Platinum deposition on functionalised graphene for corrosion resistant oxygen reduction electrodes.

Graphene-related materials are promising supports for electrocatalysts due to their stability and high surface area. Their innate surface chemistries can be controlled and tuned via functionalisation to improve the stability of both the carbon support and the metal catalyst. Functionalised graphenes were prepared using either aryl diazonium functionalisation or non-destructive chemical reduction, to provide groups adapted for platinum deposition. XPS and TGA-MS measurements confirmed the presence of polyethyleneglycol and sulfur-containing functional groups, and provided consistent values for the extent of the reactions. The deposited platinum nanoparticles obtained were consistently around 2 nm via reductive chemistry and around 4 nm via the diazonium route. Although these graphene-supported electrocatalysts provided a lower electrochemical surface area (ECSA), functionalised samples showed enhanced specific activity compared to a commercial platinum/carbon black system. Accelerated stress testing (AST) showed improved durability for the functionalised graphenes compared to the non-functionalised materials, attributed to edge passivation and catalyst particle anchoring.

Quantifying impacts of titanium dioxide nanoparticles on natural assemblages of riverine phytobenthos and phytoplankton in an outdoor setting.

Impacts of widespread release of engineered titanium dioxide nanoparticles (nTiO2) on freshwater phytoplankton and phytobenthic assemblages in the field, represents a significant knowledge gap. Using outdoor experiments, we quantified impacts of nTiO2 on phytoplankton and periphyton from UK rivers, applied at levels representative of environmentally realistic concentrations (0.05 mg/L) and hot spots of accumulation (5.0 mg/L). Addition of nTiO2 to river water led to rapid temporal size changes in homoagglomerates and many heteroaggregates of nTiO2 with cells in the phytoplankton, including green algae, pennate and centric diatoms, increasing settlement of some cells. Changes in phytoplankton composition were evident after 72-h resulting from a significant decline in the relative abundance of very small phytoplankton cells (1-3 µm), often accompanied by increases in centric diatoms at both concentrations. Significant changes detected in the composition of the phytobenthos after 12 days, following nTiO2 treatments, were not evident when using benthic diatoms alone after 56 days. A lack of inhibition in the maximum quantum yield (Fv/Fm) in phytobenthos after 72-h exposures contrasted with a significant inhibition in Fv/Fm in 75% of phytoplankton samples, the highest recorded in Rutile nTiO2 exposures at both concentrations of nTiO2. After 12 days, strong positive stimulatory responses were recorded in the maximum relative electron transport rate (rETRmax) and the maximum non-photochemical coefficient (NPQmax), in phytoplankton and phytobenthos samples exposed to the higher Anatase nTiO2 concentration, were not measured in Rutile exposed biota. Collectively, these results indicate that the Rutile phase of nTiO2 has more negative impacts on freshwater algae than the Anatase form, at specific time scales, and phytoplankton may be more impacted by nTiO2 than phytobenthos. We caution that repeated release of nTiO2, could lead to significant changes in riverine algal biomass and species composition, dependent on the phase and concentration of nTiO2.

Early follow-up at outpatient care after discharge improves long-term heart failure readmission rate and prognosis.

AIMS: It has been reported that congestive heart failure (CHF) readmission has not decreased in the last decade. It is also reported that CHF readmission is likely to occur shortly after discharge. We investigated whether an early follow-up at outpatient care within 2 weeks after discharge affects the long-term readmission rate and prognosis. METHODS AND RESULTS: We reviewed consecutive 1002 patients admitted to our hospital due to CHF. Two-hundred and fifty-nine patients who died in-hospital or were transferred to another hospital or readmitted within 2 weeks were excluded and 743 of discharged patients were analysed. We extracted contributing variables associated with heart failure (HF) readmission and the composite adverse outcome (all cause death or HF readmissions) by univariate and multivariate analysis. Multivariate analysis showed that the early follow-up was independently associated with freedom from HF readmission and the composite outcome. We divided these patients into two groups, with/without early follow-up and performed a propensity score-matching analysis (n = 259 each). HF readmission during 2 year follow-up was significantly less in the early follow-up group [P = 0.02, hazard ratio (HR) = 0.647, 95% confidence interval (CI) = 0.447-0.935] as well as the composite outcome was less in the early follow-up group (P = 0.01, HR = 0.643, 95% CI = 0.456-0.908). Medication adjustments were done in only 33.2% of the patients. Rates of HF readmissions were comparable regardless of whether or not medication adjustment was done at the early follow-up (P = 0.505, HR = 1.208, 95% CI = 0.692-2.106). CONCLUSIONS: The present study demonstrates that an early follow-up approach after discharge in CHF patients may improve the long-term prognosis. These results may not depend on medication adjustment but rather on modifying patient factors early after discharge.

Quantification of blood-brain barrier transport and neuronal toxicity of unlabelled multiwalled carbon nanotubes as a function of surface charge.

