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Morovat A, James TS, Cox SD, Norris SG, Rees MC, Gales MA, Taylor RP. Comparison of Bayer Advia Centaur immunoassay results obtained on samples collected in four different Becton Dickinson Vacutainer tubes. Ann Clin Biochem 2007; 43:481-7. [PMID: 17132279 DOI: 10.1258/000456306778904713] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Medicines and Healthcare products Regulatory Agency's (MHRA's) Medical Device Alert MDA/2004/048 described bias in some endocrine test results obtained on a few immunoassay platforms, particularly the Bayer Advia Centaur instrument, when using blood specimens collected into Becton Dickinson (BD) Vacutainer SSTII Advance tubes. As users of BD tubes and the Advia Centaur instrument, we addressed our concerns about the quality of the results that we had previously reported by undertaking an independent study. METHOD We compared the results of 15 immunoassays performed on Bayer Advia Centaur using blood specimens collected into four different BD Vacutainer tubes (plain, old and newly released BD SSTII Advance, and BD PSTII). RESULTS Compared with plain tubes, old SSTII Advance tube results showed no bias for testosterone, CA15-3, follicle-stimulating hormone and folate assays, but gave a positive bias for cortisol and a negative bias for vitamin-B12. Compared with plain tubes, BD PSTII tubes gave no significant bias for thyroid function tests, prolactin, parathyroid hormone, and CA125, but gave a negative bias for steroid assays, and a positive bias for gonadotrophins. The results obtained using new BD SSTII Advance tubes were generally comparable with those on plain tubes. CONCLUSIONS Only for cortisol did our findings support the bias described by MHRA. Based on our results, apart from vitamin-B12 and possibly cortisol, there may have been no significant influence on clinical decisions as a result of using the old BD SSTII Advance specimen tubes. New BD SSTII Advance tubes and plain tubes give generally comparable results. BD PSTII tubes should not be used for steroid hormone measurements on the Bayer Advia Centaur instrument.
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Linke H, Alemán BJ, Melling LD, Taormina MJ, Francis MJ, Dow-Hygelund CC, Narayanan V, Taylor RP, Stout A. Self-propelled Leidenfrost droplets. PHYSICAL REVIEW LETTERS 2006; 96:154502. [PMID: 16712160 DOI: 10.1103/physrevlett.96.154502] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Indexed: 05/09/2023]
Abstract
We report that liquids perform self-propelled motion when they are placed in contact with hot surfaces with asymmetric (ratchetlike) topology. The pumping effect is observed when the liquid is in the Leidenfrost regime (the film-boiling regime), for many liquids and over a wide temperature range. We propose that liquid motion is driven by a viscous force exerted by vapor flow between the solid and the liquid.
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Marlow CA, Taylor RP, Fairbanks M, Shorubalko I, Linke H. Experimental investigation of the breakdown of the Onsager-Casimir relations. PHYSICAL REVIEW LETTERS 2006; 96:116801. [PMID: 16605849 DOI: 10.1103/physrevlett.96.116801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Indexed: 05/08/2023]
Abstract
We use magnetoconductance fluctuation measurements of phase-coherent semiconductor billiards to quantify the contributions to the nonlinear electric conductance that are asymmetric under reversal of magnetic field. We find that the average asymmetric contribution is linear in magnetic field (for magnetic flux much larger than 1 flux quantum) and that its magnitude depends on billiard geometry. In addition, we find an unexpected asymmetry in the power spectrum of the magnetoconductance with respect to reversal of magnetic field and bias voltage.
