Continuous-flow enzymatic determination of creatinine with improved on-line removal of endogenous ammonia

A new continuous-flow automated enzymatic method suitable for the direct determination of creatinine in physiological samples is described. The proposed system utilizes an on-line gas predialysis unit in conjuction with a flow-through enzyme reactor coil and a potentiometric ammonia detector. The enzyme reactor contains immobilized creatinine iminohydrolase (EC 3.5.4.21) which converts creatinine to ammonia and N-methylhydantoin. Ammonia liberated from this reaction is detected downstream with the membrane electrode-based detector. The novel gas predialysis unit effectively removes>99.8% of endogenous ammonia (up to 1 mM) present in the sample. Thus, final peak potentials recorded by the electrode detector are directly proportional to the logarithm of creatinine concentrations present. The method is shown to be precise (<3%), selective, and capable of accurately determining creatinine in serum and urine samples containing abnormally high endogenous ammonia levels. Determinations of creatinine in serum samples (n = 30) using this new method correlate well with an existing Technicon AutoAnalyzer colorimetric method (r = 0.996).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26866/1/0000431.pd

Sulfite-sensitive solvent/polymeric-membrane electrode based on bis(diethyldithiocarbamato)mercury(II)

A new solvent/polymeric-membrane electrode which exhibits significant potentiometric response toward sulfite ion in the 1 x 10-6-1 x 10-3 M range is described. The membrane is prepared by incorporation of neutral bis(diethyldithiocarbamato)mercury (II) in a thin film of plasticized poly (vinyl chloride). In sharp contrast to classical Hofmeister behavior, the resulting membrane displays little or no response to a wide range of anions (log Kpoti,j [les] -4, i being sulfite) including sulfate, nitrate, nitrite, chloride, perchlorate, salicylate, and alkylsulfonates. Bromide and thiocyanate are moderate interferents, while significant response to iodide, thiosulfate, and sulfide is observed. These selectivity data, along with other response characteristics of the membrane, are used to postulate the mechanism by which the electrode responds to sulfite. Preliminary studies demonstrate that the electrode can be used in conjunction with an outer gas-permeable membrane for highly selective detection of total sulfite species in the form of sulfur dioxide.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28138/1/0000589.pd

1,1′-Dimeth­oxy-3,3′-dimethyl-3,3′-(hexane-1,6-di­yl)bis(triazen-2-ium-2-olate): a nitric oxide donor

The title compound, C10H24N6O4, is the most stable type of nitric oxide (NO) donor among the broad category of discrete N-diazeniumdiolates (NO adducts of nucleophilic small mol­ecule amines). Sitting astride a crystallographic inversion center, the mol­ecule contains a symmetric dimethyl­hexane-1,6-diamine structure bearing two planar O 2-methyl­ated N-di­azeniumdiolate functional groups [N(O)=NOMe]. These two groups are parallel to each other and have the potential to release four mol­ecules of NO. The methyl­ated diazenium­diolate substituent removes the negative charge from the typical N(O)=NO− group, thereby increasing the stability of the diazeniumdiolate structure. The crystal was nonmerohedrally twinned by a 180° rotation about the real [101] axis. This is the first N-based bis-diazeniumdiolate compound with a flexible aliphatic main unit to have its structure analyzed and this work demonstrates the utility of stabilizing the N-dia­zeniumdiolate functional group by methyl­­ation

Adolescent Injury Rates

OBJECTIVE To describe the frequency of adolescent athlete injury based upon injury location, injury diagnosis, activity, playing surface, weather condition, and sport. MAIN.OUTCOME MEASUREMENTInjury frequency per injury location, diagnosis, activity, and playing surface were determined. Injury location and diagnosis frequency were reported by weather condition. Injuries per 1000 athletic exposures were analyzed by sport

‘It stays with you’: multiple evocative representations of dance and future possibilities for studies in sport and physical cultures

This article considers the integration of arts-based representations via poetic narratives together with artistic representation on dancing embodiment so as to continue an engagement with debates regarding multiple forms/representations. Like poetry, visual images are unique and can evoke particular kinds of emotional and visceral responses, meaning that alternative representational forms can resonate in different and powerful ways. In the article, we draw on grandparent-grandchild interactions, narrative poetry, and artistic representations of dance in order to illustrate how arts-based methods might synergise to offer new ways of ‘knowing’ and ‘seeing’. The expansion of the visual arts into interdisciplinary methodological innovations is a relatively new, and sometimes contentious approach, in studies of sport and exercise. We raise concerns regarding the future for more arts-based research in the light of an ever-changing landscape of a neoliberal university culture that demands high productivity in reductionist terms of what counts as ‘output’, often within very restricted time-frames. Heeding feminist calls for ‘slow academies’ that attempt to ‘change’ time collectively, and challenge the demands of a fast-paced audit culture, we consider why it is worth enabling creative and arts-based methods to continue to develop and flourish in studies of sport, exercise and health, despite the mounting pressures to ‘perform’

Thromboresistance Characterization of Extruded Nitric Oxide Releasing Silicone Catheters

