Management of hyperkalemia in the acutely ill patient.

PURPOSE:To review the mechanisms of action, expected efficacy and side effects of strategies to control hyperkalemia in acutely ill patients. METHODS:We searched MEDLINE and EMBASE for relevant papers published in English between Jan 1, 1938, and July 1, 2018, in accordance with the PRISMA Statement using the following terms: "hyperkalemia," "intensive care," "acute kidney injury," "acute kidney failure," "hyperkalemia treatment," "renal replacement therapy," "dialysis," "sodium bicarbonate," "emergency," "acute." Reports from within the past 10 years were selected preferentially, together with highly relevant older publications. RESULTS:Hyperkalemia is a potentially life-threatening electrolyte abnormality and may cause cardiac electrophysiological disturbances in the acutely ill patient. Frequently used therapies for hyperkalemia may, however, also be associated with morbidity. Therapeutics may include the simultaneous administration of insulin and glucose (associated with frequent dysglycemic complications), β-2 agonists (associated with potential cardiac ischemia and arrhythmias), hypertonic sodium bicarbonate infusion in the acidotic patient (representing a large hypertonic sodium load) and renal replacement therapy (effective but invasive). Potassium-lowering drugs can cause rapid decrease in serum potassium level leading to cardiac hyperexcitability and rhythm disorders. CONCLUSIONS:Treatment of hyperkalemia should not only focus on the ability of specific therapies to lower serum potassium level but also on their potential side effects. Tailoring treatment to the patient condition and situation may limit the risks

Acute effects of aerobic exercise on feelings of energy in relation to age and gender

A crossover experiment was performed to determine whether age and sex, or their interaction, affect the impact of acute aerobic exercise on Vigor-Activity (VA). We also tested whether changes in VA mediated exercise effects on performance on various cognitive tasks. Sixty eight physically inactive volunteers participated in exercise and TV-watching control conditions. They completed the Vigor-Activity subscale of the Profile of Mood States immediately prior to and 2 minutes after the intervention in each condition. They also performed the Trail Making Test 3 minutes after the intervention in each condition. Statistical analyses produced a condition × age × sex interaction characterized by a higher mean VA 10 gain value in the exercise condition (compared to the VA gain value in the TV-watching condition) for young female participants only. In addition, the mediational analyses revealed that changes in VA fully mediated the effects of exercise on TMT-Part A performance

The Carrington event not observed in most ice core nitrate records

The Carrington Event of 1859 is considered to be among the largest space weather events of the last 150 years. We show that only one out of 14 well-resolved ice core records from Greenland and Antarctica has a nitrate spike dated to 1859. No sharp spikes are observed in the Antarctic cores studied here. In Greenland numerous spikes are observed in the 40 years surrounding 1859, but where other chemistry was measured, all large spikes have the unequivocal signal, including co-located spikes in ammonium, formate, black carbon and vanillic acid, of biomass burning plumes. It seems certain that most spikes in an earlier core, including that claimed for 1859, are also due to biomass burning plumes, and not to solar energetic particle (SEP) events. We conclude that an event as large as the Carrington Event did not leave an observable, widespread imprint in nitrate in polar ice. Nitrate spikes cannot be used to derive the statistics of SEPs

Factors controlling nitrate in ice cores: Evidence from the Dome C deep ice core

In order to estimate past changes in atmospheric NOx concentration, nitrate, an oxidation product of NOx, has often been measured in polar ice cores. In the frame of the European Project for Ice Coring in Antarctica (EPICA), a high-resolution nitrate record was obtained by continuous flow analysis (CFA) of a new deep ice core drilled at Dome C. This record allows a detailed comparison of nitrate with other chemical trace substances in polar snow under different climatic regimes. Previous studies showed that it would be difficult to make firm conclusions about atmospheric NOx concentrations based on ice core nitrate without a better understanding of the factors controlling NO3− deposition and preservation. At Dome C, initially high nitrate concentrations (over 500 ppb) decrease within the top meter to steady low values around 15 ppb that are maintained throughout the Holocene ice. Much higher concentrations (averaging 53 ppb) are found in ice from the Last Glacial Maximum (LGM). Combining this information with data from previous sampling elsewhere in Antarctica, it seems that under climatic conditions of the Holocene, temperature and accumulation rate are the key factors determining the NO3− concentration in the ice. Furthermore, ice layers with high acidity show a depletion of NO3−, but higher concentrations are found before and after the acidity layer, indicating that NO3− has been redistributed after deposition. Under glacial conditions, where NO3− shows a higher concentration level and also a larger variability, non-sea-salt calcium seems to act as a stabilizer, preventing volatilization of NO3− from the surface snow layers

Comment on “Low time resolution analysis of ice cores cannot detect impulsive nitrate events” by D. F. Smart et al.