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Taylor RP. Measurements of the Material Properties of a Laminated Piezoelectric Stack at Cryogenic Temperatures. ACTA ACUST UNITED AC 2006. [DOI: 10.1063/1.2192352] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Taylor RP, Spehar B, Wise JA, Clifford CWG, Newell BR, Hagerhall CM, Purcell T, Martin TP. Perceptual and physiological responses to the visual complexity of fractal patterns. NONLINEAR DYNAMICS, PSYCHOLOGY, AND LIFE SCIENCES 2005; 9:89-114. [PMID: 15629069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Fractals have experienced considerable success in quantifying the complex structure exhibited by many natural patterns and have captured the imagination of scientists and artists alike. With ever widening appeal, they have been referred to both as "fingerprints of nature" and "the new aesthetics." Our research has shown that the drip patterns of the American abstract painter Jackson Pollock are fractal. In this paper, we consider the implications of this discovery. We first present an overview of our research from the past five years to establish a context for our current investigations of human response to fractals. We discuss results showing that fractal images generated by mathematical, natural and human processes possess a shared aesthetic quality based on visual complexity. In particular, participants in visual perception tests display a preference for fractals with mid-range fractal dimensions. We also present recent preliminary work based on skin conductance measurements that indicate that these mid-range fractals also affect the observer's physiological condition and discuss future directions based on these results.
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Löfgren A, Marlow CA, Shorubalko I, Taylor RP, Omling P, Samuelson L, Linke H. Symmetry of two-terminal nonlinear electric conduction. PHYSICAL REVIEW LETTERS 2004; 92:046803. [PMID: 14995393 DOI: 10.1103/physrevlett.92.046803] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Indexed: 05/24/2023]
Abstract
The well-established symmetry relations for linear transport phenomena cannot, in general, be applied in the nonlinear regime. Here we propose a set of symmetry relations with respect to bias voltage and magnetic field for the nonlinear conductance of two-terminal electric conductors. We experimentally confirm these relations using phase-coherent, semiconductor quantum dots.
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Abstract
For many years investigators have been researching methods of preconditioning the myocardium against ischaemia-induced damage; however, a majority of this research has been carried out in young animals and cells. Normal ageing is accompanied by changes in the human myocardium that decrease its capacity to tolerate and respond to various forms of stress. Also, the likelihood of experiencing an ischaemic stress and other cardiovascular complications increases as an individual ages; therefore, an aged population would benefit most from cardioprotective treatments. Methods currently known to provide cardioprotection (or preconditioning) include exercise, heat stress, oxidative stress, brief ischaemia, stretch and certain pharmacological interventions. It is unclear whether the aged myocardium can adapt to a preconditioning stimulus; however, many researchers have observed age-related alterations in the expression and activation of proteins key to the cardioprotective process. These proteins include heat shock protein 70 (HSP70), nitric oxide synthase (NOS), the sodium-hydrogen exchanger (NHE), and the mitogen-activated protein (MAP) kinases c-Jun N-terminal Kinase (JNK), extracellular signal-regulated kinase (ERK), and p38. Therefore, the purpose of the current review will be to outline the current knowledge of these cardioprotective agents in an aged myocardium. Interactions among the cardioprotective agents outlined herein suggest that age-related changes in the myocardium will need to be better understood before cardioprotective interventions that have been proved effective in young animals can be applied to an aged human population.
