Expression and purification of bioactive high-purity human midkine in Escherichia coli

Midkine is a heparin-binding growth factor, which plays important roles in the regulation of cell growth and differentiation. The non-tagged recombinant human midkine (rhMK) is therefore required to facilitate its functional studies of this important growth factor. In the present work, rhMK was expressed in Escherichia coli (E. coli) BL21 (DE3). The expression of midkine was efficiently induced by isopropyl-β-D-thiogalactopyranoside (IPTG). After sonication, midkine was recovered in an insoluble form, and was dissolved in guanidine hydrochloride buffer. Renaturation of the denatured protein was carried out in the defined protein refolding buffer, and the refolded protein was purified using S-Sepharose ion-exchange chromatography. The final preparation of the rhMK was greater than 98% pure as measured by sodium dodecylsulfate-polyacrylamid gel electrophoresis (SDS-PAGE) and reverse phase high performance liquid chromatography (RP-HPLC). The purified rhMK enhanced the proliferation of NIH3T3 cells. Project supported in part by the Hi-Tech Research and Development Program (863) of China (No. 2007AA02Z149) and the Science and Technology Commission of Shanghai Municipality (No. 075407071), China     

A novel reduction of diketones with i-RMgBr catalyzed by Cp<Subscript>2</Subscript>TiCl<Subscript>2</Subscript> and deoxygenation of sulfoxides by Cp<Subscript>2</Subscript>TiCl<Subscript>2</Subscript>/Al system

α-diketones and β-diketones react with Grignard reagents in the presence of a catalytic amount of Cp₂TiCl₂ to yield α-ketols and corresponding ketones respectively. Sulfoxides can be deoxygenated by Cp₂TiCl₂/Al system. The possible mechanisms are also discussed. Project (No. 20072033) supported by the National Natural Science Foundation of China and the Specialized Research Fund for the Doctoral Program of Higher Education Ministry, China     

Co/Pt多层膜的铁磁共振研究

Out-of-plane angular dependence of ferromagnetic resonance spectra was measured in sputtered Co/Pt multilayers and analyzed with the Landau-Lifshitz-Gilbert equation. The effective demagnetizing field 4πMeff is found to increase with decreasing tPt and decreasing 1/tco, which can be considered as a result of interplay between the interlayer coupling and a lowdimensional effect. The g factor increases with increasing tpt and decreasing tCo, indicating contribution of spin-polarization of Pt atoms and additional contribution of orbital moment of Co atoms. The in-plane resonance line-width increases with decreasing too and increases with increasing tPt.     

Stereoselective glucuronidation of carvedilol by Chinese liver microsomes

Objective: To study the stereoselective glucuronidation of carvedilol (CARV) by three Chinese liver microsomes. Methods: The metabolites of CARV were identified by a hydrolysis reaction with β-glucuronidase and HPLC-MS/MS. The enzyme kinetics for CARV enantiomers glucuronidation was determined by a reversed phase-high pressure liquid chromatogra-phy (RP-HPLC) assay using (S)-propafenone as internal standard after precolumn derivatization with 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosylisothiocyanate. Results: Two CARV glucuronides were found in three Chinese liver microsomes incubated with CARV. The non-linear regression analysis showed that the values of Km and Vmax for (S)-CARV and (R)-CARV enantiomers were (118±44) μmol/L, (2 500±833) pmol/(min·mg protein) and (24±7) μmol/L, (953±399) pmol/(min·mg protein), respectively. Conclusion: These results suggested that there was a significant (P<0.05) stereoselective glucuronidation of CARV enantiomers in three Chinese liver microsomes, which might partly explain the enantioselective pharmacokinetics of CARV.     

