Treatment of petrochemical secondary effluent by an up-flow biological aerated filter (BAF)

In this study, petrochemical secondary effluent was treated by a 55 cm diameter pilot-scale biological aerated filter (BAF) with a media depth of 220 cm. Volcanic rock grains were filled as the BAF media. Median removal efficiency of chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) was 29.35 and 57.98%, respectively. Moreover, the removal profile of the COD, NH3-N, total nitrogen and total organic carbon demonstrated that the filter height of 140 cm made up to 90% of the total removal efficiency of the final effluent. By gas chromatography-mass spectrometry, removal efficiencies of 2-chloromethyl-1,3-dioxolane, and benzonitrile, indene and naphthalene were obtained, ranging from 30.12 to 63.01%. The biomass and microbial activity of the microorganisms on the filter media were in general reduced with increasing filter height, which is consistent with the removal profile of the contaminants. The detected genera Defluviicoccus, Betaproteobacteria_unclassified and the Blastocatella constituted 1.86-6.75% of the identified gene, enhancing the COD and nitrogen removal in BAF for treating petrochemical secondary effluent.

3D Modelling on Biodegradable Nanoparticle-Enhanced Cryoablation of Liver Tumor Based on Real Anatomical Model

BACKGROUND

Nanoparticle-enhanced freezing is of great importance for developing a conformal targeted cryoablation for liver tumor with complex shape. However, the safety and biocompatibility of nanoparticles should also be of major concerns.

OBJECTIVE

This study is to investigate the enhanced cryoablation mediated by the MgO nanoparticles which are nontoxic, biodegradable, and have few side-effects on the human body.

MATERIALS AND METHODS

A three-dimensional numerical model has been developed based on a real geometrical anatomical structure to characterize such nanocryosurgical freezing of liver tumor. The evolutions of temperature field and ablation volume were investigated subject to different concentrations and scopes of the loaded nanoparticles, respectively. Additionally, the results of different probe numbers were also taken into consideration.

RESULTS

It was found that the lesion growth was evidently affected by the configurations of both the nanoparticles and cryoprobes. Both ablation and frozen regions were enlarged with the increase of the loading ratio and scope of MgO nanoparticles. It was worth mentioning that thermal-physiological behavior of the adjacent large blood vessels also played an important role in affecting the target temperature field distribution.

CONCLUSION

The present study established a feasible way for verisimilarly simulating the physiological manifestation of human liver in the process of nano-freezing modality, which would provide a valuable guidance for future clinical practice of conformal nano-cryoablation on liver tumor.

Effect of gene polymorphims on the warfarin treatment at initial stage

The adverse reactions of warfarin that were found mainly occurred in the first month. This study was carried out to observe the effect of gene polymorphisms on the warfarin therapy at the initial stage. Four-hundred and sixty Chinese patients began warfarin treatment with daily 2.5 mg after heart valve replacement operations were enrolled. The daily international normalized ratio (INR) for anticoagulation were recorded till the seventh day. Blood samples were collected and used to detect genotypes for VKORC1 rs7294, CYP2C9 rs1057910, CYP4F2 rs2108622 and ORM1 rs17650. INR and their changes were compared among genotypes. INR was partially correlated with the VKORC1 rs7294, CYP2C9 rs1057910, CYP4F2 rs2108622 and ORM1 rs17650 polymorphisms from the third, fourth and sixth day on, respectively. VKORC1 rs7294 and CYP4F2 rs2108622 carriers responded lower than the wild genotype, whereas CYP2C9 rs1057910 and ORM1 rs17650 carriers responded higher, respectively. Fifty percent of AA/*1*3/CC/*S*S patients and 16% of AA/*1*1/CC/*S*S patients were over anticoagulation treated with INR >4.0 at the third day. Ninety percent of VKORC1 rs7294 carrier patients have INR <1.63, a mark of the 25% of lower responders of the wild genotype. Our study provided another kind of evidence that VKORC1 rs7294, CYP2C9 rs1057910, CYP4F2 rs2108622 and ORM1 rs17650 affected the action of warfarin in different styles. Patients with AA/*1*1/CC/*S*S, AA/*1*3/CC/*S*S should use a less initial dosage to avoid over anticoagulation, and patients with VKORC1 rs7294 should use larger initial dose to proof an effective therapy.