Nanoparticles capable of penetrating the blood-brain barrier (BBB) will greatly advance the delivery of therapies against brain disorders. Carbon nanotubes hold great potential as delivery vehicles due to their high aspect-ratio and cell-penetrating ability. Studies have shown multiwalled carbon nanotubes (MWCNT) cross the BBB, however they have largely relied on labelling methods to track and quantify transport, or on individual electron microscopy images to qualitatively assess transcytosis. Therefore, new direct and quantitative methods, using well-defined and unlabelled MWCNT, are needed to compare BBB translocation of different MWCNT types. Using highly controlled anionic (-), cationic (+) and non-ionic (0) functionalized MWCNT (fMWCNT), we correlate UV-visible spectroscopy with quantitative transmission electron microscopy, quantified from c. 270 endothelial cells, to examine cellular uptake, BBB transport and neurotoxicity of unlabelled fMWCNT. Our results demonstrate that: (i) a large fraction of cationic and non-ionic, but not anionic fMWCNT become trapped at the luminal brain endothelial cell membrane; (ii) despite high cell association, fMWCNT uptake by brain endothelial cells is low (<1.5% ID) and does not correlate with BBB translocation, (iii) anionic fMWCNT have highest transport levels across an in vitro model of the human BBB compared to non-ionic or cationic nanotubes; and (iv) fMWCNT are not toxic to hippocampal neurons at relevant abluminal concentrations; however, fMWCNT charge has an effect on carbon nanotube neurotoxicity at higher fMWCNT concentrations. This quantitative combination of microscopy and spectroscopy, with cellular assays, provides a crucial strategy to predict brain penetration efficiency and neurotoxicity of unlabelled MWCNT and other nanoparticle technologies relevant to human health.

Plaque modification using a cutting balloon is more effective for stenting of heavily calcified lesion than other scoring balloons.

Cutting balloons (CBs) and other scoring balloons are known to be useful for plaque modification in heavily calcified lesions. There have been some reports of the efficacy of these balloons compared to conventional balloons. However, there have been no reports exploring which balloon is most effective among these three types of balloons. We, therefore, compared these three balloons with respect to effectiveness in plaque modification of calcified lesions. We retrospectively investigated 201 cases using these three balloons from April 2015 to December 2017. Of these cases, 156 with severe calcified lesions that had undergone intravascular ultrasound (IVUS) or optical frequency domain imaging (OFDI) were enrolled. The ratio of severe calcified lesion was higher in the CB group than in the groups of other balloons (p = 0.001), and IVUS and OFDI showed that a CB was more effective in plaque modification than the other balloons. The acute gain (minimum stent diameter minus minimum lumen diameter) and acute cross-sectional area (CSA) gain (minimum stent area minus minimum lumen area) were both larger in the CB group than in the others, and the stent symmetry index (minimum stent diameter/maximum stent diameter) showed that the CB group more closely approximated a perfect circle than the other groups (p = 0.0001, 0.006 and 0.002 for the acute gain, acute CSA gain and the stent symmetry index). Similar results were obtained in cases without rotational atherectomy. These data suggest that CB is more effective for plaque modification in cases of severe calcified lesions than other scoring balloons.

A case of coronary subclavian vertebral steal syndrome successfully treated with stenting to the stenosis of left subclavian artery.

Coronary subclavian vertebral steal syndrome (CSVSS) is a rare but important complication of coronary artery bypass graft surgery (CABG) when an internal mammary artery (IMA) is used. This syndrome is defined as a retrograde flow from coronary artery via the IMA and the vertebral artery to the subclavian artery due to a proximal subclavian artery stenosis. We describe a case of a 64-year-old female who underwent CABG, complaining of dyspnea and chest pain by exercise of left arm, and dizziness when she turned her face to the left. Her blood pressure was 113/69 mmHg in the left arm and 137/84 mmHg in the right arm. Coronary angiography revealed retrograde flow from the left anterior descending (LAD) artery to the left IMA. Aortography showed that the ostium of the left subclavian artery had a severe stenosis and that the left vertebral artery was visualized retrogradely. Thereby, the diagnosis of CSVSS was made. The stenosis of the left subclavian artery was successfully treated with a percutaneous transluminal angioplasty and stent implantation, resulting in the restoration of antegrade flow from the left IMA to the LAD artery and from the left subclavian artery to the left vertebral artery. She was discharged with no chest pain and dizziness. .

A case of Kounis syndrome associated with transcatheter arterial chemoembolization for hepatocellular carcinoma.

Kounis syndrome, which is known as allergic angina and allergic myocardial infarction today, was described as the coexistence of acute coronary syndrome with allergic reactions in 1991 by Kounis and Zavras. We report a case of a 79-year-old man with hypertension, hepatocellular carcinoma (HCC), and no allergic history. He had received transcatheter arterial chemoembolization (TACE) for treatment of HCC five times without allergic reactions. At the sixth time of TACE, he presented an anaphylactic reaction such as systemic erythema and severe arterial hypotension. Simultaneously, he complained of anterior chest pain and electrocardiogram showed significant ST segment elevation in inferior leads, indicating inferior myocardial infarction. Emergency coronary angiography, however, did not demonstrate any organic stenoses or occluded lesions of the coronary arteries. We made the diagnosis of Kounis syndrome associated with TACE. Although Kounis syndrome is a rare condition, physicians should be aware of possible co-occurrence of anaphylactic reactions and acute coronary syndrome. .