Intravascular catheters used in clinical practice can activate platelets, leading to thrombus formation and stagnation of blood flow. Nitric oxide (NO)-releasing polymers have been shown previously to reduce clot formation on a number of blood contacting devices. In this work, trilaminar NO-releasing silicone catheters were fabricated and tested for their thrombogenicity. All catheters had specifications of L = 6 cm, inner diameter = 21 gauge (0.0723 cm), outer diameter = 12 gauge (0.2052 cm), and NO-releasing layer thickness = 200 ± 11 µm. Control and NO-releasing catheters were characterized in vitro for their NO flux and NO release duration by gas phase chemiluminescence measurements. The catheters were then implanted in the right and left internal jugular veins of (N = 6 and average weight = 3 kg) adult male rabbits for 4 hours thrombogenicity testing. Platelet counts and function, methemoglobin (metHb), hemoglobin (Hb), and white cell counts and functional time (defined as patency time of catheter) were monitored as measured outcomes. Nitric oxide-releasing catheters (N = 6) maintained an average flux above (2 ± 0.5) × 10−10 mol/min/cm2 for more than 24 hours, whereas controls showed no NO release. Methemoglobin, Hb, white cell, and platelet counts and platelet function at 4 hours were not significantly different from baseline (α = 0.05). However, clots on controls were visibly larger and prevented blood draws at a significantly (p \u3c 0.05) earlier time (2.3 ± 0.7 hours) into the experiment, whereas all NO-releasing catheters survived the entire 4 hours test period. Results indicate that catheter NO flux levels attenuated thrombus formation in a short-term animal model

Effects of the Neutron Spin-Orbit Density on Nuclear Charge Density in Relativistic Models

The neutron spin-orbit density contributes to the nuclear charge density as a relativistic effect. The contribution is enhanced by the effective mass stemming from the Lorentz-scalar potential in relativistic models. This enhancement explains well the difference between the cross sections of elastic electron scattering off $^{40}$Ca and $^{48}$Ca which was not reproduced in non-relativistic models. The spin-orbit density will be examined in more detail in electron scattering off unstable nuclei which would be available in the future.Comment: 4 pages with 3 eps figures, revte

Decoupling Inflation From the String Scale

When Inflation is embedded in a fundamental theory, such as string theory, it typically begins when the Universe is already substantially larger than the fundamental scale [such as the one defined by the string length scale]. This is naturally explained by postulating a pre-inflationary era, during which the size of the Universe grew from the fundamental scale to the initial inflationary scale. The problem then arises of maintaining the [presumed] initial spatial homogeneity throughout this era, so that, when it terminates, Inflation is able to begin in its potential-dominated state. Linde has proposed that a spacetime with compact negatively curved spatial sections can achieve this, by means of chaotic mixing. Such a compactification will however lead to a Casimir energy, which can lead to effects that defeat the purpose unless the coupling to gravity is suppressed. We estimate the value of this coupling required by the proposal, and use it to show that the pre-inflationary spacetime is stable, despite the violation of the Null Energy Condition entailed by the Casimir energy.Comment: 24 pages, 5 eps figures, references added, stylistic changes, version to appear in Classical and Quantum Gravit

The Hemocompatibility of a Nitric Oxide Generating Polymer that Catalyzes S-nitrosothiol Decomposition in an Extracorporeal Circulation Model

Nitric oxide (NO) generating (NOGen) materials have been shown previously to create localized increases in NO concentration by the catalytic decomposition of blood S-nitrosothiols (RSNO) via copper (Cu)-containing polymer coatings and may improve extracorporeal circulation (ECC) hemocompatibility. In this work, a NOGen polymeric coating composed of a Cuo-nanoparticle (80 nm)-containing hydrophilic polyurethane (SP-60D-60) combined with the intravenous infusion of an RSNO, S- nitroso-N-acetylpenicillamine (SNAP), is evaluated in a 4 h rabbit thrombogenicity model and the anti-thrombotic mechanism is investigated. Polymer films containing 10 wt.% Cuo-nanoparticles coated on the inner walls of ECC circuits are employed concomitantly with systemic SNAP administration (0.1182 μmol/kg/min) to yield significantly reduced ECC thrombus formation compared to polymer control + systemic SNAP or 10 wt.% Cu NOGen + systemic saline after 4 h blood exposure (0.4 ± 0.2 NOGen/SNAP vs 4.9 ± 0.5 control/SNAP or 3.2 ± 0.2 pixels/cm2 NOGen/saline). Platelet count (3.9 ± 0.7 NOGen/SNAP vs 1.8 ± 0.1 control/SNAP or 3.0 ± 0.2 × 108/ml NOGen/saline) and plasma fibrinogen levels were preserved after 4 h blood exposure with the NOGen/SNAP combination vs either the control/SNAP or the NOGen/saline groups. Platelet function as measured by aggregometry (51 ± 9 NOGen/SNAP vs 49 ± 3% NOGen/saline) significantly decreased in both the NOGen/SNAP and NOGen/saline groups while platelet P-selectin mean fluorescence intensity (MFI) as measured by flow cytometry was not decreased after 4 h on ECC to ex vivo collagen stimulation (26 ± 2 NOGen/SNAP vs 29 ± 1 MFI baseline). Western blotting showed that fibrinogen activation as assessed by Aγ dimer expression was reduced after 4 h on ECC with NOGen/SNAP (68 ± 7 vs 83 ± 3% control/SNAP). These results suggest that the NOGen polymer coating combined with SNAP infusion preserves platelets in blood exposure to ECCs by attenuating activated fibrinogen and preventing platelet aggregation. These NO-mediated platelet changes were shown to improve thromboresistance of the NOGen polymer-coated ECCs when adequate levels of RSNOs are present

Remarks on 2+1 Self-dual Chern-Simons Gravity

We study 2+1 Chern-Simons gravity at the classical action level. In particular we rederive the linear combinations of the ``standard'' and ``exotic'' Einstein actions, from the (anti) self-duality of the ``internal'' Lorentzian indices. The relation to a genuine four-dimensional (anti)self-dual topological theory greatly facilitates the analysis and its relation to hyperbolic three-dimensional geometry. Finally a non-abelian vector field ``dual'' action is also obtained.Comment: 16+1 pages, LaTeX file, no figures, clarifications and comments added, typos corrected and one reference adde