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Strong ion difference in urine: new perspectives in acid-base assessment
Luciano Gattinoni, Eleonora Carlesso, Paolo Cadringher, Pietro Caironi
Critical Care , 2006, DOI: 10.1186/cc4890
Abstract: Traditionally, the assessment of metabolic acidosis and alkalosis relies on measurement of the base excess, which is the difference between the 'ideal' buffer base [1] (i.e. the sum of the negatively charged forms of weak acids, [A-] + [HCO3-] + [H2PO4-], at standard conditions (pH 7.4, temperature 37°C, partial carbon dioxide tension 40 mmHg) and the 'actual' buffer base [2]):Base excess = buffer baseactual - buffer baseideal (1)During the past few years a novel approach based on assessment of the strong ion difference (SID) has been introduced to evaluate metabolic acidosis and alkalosis. For simplicity, we limit our discussion to these two disturbances.Please note that in the following discussion we will refer to the amount of strong ion difference as SID (mEq), while we will refer to the strong ion difference concentration as [SID] (mEq/l).By definition, strong ions are always dissociated in a solution. In plasma, as well as in interstitial fluids, the sum of positively charged ions (primarily Na+, K+, Ca2+ and Mg2+) exceeds the sum of the negatively charged strong ions (primarily Cl- and lactate-) of about 42 mEq/l. This difference is called the SID, and according to the Stewart model [3] its variation is one of the determinants of acid–base status. Looking at Figure 1, the connection between base excess and SID is apparent. The buffer base and SID are equivalent. In fact, because the ideal SID is equal to 42 mEq/l (as is the normal buffer base), it follows thatBase excess = SIDactual - SIDideal = buffer baseactual - buffer baseideal (2)Because computation of the actual SID is rather complicated, requiring the determination of all of the strong ion concentrations, we believe that the base excess approach may be easier, more rapid and adequate for clinical purposes. Indeed, the frequent debate involving the comparison of the 'SID approach' with the 'base excess approach' to assessment of metabolic acidosis [4,5] appears futile because their physiological meaning
Acetazolamide-mediated decrease in strong ion difference accounts for the correction of metabolic alkalosis in critically ill patients
Miriam Moviat, Peter Pickkers, Peter HJ van der Voort, Johannes G van der Hoeven
Critical Care , 2005, DOI: 10.1186/cc3970
Abstract: Fifteen consecutive intensive care unit patients with metabolic alkalosis (pH ≥ 7.48 and HCO3- ≥ 28 mmol/l) were treated with a single administration of 500 mg acetazolamide intravenously. Serum levels of strong ions, creatinine, lactate, weak acids, pH and partial carbon dioxide tension were measured at 0, 12, 24, 48 and 72 hours. The main strong ions in urine and pH were measured at 0, 3, 6, 12, 24, 48 and 72 hours. Strong ion difference (SID), strong ion gap, sodium–chloride effect, and the urinary SID were calculated. Data (mean ± standard error were analyzed by comparing baseline variables and time dependent changes by one way analysis of variance for repeated measures.After a single administration of acetazolamide, correction of serum pH (from 7.49 ± 0.01 to 7.46 ± 0.01; P = 0.001) was maximal at 24 hours and sustained during the period of observation. The parallel decrease in partial carbon dioxide tension was not significant (from 5.7 ± 0.2 to 5.3 ± 0.2 kPa; P = 0.08) and there was no significant change in total concentration of weak acids. Serum SID decreased significantly (from 41.5 ± 1.3 to 38.0 ± 1.0 mEq/l; P = 0.03) due to an increase in serum chloride (from 105 ± 1.2 to 110 ± 1.2 mmol/l; P < 0.0001). The decrease in serum SID was explained by a significant increase in the urinary excretion of sodium without chloride during the first 24 hours (increase in urinary SID: from 48.4 ± 15.1 to 85.3 ± 7.7; P = 0.02).A single dose of acetazolamide effectively corrects metabolic alkalosis in critically ill patients by decreasing the serum SID. This effect is completely explained by the increased renal excretion ratio of sodium to chloride, resulting in an increase in serum chloride.Metabolic alkalosis is a common acid–base disturbance in the intensive care unit (ICU) that is associated with increased ICU mortality and morbidity [1,2], with adverse effects on cardiovascular, pulmonary and metabolic function [3,4]. Additionally, such patients are characterized by
Sid knocks them out
John C Rockett
Genome Biology , 2002, DOI: 10.1186/gb-2002-3-7-reports0034
Abstract: In a genetic screen, three major complementation groups with systemic RNAi-defective (SID) phenotypes were identified. One of these was further characterized by a variety of methods. The cDNA sequence of the responsible gene (sid-1) was isolated, where and when the gene is expressed was determined, and the overall protein structure predicted from its sequence. The sid-1 gene is initially expressed in late-stage embryos and continually thereafter in nearly all non-neural cell types, with the highest levels expressed in cells and tissues exposed to the environment. At the subcellular level, significant enrichment of sid-1 was seen at the cell periphery, a location consistent with the presence of predicted transmembrane regions in the protein.The authors constructed a transgenic strain (HC57) of C. elegans that allows simultaneous monitoring of localized RNAi (myo-2::GFP, in the pharyngeal muscles) and systemic RNAi (myo-3::GFP, in the body wall muscles) through the expression of green fluorescent protein (GFP). RNAi was initiated through a third transgene (myo-2::GFP dsRNA) under control of the pharynx-specific myo-2 promoter. Mutants resistant to systemic RNAi were identified by screening for those that were resistant to systemic RNAi of myo-3, but sensitive to the local RNAi of myo-2.Supplementary data to Science295:2456-2459 include figures and details of experimental procedures and are available at free of charge. The homepage of Craig Hunter's laboratory contains a link to a full copy of the paper.The authors suggest that, on the basis of the proposed protein structure, SID-1 may act as a channel through which dsRNA can pass between cells. In addition, SID-1 has strong similarity to predicted human and mouse proteins, suggesting the possibility that RNAi may be systemic in mammals, and that the mechanism may share some components found in C. elegans.In this classic piece of genetic work, Winston et al. demonstrated considerable skill and persistence in teasing ou
The SiD Detector Concept  [PDF]
Andrew P. White
Physics , 2010,
Abstract: The SiD detector concept is one of two currently accepted approaches to providing a detector for the future International Linear Collider. The SiD design philosophy is described and an overview of the concept given. Each major component of SiD is described, with emphasis on the critical R&D issues in each area. The context of the paper is evolution of the SiD design and the associated R&D towards the Detailed Baseline Design in late 2012.
