Insights into historical drainage evolution based on the phylogeography of the chevron snakehead fish (Channa striata) in the Mekong Basin

1. The phylogeography of freshwater taxa is often integrally linked with landscape changes such as drainage re-alignments that may present the only avenue for historical dispersal for these taxa. Classical models of gene flow do not account for landscape changes and so are of little use in predicting phylogeography in geologically young freshwater landscapes. When the history of drainage formation is unknown, phylogeographical predictions can be based on current freshwater landscape structure, proposed historical drainage geomorphology, or from phylogeographical patterns of co-distributed taxa. 2. This study describes the population structure of a sedentary freshwater fish, the chevron snakehead (Channa striata), across two river drainages on the Indochinese Peninsula. The phylogeographical pattern recovered for C. striata was tested against seven hypotheses based on contemporary landscape structure, proposed history and phylogeographical patterns of codistributed taxa. 3. Consistent with the species ecology, analysis of mitochondrial and microsatellite loci revealed very high differentiation among all sampled sites. A strong signature of historical population subdivision was also revealed within the contemporary Mekong River Basin (MRB). Of the seven phylogeographical hypotheses tested, patterns of co-distributed taxa proved to be the most adequate for describing the phylogeography of C. striata. 4. Results shed new light on SE Asian drainage evolution, indicating that the Middle MRB probably evolved via amalgamation of at least three historically independent drainage sections and in particular that the Mekong River section centred around the northern Khorat Plateau in NE Thailand was probably isolated from the greater Mekong for an extensive period of evolutionary time. In contrast, C. striata populations in the Lower MRB do not show a phylogeographical signature of evolution in historically isolated drainage lines, suggesting drainage amalgamation has been less important for river landscape formation in this region.

ECMO : the clinician’s view

Background: Extra corporeal membrane oxygenation (ECMO) is a complex rescue therapy used to provide cardiac and/or respiratory support for critically ill patients who have failed maximal conventional medical management. ECMO is based on a modified cardiopulmonary bypass (CPB) circuit, and can provide cardiopulmonary support for up-to several months. It can be used in a veno venous configuration for isolated respiratory failure, (VV-ECMO), or in a veno arterial configuration (VA-ECMO) where support is necessary for cardiac +/- respiratory failure. The ECMO circuit consists of five main components: large bore cannulae (access cannulae) for drainage of the venous system, and return cannulae to either the venous (in VV-ECMO) or arterial (in VA ECMO) system. An oxygenator, with a vast surface area of hollow filaments, allows addition of oxygen and removal of carbon dioxide; a centrifugal blood pump allows propulsion of blood through the circuit at upto 10 L/minute; a control module and a thermoregulatory unit, which allows for exact temperature control of the extra corporeal blood. Methods: The first successful use of ECMO for ARDS in adults occurred in 1972, and its use has become more commonplace over the last 30 years, supported by the improvement in design and biocompatibility of the equipment, which has reduced the morbidity associated with this modality. Whilst the use of ECMO in neonatal population has been supported by numerous studies, the evidence upon which ECMO was integrated into adult practice was substantially less robust. Results: Recent data, including the CESAR study (Conventional Ventilatory Support versus Extra corporeal membrane oxygenation for Severe Respiratory failure) has added a degree of evidence to the role of ECMO in such a patient population. The CESAR study analysed 180 patients, and confirmed that ECMO was associated with an improved rate of survival. More recently, ECMO has been utilized in numerous situations within the critical care area, including support in high-risk percutaneous interventions in cardiac catheter lab; the operating room, emergency department, as well in specialized inter-hospital retrieval services. The increased understanding of the risk:benefit profile of ECMO, along with a reduction in morbidity associated with its use will doubtless lead to a substantial rise in the utilisation of this modality. As with all extra-corporeal circuits, ECMO opposes the basic premises of the mammalian inflammation and coagulation cascade where blood comes into foreign circulation, both these cascades are activated. Anti-coagulation is readily dealt with through use of agents such as heparin, but the inflammatory excess, whilst less macroscopically obvious, continues un-abated. Platelet consumption and neutrophil activation occur rapidly, and the clinician is faced with balancing the need of anticoagulation for the circuit, against haemostasis in an acutely bleeding patient. Alterations in pharmacokinetics may result in inadequate levels of disease modifying therapeutics, such as antibiotics, hence paradoxically delaying recovery from conditions such as pneumonia. Key elements of nutrition and the innate immune system maysimilarly be affected. Summary: This presentation will discuss the basic features of ECMO to the nonspecialist, and review the clinical conundrum faced by the team treating these most complex cases.

