碳酸酐酶在聚甲基戊烯中空纤维膜表面的固定及其性能分析

采用两步法将碳酸酐酶共价键合在聚甲基戊烯(Polymethyl-pentene,PMP)膜式氧合器表面以提高其清除血液中CO2的能力。首先采用等离子体处理法将羟基引入PMP表面,然后用偶联剂溴化氰(CNBr)将碳酸酐酶(Carbonic anhydrase,CA)固定在PMP膜表面。采用XPS、表面接触角测定仪对等离子体处理后材料表面的物理化学性质进行了表征。以对硝基苯酚乙酸酯(p-nitrophenyl acetate,p-NPA)为底物,采用紫外分光光度计测定了接枝CA的活性、浓度、重复利用性、储存稳定性。结果表明,等离子体处理方法能将羟基成功引入PMP表面;CA能被成功地偶联在无活性官能团聚合物表面,在保持酶活性的同时获得较高的接枝效率;共价接枝CA(Covalently immobilized CA,CACI)的浓度随CNBr浓度的增加而增加,最大可达理论单分子层接枝量的73%;CACI比物理吸附的CA(Physically adsorbed CA,CAPA)具更好的重复利用性;37oC下,CACI比CA溶液表现出更好的储存稳定性。本方法有望应用在膜式氧合器上以提高其对血液中CO2的排除效率。     

Reactor performance and microbial community of an EGSB reactor operated at 20 and 15°C

Aims:  To investigate the effects of low temperatures on the performance and microbial community of anaerobic wastewater treatment.
Methods and Results:  An expanded granular sludge bed (EGSB) reactor was employed to treat synthetic brewery wastewater at 20 and 15°C. Reactor performance was represented by chemical oxygen demand (COD) removal efficiency, while the microbial community was analysed using denaturing gradient gel electrophoresis (DGGE) and clone technology. When the hydraulic retention time (HRT) was maintained at 18 h, COD removal efficiencies above 85% were obtained at both 20 and 15°C, with influent COD concentrations up to 7300 and 4100 mg l⁻¹, respectively. At 15°C, the COD removal efficiency was more easily manipulated by increasing the influent COD concentration. DGGE and clone results for both temperatures revealed that Methanosaeta and Methanobacterium were two dominant methanogens, and that the majority of the eubacterial clones were represented by Firmicutes . When the temperature decreased from 20 to 15°C, both archaeal and eubacterial communities had higher diversity, and the proportion of Methanosaeta (acetate-utilizing methanogens) decreased markedly from 60·0% to 49·3%, together with an increase in proportions of hydrogen-utilizing methanogens (especially Methanospirillum ).
Conclusions:  The feasibility of psychrophilic anaerobic treatment of low and medium strength organic wastewaters was demonstrated, although lower temperature could significantly affect both reactor performance and the anaerobic microbial community.
Significance and Impact of the Study:  The findings enrich the theory involving the microbial community and the application of anaerobic treatment in a psychrophilic environment.     

Isolation and characterization of halophilic Archaea able to produce biosurfactants

Halotolerant microorganisms able to live in saline environments offer a multitude of actual or potential applications in various fields of biotechnology. This is why some strains of Halobacteria from an Algerian culture collection were screened for biosurfactant production in a standard medium using the qualitative drop-collapse test and emulsification activity assay. Five of the Halobacteria strains reduced the growth medium surface tension below 40 mN m⁻¹, and two of them exhibited high emulsion-stabilizing capacity. Diesel oil-in-water emulsions were stabilized over a broad range of conditions, from pH 2 to 11, with up to 35% sodium chloride or up to 25% ethanol in the aqueous phase. Emulsions were stable to three cycles of freezing and thawing. The components of the biosurfactant were determined; it contained sugar, protein and lipid. The two Halobacteria strains with enhanced biosurfactant producers, designated strain A21 and strain D21, were selected to identify by phenotypic, biochemical characteristics and by partial 16S rRNA gene sequencing. The strains have Mg²⁺, and salt growth requirements are always above 15% (w/v) salts with an optimal concentration of 15–25%. Analyses of partial 16S rRNA gene sequences of the two strains suggested that they were halophiles belonging to genera of the family Halobacteriaceae, Halovivax (strain A21) and Haloarcula (strain D21). To our knowledge, this is the first report of biosurfactant production at such a high salt concentration.     

Effects of cell entrapment on growth rate and metabolic activity of pure cultures commonly found in biological wastewater treatment

The effects of cell entrapment on the growth rate and metabolic activity of major groups of bacteria (betaproteobacteria and gammaproteobacteria) in biological municipal wastewater treatment were investigated. Three different cell entrapment media (alginate, carrageenan and polyvinyl alcohol) and three cell-to-matrix ratios (0.1%, 0.2% and 0.6%, w v⁻¹) were examined. Representative species of betaproteobacteria were Alcaligenes faecalis and Comamonas testosteroni whereas Pseudomonas putida was a gammaproteobacteria species studied. Free (non-entrapped) cells were included in the study for comparative purpose. Results indicated that the entrapment, type of entrapment media, and cell-to-matrix ratio had significant effects on the growth and metabolic activity of major groups of bacteria in wastewater treatment. Polyvinyl alcohol entrapped cells had the highest specific growth and specific substrate utilization rates. Increase of cell-to-matrix ratio (from 0.1% to 0.2% or 0.6%) did not improve the specific growth and specific substrate utilization rates. The relative performances provided by different entrapment media of the three species studied were quite consistent. This study showed that the suitable choices of entrapment media and cell-to-matrix ratio are important but similar for major groups of bacteria in wastewater treatment.     