[Assessment of quality of life after multiple arthroplasty]

OBJECTIVE

To evaluate the effectiveness of conducting multiple arthroplasty to treat multiple joints disease in terms of quality of life (QOL) and function improvement.

METHODS

We compared our results with the reported results of single and dual arthroplasty to see if there is any improvement in QOL, functional scores or complications. In this study, 13 patients admitted to Department of Adult Reconstructive Surgery, Beijing Jishuitan hospital from 2005 to 2009 were included. Questionnaires SF-36 were used to evaluate the QOL. Harris hip score, American Knee Society Score (KSS) were used to evaluate the joint function. The patients were evaluated before surgery to the latest follow up.

RESULTS

SF-36 has changed as follow: physical function 4.17 ± 14.43 → 65.83 ± 24.76, role physical 25.00 ± 26.11 → 60.42 ± 45.8, bodily pain 23.83 ± 21.41 → 76.88 ± 20.89, general health 53.33 ± 33.87 → 76.67 ± 14.67, vitality 50.42 ± 17.25 → 71.67 ± 16.28, social functioning 29.17 ± 33.50 → 73.96 ± 33.90, role emotional 22.08 ± 35.61 → 77.77 ± 41.03, mental health 53.33 ± 25.70 → 82.67 ± 14.41, which indicated that they all improved greatly after the surgery (P < 0.05). Harris score increased from 37.68 ± 14.71 before the surgery to 83.36 ± 13.54 after the surgery. KSS has also showed sharp improvement (P < 0.001) in both clinical score (42.52 ± 23.83 → 77.74 ± 20.67) and function score (-2.61 ± 22.56 → 65.65 ± 30.76).

CONCLUSION

Multiple arthroplasty is one of the most effective methods which can markedly improve the quality of life in patients with multiple joints disease. But complications are common and joint functions are relatively poor.

[Comparative study of total hip arthroplasty with subtrochanteric osteotomy for treating Hartofilakidis types C1 and C2 developmental dysplasia of the hip]

OBJECTIVE

To compare efficacies and complications of total hip arthroplasty (THA) with subtrochanteric osteotomy for treating patients with Hartofilakidis types C1 and C2 developmental dysplasia of the hip (DDH).

METHODS

Retrospective analysis was performed in 32 patients with DDH who underwent THA. These patients were divided into two groups according to Hartofilakidis classification, 17 patients in type C1 and 15 in type C2. Their HSS and WOMAC scores, leg length discrepancy (LLD), hip joint image data and complications were evaluated.

RESULTS

HSS scores in type C1 was changed from preoperative 43.7±4.6 to postoperative 87.2±7.1 (P<0.001), together with WOMAC scores 43.6±4.3 to 87.5±6.7 (P<0.001). HSS scores in type C2 was changed from preoperative 44.4±5.4 to postoperative 86.5±8.0 (P<0.001), together with WOMAC scores 44.1±4.1 to 86.7±8.1 (P<0.001). Four cases in type C2 and one case in type C1 presented intraoperative fracture which all healed during the postoperative follow-up. The postoperative X-ray films showed that the joint prosthesis location was satisfactory, the surrounding bone was not dissolved and the bone at femur osteotomy site healed with no infection.

CONCLUSION

For unilateral high dislocation DDH patients, THA with femur osteotomy can be effective and safe. No significant differences were found between types C1 and C2, however intraoperative fracture in type C2 should be paid attention to.

[Source identification of toxic wastewaters in a petrochemical industrial park]

Petrochemical wastewaters have toxic impacts on the microorganisms in biotreatment processes, which are prone to cause deterioration of effluent quality of the wastewater treatment plants. In this study, the inhibition effects of activated sludge's oxygen consumption were tested to evaluate the toxicity of production wastewaters in a petrochemical industrial park. The evaluation covered the wastewaters from not only different production units in the park, but also different production nodes in each unit. No direct correlation was observed between the toxicity effects and the organic contents, suggesting that the toxic properties of the effluents could not be predicted by the organic contents. In view of the variation of activated sludge sensitivity among different tests, the toxicity data were standardized according to the concentration-effect relationships of the standard toxic substance 3, 5-dichlorophenol on each day, in order to improve the comparability among the toxicity data. Furthermore, the Quality Emission Load (QEL) of corresponding standard toxic substance was calculated by multiplying the corresponding 3, 5-dichlorophenol concentration and the wastewater flow quantity, to indicate the toxicity emission contribution of each wastewater to the wastewater treatment plant. According to the rank list of the toxicity contribution of wastewater from different units and nodes, the sources of toxic wastewater in the petrochemical industrial park were clearly identified. This study provides effective guidance for source control of wastewater toxicity in the large industrial park.

