Accurately quantifying the reductive capacity of microbial extracellular polymeric substance by mediated electrochemical oxidation method.

The reductive capacity of microbial extracellular polymeric substances (EPS) plays important roles in environmental processes involved in heavy metal detoxification and organic contaminant degradation. However, the crucial parameter to evaluate the reductive capacity of EPS, electron donating capacity (EDC) lacks a quantitative approach. In this study, a novel mediated electrochemical oxidation (MEO) method was developed to investigate the EDCs of microbial EPS extracted from Shewanella oneidensis MR-1 (S. oneidensis MR-1), Escherichia coli (E. coli) and activated sludge. The results indicate that the MEO approach rapidly and accurately quantifies the EDCs of microbial EPS. S. oneidensis MR-1 EPS possessed the highest EDC value ascribed to their specific redox proteins components. EDCs of S. oneidensis MR-1 EPS were dependent on measurement conditions and increased with growing solution pH and applied potential. EDCs of S. oneidensis MR-1 EPS were depleted gradually during the redox reaction with irreversible oxidation of EPS. The reductive property of microbial EPS was accurately evaluated by quantifying the EDCs of EPS using the MEO approach, as well as their potential in environmental remediation.

[Carotid artery stenosis treated with modified carotid endarterectomy: report of two cases].

OBJECTIVE: Based on standard carotid endarterectomy, we performed modified carotid endarterectomy in two cases of carotid artery stenosis by changing the direction of the carotid artery incision to avoid restenosis of the internal carotid artery without using a patch. The two patients recovered smoothly without any complications. Compared with eversion or patch endarterectomy, this modified carotid endarterectomy avoids restenosis of the carotid artery and shortens operation time.

Hairy/enhancer of Split Homologue-1 Suppresses Vascular Endothelial Growth Factor-induced Angiogenesis via Downregulation of Osteopontin Expression.

Angiogenesis plays a critical role in the progression and vulnerability of atherosclerotic plaques; however, the orchestration of angiogenesis in atherosclerotic plaque formation remains unclear. The results of microarray analysis, real-time PCR and immunohistochemical analyses showed that Hairy/enhancer of split homologue-1 (Hes-1) expression was significantly decreased, while that of osteopontin (OPN) was increased, in atherosclerotic plaques. Meanwhile, immunofluorescence results demonstrated that both Hes-1 and OPN were expressed in endothelial cells (ECs) of neovessels in atherosclerotic plaques. The results of an in vitro study showed that Hes-1 was downregulated, while OPN was upregulated, in a time- and dose-dependent manner in human umbilical vein endothelial cells (HUVECs) by VEGF treatment. In addition, Hes-1 knockdown was found to have transcriptional promotion effect on OPN expression in HUVECs and enhance OPN-induced angiogenesis in response to VEGF. On the contrary, Hes-1 overexpression inhibited OPN expression in HUVECs and reduced angiogenesis in vitro and in vivo. The results of this study suggest that decreased Hes-1 expression in atherosclerotic plaques exaggerate VEGF-induced angiogenesis by upregulating OPN. Therefore, restoring Hes-1 expression and inhibiting OPN expression may be a promising strategy to prevent vulnerable plaque formation in patients with atherosclerosis.

Denitrification in an integrated bioelectro-photocatalytic system.

Since nitrate causes severe ecological and health risks, nitrate contamination of drinking water sources has become one of the most important water quality concerns all over the world. Photocatalytic reduction of nitrate to molecular nitrogen presents a promising approach to remove nitrate from drinking water sources. However, harmful intermediates like NO2-, NO, NO2 and N2O are usually formed, and metal loading or hole scavengers are generally needed to reduce the recombination of photo-generated electrons and holes, which will cause secondary pollution to drinking water. In this work, an efficient, selective and sustainable bioelectro-photocatalytic nitrate-reducing system by utilizing commercial TiO2 nanoparticles P25 as the photocatalyst and bio-electrons from microbial metabolism as the hole scavenger is reported. In this system, bio-electrons extracted from organic substrates in bioanode are transferred to the photocathode through an external circuit for hole quenching. With the utilization of the residual photogenerated electrons, nitrate is completely reduced to nitrogen without accumulation of harmful nitrite or ammonium. The experimental results and the mechanistic analysis using the first-principles density functional theory calculations demonstrate that toxic by-products like nitrite or ammonium will not be accumulated in this system. Thus, this approach has a great potential for sustainable remediation of nitrate-contaminated drinking water sources.