Smart et al. (2014) suggested that the detection of nitrate spikes in polar ice cores from solar energetic particle (SEP) events could be achieved if an analytical system with sufficiently high resolution was used. Here we show that the spikes they associate with SEP events are not reliably recorded in cores from the same location, even when the resolution is clearly adequate. We explain the processes that limit the effective resolution of ice cores. Liquid conductivity data suggest that the observed spikes are associated with sodium or another nonacidic cation, making it likely that they result from deposition of sea salt or similar aerosol that has scavenged nitrate, rather than from a primary input of nitrate in the troposphere. We consider that there is no evidence at present to support the identification of any spikes in nitrate as representing SEP events. Although such events undoubtedly create nitrate in the atmosphere, we see no plausible route to using nitrate spikes to document the statistics of such events

On the land shells of Tasmania

When Woodward classed the terrestrial mollusks of Tasmania, with those of Australia, south of the tropic, but little was known of them. At the time he wrote the number of described species of Helix was six, two of which have since proved to be identical, and two others doubtfully Tasmanian, thus reducing the number to three

Lyman alpha line formation in starbursting galaxies II. Extremely Thick, Dustless, and Static HI Media

The Lya line transfer in an extremely thick medium of neutral hydrogen is investigated by adopting an accelerating scheme in our Monte Carlo code to skip a large number of core or resonant scatterings. This scheme reduces computing time significantly with no sacrifice in the accuracy of the results. We applied this numerical method to the Lya transfer in a static, uniform, dustless, and plane-parallel medium. Two types of photon sources have been considered, the midplane source and the uniformly distributed sources. The emergent profiles show double peaks and absorption trough at the line-center. We compared our results with the analytic solutions derived by previous researchers, and confirmed that both solutions are in good agreement with each other. We investigated the directionality of the emergent Lya photons and found that limb brightening is observed in slightly thick media while limb darkening appears in extremely thick media. The behavior of the directionality is noted to follow that of the Thomson scattered radiation in electron clouds, because both Lya wing scattering and Thomson scattering share the same Rayleigh scattering phase function. The mean number of wing scatterings just before escape is in exact agreement with the prediction of the diffusion approximation. The Lya photons constituting the inner part of the emergent profiles follow the relationship derived from the diffusion approximation. We present a brief discussion on the application of our results to the formation of Lya broad absorption troughs and P-Cygni type Lya profiles seen in the UV spectra of starburst galaxies.Comment: 24 papges, 12 figures, The revised version submitted to Ap

An imaging and spectroscopic study of the very metal-deficient blue compact dwarf galaxy Tol 1214--277

We present a spectrophotometric study based on VLT/FORS I observations of one of the most metal-deficient blue compact dwarf (BCD) galaxies known, Tol 1214-277 (Z ~ Zsun/25). The data show that roughly half of the total luminosity of the BCD originates from a bright and compact starburst region located at the northeastern tip of a faint dwarf galaxy with cometary appearance. The starburst has ignited less than 4 Myr ago and its emission is powered by several thousands O7V stars and ~ 170 late-type nitrogen Wolf-Rayet stars located within a compact region with < 500 pc in diameter. For the first time in a BCD, a relatively strong [Fe V] 4227 emission line is seen which together with intense He II 4686 emission indicates the presence of a very hard radiation field in Tol 1214-277. We argue that this extraordinarily hard radiation originates from both Wolf--Rayet stars and radiative shocks in the starburst region. The structural properties of the low-surface-brightness (LSB) component underlying the starburst have been investigated by means of surface photometry down to 28 B mag/sq.arcsec. We find that, for a surface brightness level fainter than ~ 24.5 B mag/sq.arcsec, an exponential fitting law provides an adequate approximation to its radial intensity distribution. The broad-band colors in the outskirts of the LSB component of Tol 1214-277 are nearly constant and are consistent with an age below one Gyr. This conclusion is supported by the comparison of the observed spectral energy distribution (SED) of the LSB host with theoretical SEDs.Comment: 17 pages, 11 Postscript figures, uses emulateapj.sty, to appear in Astronomical Journa

Hydrogenation of CO on a silica surface: an embedded cluster approach

The sequential addition of H atoms to CO adsorbed on a siliceous edingtonite surface is studied with an embedded cluster approach, using density functional theory for the quantum mechanical (QM) cluster and a molecular force field for the molecular mechanical (MM) cluster. With this setup, calculated QM/MM adsorption energies are in agreement with previous calculations employing periodic boundary conditions. The catalytic effect of the siliceous edingtonite (100) surface on CO hydrogenation is assessed because of its relevance to astrochemistry. While adsorption of CO on a silanol group on the hydroxylated surface did not reduce the activation energy for the reaction with a H atom, a negatively charged defect on the surface is found to reduce the gas phase barriers for the hydrogenation of both CO and H2C = O. The embedded cluster approach is shown to be a useful and flexible tool for studying reactions on (semi-)ionic surfaces and specific defects thereon. The methodology presented here could easily be applied to study reactions on silica surfaces that are of relevance to other scientific areas, such as biotoxicity of silica dust and geochemistry