocarbon (Δ14C). The two records show broadly synchronous fluctuations at the YD onset. Specifically, the IntCal13 record documents decreasing Δ14C just before the YD onset when pCO2 peaks, consistent with a source of “old” CO2 from the deep ocean. We propose that this fluctuation occurred due to a major ocean flushing event. The cause of the flushing event remains speculative but could be related to the hypothesis of the glacial ocean as a thermobaric capacitor. We confirm that the earth system can produce such large multi-decadal timescale fluctuations in pCO2 through simulating an artificial ocean flushing event with the GENIE Earth System Model. We suggest that sharp transitions of pCO2 may have remained undetected so far in ice cores due to inter-firn gas exchange and time-averaging. The stomatal proxy record is a powerful complement to the ice core records for the study of rapid climate change.

Late-Glacial and early Holocene marine 14C reservoir ages off North Iceland (16-9 cal kyr BP)

Tephrochronological age models and 48 14C age determinations on molluscs and foraminifera (planktonic and benthic) are applied for the calculation of marine 14C reservoir age variability during a time period covering the Heinrich event H1 to early Holocene (16–9 cal kyr BP). Our data source consists of four high-resolution marine sediment cores (HM107-04, HM107-05, MD99-2271, MD99-2275) from the North Icelandic shelf. The marine reservoir age (ΔR) is found to be extremely variable, ranging from 385 to 1065 14C years. Extreme ΔR values occur at the end of H1, with values around 1000 14C years (~15 cal kyr BP), probably due to reduced northward flow of well-ventilated subtropical surface waters and a southward expansion of polar waters, as well as an expansion of sea ice limiting air-sea gas exchange. With the onset of the Bølling-Allerød interstadial, the ΔR values decrease towards 0 14C years suggesting a more vigorous North Atlantic Current and an active meridional overturning circulation system. During the Younger Dryas stadial, ΔR values are consistently around 700 14C years suggesting e renewed expansion of polar waters and a weakened meridional overtuning circulation. Interestingly, ΔR values remain high (~200 14C years) at the onset of the Holocene suggesting continued high influence of polar waters. Subsequently, ΔR values rapidly decrease to ~¬ 250 14C years around 11 cal kyr BP, indicating increased air-sea CO2 exchange with the coeval atmosphere. The ΔR values average around 0 14C years from around 10.5 to 9.0 cal kyr BP.

Non-invasive ventilation for cystic fibrosis.

Non-invasive ventilation may be a means to temporarily reverse or slow the progression of respiratory failure in cystic fibrosis. To compare the effect of non-invasive ventilation versus no non-invasive ventilation in people with cystic fibrosis. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. We searched the reference lists of each trial for additional publications possibly containing other trials.Most recent search: 22 February 2013. Randomised controlled trials comparing a form of pressure preset or volume preset non-invasive ventilation to no non-invasive ventilation in people with acute or chronic respiratory failure in cystic fibrosis. Three reviewers independently assessed trials for inclusion criteria and methodological quality, and extracted data. Fifteen trials were identified; seven trials met the inclusion criteria with a total of 106 participants. Six trials evaluated single treatment sessions and one evaluated a six-week intervention.Four trials (79 participants) evaluated non-invasive ventilation for airway clearance compared with an alternative chest physiotherapy method and showed that airway clearance may be easier with non-invasive ventilation and people with cystic fibrosis may prefer it. We were unable to find any evidence that NIV increases sputum expectoration, but it did improve some lung function parameters.Three trials (27 participants) evaluated non-invasive ventilation for overnight ventilatory support, measuring lung function, validated quality of life scores and nocturnal transcutaneous carbon dioxide. Due to the small numbers of participants and statistical issues, there were discrepancies in the results between the RevMan and the original trial analyses. No clear differences were found between non-invasive ventilation compared with oxygen or room air except for exercise performance, which significantly improved with non-invasive ventilation compared to room air over six weeks. Non-invasive ventilation may be a useful adjunct to other airway clearance techniques, particularly in people with cystic fibrosis who have difficulty expectorating sputum. Non-invasive ventilation, used in addition to oxygen, may improve gas exchange during sleep to a greater extent than oxygen therapy alone in moderate to severe disease. These benefits of non-invasive ventilation have largely been demonstrated in single treatment sessions with small numbers of participants. The impact of this therapy on pulmonary exacerbations and disease progression remain unclear. There is a need for long-term randomised controlled trials which are adequately powered to determine the clinical effects of non-invasive ventilation in cystic fibrosis airway clearance and exercise.