Pitavastatin-incorporated nanoparticle-eluting stents attenuate in-stent stenosis without delayed endothelial healing effects in a porcine coronary artery model.

AIM: The use of currently marketed drug-eluting stents presents safety concerns including increased late thrombosis, which is thought to result mainly from delayed endothelial healing effects (impaired re-endothelialization resulting in abnormal inflammation and fibrin deposition). We recently developed a bioabsorbable polymeric nanoparticle (NP)-eluting stent using a novel cationic electrodeposition technology. Statins are known to inhibit the proliferation of vascular smooth muscle cells (VSMC) and to promote vascular healing. We therefore hypothesized that statin-incorporated NP-eluting stents would attenuate in-stent stenosis without delayed endothelial healing effects. METHODS: Among six marketed statins, pitavastatin (Pitava) was found to have the most potent effects on VSMC proliferation and endothelial regeneration in vitro. We thus formulated a Pitava-NP-eluting stent (20µg Pitava per stent). RESULTS: In a pig coronary artery model, Pitava-NP-eluting stents attenuated in-stent stenosis as effectively as polymer-coated sirolimus-eluting stents (SES). At SES sites, delayed endothelial healing effects were noted, whereas no such effects were observed in Pitava-NP-eluting stent sites. CONCLUSION: Pitava-NP-eluting stents attenuated in-stent stenosis as effectively as SES without the delayed endothelial healing effects of SES in a porcine coronary artery model. This nanotechnology platform could be developed into a safer and more effective device in the future.

Imatinib mesylate-incorporated nanoparticle-eluting stent attenuates in-stent neointimal formation in porcine coronary arteries.

AIM: The use of currently marketed drug-eluting stents (DES) presents safety concerns, including an increased risk for late thrombosis in the range of 0.6% per year in patients, including acute coronary syndrome, which is thought to result from delayed endothelial healing effects. A new DES system targeting vascular smooth muscle cells without adverse effects on endothelial cells is therefore needed. Platelet-derived growth factor (PDGF) plays a central role in the pathogenesis of restenosis; therefore, we hypothesized that imatinib mesylate (PDGF receptor tyrosine kinase inhibitor) encapsulated bioabsorbable polymeric nanoparticle (NP)-eluting stent attenuates in-stent neointima formation. METHODS: Effects of imatinib-incorporated NP-eluting stent on neointima formation and endothelial healing were examined in a pig coronary artery stent model. Effects of imatinib-NP were also examined in cultured cells. RESULTS: In a cultured cell study, imatinib-NP attenuated the proliferation of vascular smooth muscle cells associated with inhibition of the target molecule (phosphorylation of PDGF receptor-ß), but showed no effect on endothelial proliferation. In a pig coronary artery stent model, imatinib-NP-eluting stent markedly attenuated in-stent neointima formation and stenosis by approximately 50% as assessed by angiographic, histopathological, and intravascular ultrasound imaging analyses. Imatinib-NP-eluting stent also attenuated MAP kinase activity, but did not affect inflammation and re-endothelialization. CONCLUSION: These data suggest that suppression of neointima formation by a imatinib-NP-eluting stent holds promise as a molecular-targeting NP delivery system for preventing in-stent restenosis.

Formulation of nanoparticle-eluting stents by a cationic electrodeposition coating technology: efficient nano-drug delivery via bioabsorbable polymeric nanoparticle-eluting stents in porcine coronary arteries.

OBJECTIVES: The objective of this study was to formulate a nanoparticle (NP)-eluting drug delivery stent system by a cationic electrodeposition coating technology. BACKGROUND: Nanoparticle-mediated drug delivery systems (DDS) are poised to transform the development of innovative therapeutic devices. Therefore, we hypothesized that a bioabsorbable polymeric NP-eluting stent provides an efficient DDS that shows better and more prolonged delivery compared with dip-coating stent. METHODS: We prepared cationic NP encapsulated with a fluorescence marker (FITC) by emulsion solvent diffusion method, succeeded to formulate an NP-eluting stent with a novel cation electrodeposition coating technology, and compared the in vitro and in vivo characteristics of the FITC-loaded NP-eluting stent with dip-coated FITC-eluting stent and bare metal stent. RESULTS: The NP was taken up stably and efficiently by cultured vascular smooth muscle cells in vitro. In a porcine coronary artery model in vivo, substantial FITC fluorescence was observed in neointimal and medial layers of the stented segments that had received the FITC-NP-eluting stent until 4 weeks. In contrast, no substantial FITC fluorescence was observed in the segments from the polymer-based FITC-eluting stent or from bare metal stent. The magnitudes of stent-induced injury, inflammation, endothelial recovery, and neointima formation were comparable between bare metal stent and NP-eluting stent groups. CONCLUSIONS: Therefore, this NP-eluting stent is an efficient NP-mediated DDS that holds as an innovative platform for the delivery of less invasive nano-devices targeting cardiovascular disease.