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Tan GD, Lewis AV, James TJ, Altmann P, Taylor RP, Levy JC. Clinical usefulness of cystatin C for the estimation of glomerular filtration rate in type 1 diabetes: reproducibility and accuracy compared with standard measures and iohexol clearance. Diabetes Care 2002; 25:2004-9. [PMID: 12401747 DOI: 10.2337/diacare.25.11.2004] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE-Assessment and follow-up of early renal dysfunction is important in diabetic nephropathy. Plasma creatinine is insensitive for a glomerular filtration rate (GFR) >50 ml/min and creatinine clearance is unwieldy and subject to collection inaccuracies. We aimed to assess the reproducibility, reliability, and accuracy of plasma cystatin C as a measure of GFR ranging from normal to moderate impairment due to type 1 diabetes in the presence of a normal plasma creatinine concentration. RESEARCH DESIGN AND METHODS-A sensitive immunoturbidimetric cystatin C assay was examined in 29 subjects with type 1 diabetes and 11 nondiabetic subjects. Duplicate measurements of the following were collected from each subject, 2 weeks apart: cystatin C, enzymatic plasma creatinine, 24-h creatinine clearance, GFR estimated from plasma creatinine by the Cockcroft-Gault equation, and iohexol clearance as a gold standard. RESULTS-Iohexol clearance ranged from 35 to 132 ml. min(-1). 1.73 m(-2). Plasma cystatin C compared well with the other clinically used tests. The reliability of cystatin C, as assessed by the discriminant ratio, was superior to creatinine clearance (3.4 vs. 1.5, P < 0.001) and the correlation of cystatin C with iohexol clearance (Rs -0.80) was similar to that of creatinine clearance (Rs -0.74) and superior to that of plasma creatinine and the Cockcroft-Gault estimate (Rs -0.54 and 0.66, respectively). Duplicate estimations were used to provide an unbiased equation to convert plasma cystatin C to GFR. CONCLUSIONS-Based on this study, cystatin C is a more reliable measure of GFR than creatinine clearance, is more highly correlated with iohexol clearance than plasma creatinine, and is worthy of further investigation as a clinical measure of GFR in type 1 diabetes.
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Humphrey TE, Newbury R, Taylor RP, Linke H. Reversible quantum brownian heat engines for electrons. PHYSICAL REVIEW LETTERS 2002; 89:116801. [PMID: 12225160 DOI: 10.1103/physrevlett.89.116801] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2001] [Indexed: 05/23/2023]
Abstract
Brownian heat engines use local temperature gradients in asymmetric potentials to move particles against an external force. The energy efficiency of such machines is generally limited by irreversible heat flow carried by particles that make contact with different heat baths. Here we show that, by using a suitably chosen energy filter, electrons can be transferred reversibly between reservoirs that have different temperatures and electrochemical potentials. We apply this result to propose heat engines based on mesoscopic semiconductor ratchets, which can quasistatically operate arbitrarily close to Carnot efficiency.
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Pitts JN, Letsinger RL, Taylor RP, Patterson JM, Recktenwald G, Martin RB. Photochemical Reactions of Benzophenone in Alcohols1. J Am Chem Soc 2002. [DOI: 10.1021/ja01514a014] [Citation(s) in RCA: 191] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Taylor RP, Blacet FE. Photochemical Oxidation of Biacetyl by Molecular Oxygen. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/ie51400a037] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kuntz ID, Gasparro FP, Johnston MD, Taylor RP. Molecular interactions and the Benesi-Hildebrand equation. J Am Chem Soc 2002. [DOI: 10.1021/ja01020a004] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Taylor RP, Kuntz ID. Proton acceptor abilities of anions and possible relevance to the Hofmeister series. J Am Chem Soc 2002. [DOI: 10.1021/ja00778a004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Lindorfer MA, Hahn CS, Foley PL, Taylor RP. Heteropolymer-mediated clearance of immune complexes via erythrocyte CR1: mechanisms and applications. Immunol Rev 2001; 183:10-24. [PMID: 11782244 DOI: 10.1034/j.1600-065x.2001.1830102.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Opsonization of particulate pathogens by antibodies and complement can lead to their binding to the complement receptor (CR1), specific for C3b, on primate erythrocytes (E). This process of immune adherence may play a role in immunologic defense by immobilizing bacteria and viruses, thus preventing them from leaving the bloodstream to invade susceptible tissue and organs. Immune adherence of C3b-opsonized and immune complexed pathogens to E may also facilitate their transfer to, and destruction by, fixed tissue macrophages. We have used mAbs specific for CR1 crosslinked with pathogen specific mAbs to generate heteropolymers (HP) which can bind a wide range of substrates to primate erythrocytes. Both prototype and bonafide pathogens bound to primate E via HP are handled in the circulation of non-human primates in a manner which appears to be virtually identical to the mechanism by which C3b-opsonized substrates bound to E CR1 are cleared. In this process of focused phagocytosis, Fc receptors on the phagocytic cell engage the E-bound complex, CR1 is removed by proteolysis, and the entire immune complex and CR1 are internalized while sparing the E. It may be possible to use HP to target pathogens in the bloodstream in a wide range of therapeutic applications.