An investigation of possible mechanisms of the water-gas shift reaction over a ZrO2-supported Pt catalyst

The present work investigates the reactivity of the surface species observable by in situ DRIFTS formed over a Pt/ZrO2 during the water-gas shift (WGS) reaction. A DRIFTS cell/mass spectrometer system was operated at the chemical steady state during isotopic transients to yield information about the true nature (i.e., main reaction intermediate or spectators) of adsorbates. Only carbonyl and formate species were observed by DRIFTS under reaction conditions; the surface coverage of carbonate species was negligible. Isotopic transient kinetic analyses revealed that formates exchanged uniformly according to a first-order law, suggesting that most formates observed by DRIFTS were of the same reactivity. In addition, the time scale of the exchange of the reaction product CO2 was significantly shorter than that of the surface formates. Therefore, a formate route based on the formates as detected by DRIFTS can be ruled out as the main reaction pathway in the present case. The number of precursors of the reaction product CO2 was smaller than the number of surface Pt atoms, suggesting that carbonyl species or some \

Quantitative DRIFTS investigation of possible reaction mechanisms for the water-gas shift reaction on high-activity Pt- and Au-based catalysts

The present work emphasizes the importance of including a full quantitative analysis when in situ operando methods are used to investigate reaction mechanisms and reaction intermediates. The fact that some surface species exchange at a similar rate to the reaction product during isotopic transients is a necessary but not sufficient criterion for participation as a key reaction intermediate. This is exemplified here in the case of highly active low-temperature water-gas shift (WGS) catalysts based on gold and platinum. Operando DRIFTS data, isotopic exchanges, and DRIFTS calibration curves relating the concentration of formate species to the corresponding DRIFTS band intensity were combined to obtain a quantitative measure of the specific rate of formate decomposition. Despite displaying a rapid isotopic exchange rate (sometimes as fast as that of the reaction product CO2), the concentration of formates seen by DRIFTS was found to account for at most only 10% of the CO2 produced under the experimental conditions reported herein. These new results obtained on Au/CeZrO4 and Pt/CeO2 preparations (which are among the most active low-temperature WGS catalysts reported to date), led to the same conclusions regarding the minor role of IR-observable formates as those obtained in the case of less active Au/Ce(La)O-2 and Pt/ZrO2 catalysts. (c) 2007 Elsevier Inc. All rights reserved.

On the complexity of the water-gas shift reaction mechanism over a Pt/CeO2 catalyst: Effect of the temperature on the reactivity of formate surface species studied by operando DRIFT during isotopic transient at chemical steady-state

The present report investigates the role of formate species as potential reaction intermediates for the WGS reaction (CO + H2O -> CO2 + H-2) over a Pt-CeO2 catalyst. A combination of operando techniques, i.e., in situ diffuse reflectance FT-IR (DRIFT) spectroscopy and mass spectrometry (MS) during steady-state isotopic transient kinetic analysis (SSITKA), was used to relate the exchange of the reaction product CO2 to that of surface formate species. The data presented here suggest that a switchover from a non-formate to a formate-based mechanism could take place over a very narrow temperature range (as low as 60 K) over our Pt-CeO2 catalyst. This observation clearly stresses the need to avoid extrapolating conclusions to the case of results obtained under even slightly different experimental conditions. The occurrence of a low-temperature mechanism, possibly redox or Mars van Krevelen-like, that deactivates above 473 K because of ceria over-reduction is suggested as a possible explanation for the switchover, similarly to the case of the CO-NO reaction over Cu, I'd and Rh-CeZrOx (see Kaspar and co-workers [1-3]). (c) 2006 Elsevier B.V. All rights reserved.