[Species selection methods in deriving water quality criteria for aquatic life]

The Mann-Whitney U test method was used to analyze the species sensitivity to ammonia toxicity. And based on the analysis, the relationship between species selection method and WQC deriving method was studied by using toxicology, biological taxonomy and sampling-inference theory. Results showed that vertebrate species, especially the Actinopterygii, accounted for the vast majority in the toxicity test species. And the species composition of toxicity test species was inconsistent with the species composition of the ecosystem. Sensitivity to ammonia toxicity among different taxa varied significantly for most species except some species in individual taxa, especially the less sensitive species. The variable coefficient of interspecies decreased with the reduction of biological classification level. To a certain extent, it showed that the species sensitivities in the same taxa to toxicant were more similar than those in different taxa. According to sampling-inference theory, the WQC for aquatic life deriving method belonged to the design-based inference. And taxonomic groups could be used as auxiliary variables to conduct a stratifactory sampling for species selection in WQC deriving which could improve the sampling efficiency and precision.

[Denitrification performance of PBS as a solid carbon source of denitrification]

Poly-butylenes succinate (PBS) was used as solid denitrification carbon source and biofilm carrier, to investigate the denitrification performance and the influence of adding inert carrier. The experimental results showed that PBS could serve as solid carbon source for denitrification of low C/N ratio wastewater, but the startup time was longer, about 33 d. There was no accumulation of nitrite nitrogen in the process of denitrification, but it produced less than 0.8 mg x L(-1) ammonia nitrogen. Increasing the amount of biofilm in PBS supported denitrification system by adding the inert carrier could improve the denitrification rate. The denitrification rates of PBS, PBS + 30 g gravel, PBS + 60 g gravel and PBS +90 g gravel systems were 5.33, 7.04, 10.05 and 6.93 mg x (L x h)(-1), respectively, and all reactions were zero order. During the denitrification process (0-9 h), DOC increased before it was reduced. At the end of the denitrification reaction (24 h), DOC of the denitrification system with inert carrier 60 g gravel and 90 g gravel was 16.34 mg x L(-1) and 19.22 mg x L(-1), respectively, higher than that without gravel of 13.48 mg x L(-1). The pH of all denitrification systems were lower than the initial value, which was the result of comprehensive function of acidic substances and alkalinity produced in the process of degradation of solid carbon source and denitrification, respectively.

[Variation characteristics and removal rate of fluorescence organic matter in the petrochemical wastewater treatment process]

Petrochemical wastewater is of huge quantity released during the production and complicated contaminants of petrochemical wastewater will have immense negative impact on ecology environment. Three-dimensional excitation-emission matrix fluorescence(3D-EEM) was used to investigate the characteristic fluorescence of influent and effluent from each processing unit of Hydrolysis-acidification +A/O+ Contact-oxidation Process in a typical petrochemical wastewater treatment plant . The results showed that there were 4 fluorescence peaks named Peak A, Peak B, Peak D, Peak E in the spectrum chart of influent, they are around lambda(ex/lambda(em) = 220/300, 225/340, 270/300, 275/340 nm, the primary source of fluorescence organic matter(FOM) is industrial wastewater. The fluorescence intensity of each fluorescence peak was decreased, while location was unchanged in the effluent of Hydrolysis-acidification. Peak C appeared from the effluent of anaerobic tank at lambda(ex)/lambda(em) = 250/425 nm, then the fluorescence intensity of Peak C was enhanced in the effluent of aerobic tank. Peak A disappeared from the effluent of secondary sedimentation tank. The spectrum chart of the wastewater had no obvious variation after secondary sedimentation tank. The removal rate of FOM was expressed with the degradation percentage of the fluorescence intensity, the total FOM was reduced by 92.0% after processing, and the removal rate of the FOM fluoresce around Peak A, Peak B, Peak D, Peak E were 100.0%, 91.2%, 80.3%, 92.0% respectively. A volatile I(Peak B)/I(Peak E) value of influent but a relatively stable value of effluent demonstrated that the wastewater treatment plant operated steadily and the process has higher capacity in resistance to shock loading.