Risk modelling in quality clinical registries : Monitoring lesion treatment failure rate in percutaneous coronary interventions

Aims: This paper describes the development of a risk adjustment (RA) model predictive of individual lesion treatment failure in percutaneous coronary interventions (PCI) for use in a quality monitoring and improvement program. Methods and results: Prospectively collected data for 3972 consecutive revascularisation procedures (5601 lesions) performed between January 2003 and September 2011 were studied. Data on procedures to September 2009 (n = 3100) were used to identify factors predictive of lesion treatment failure. Factors identified included lesion risk class (p < 0.001), occlusion type (p < 0.001), patient age (p = 0.001), vessel system (p < 0.04), vessel diameter (p < 0.001), unstable angina (p = 0.003) and presence of major cardiac risk factors (p = 0.01). A Bayesian RA model was built using these factors with predictive performance of the model tested on the remaining procedures (area under the receiver operating curve: 0.765, Hosmer–Lemeshow p value: 0.11). Cumulative sum, exponentially weighted moving average and funnel plots were constructed using the RA model and subjectively evaluated. Conclusion: A RA model was developed and applied to SPC monitoring for lesion failure in a PCI database. If linked to appropriate quality improvement governance response protocols, SPC using this RA tool might improve quality control and risk management by identifying variation in performance based on a comparison of observed and expected outcomes.

Effect of reactive bed mineralogy on arsenic retention and permeability of synthetic arsenic-containing acid mine drainage

Successive alkalinity producing systems (SAPSs) are widely used for treating acid mine drainage (AMD) and alleviating clogging commonly occurring in limestone systems due to an amorphous ferric precipitate. In this study, iron dust, bone char, micrite and their admixtures were used to treat arseniccontaining AMD. A particular interest was devoted to arsenic removal performance, mineralogical constraints on arsenic retention ability and permeability variation during column experiment for 140 days. The results showed that the sequence of the arsenic removal capacity was as follows: bone char > micrite > iron dust. The combination of 20% v/v iron dust and 80% v/v bone char/micrite columns can achieve better hydraulic conductivity and phosphorus-retention capacity than single micrite and bone char columns. The addition of iron dust created reductive environment and resulted in the transformation of coating material from colloidal phase to secondary mineral phase, such as green rust and phosphoerrite, which obviously ameliorates hydraulic conductivity of systems. The sequential extraction experiments indicated that the stable fractions of arsenic in columns were enhanced with help of iron dust compared to single bone char and micrite columns. A combination of iron dust and micrite/bone char represented a potential SAPS for treating As-containing AMD.

Percutaneous patent foramen ovale closure : outcomes with the Premere and Amplatzer devices

BACKGROUND: Transcatheter closure of patent foramen ovale (PFO) has rapidly evolved as the preferred management strategy for the prevention of recurrent cerebrovascular events in patients with cryptogenic stroke and presumed paradoxical embolus. There is limited outcome data in patients treated with this therapy particularly for the newer devices. METHODS: Data from medical records, catheter, and echocardiography databases on 70 PFO procedures performed was collected prospectively. RESULTS: The cohort consisted of 70 patients (mean age 43.6 years, range 19 to 77 years), of whom 51% were male. The indications for closure were cryptogenic cerebrovascular accident (CVA) or transient ischemic attack (TIA) in 64 (91%) and peripheral emboli in two (2.8%) patients and cryptogenic ST-elevation myocardial infarction in one (1.4%), refractory migraine in one (1.4%), decompression sickness in one (1.4%), and orthodeoxia in one (1.4%) patient, respectively. All patients had demonstrated right-to-left shunting on bubble study. The procedures were guided by intracardiac echocardiography in 53%, transesophageal echocardiography in 39%, and the remainder by transthoracic echo alone. Devices used were the Amplatzer PFO Occluder (AGA Medical) (sizes 18-35 mm) in 49 (70%) and the Premere device (St. Jude Medical) in 21 (30%). In-hospital complications consisted of one significant groin hematoma with skin infection. Echocardiographic follow-up at 6 months revealed that most patients had no or trivial residual shunt (98.6%), while one patient (1.4%) had a mild residual shunt. At a median of 11 months' follow-up (range 1 month to 4.3 years), no patients (0%) experienced further CVA/TIAs or paradoxical embolic events during follow-up. CONCLUSION: PFO causing presumed paradoxical embolism can be closed percutaneously with a low rate of significant residual shunting and very few complications. Recurrent index events are uncommon at medium-term (up to 4 years) follow-up.

