Persistently elevated CKMB and negative troponin T in a patient at ischaemic risk with chest pain.

Analytical interference in laboratory assays is not only unpredictable but also an underestimated problem. Not recognising these interferences can lead to misdiagnosis and mismanagement of patients. We present a case of a patient with chest pain and ischaemic risk factors with incongruent biochemical results. These results were discovered to be due to the presence of macro-creatine kinase (macro-CK) in vivo interfering with the CKMB activity assay.

Towards optimum permeability reduction in porous media using biofilm growth simulations.

While biological clogging of porous systems can be problematic in numerous processes (e.g., microbial enhanced oil recovery-MEOR), it is targeted during bio-barrier formation to control sub-surface pollution plumes in ground water. In this simulation study, constant pressure drop (CPD) and constant volumetric flow rate (CVF) operational modes for nutrient provision for biofilm growth in a porous system are considered with respect to optimum (minimum energy requirement for nutrient provision) permeability reduction for bio-barrier applications. Biofilm growth is simulated using a Lattice-Boltzmann (LB) simulation platform complemented with an individual-based biofilm model (IbM). A biomass detachment technique has been included using a fast marching level set (FMLS) method that models the propagation of the biofilm-liquid interface with a speed proportional to the adjacent velocity shear field. The porous medium permeability reduction is simulated for both operational modes using a range of biofilm strengths. For stronger biofilms, less biomass deposition and energy input are required to reduce the system permeability during CPD operation, whereas CVF is more efficient at reducing the permeability of systems containing weaker biofilms.

Biofouling of spiral-wound nanofiltration and reverse osmosis membranes: a feed spacer problem.

Biofouling was studied in full-scale and pilot-scale installations, test-rigs and membrane fouling monitors by conventional methods as well as Magnetic Resonance Imaging (MRI). Independent of permeate production, the feed spacer channel pressure drop and biomass concentration increased similarly in a nanofiltration pilot installation. In the presence of a feed spacer the absolute feed channel pressure drop increase caused by biomass accumulation was much higher than when a feed spacer was absent: in both spiral-wound nanofiltration and reverse osmosis systems biofouling is dominantly a feed spacer problem. This conclusion is based on (i) in-situ visual observations of the fouling accumulation, (ii) in-situ non-destructive observations of the fouling accumulation and velocity distribution profiles using MRI, and (iii) differences in pressure drop and biomass development in monitors with and without feed spacer. MRI studies showed that even a restricted biofilm accumulation on the feed channel spacer influenced the velocity distribution profile strongly. Biofouling control should be focused on the development of low fouling feed spacers and hydrodynamic conditions to restrict the impact of biomass accumulation on the feed channel pressure drop increase.

Non-invasive mass transfer measurements in complex biofilm-coated structures.

We demonstrate a novel application of (13)C pulsed field gradient (PFG) NMR to monitor mass transfer, due to both flow and diffusion, in a 3D complex porous support structure modified by biofilm growth. This enables timescales an order of magnitude larger than previously possible to be accessed with respect to displacement probability distribution (propagator) measurements. The evolution in the propagator shape with observation time to the Gaussian asymptote (constant dispersion coefficient) is consequently well resolved. We also simulated the measured displacement propagators with good agreement between experiment and prediction. The methodology has significant potential for the selective characterization of the transport of nutrients, metabolic products, pollutants and biocides in such complex biofilm-containing structures.

Determining NMR flow propagator moments in porous rocks without the influence of relaxation.

Flow propagators, used for the study of advective motion of brine solution in porous carbonate and sandstone rocks, have been obtained without the influence of Nuclear Magnetic Resonance (NMR) relaxation times, T1 and T2. These spin relaxation mechanisms normally result in a loss of signal that varies depending on the displacement zeta of the flowing spins, thereby preventing the acquisition of quantitative propagator data. The full relaxation behaviour of the system under flow needs to be characterised to enable the implementation of a true quantitative measurement. Two-dimensional NMR correlations of zeta-T2 and T1-T2 are used in combination to provide the flow propagators without relaxation weighting. T1-zeta correlations cannot be used due to the loss of T1 information during the displacement observation time Delta. Here the moments of the propagators are extracted by statistical analysis of the full propagator shape. The measured displacements (first moments) are seen to correlate with the expected mean displacements for long observation times Delta. The higher order moments of the propagators determined by this method indicate those obtained previously using a correction were overestimated.