[Treatment of petrochemical secondary effluent by ozone-biological aerated filter]

The advanced treatment of petrochemical secondary wastewater by ozone- aerated biological filter was carried out in this study. The effect of pH on ozonation and the removal of COD and UV254 by the ozone-aerated biological filter combined process were investigated. In addition, the variation of relative molecular mass distribution of organics and the characteristics of three-dimensional fluorescence spectra of the wastewater were also investigated. The results showed that the suitable operating conditions of the ozonation unit were: ozone dosage 10 mg x L(-1), contact time 4 min and slightly alkaline pH. Ozonation can transfer macromolecular organics into small molecular organics, resulting in a 15% increase in the percentage of the organics with small relative molecular mass (less than 1 000). The biodegradability of the petrochemical secondary effluent was significantly improved by ozonation, making it more suitable for the treatment by aerated biological filter. The removal efficiency of COD and UV254 were 40.8% and 45.8% when the hydraulic retention time was 3 hours and the gas to water ratio was 3:1 for BAF. The average COD of the petrochemical wastewater was 86.5 mg x L(-1) while the average COD of the effluent of the combined process was 49.4 mg x L(-1) when it was operated under optimal conditions.

[Toxicity of nitrate-N to freshwater aquatic life and its water quality criteria]

The toxicity sensitivity of different freshwater aquatic organisms was analyzed using the collected toxicity data in this paper. Three methods were used to estimate the criteria of nitrate to protect the freshwater aquatic life. The results showed that the species sensitivity to nitrate followed the order of Arthropoda > Mollusca > Chordata, and Crustacea > Insecta > Gastropoda > Bivalvia > Amphibia > Actinopterygii. Moreover, the output of assessment factor method, species sensitivity distribution method and USEPA's method was significantly different. Finally, criterias of 87.97 mg x L(-1) and 5.17 mg x L(-1) to protect aquatic life from acute and chronic toxicity were proposed using USEPA's method.

[Pretreatment of high-concentration acrylic acid wastewater by the multi-stage microaerobic biological fluidized bed reactor]

A multi-stage microaerobic biological fluidized bed reactor was used for the pretreatment of synthetic wastewater containing high concentration of acrylic acid (AA). The effect of influent load was investigated and the intermediate products of acrylic acid degradation were analyzed. It indicated that the removal rate of AA was above 95% with effluent acrylic acid less than 150 mg x L(-1) and COD removal rate of 15%-30%, under the following conditions: hydraulic retention time of 12 h, waste water temperature of 25 degrees C, influent acrylic acid concentration of 3 000-9 000 mg x L(-1), volume load of 6.0-18.0 kg x (m3 x d)(-1). The main intermediate products of acrylic acid degradation were acetic and propionic acids. The multi-stage microaerobic biological fluidized bed reactor can transform each 1.00 mol acrylic acid into 0.22 mol acetic acid and 0.36 mol propionic acid, and achieve the pretreatment of acrylic acid wastewater at high loads.

[Denitrification on secondary effluent of acrylic fiber wastewater by tri-stage biofilm advanced reactor]

To resolve the shortage of carbon source during traditional denitrification used to treat secondary effluent of acrylic fiber wastewater, tri-stage biofilm reactor was used, the influence of pH of influent, HRT, and NH4(+) -N concentration in raw water on NH4(+) -N removal was investigated. Efficiency of TN removal was also investigated. It demonstrated that the optimal HRT and pH were 24 hours and 7.8-8.0 respectively. Under these conditions the removal efficiencies of NH4(+) -N and TN were 94. 6% and 53% respectively. And the removal efficiency of NH4(+) -N had no relationship with the concentration of the inflow water. With absence of organic carbon source in the reactor, efficiency of TN removal was obvious, the average and the highest removal efficiencies of TN were 53% and 66% respectively, efficiency of secondary effluent of acrylic fiber wastewater nitrogen removal was obvious when treated with Tri-stage biofilm reactor.