Kinetic analysis of metal uptake by dry and gel alginate particles

The kinetics of metal uptake by gel and dry calcium alginate beads was analysed using solutions of copper or lead ions. Gel beads sorbed metal ions faster than the dry ones and larger diffusivities of metal ions were calculated for gel beads: approximately 10⁻⁴ cm²/min vs. 10⁻⁶ cm²/min for dry beads. In accordance, scanning electron microscopy and nitrogen adsorption data revealed a low porosity of dry alginate particles. However, dry beads showed higher sorption capacities and a mechanical stability more suitable for large-scale use. Two sorption models were fitted to the kinetic results: the Lagergren pseudo-first order and the Ho and McKay pseudo-second order equations. The former was found to be the most adequate to model metal uptake by dry alginate beads and kinetic constants in the orders of 10⁻³ and 10⁻² min⁻¹ were obtained for lead solutions with concentrations up to 100 g/m³. The pseudo-first order model was also found to be valid to describe biosorbent operation with a real wastewater indicating that it can be used to design processes of metal sorption with alginate-based materials.     

The expense for one implantation of a banked bone allograft from a cadaveric donor and the issues affecting current advanced medical treatment in the Japanese orthopaedic field

Demand for banked bone allografts is increasing in Japan; however, there are too few bone banks and the bone bank network is not well-established. One reason for this was lack of funding for banks. Bone banks had to bear all material expenses of banked bone allografts themselves because this was not designated a covered expense. In December 2004, the Japanese government started a new “Advanced Medical Treatment” administration system which allowed an approved institution to charge the expense of authorized advanced medical treatments directly to patients. The treatment named “Cryopreserved allogenic bone and ligamentous tissue retrieved from cadaveric donor” was approved as an advanced medical treatment in March 2007. We present the calculation method and the expense per implantation of a banked bone allograft from a cadaveric donor under this treatment and raise issues which affect this advanced medical treatment and remain to be resolved in the Japanese orthopaedic field.     

基于微藻的水产养殖废水处理技术研究进展

摘要：利用微藻处理水产养殖废水是一项污水资源化生物技术。近年来,国内外开展了大量有关藻类培养和废水处理的研究,发展了藻类处理技术,包括藻类塘、活性藻、固定化藻类、光生物反应器。本文综述了微藻净化水产养殖废?水的原理、研究成果及应用实例,并对今后的研究方向提出了建议。     

The affinity of human RANK binding to its ligand RANKL

Receptor activator of nuclear factor-kappa B (RANK) and its ligand, RANKL play critical roles in bone re-modeling, immune function, vascular disease and mammary gland development. To study the interaction of RANK and RANKL, we have expressed both extracellular domain of RANK and ectodomain of RANKL using Escherichia coli expression system. RANK was expressed as an inclusion body first which properly refolded later, while RANKL was initially produced as a GST fusion protein, after which the GST was removed by enzyme digestion. Soluble RANK existed as a monomer while RANKL was seen as a trimer in solution, demonstrated by gel filtration chromatography and cross-linking experiment. The recombinant RANK and RANKL could bind to each other and the binding affinity of RANKL for RANK was measured with surface plasmon resonance technology and K_D value is about 1.09 × 10⁻¹⁰ M.     

The binding of von Willebrand factor type C domains of Chordin family proteins to BMP-2 and Tsg is mediated by their SD1 subdomain

The VWC domain of Chordin family proteins consists of subdomains SD1 and SD2. In previous experiments with VWC1 from CV-2 SD-1 was shown to be crucial for BMP interaction. Now the SD1 from VWC1 and VWC3 of Chordin and CHL2 were established to confer BMP affinity and specificity to these proteins also. In addition, these SD1 subdomains are mediating binding to Tsg. Mutational analysis revealed similar binding epitopes of the various SD1 proteins for BMP-2 and Tsg. Inhibitory activity of CHL2 in C2C12 cells is reduced by mutations in SD1 of VWC1 and even more of VWC3. These results together provide strong evidence that the SD1 subdomain module of about 40 residues represents the crucial binding partner for BMPs and Tsg in these Chordin family proteins and likely in other BMP-binding VWC domains also.     

Evaluation of a biosensor immunoassay for simultaneous characterization of isotype and binding region of human anti-tocilizumab antibodies with control by surrogate standards

This article describes the simultaneous Biacore analysis of human anti-human antibodies (HAHAs) with respect to the binding region and the isotype by a combination of 11 single measurements per sample. The multiplexing single assay setup made efficient use of the four parallel flow cells on one biosensor chip by immobilization of full-length antibody and its constant (Fc) and antigen binding (Fab) fragments for differential binding analysis of anti-drug antibodies (ADAs). Thereby, a complete time-specific immunogenicity profile (intensity, isotype, specificity, and kinetics) of a patient could be obtained by assessing the response patterns of serially collected samples analyzed in a single measurement run. The use of functionally active standard conjugates allowed control of the assay performance throughout the whole procedure. The positive control standard conjugates mimicking polyclonal human ADAs of different isotypes were obtained by conjugating polyclonal rabbit antibodies against the therapeutic antibody to human immunoglobulin (Ig) M, IgG, or IgE. In this article, the qualification of the assay is demonstrated and the application of the methodology to six representative rheumatoid arthritis patients treated with the therapeutic humanized IgG1 antibody tocilizumab (anti-IL-6R) is shown to illustrate the versatility of the assay. The presented method allows one to differentiate specific ADAs from drug-unspecific responses (e.g., rheumatoid factors). In addition, the method can be used to discriminate between isotype responses of the IgG, IgM, and IgE types and, thereby, allows one to describe the time course of specific ADA formation and its disappearance on the single patient level.