Percutaneous coronary intervention with drug-eluting stents or coronary artery bypass surgery in subjects with type 2 diabetes : evaluation of: Farkouth ME, Domanski M, Sleeper LA, et al. Strategies for multivessel revascularization in patients with diabetes. N Engl J Med 2012;367(25):2375-84, and Contini GA, Nicolini F, Fortuna D, et al. Five-year outcomes of surgical or percutaneous myocardial revascularization in diabetic patients. Int J Cardiol 2012. [Epub ahead of print]

There is debate as to whether percutaneous coronary intervention (PCI) with drug-eluting stents or coronary artery bypass surgery (CABG) is the best procedure for subjects with type 2 diabetes and coronary artery disease requiring revascularization. There is some evidence that following these procedures there is less further revascularization with CABG than PCI in subjects with diabetes. Two recent studies; the FREEDOM (Future Revascularization Evaluation in patients with Diabetes mellitus: Optimal Management of Multivessel Disease) trial, and a trial using a real world diabetic population from a Registry, have shown that the benefits of CABG over PCI in subjects with type 2 diabetes extends to lower rates of death and myocardial infarct, in addition to lower rates of revascularization. However, the rates of stroke may be higher with CABG than PCI with drug-eluting stents in this population. Thus, if CABG is going to be preferred to PCI in subjects with type 2 diabetes and multivessel coronary disease, consideration should be given to how to reduce the rates of stroke with CABG.

Increased generation of platelet-derived microparticles following percutaneous transluminal coronary angioplasty

Platelet-derived microparticles (PMPs) which are produced during platelet activation contribute to coagulation1 and bind to traumatized endothelium in an animal model2. Such endothelial injury occurs during percutaneous transluminal coronary angioplasty (PTCA), a procedure which restores the diameter of occluded coronary arteries using balloon inflations. However, re-occlusions subsequently develop in 20-25% of patients3, although this is limited by treatment with anti-platelet glycoprotein IIb/IIIa receptor drugs such as abciximab4. However, abciximab only partially decreases the need for revascularisation5, and therefore other mechanisms appear to be involved. As platelet activation occurs during PTCA, it is likely that PMPs may be produced and contribute to restenosis. This study population consisted of 113 PTCA patients, of whom 38 received abciximab. Paired peripheral arterial blood samples were obtained from the PTCA sheath: 1) following heparinisation (baseline); and 2) subsequent to all vessel manipulation (post-PTCA). Blood was prepared with an anti-CD61 (glycoprotein IIIa) fluorescence conjugated antibody to identify PMPs using flow cytometry, and PMP results expressed as a percentage of all CD61 events. The level of PMPs increased significantly from baseline following PTCA in the without abciximab group (paired t test, P=0.019). However, there was no significant change in the level of PMPs following PTCA in patients who received abciximab. Baseline clinical characteristics between patient groups were similar, although patients administered abciximab had more complex PTCA procedures, such as increased balloon inflation pressures (ANOVA, P=0.0219). In this study, we have clearly demonstrated that the level of CD61-positive PMPs increased during PTCA. This trend has been demonstrated previously, although a low sample size prevented statistical significance being attained6. The results of our work also demonstrate that there was no increase in PMPs after PTCA with abiciximab treatment. The increased PMPs may adhere to traumatized endothelium, contributing to re-occlusion of the arteries, but this remains to be determined. References: (1) Holme PA, Brosstad F, Solum NO. Blood Coagulation and Fibrinolysis. 1995;6:302-310. (2) Merten M, Pakala R, Thiagarajan P, Benedict CR. Circulation. 1999;99:2577-2582. (3) Califf RM. American Heart Journal.1995;130:680-684. (4) Coller BS, Scudder LE. Blood. 1985;66:1456-1459. (5) Topol EJ, Califf RM, Weisman HF, Ellis SG, Tcheng JE, Worley S, Ivanhoe R, George BS, Fintel D, Weston M, Sigmon K, Anderson KM, Lee KL, Willerson JT on behalf of the EPIC investigators. Lancet. 1994;343:881-886. (6) Scharf RE, Tomer A, Marzec UM, Teirstein PS, Ruggeri ZM, Harker LA. Arteriosclerosis and Thrombosis. 1992;12:1475-87.