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Wilkinson PB, Fromhold TM, Tench CR, Taylor RP, Micolich AP. Compact fourth-order finite difference method for solving differential equations. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 64:047701. [PMID: 11690185 DOI: 10.1103/physreve.64.047701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2001] [Indexed: 05/23/2023]
Abstract
We present a fourth-order finite difference (FD) method for solving two-dimensional partial differential equations. The FD operator uses a compact nine-point stencil on a regular square grid. Despite the regular grid, Dirichlet boundary conditions can be applied on an arbitrarily shaped boundary without resorting to the usual stepped approximation. We demonstrate the superior convergence of the method over second-order techniques by solving the Schrödinger equation for an electron in a semiconductor quantum dot with a smoothly varying potential which generates classically chaotic dynamics.
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McGuire JB, James TJ, Taylor RP. Correction to 'improved immunoturbidimetric assay for cystatin C'. Ann Clin Biochem 2001; 38:572-3. [PMID: 11587141 DOI: 10.1177/000456320103800520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Lindorfer MA, Nardin A, Foley PL, Solga MD, Bankovich AJ, Martin EN, Henderson AL, Price CW, Gyimesi E, Wozencraft CP, Goldberg JB, Sutherland WM, Taylor RP. Targeting of Pseudomonas aeruginosa in the bloodstream with bispecific monoclonal antibodies. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:2240-9. [PMID: 11490011 DOI: 10.4049/jimmunol.167.4.2240] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We examined the ability of a bispecific mAb reagent, consisting of a mAb specific for the primate erythrocyte complement receptor cross-linked with an anti-bacterial mAb, to target bacteria in the bloodstream in an acute infusion model in monkeys. In vitro studies demonstrated a variable level of complement-mediated binding (immune adherence) of Pseudomonas aeruginosa (strain PAO1) to primate E in serum. In vivo experiments in animals depleted of complement revealed that binding of bacteria to E was <1% before administration of the bispecific reagent, but within 5 min of its infusion, >99% of the bacteria bound to E. In complement-replete monkeys, a variable fraction of infused bacteria bound to E. This finding may have significant implications in the interpretation of animal models and in the understanding of bacteremias in humans. Treatment of these complement-replete monkeys with the bispecific reagent led to >99% binding of bacteria to E. Twenty-four-hour survival studies were conducted; several clinical parameters, including the degree of lung damage, cytokine levels, and liver enzymes in the circulation, indicate that the bispecific mAb reagent provides a degree of protection against the bacterial challenge.
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Wilkinson PB, Fromhold TM, Taylor RP, Micolich AP. Effects of geometrical ray chaos on the electromagnetic eigenmodes of a gradient index optical cavity. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 64:026203. [PMID: 11497673 DOI: 10.1103/physreve.64.026203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2001] [Indexed: 05/23/2023]
Abstract
Electromagnetic analogies of quantum chaos are investigated in two-dimensional optical cavities which have reflective surfaces and contain a gradient refractive index medium. As the shape of the cavity is transformed continuously from a rectangle to a parallelogram, the geometrical ray paths undergo a transition from stable to chaotic dynamics. In the chaotic regime, the spectral statistics of the cavity are accurately described by random matrix theory. In addition, the electromagnetic mode spectrum of the cavity is modulated by both real and ghost periodic ray paths. These paths also "scar" the electric field intensity distributions of regular subsets of cavity eigenmodes.