[A method for determination of trace naphthalene and phenanthrene in water using constant-wavelength synchronous fluorescence spectrometry]

In view of synchronous fluorescence possessing the character of good selectivity, high sensitivity, less interference, etc. it can be used for simultaneous determination of multi-component mixtures of polycyclic aromatic hydrocarbons (PAHs). A new method of constant-wavelength synchronous fluorescence spectrometry to determine two naphthalene and phenanthrene of PAHs was developed in this study. The effect of different experimental conditions, such as different disolvents for character of fluorescence spectra and the choose of the optimal wavelength difference were studied. Experiment showed that the simultaneous indentification and quantitative determination of the two PAHs when delta lambda = 100 was chosen. The fluorescence intensity was linearly related to naphthalene and phenanthrene concentration in the range of 0.5-25.0 microg x L(-1) with correlation coefficient 0.999 5 and 0.999 7, respectively. The detection limits were all lower than 0.03 microg x L(-1), and the relative standard deviations for naphthalene and phenanthrene were 1.19% and 180% (n=7), respectively. Results show that the compounds can be analyzed qualitatively and quantitatively by synchronous fluorescence spectrometry.

Understanding the granulation process of activated sludge in a biological phosphorus removal sequencing batch reactor

The granulation of activated sludge was investigated using two parallel sequencing batch reactors (SBRs) operated in biological nitrogen and phosphorus removal conditions though the reactor configuration and operating parameters did not favor the granulation. Granules were not observed when the SBR was operated in biological nitrogen removal period for 30d. However, aerobic granules were formed naturally without the increase of aeration intensity when enhanced biological phosphorus removal (EBPR) was achieved. It can be detected that plenty of positive charged particles were formed with the release of phosphorus during the anaerobic period of EBPR. The size of the particles was about 5-20 μm and their highest positive ζ potential was about 73 mV. These positive charged particles can stimulate the granulation. Based on the experimental results, a hypothesis was proposed to interpret the granulation process of activated sludge in the EBPR process in SBR. Dense and compact subgranules were formed stimulated by the positive charged particles. The subgranules grew gradually by collision, adhesion and attached growth of bacteria. Finally, the extrusion and shear of hydrodynamic shear force would help the maturation of granules. Aerobic granular SBR showed excellent biological phosphorus removal ability. The average phosphorus removal efficiency was over 95% and the phosphorus in the effluent was below 0.50 mg L(-1) during the operation.

[Treatment of acrylate wastewater by electrocatalytic reduction process]

High-concentration acrylate wastewater was treated by an electrocatalytic reduction process. The effects of the cation exchange membrane (CEM) and cathode materials on acrylate reduction were investigated. It indicated that the acrylate could be reduced to propionate acid efficiently by the electrocatalytic reduction process. The addition of CEM to separator with the cathode and anode could significantly improve current efficiency. The cathode materials had significant effect on the reduction of acrylate. The current efficiency by Pd/Nickel foam, was greater than 90%, while those by nickel foam, the carbon fibers and the stainless steel decreased successively. Toxicity of the wastewater decreased considerably and methane production rate in the biochemical methane potential (BMP) test increased greatly after the electrocatalytic reduction process.

[Optimization of acrylic fiber polymerization wastewater treatment condition by three-dimensional electrode]

The research was focus on the influence of experimental conditions to the removal efficiency of contaminant and the change of biodegradability in the treatment of acrylic fiber polymerization wastewater using three-dimensional electrode reactor with granular activated carbon. The anode was Ti/SnO2-Sb2O3 expanded metal sheet electrode. The cathode was Ti expanded metal sheet electrode. The parameters investigated were the reaction time, electrolytic voltage, initial pH value and aeration amount. The results show that the electrolytic voltage and initial pH value had greater impact on the removal efficiency of organic pollutants. Under the optimal experimental condition with electrolytic voltage 15 V, initial pH value 3, aeration amount 400 mL/min, the removal rates of COD, TOC and acrylonitrile were 32.59%, 22.17% and 89.70%, respectively,and the value of BOD5/COD increased from 0.02 to 0.42 within 120 min, which improved the biodegradability greatly and was beneficial for further biological treatment.