The use of phospholipid fatty acid analysis to measure impact of acid rock drainage on microbial communities in sediments

The impact of acid rock drainage (ARD) and eutrophication on microbial communities in stream sediments above and below an abandoned mine site in the Adelaide Hills, South Australia, was quantified by PLFA analysis. Multivariate analysis of water quality parameters, including anions, soluble heavy metals, pH, and conductivity, as well as total extractable metal concentrations in sediments, produced clustering of sample sites into three distinct groups. These groups corresponded with levels of nutrient enrichment and/or concentration of pollutants associated with ARD. Total PLFA concentration, which is indicative of microbial biomass, was reduced by >70% at sites along the stream between the mine site and as far as 18 km downstream. Further downstream, however, recovery of the microbial abundance was apparent, possibly reflecting dilution effect by downstream tributaries. Total PLFA was >40% higher at, and immediately below, the mine site (0-0.1 km), compared with sites further downstream (2.5-18 km), even after accounting for differences in specific surface area of different sediment samples. The increased microbial population in the proximity of the mine source may be associated with the presence of a thriving iron-oxidizing bacteria community as a consequence of optimal conditions for these organisms while the lower microbial population further downstream corresponded with greater sediments' metal concentrations. PCA of relative abundance revealed a number of PLFAs which were most influential in discriminating between ARD-polluted sites and the rest of the sites. These PLFA included the hydroxy fatty acids: 2OH12:0, 3OH12:0, 2OH16:0; the fungal marker: 18:2ω6; the sulfate-reducing bacteria marker 10Me16:1ω7; and the saturated fatty acids 12:0, 16:0, 18:0. Partial constrained ordination revealed that the environmental parameters with the greatest bearing on the PLFA profiles included pH, soluble aluminum, total extractable iron, and zinc. The study demonstrated the successful application of PLFA analysis to rapidly assess the toxicity of ARD-affected waters and sediments and to differentiate this response from the effects of other pollutants, such as increased nutrients and salinity.

Increased platelet-derived microparticles in the coronary circulation of percutaneous transluminal coronary angioplasty patients

Platelet-derived microparticles that are produced during platelet activation are capable of adhesion and aggregation. Endothelial trauma that occurs during percutaneous transluminal coronary angioplasty (PTCA) may support platelet-derived microparticle adhesion and contribute to development of restenosis. We have previously reported an increase in platelet-derived microparticles in peripheral arterial blood with angioplasty. This finding raised concerns regarding the role of plateletderived microparticles in restenosis, and therefore the aim of this study was to monitor levels in the coronary circulation. The study population consisted of 19 angioplasty patients. Paired coronary artery and sinus samples were obtained following heparinization, following contrast administration, and subsequent to all vessel manipulation. Platelet-derived microparticles were identified with an anti-CD61 (glycoprotein IIIa) fluorescence-conjugated antibody using flow cytometry. There was a significant decrease in arterial platelet-derived microparticles from heparinization to contrast administration (P 0.001), followed by a significant increase to the end of angioplasty (P 0.004). However, there was no significant change throughout the venous samples. These results indicate that the higher level of platelet-derived microparticles after angioplasty in arterial blood remained in the coronary circulation. Interestingly, levels of thrombin–antithrombin complexes did not rise during PTCA. This may have implications for the development of coronary restenosis post-PTCA, although this remains to be determined.