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Micolich AP, Taylor RP, Davies AG, Bird JP, Newbury R, Fromhold TM, Ehlert A, Linke H, Macks LD, Tribe WR, Linfield EH, Ritchie DA, Cooper J, Aoyagi Y, Wilkinson PB. Evolution of fractal patterns during a classical-quantum transition. PHYSICAL REVIEW LETTERS 2001; 87:036802. [PMID: 11461579 DOI: 10.1103/physrevlett.87.036802] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2000] [Indexed: 05/23/2023]
Abstract
We investigate how fractals evolve into nonfractal behavior as the generation process is gradually suppressed. Fractals observed in the conductance of semiconductor billiards are of particular interest because the generation process is semiclassical and can be suppressed by transitions towards either fully classical or fully quantum-mechanical conduction. Investigating a range of billiards, we identify a "universal" behavior in the changeover from fractal to nonfractal conductance, which is described by a smooth evolution rather than deterioration in the fractal scaling properties.
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James TJ, Hughes MA, Hofman D, Cherry GW, Taylor RP. Antioxidant characteristics of chronic wound fluid. Br J Dermatol 2001; 145:185-6. [PMID: 11453942 DOI: 10.1046/j.1365-2133.2001.04317.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Wilkinson PB, Fromhold TM, Taylor RP, Micolich AP. Electromagnetic wave chaos in gradient refractive index optical cavities. PHYSICAL REVIEW LETTERS 2001; 86:5466-5469. [PMID: 11415277 DOI: 10.1103/physrevlett.86.5466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2000] [Indexed: 05/23/2023]
Abstract
Electromagnetic wave chaos is investigated using two-dimensional optical cavities formed in a cylindrical gradient refractive index lens with reflective surfaces. When the planar ends of the lens are cut at an angle to its axis, the geometrical ray paths are chaotic. In this regime, the electromagnetic mode spectrum of the cavity is modulated by both real and ghost periodic ray paths, which also "scar" the electric field intensity distributions of many modes. When the cavity is coupled to waveguides, the eigenmodes generate complex series of resonant peaks in the electromagnetic transmission spectrum.
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Knight SL, Taylor RP, Polliack AA, Bader DL. Establishing predictive indicators for the status of loaded soft tissues. J Appl Physiol (1985) 2001; 90:2231-7. [PMID: 11356787 DOI: 10.1152/jappl.2001.90.6.2231] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Two complementary techniques were employed to assess the soft tissue response to applied pressure. The noninvasive methods involve the simultaneous measurement of the local tensions of oxygen and carbon dioxide (tcPo 2 and tcPco 2) and the collection and subsequent analysis of sweat collected from the sacrum, a common site for the development of pressure sores. All tests were performed on able-bodied subjects. Results have indicated that oxygen levels (tcPo 2) were lowered in soft tissues subjected to applied pressures of between 40 (5.3 kPa) and 120 mmHg (16.0 kPa). At the higher pressures, this decrease was generally associated with an increase in carbon dioxide levels (tcPco 2) well above the normal basal levels of 45 mmHg (6 kPa). There were also considerable increases, in some cases up to twofold, in the concentrations of both sweat lactate and urea at the loaded site compared with the unloaded control. By comparing selected parameters, a threshold value for loaded tcPo 2 was identified, representing a reduction of ∼60% from unloaded values. Above this threshold, there was a significant relationship between this parameter and the loaded/unloaded concentration ratios for both sweat metabolites. These parameters may prove useful in identifying those subjects whose soft tissue may be compromised during periods of pressure ischemia.
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Abstract
An immunoturbidimetric assay for cystatin C was optimized with respect to assay imprecision. After investigating the optimum pH, polyethylene glycol concentration and specimen volume, two modifications were introduced: an increase in specimen volume to 25 microL; and an extension of the pre-incubation period to 240 s. These modifications produced an assay with between-batch imprecision (coefficient of variation, n = 10 or 11) ranging from 3-9% at 0.72 mg/L to 1.3% at 5.29 mg/L. The assay was susceptible to interference from lipaemia and haemolysis but not bilirubinaemia in both the original and modified protocol. Extending the pre-incubation to 240 s improved tolerance to common interferences and retained assay applicability in the routine clinical setting.
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