PFA Performance for SiD  [PDF]
M. J. Charles
Physics , 2009,
Abstract: A PFA has been developed for the SiD detector concept at a future Linear Collider. The performance of the version of this PFA used in the SiD LOI is presented for a number of physics processes with two hadronic jets. Presented at LCWS08.
The limit of strong ion coupling due to electron shielding  [PDF]
M. Lyon,S. D. Bergeson,M. S. Murillo
Physics , 2012, DOI: 10.1103/PhysRevE.87.033101
Abstract: We show that strong coupling between ions in an ultracold neutral plasma is limited by electron screening. While electron screening reduces the quasi-equilibrium ion temperature, it also reduces the ion-ion electrical potential energy. The net result is that the ratio of nearest-neighbor potential energy to kinetic energy in quasi-equilibrium is constant and limited to approximately 2 unless the electrons are heated by some external source. We support these conclusions by reporting new measurements of the ion velocity distribution in an ultracold neutral calcium plasma. These results match previously reported simulations of Yukawa systems. Theoretical considerations are used to determine the screened nearest-neighbor potential energy in the plasma.
Colloids electrophoresis for strong and weak ion diffusivity  [PDF]
Giovanni Giupponi,Ignacio Pagonabarraga
Physics , 2011, DOI: 10.1103/PhysRevLett.106.248304
Abstract: We study the electrophoretic flow of suspensions of charged colloids with a mesoscopic method that allows to model generic experimental conditions. We show that for highly charged colloids their electrophoretic mobility increases significantly and displays a mobility maximum on increasing the colloidal charge for all salt concentrations. The electrophoretic mobility of highly charged colloids is also enhanced significantly when ion advection is dominant, leading to a strong heterogeneity in the local electrophoretic response especially at low salt concentration, when ion diffuse layers overlap.
SiD Letter of Intent  [PDF]
H. Aihara,P. Burrows,M. Oreglia
Physics , 2009,
Abstract: Letter of intent describing SiD (Silicon Detector) for consideration by the International Linear Collider IDAG panel. This detector concept is founded on the use of silicon detectors for vertexing, tracking, and electromagnetic calorimetry. The detector has been cost-optimized as a general-purpose detector for a 500 GeV electron-positron linear collider.
Toward Thermalization in Heavy Ion Collisions at Strong Coupling  [PDF]
Yuri V. Kovchegov,Shu Lin
Physics , 2009, DOI: 10.1007/JHEP03(2010)057
Abstract: We find the trapped surface for a collision of two sourceless shock waves in AdS$_5$ and conclude that such collisions always lead to a creation of a black hole in the bulk. Due to holographic correspondence, in the boundary gauge theory this result proves that a thermalized medium (quark-gluon plasma) is produced in heavy ion collisions at strong coupling (albeit in ${\cal N} =4$ super-Yang-Mills theory). We present new evidence supporting the analytic estimate for the time of thermalization that exists in the literature and find that thermalization time is parametrically much shorter than the time of shock wave stopping, indicating that our result may be relevant for description of heavy ion collision experiments.
The SiD Detector for the International Linear Collider  [PDF]
Andrew P. White
Physics , 2015,
Abstract: The SiD Detector is one of two validated detector designs for the future International Linear Collider. SiD features a compact, cost-constrained design for precision Higgs couplings determination, and other measurements, and sensitivity to a wide range of possible new phenomena. A robust silicon vertex and tracking system, combined with a 5 Tesla central solenoidal field, provides excellent momentum resolution. The highly granular calorimeter system is optimized for Particle Flow application to achieve very good jet energy resolution over a wide range of energies. Details of the proposed implementation of the SiD subsystems, as driven by the physics requirements, will be given. The shared interaction point, push-pull mechanism, will be described, together with the estimated timeline for construction.
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