Increased generation of platelet-derived microparticles following percutaneous transluminal coronary angioplasty

Platelet-derived microparticles that are produced during platelet activation bind to traumatized endothelium. Such endothelial injury occurs during percutaneous transluminal coronary angioplasty. Approximately 20% of these patients subsequently develop restenosis, although this is improved by treatment with the anti-platelet glycoprotein IIb/IIIa receptor drug abciximab. As platelet activation occurs during angioplasty, it is likely that platelet-derived microparticles may be produced and hence contribute to restenosis. This study population consisted of 113 angioplasty patients, of whom 38 received abciximab. Paired peripheral arterial blood samples were obtained following heparinization and subsequent to all vessel manipulation. Platelet-derived microparticles were identified using an anti-CD61 (glycoprotein IIIa) fluorescence-conjugated antibody and flow cytometry. Baseline clinical characteristics between patient groups were similar. The level of platelet-derived microparticles increased significantly following angioplasty in the group without abciximab (paired t test, P 0.019). However, there was no significant change in the level of platelet-derived microparticles following angioplasty in patients who received abciximab, despite requiring more complex angioplasty procedures. In this study, we have demonstrated that the level of platelet-derived microparticles increased during percutaneous transluminal coronary angioplasty, with no such increase with abciximab treatment. The increased platelet-derived microparticles may adhere to traumatized endothelium, contributing to re-occlusion of the arteries, but this remains to be determined.

Impacts of sodic soil amelioration on hydraulic conductivity and deep drainage in the Lower Burdekin

An understanding of the influence of soil chemistry on soil hydraulic properties is of critical importance for the management of sodic soils under irrigation. The hydraulic conductivity of sodic soils has been shown to be affected by properties of the applied solution including pH (Suarez et al. 1984), sodicity and salt concentration (McNeal and Coleman 1966). The changes in soil hydraulic conductivity are the result of changes in the spacing between clay layers in response to changes in soil solution chemistry. While the importance o f soil chemistry in controlling hydraulic conductivity is known, the exact impacts of sodic soil amelioration on hydraulic conductivity and deep drainage at a given location are difficult to predict. This is because the relationships between soil chemical factors and hydraulic conductivity are soil specific and because local site specific factors also need to be considered to determine the actual impacts on deep drainage rates.

A Network Model of Static Foam Drainage

On the basis of a more realistic tetrakaidecahedral structure of foam bubbles, a network model of static foam drainage has been developed. The model considers the foam to be made up of films and Plateau borders. The films drain into the adjacent Plateau borders, which in turn form a network through which the liquid moves from the foam to the liquid pool. From the structure, a unit flow cell was found, which constitutes the foam when stacked together both horizontally and vertically. Symmetry in the unit flow cell indicates that the flow analysis of a part of it can be employed to obtain the drainage for the whole foam. Material balance equations have been written for each segment of this subsection, ensuring connectivity, and solved with the appropriate boundary and initial conditions. The calculated rates of drainage, when compared with the available experimental results, indicate that the model predicts the experimental results well.

Comparison of Radiation Doses for Catheter Ablation Procedures for Atrial Fibrillation with Percutaneous Coronary Intervention Cases

Background: Catheter ablation procedures for atrial fibrillation (AF) may frequently require long fluoroscopic times. We sought to undertake a review of radiation safety practice in our Cardiac Electrophysiology Laboratory and implement changes to minimize fluoroscopic doses. We also sought to compare the results with radiation doses for percutaneous coronary intervention (PCI) cases performed in our hospital. Methods: Fluoroscopic times and doses for AF ablation procedures performed by a single operator on a Philips Integris H3000 image-intensifier were analysed for 11-month period. Results were compared with all PCI procedures performed over a similar period by multiple operators on a Philips Integris Allura FD system. Comprehensive review of radiation practice in the Electrophysiology laboratory identified the potential to reduce pulse frame rates and doses, and to narrow the field of interest without impacting the performance of the procedure. These changes were implemented and results analysed after a further 11 months. Results: In the pre-intervention period 50 AF catheter ablations had a mean fluoroscopic time of 86.4 min and mean fluoroscopic dose 68.4 Gy/cm2. Post-intervention 75 procedures had a mean fluorosocopic time of 68.9 min (p < 0.0001) and mean dose of 14.3 Gy/cm2 (p < 0.0001) 128 PCI procedures had a mean combined fluoroscopic and image acquisition time of 10.0 min and mean total dose 38.8 Gy/cm2. Conclusions: Catheter ablation procedures for AF may require lengthy use of fluoroscopy but simple modifications to radiation practice can result in marked reductions in radiation dose that compare favourably with PCI case doses