Acute rejection correlates with expression of major histocompatibility complex class I antigens on peripheral blood CD3(+)CD8(+) T-lymphocytes following skin transplantation in mice

This study investigated major histocompatibility complex class I (MHC-I) antigen expression on peripheral blood T-cells after transplantation to assess its potential as an early marker of acute graft rejection (AGR). Using a mouse model with or without immunosuppressive treatment, the expression of MHC-I antigens on CD3(+)CD8(+) T-lymphocytes was assessed by flow cytometry following syngeneic graft (n = 138) or allograft (n = 138) skin transplantation. The occurrence of AGR was assessed by examining the degree of lymphocyte and monocyte infiltration in transplant biopsies. During AGR, expression of MHC-I antigens increased significantly compared with pre-transplant levels in the allograft group, even with immunosuppressive treatment. The highest expression of MHC-I antigens occurred 5 - 6 days before macroscopic rejection. These results suggest that expression of MHC-I antigens on peripheral blood CD3(+)CD8(+) T-lymphocytes could be used as an early marker for predicting AGR.

[The variation trend of fluorescence characteristics of DOM in the acetophenone degradation process by electro-Fenton]

In the acetophenone degradation process by electro-Fenton, the variation trend of fluorescence characteristics of dissolved organic matter (DOM) in acetophenone synthetic wastewater was detected by excitation-emission matrix (EEM) fluorescence spectra. The fluorescence spectra characteristics of acetophenone were studied, and the fitting line of fluorescence intensity and acetophenone removal efficiency was discussed in detail. The results show that the locations of the two fluorescence centers of acetophenone synthetic wastewater are at lambda(Ex/Em) = 270/305 nm (Peak A) and lambda(Ex/Em) = 215/305 nm (Peak B), respectively, and the ratio of Peak A/Peak B is 1.22. In the electro-Fenton treatment process, firstly, acetophenone was decomposed into unsaturated fatty acid which had stronger fluorescence intensity, further, it was degraded into short-chain small molecular compounds which have weaker fluorescence intensity. Therefore, the fluorescence intensity of synthetic wastewater was increased at first and decreased afterwards in the entire 180 min electro-Fenton treatment process. The two-dimensional fluorescence peak at 285-375 nm of emission wavelength (at lambda(Ex) = 250 nm) had a good linear relationship with the removal efficiency of acetophenone, therefore, it could reflect effectively the removal efficiency of acetophenone in the whole electro-Fenton treatment process.

[Wastewater from the condensation and drying section of ABS was pretreated by microelectrolysis]

Wastewater from the condensation and drying section of acrylonitrile-butadiene-styrene (ABS) resin plant was pretreated by the microelectrolysis, and the effect of the influent pH value on the pollution removal efficiency of the microelectrolysis was mainly studied. In order to study the electrochemical action of the microelectrolysis for the degradation of toxic refractory organic pollutants, two control experiments of activated carbon and iron were set up. The results showed that the TOC removal efficiencies were all fluctuated between 40% and 60% under the condition of different influent pH values. The microelectrolysis can decompose and transform the toxic refractory organic pollutants and increase the BOD5/COD ratio from 0.32 to 0.60, which increased the biodegradability of ABS resin wastewater significantly. When the pH value of influent was 4.0, the BOD5/COD ratio of effluent reached 0.71. The result of UV-vis spectra indicates that the removal efficiency of the organic nitrile was the highest with influent pH was 4.0. Therefore, the best influent pH value of microelectrolysis was 4.0.

Long-term outcomes following repair or replacement in degenerative mitral valve disease

BACKGROUND

We studied whether mitral valvuloplasty (MVP) was superior to mitral valve replacement (MVR) in patients with degenerative mitral regurgitation (MR), and analyzed the independent risk factors for survival and reoperation.

METHODS

326 patients with degenerative MR underwent MVP (n = 241), mitral valve replacement (MVR) (n = 78) or emergent MVR due to failure of repair (EMVR). Clinical data were analyzed retrospectively.

