Water-induced reordering in ultrathin ionic liquid films.

Water-induced reordering in ultrathin ionic liquid films has been observed using in situ x-ray photoelectron spectroscopy. An ultrathin layer of 1-butyl-3-methylimidazolium tetrafluoroborate ([C4C1Im][BF4]) was deposited on a rutile TiO2 (1 1 0) single crystal and exposed to water vapour at a relative humidity of ~70% in an in situ cell. Water was found to adsorb onto the ionic liquid surface, causing a reordering of the ions at the interface. Water initially remained trapped on the ionic liquid surface as the in situ cell was evacuated. This could have negative implications for supported ionic liquid phase catalysis, where reactants and products move in and out of an ionic liquid containing the catalyst. This insight into the behaviour at the water/ionic liquid interface provides a basis for understanding interfacial behaviour in more complex gas/ionic liquid systems.

The offset droplet: a new methodology for studying the solid/water interface using x-ray photoelectron spectroscopy.

The routine study of the solid-water interface by XPS is potentially revolutionary as this development opens up whole new areas of study for photoelectron spectroscopy. To date this has been realised by only a few groups worldwide and current techniques have significant restrictions on the type of samples which can be studied. Here we present a novel and uniquely flexible approach to the problem. By introducing a thin capillary into the NAP-XPS, a small droplet can be injected onto the sample surface, offset from the analysis area by several mm. By careful control of the droplet size a water layer of controllable thickness can be established in the analysis area-continuous with the bulk droplet. We present results from the solid-water interface on a vacuum prepared TiO2(110) single crystal and demonstrate that the solid/liquid interface is addressable.

Edge reactivity and water-assisted dissociation on cobalt oxide nanoislands.

Transition metal oxides show great promise as Earth-abundant catalysts for the oxygen evolution reaction in electrochemical water splitting. However, progress in the development of highly active oxide nanostructures is hampered by a lack of knowledge of the location and nature of the active sites. Here we show, through atom-resolved scanning tunnelling microscopy, X-ray spectroscopy and computational modelling, how hydroxyls form from water dissociation at under coordinated cobalt edge sites of cobalt oxide nanoislands. Surprisingly, we find that an additional water molecule acts to promote all the elementary steps of the dissociation process and subsequent hydrogen migration, revealing the important assisting role of a water molecule in its own dissociation process on a metal oxide. Inspired by the experimental findings, we theoretically model the oxygen evolution reaction activity of cobalt oxide nanoislands and show that the nanoparticle metal edges also display favourable adsorption energetics for water oxidation under electrochemical conditions.

Soluble vascular endothelial growth factor receptor-1 is reduced in patients with resistant hypertension after renal denervation.

Renal denervation (RDN) has been shown in several studies to reduce blood pressure (BP) in patients with resistant hypertension (RH). Data on potential biomarkers associated with BP changes remain scarce. We evaluated whether soluble vascular endothelial growth factor receptor (sVEGFR-1) is affected by the procedure. A total of 57 patients with RH participated in this study. BP and heart rate were recorded at baseline and at 3 months follow-up, at which time blood samples were collected to determine the levels of sVEGFR-1, VEGF-A, VEGF-C, nitric oxide (NO), soluble vascular adhesion molecule 1 and soluble intracellular adhesion molecule 1. None of the biomarkers had a predictive value that could identify responders vs non-responders to RDN. However, sVEGFR-1 concentration was dramatically reduced after RDN (5913±385 vs 280±57 pg ml-1, P<0.001). At the same time VEGF-A levels were significantly increased (10.0±3.0 vs 55.5±7.9 pg ml-1, P<0.001), without significant changes in VEGF-C. NO levels were significantly increased after RDN in the whole group (82.6±6.2 vs 106.9±7.8 µM, P=0.021). Interestingly, the elevation in NO levels at 3 months was only seen in patients who demonstrated a reduction in systolic BP of ⩾10 mm Hg (78.9±8.3 vs 111.6±11.7 µM, P=0.018). We report a significant reduction in sVEGFR-1 levels after RDN procedure, which was accompanied by a significant increase in VEGF-A concentration as well as NO. Changes in plasma cytokines were not quantitatively linked to magnitude of BP reduction. An RDN-induced reduction in sVEGFR-1 plasma levels and increase in VEGF-A would raise the VEGF-A/sVEGFR-1 ratio, thereby increasing VEGF-A bioavailability to act on its full-length receptor and may contribute to the BP-lowering effect potentially via NO-mediated pathways.