Spectroscopic characterization of the complexes between Fe/Mn and natural organic matters by electron paramagnetic resonance and synchrotron-based techniques.

The surface interaction between heavy metals and natural organic matters (NOM) substantially affects their migration and conversion in natural environments. In this study, the chemical speciation and element mapping of Fe and Mn in reduced NOM were investigated. The results show that quinone and semiquinone moieties dominated the redox properties in NOM, and the EPR signal intensity exhibited pH dependence with an increase of EPR signal intensity at a higher pH value. The EPR results indicate that the complexes displayed the characteristics of superparamagnetic oxides/oxyhydroxides after Fe/Mn complexed with NOM. µ-XRF results suggest that the scatterplots of Fe and Mn distributions at pH 11 had the most positive linearly-related plot points, indicating strong correlations for Mn-Fe binary metallic ions. µ-XANES results further interpret the presence of higher Mn oxidation state at pH 11, while Fe kept trivalent in all samples. These results reveal that the surface interactions are closely related to the redox state of NOM and are beneficial for better understanding the speciation, immobilization, transport, and toxicity of metal ions in natural waters.

[Hybrid operation for acute left leg deep venous thrombosis secondary to left iliac vein compression syndrome: analysis of 36 cases].

OBJECTIVE: To evaluate the surgical techniques for acute left deep venous thrombosis (LDVT) secondary to left iliac vein compression syndrome (IVCS). METHODS: Thirty-six patients with acute LDVT secondary to IVCS received inferior vena cava filter placement, and in 2 of the cases, stent implantation was canceled for acute episode of obsolete DVT. The remaining 34 patients underwent left femoral venotomy for iliofemoral thrombectomy with Fogarty catheter and distal femoral vein thrombus removal by sequential compression of the legs, followed by implantation of stent-graft (2 cases) or bare-metal stents (32 cases) in the left common iliac veins. With routine anticoagulation and thrombolytic treatments, the patients were regularly examined for postoperative blood flow in the affected limb. RESULTS: In 2 of the cases undergoing bare-metal stent implantation, the residue thrombi were squeezed into the stent by balloon, which was managed subsequently with local thrombolysis. One patient with bare-metal stent implantation received a secondary stenting for posterior stent displacement. Three patients had self-limited bleeding due to decreased serum FBG. Significant improvements were achieved at 3, 6, 30 and 180 days postoperatively in the circumferences of the affected limb (P<0.05) and in the levels of D-dimer (P=0.011), and FBG level showed no significant variations (F=1.163, P=0.345). The total rate of excellent outcomes was 83.3% (26/34) with a total effective rate of 91.2% (31/34) in these cases. CONCLUSIONS: Thrombectomy to revascularize the inflow tract and stent implantation to enlarge stenosed iliac veins are key issues in treatment of acute LDVT secondary to IVCS.

A plate-based electrochromic approach for the high-throughput detection of electrochemically active bacteria.

Electrochemically active bacteria (EAB) have the ability to transfer electrons to electron acceptors located outside the cell, and they are widely present in diverse environments. In spite of their important roles in geochemical cycles, environmental remediation and electricity generation, so far, only a limited number and types of EAB have been isolated and characterized. Thus, effective and rapid EAB identification methods are highly desirable. In this protocol, we describe a photometric protocol for the visualization and high-throughput identification and isolation of EAB. The protocol relies on the fast electron acquisition and color change ability of an electrochromic material, namely a tungsten trioxide (WO3) nanorod assembly. The extracellular electron transfer (EET) from EAB to the WO3 nanorod assembly probe is accompanied by a bioelectrochromic reaction made evident by the color change of the probe. This protocol enables researchers to rapidly identify EAB and evaluate their EET ability either qualitatively with the naked eye or quantitatively by image analysis. We have also successfully used this protocol to isolate EAB from environmental samples. The time needed to complete this protocol is ∼2 d, with the actual EAB identification process taking about 5 min.

Nitrate formation from atmospheric nitrogen and oxygen photocatalysed by nano-sized titanium dioxide.