Spatially resolved quantification of metal ion concentration in a biofilm-mediated ion exchanger.

A bioremediation process to remove Co(2+) from aqueous solution is investigated in this study using a magnetic resonance imaging (MRI) protocol to rapidly obtain multiple 2D spatially resolved Co(2+) ion concentration maps. The MRI technique is described in detail and its ability to determine the evolution in both axial and radial concentration profiles demonstrated, from which total column capacity can be determined. The final ion exchange column design allows operation in the 'plug flow' regime, hence making use of its full capacity before breakthrough. Conventional techniques for such process optimization are either restricted to the analysis of the exchanger outlet, which provides no information on the spatial heterogeneity of the system, or are invasive and need a variety of sample points to obtain 1D concentration information. To the best of our knowledge, our results represent the first concentration maps describing the bioremediation of metal ion contaminated water.

Modelling biofilm-modified hydrodynamics in 3D.

A simulation-based study to predict the impact of biofilm growth on displacement distributions for flow of water through a supporting packed bed is presented. The lattice Boltzmann method and a directed random walk algorithm are used, and are applied to the system with and without biofilm being present. The aim of this simulation study is to model the anomalous transport dynamics induced by biofilm, as reported in the literature, and thus to study the impact of observation time, delta, on the shape of the displacement distributions (propagators). We believe that this is the first demonstration of a propagator simulation for flow through a complex porous structure modulated by biofilm growth. The propagator distributions undergo a transition from a pre-asymptotic to a Gaussian-shaped distribution with increasing delta. The propagators were simulated for a wide range of delta going up to 500 seconds. This transition occurs with and without biofilm, but is very significantly delayed when biofilm is present due to the consequential development of essentially stagnant regions. The transition can be classified into three stages: a diffusion-dominated stage, a "twin-peak" stage and an advection-dominated stage.

Dietary iron alters liver, erythrocyte and plasma antioxidant and nitrite levels, and also sensitizes the heart to ischemia/reperfusion.

The aim of the study was to determine whether dietary iron within the normal range is (i) responsible for oxidative changes in the liver, erythrocytes and plasma; and (ii) make the heart more susceptible to ischemia/reperfusion injury. Female rats were allocated to four groups according to diet supplemented with either 15, 35, 150, or 300 mg iron/kg diet. After 4 months the following statistical difference in the two higher dietary groups were observed compared to the lower ones: (i) decreased antioxidant concentrations in liver, plasma and erythrocytes (alpha-tocopherol and ascorbic acid); (ii) increased plasma nitrite concentration; (iii) ischemia/reperfusion elevated LMWI and MDA concentrations and decreased ascorbate concentrations. This study clearly showed that increased dietary iron concentration causes oxidative changes in plasma, erythrocytes and liver. Higher dietary iron aggravated the outcome of ischemia/reperfusion injury as indicated by an elevated malondialdehyde concentration in the two higher dietary iron groups.

Effect of flavonoids on the outcome of myocardial mitochondrial ischemia/reperfusion injury.

There is evidence that flavonoid intake correlates inversely with coronary heart disease risk. Flavonoids are widely distributed in food and drinks and act as antioxidants and iron chelators. The aim of this study was to determine whether pycnogenol (a flavonoid extracted from the bark of Pinus pinaster) and catechin could minimise the myocardial mitochondrial damage due to ischemia/reperfusion. Using the rat heart model of ischemia/reperfusion we found that pycnogenol had no significant effect on the resultant damage, while catechin suppressed the observed elevation of low molecular weight iron during ischemia/reperfusion which might explain the significantly reduced mitochondrial injury when using catechin in the perfusate. Our results suggest that some flavonoids might be effective in minimizing ischaemic/reperfusion injury and would require further detailed investigation.