The role of renal denervation for the treatment of resistant hypertension.

Hypertension affects more than one-fourth of the adult population worldwide and is a major risk factor for cardiovascular and kidney disease. Currently, the majority of patients with hypertension do not reach goal blood pressure (BP) targets, and cardiovascular risk is increased further for patients with treatment-resistant hypertension, defined as office BP above goal despite pharmacological treatment with three or more antihypertensive medications at optimal doses including a diuretic. Although missed diagnosis of secondary forms of hypertension, physician inertia and non-adherence with prescribed medication are important contributors to the phenomenon of resistant hypertension that need to be addressed, there is a need for alternative therapeutic approaches. Renal sympathetic denervation is a minimally invasive endovascular procedure that disrupts renal efferent and afferent neural connections, both of which are important regulators of BP control. Limited data from recent clinical trials indicate that this approach is safe and effectively lowers BP in patients with treatment-resistant hypertension. Accumulating data is emerging to suggest that renal sympathetic denervation may also have utility beyond treatment-resistant hypertension. This review aims to briefly summarize the existing evidence for the use of renal denervation (RDN) in patients with treatment-resistant hypertension and to explore the potential utility of RDN in other pathological states associated with sympathetic dysfunction.

Magnetic field enhanced nano-tip fabrication for four-probe STM studies.

We present an improved method for fabricating tungsten STM tips for measuring nanoscale objects using a multiprobe STM. The tips were prepared by a 'drop-off' technique combined with a magnetic field. For magnetic field strengths above 150 Oe the electrolyte was seen to rotate about the tungsten anode. This rotation reduced the adhesion of bubbles and led to a reduction in the cone angle of the tips produced. This property is advantageous for multiprobe measurements as it allows one to bring multiple tips into close proximity.

Four-probe electrical characterization of Pt-coated TMV-based nanostructures.

The electrical transport and structural properties of tobacco mosaic virus (TMV)-based nanostructures have been studied. Electroless deposition was used to coat the TMV outer surface with a 13 nm thick homogeneous Pt layer. SEM, TEM and electrical characterization of the obtained nanostructures has been performed. Using four independently controlled scanning tunnelling microscope tips we were able to perform four-point probe resistance measurements on linear virus assemblies and demonstrate the continuous nature of the metallic coating. The measured resistivity values of the virial nanowires exceeded the bulk value by 10-100 times; notwithstanding this the coated structure allowed high current densities, of the order of 10(5)-10(8) A cm(-2). The four-probe technique proved to be useful for analysing the electrical properties of bio-inorganic nanowires.

Percutaneous method of laser transmyocardial revascularization.

Laser transmyocardial revascularization (TMR) creates conduits from the left ventricular cavity into the myocardium and has been forwarded as a potential method of perfusing ischemic myocardium. The procedure typically employs a CO2 laser to produce transmyocardial channels from the epicardial to the endocardial surface via an open thoracotomy. Preliminary studies in animals and human subjects have yielded promising results, and clinical trials evaluating the long-term efficacy of the procedure are in progress. We now report the use of a percutaneous method of TMR using a laser delivered through a novel catheter system. To assess the feasibility of performing percutaneous TMR, studies were performed on 15 adult canine subjects utilizing a holmium:YAG laser. Via a femoral artery approach, novel laser catheters were introduced into the left ventricular cavity under fluoroscopic guidance. Biplane coronary angiography, ventriculography, and transesophageal echocardiography were employed to direct catheters to specific regions and assess the efficacy of creating transmyocardial channels. Multiple channels could be created in the anterior, lateral, inferoposterior, and septal regions as demonstrated by contrast ventriculography with confirmation by subsequent gross and histologic examination. The procedure was tolerated well without any ventricular dysfunction or sustained ventricular arrhythmias. We have demonstrated that laser transmyocardial revascularization via a percutaneous approach is feasible with creation of channels from the endocardial surface of the left ventricle into the myocardium. On gross and histological examination, these channels are similar in appearance to those created by the currently employed open chest, epicardial method of TMR.

High-speed rotational atherectomy: six-month serial quantitative coronary angiographic follow-up.