The concentration of nitrate in aquatic systems is rising with the development of modern industry and agriculture, causing a cascade of environmental problems. Here we describe a previously unreported nitrate formation process. Both indoor and outdoor experiments are conducted to demonstrate that nitrate may be formed from abundant atmospheric nitrogen and oxygen on nano-sized titanium dioxide surfaces under UV or sunlight irradiation. We suggest that nitric oxide is an intermediate product in this process, and elucidate its formation mechanisms using first-principles density functional theory calculations. Given the expanding use of titanium dioxide worldwide, such a titanium dioxide-mediated photocatalysis process may reveal a potentially underestimated source of nitrate in the environment, which on one hand may lead to an increasing environmental pollution concern, and on the other hand may provide an alternative, gentle and cost-effective method for nitrate production.

A photometric high-throughput method for identification of electrochemically active bacteria using a WO3 nanocluster probe.

Electrochemically active bacteria (EAB) are ubiquitous in environment and have important application in the fields of biogeochemistry, environment, microbiology and bioenergy. However, rapid and sensitive methods for EAB identification and evaluation of their extracellular electron transfer ability are still lacking. Herein we report a novel photometric method for visual detection of EAB by using an electrochromic material, WO(3) nanoclusters, as the probe. This method allowed a rapid identification of EAB within 5 min and a quantitative evaluation of their extracellular electron transfer abilities. In addition, it was also successfully applied for isolation of EAB from environmental samples. Attributed to its rapidness, high reliability, easy operation and low cost, this method has high potential for practical implementation of EAB detection and investigations.

[Efficacy of regional administration of urokinase and argatroban via small saphenous vein catheter for treatment of acute deep venous thrombosis in the lower limb].

OBJECTIVE: To investigate the clinical value of local regional administration of urokinase and argatroban through small saphenous vein (SSV) catheter in the treatment of acute deep venous thrombosis in the lower limb (LDVT). METHODS: Fifty-six patients with acute LDVT were prospectively randomized into the study group (21 cases, 24 limbs) and control group (35 cases, 36 limbs) for treatment with urokinase and argatroban regionally administered via the SSV catheter and with the same agents given via the peripheral vein, respectively. The patients were examined for changes in serum fibrinogen (FBG) and D-dimer and the perimeter of the affected limbs, and the complications in relation to the agents were observed. RESULTS: By corrected Chi-square test, the incidence of complications was significantly lower in the study group than in the control group (1/21 vs 4/36, χ(2)=1.92, P≤0.05). Wilcoxon's sign rank test suggested no statistically significant difference between the two groups in the total effective rate (95.8% vs 94.4%, V=0.52, P>0.05), but the total excellent rate differed significantly between them (83.3% vs 55.6%, V=2.36, P≤0.05). Serum FBG underwent no significant variations in the study group during thrombolysis (P>0.05), but decreased significantly in the control group (P≤0.05). The decreases in serum D-dimer and perimeter of the affected limbs occurred earlier in the study group than in the control group (P≤0.05). CONCLUSION: Regional administration of urokinase and argatroban via small saphenous vein catheter can promote the thrombolytic effect and reduce the risk of hemorrhage in the treatment of LDVT.

Degradation of organic pollutants in a photoelectrocatalytic system enhanced by a microbial fuel cell.

Photocatalytic oxidation mediated by TiO(2) is a promising oxidation process for degradation of organic pollutants, but suffers from the decreased photocatalytic efficiency attributed to the recombination of photogenerated electrons and holes. Thus, a cost-effective supply of external electrons is an effective way to elevate the photocatalytic efficiency. Here we report a novel bioelectrochemical system to effectively reduce p-nitrophenol as a model organic pollutant with utilization of the energy derived from a microbial fuel cell. In such a system, there is a synergetic effect between the electrochemical and photocatalytic oxidation processes. Kinetic analysis shows that the system exhibits a more rapid p-nitrophenol degradation at a rate two times the sum of rates by the individual photocatalytic and electrochemical methods. The system performance is influenced by both external resistor and electrolyte concentration. Either a lower external resistor or a lower electrolyte concentration results in a higher p-nitrophenol degradation rate. This system has a potential for the effective degradation of refractory organic pollutants and provides a new way for utilization of the energy generated from conversion of organic wastes by microbial fuel cells.

Ultrasound ablation of intravascular plaque for treating atherosclerosis obliterans of bilateral iliofemoral arteries: report of one case.

OBJECTIVE: A patient with atherosclerosis obliterans of bilateral iliofemoral arteries was successfully treated by ultrasound ablation of intravascular plaque, who had an uneventful postoperative recovery.