RESULTS

Thirty-day mortality was lower after MVP (2.5 %) compared to MVR (9.0 %) ( P < 0.05). Late survival at 1 and 5 years in the MVP group was 94.4 % and 84.3 % versus 80.4 % and 64.6 % in the MVR group ( P < 0.05), respectively. After adjusting the baseline characteristics by the propensity score method, a significant survival benefit was found for patients who underwent MVP. Multivariable analysis showed that MVR was an independent predictor of thirty-day mortality and survival. There was no significant difference in thirty-day mortality and survival between the EMVR and MVR groups. The need for reoperation was not significantly different between the MVP and MVR groups. In the MVP group, the risk factors for survival and reoperation were identified.

CONCLUSIONS

MVP is superior to MVR for the treatment of degenerative MR despite the impact of repair failure. Age less than 60 years, ring size to body surface area greater than 19.0, absence of a prosthetic ring and residual MR at the end of surgery (≥ 1/4) reduce the durability of MVP.

Safe zone for transacetabular screw fixation in prosthetic acetabular reconstruction of high developmental dysplasia of the hip

BACKGROUND

Prosthetic reconstruction of hips with Crowe type-IV developmental dysplasia (a high complete dislocation) is technically demanding. Insufficient osseous coverage and osteopenic bone stock frequently necessitate transacetabular screw fixation to augment primary stability of the metal acetabular shell. We sought to determine whether a previously reported quadrant system for screw fixation of the acetabular cup can be applied in patients with high dislocation of the hip and to define a specialized safe zone for screw fixation in these hips, if needed.

METHODS

Using volumetric computed tomographic data and image-processing software, we made three-dimensional reconstructions of the osseous and vascular structures in eighteen hips in twelve patients. We virtually reconstructed a cup in the true acetabulum and dynamically simulated transacetabular screw fixation. We mapped the hemispheric cup into several areas and, for each, measured the distance between the virtual screw and the external iliac (femoral) and obturator blood vessels. In the six patients with unilateral high dislocation of the hip and a relatively normal, contralateral hip, the six relatively normal hips served as controls.

RESULTS

Reconstruction of the cup at the level of the true acetabulum shifted the center of rotation anteroinferiorly in the hips with a high, complete dislocation. Screws guided by the quadrant system frequently injured the obturator blood vessels in the hips with a high dislocation. In these patients, the safe zone shifted as a result of moving the prosthetic cup.

CONCLUSIONS

The quadrant system, although helpful in determining screw placement in hips with a normal center of rotation, can be misleading and of less value in guiding screw insertion to augment acetabular shells for hips with a high dislocation. We believe that a safe zone specific to hips with a high dislocation should be used to guide transacetabular screw fixation.

Scavenger Receptor Class B Type I Mediates Cell Entry of Hepatitis C Virus

This study assessed the functional role of human scavenger receptor class B type I (SR-BI) as a putative hepatitis C virus (HCV) receptor using Chinese hamster ovary (CHO) cells transfected with human SR-BI (CHO–huSR-BI). The expression of SR-BI by primary Tupaia hepatocytes (PTHs), human hepatocarcinoma cell line (HepG2) cells, untransfected CHO cells and CHO–huSR-BI cells was analysed by Western blotting. Receptor competition assays showed that anti-SR-BI antibodies that block the binding of soluble envelope glycoprotein E2 could prevent HCV infection. Pre-incubation of CHO–huSR-BI and HepG2 cells with anti-SR-BI antibodies resulted in marked inhibition of E2 binding. After incubation with HCV RNA-positive serum from a patient with chronic HCV infection, however, HCV infection could not be detected in CHO–huSR-BI cells, but was detected in PTHs. These results demonstrate that, whilst SR-BI represents an important cell surface molecule for HCV infection, the presence of SR-BI alone is insufficient for HCV entry.

Current through single conjugated molecules: calculations versus measurements

We use density functional theory based nonequilibrium Green's function to calculate the current through the different rodlike molecules at the finite temperatures self-consistently, which was compared to the experimental measurements presented by Reichert et al. [Phys. Rev. Lett. 88, 176804 (2002)] and by Mayor et al. [Angew. Chem. Int. Ed. 42, 5834 (2003)], respectively. Our results agree with the measurements very well, especially for the bias around +/-1.0 V. The investigation of the topological effect for the symmetrical molecule reveals the fact that the para position compound provides a considerably larger conductance than the meta one.