One hundred twenty-three patients treated with high-speed rotational atherectomy (HSRA) were restudied 6.9 +/- 1.2 months later. At the follow-up, the number of focal concentric lesions increased from 32.2 percent to 63.0 percent, p<0.01, with decrease of type C lesions from 54.8 percent to 30.8 percent, p<0.05. Comparison of the degree of the net gain (NG) showed more severe baseline lesions in the high-gain group (NG >20 percent) compared with the moderate-gain group (20 percent > NG > 0 percent) and to the loss group (minimal luminal diameter [MLD] 0.8 +/- 0.4 mm vs 1.0 +/ 0.4 mm, p<0.05; and 1.2 +/- 0.5 mm; p<0.01, respectively). Highest initial gain (36.5 percent +/- 26.2 percent vs 24.5 percent +/- 18.1 percent; p<0.015; and 19.0 percent +/- 23.2 percent; p<0.001) as well as lowest late loss (1.8 percent +/- 21.7 percent vs 14.0 percent +/-18.4 percent; p<0.01 and 28.1 percent +/- 25.0 percent; p<0.01) were found in the high NG group. A higher interaction between burr and atheroma resulted in the lowest restenosis rate of 6 percent.

Outcome of narrowing related side branches after high-speed rotational atherectomy.

High-speed rotational atherectomy (HSRA) is advocated for calcified and diffusely narrowed coronary arteries. There are often side branches involving these kinds of lesions. The presence of significant lesion-related side branches has been considered a relative contraindication to rotational atherectomy. This study was performed to determine the rate, predictors, and outcome of side branch occlusion after HSRA. The angiograms of 418 patients were examined with 320 side branches in 240 target vessels of > or = 1 mm in diameter being identified. Vessels were scored as either perfused (Thrombolysis In Myocardial Infarction 2 or 3 flow) or occluded (Thrombolysis In Myocardial Infarction 0 or 1 flow before and after the procedure. A detailed quantitative angiographic analysis was performed on a total of 108 side branches including all cases of branch occlusion. Clinical outcomes were determined in all cases with side branch loss. There were 24 occlusions in 21 patients after the procedure, giving a rate of branch loss of 7.5%. Follow-up angiography of > or = 24 hours was available for 13 of the occluded branches and 12 were found to be patent. In the 21 patients with branch occlusion, 6 sustained a myocardial infarct (of which 5 were non-Q-wave), 2 underwent coronary artery bypass grafting, and 2 died. There are frequently lesion-associated side branches in the types of vessels to undergo HSRA. These branches remained patent 92.5% of the time, with occlusion occurring infrequently and usually being transient. When occlusion did occur, there was a 29% incidence of myocardial infarction.

Effects of technique modification on immediate results of high speed rotational atherectomy in 710 procedures on 656 patients.

Seven hundred ten high speed rotational atherectomy (HSRA) procedures were performed in a single consecutive series of 656 patients. Stand alone HSRA was performed in 253 patients (35%). HSRA with adjunctive low pressure (< or = 2 ATM) balloon angioplasty (LP BA) was performed in 221 patients (31%), and HSRA with adjunctive high pressure (> or = 4 ATM) balloon angioplasty (HP BA) was performed in 236 patients (34%). Prognostically unfavorable Type B2 and C lesions dominated the study group (74.7%). Procedural success rate was 96%. Emergency coronary artery bypass surgery was performed in 1.4% of cases, Q wave myocardial infarction occurred in 3.4% and death, related to procedure, was consequent in 0.5% of cases. Incidence of flow limiting dissections was 3.1%, distal spasm was 5.3%, and "no reflow" phenomenon was 1.8%. The recent technique modifications included continuous advancer/guiding catheter infusion of the nitroglycerin-verapamil mixture, limitation of duration of lesion engagement by the burr, stepwise increase in the burr size, decrease of rotational speed, and strict control of rpm drop during lesion ablation. Evolution of the interventional technique involved trends towards decrease of the use of HP BA in conjunction with steady increase in the percentage of SA and LP BA procedures over time. These technique changes resulted in complete absence of "no reflow" in 1994, as well as a generalized decrease in overall coronary vascular reactivity from all burr passes.

Myocardial infarction after electrocution.

A case of acute anterior myocardial infarction in a 16-year-old boy who suffered electrocution is described. In spite of extensive electrocardiographic changes of transmural (Q-wave) infarction, left ventricular function was preserved well. Coronary angiography subsequently revealed normal coronary arteries.