L^p-estimates on a ratio involving a Bessel process

INTRODUCTION Throughout this paper, we shall work with a filtered complete probability space (?,F,(Ft),P) sat-isfying the usual conditions. Let B=(Bt)t≥0 be a stan-dard Brownian motion with B0=0. Denote by ú the set of all non-negative real numbers. Recall that a diffusion process X starting at x≥0 is called the square of a Bessel process of dimension δ>0 if d X t = δd t 2 | X t |d Bt , X 0= x, (1) Clearly, this equation has a unique non-negative strong solution X, i.e., …     

Pharmacokinetic study with N-Ile1-Thr2-63-desulfato-r-hirudin in rabbits by means of bioassay

INTRODUCTION Hirudin, a naturally occurring polypeptide from salivary glands of medicinal leech (Hirudo Medici-nalis) and an important effective component of tradi-tional Chinese medicine Shui Zhi, has proven to be a highly selective direct thrombin inhibitor (Markwardt, 1994). Currently, in China recombinant-hirudin has been developed by DNA recombination technique and is undergoing extensive preclinical and clinical evaluation. Over the past decade, much effort in our lab was devote…     

CoNi/CoO 双层膜磁化反转机制与温度的依赖关系

Exchange coupling and magnetization reversal mechanism in two series of Co_xNi_(1-x)/CoO(30 nm)(x=0.2 and 0.4)bilayers are studied by vector magnetometer.Two components of magnetization are measured parallel and perpendicular to the applied field.At low temperatures,coercivity H_c∝(t_(FM))~(-n),n=1.5 and 1.38 for x=0.2 and 0.4,respectively,in agreement with the random field model.At room temperature,the coercivity is nearly proportional to the inverse FM layer thickness.In addition to the exchange field and the coercivity,the characteristic of the magnetization reversal mechanism was found to change with temperature.At temperatures below 180 K,magnetization reversal process along the unidirectional axis is accompanied only by nucleation and pinning of domain wall while magnetization rotation is also involved at high temperatures.     

A system for screening agonists targeting β2-adrenoceptor from chinese medicinal herbs

In order to develop a model for screening the agonists of human β₂-adrenoceptor from Chinese medicinal herbs extracts, we used a cell-based functional assay based on a common G protein-coupled receptor (GPCR) regulation mechanism and destabilized enhanced green fluorescent protein (d₂EGFP) reporter gene technique. The positive cell clone was confirmed by real-time polymerase chain reaction (PCR) and imaging analysis. To assess the value of this model, we screened over 2000 high performance liquid chromatography (HPLC)-fractionated samples from the ethanol extracts of Chinese medicinal herbs. Six fractions (isolated from Panax japonicus, Veratrum nigrum, Phellodendron amurense, Fructus Aurantii Immaturus, Chaenomeles speciosa, and Dictamnus dasycarpus) showed significant effects on active reporter gene expression, three of which (isolated from Phellodendron amurense, Fructus Aurantii Immaturus, and Chaenomeles speciosa) were selected for further concentration response analysis and the half maximal effective concentration (EC_{1/2 max}) values were 4.2, 2.7, and 4.8 μg/ml, respectively. Therefore, this reporter gene assay was suitable for screening β₂-adrenoceptor agonists. The results suggest that the six herbal extracts are the possible agonists of β₂-adrenoceptor. Project (No. 30873103) supported by the National Natural Science Foundation of China     

Control mesh representation of a class of minimal surfaces

INTRODUCTION The problem of minimal surface is an old and active problem in the field of differential geometry. The minimal surface has been employed in many areas such as architecture, material science, aviation, ship manufacture, biology, crystallogeny, and so on. The history of minimal surface began with La- grange in 1762 (Nitsche, 1989). Many literature on the minimal surface exist in the last two hundred years (Nitsche, 1989; Osserman, 1986), but few on the minimal surface from the…     

Genetic basis of heterosis and inbreeding depression in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

The genetic basis of heterosis was studied through mid-parent, standard variety and better parent for 11 quantitative traits in 17 parental lines and their 10 selected hybrids in rice (Oryza sativa L.). The characters were plant height. days to flag leaf initiation, days to first panicle initiation, days to 100% flowering, panicle length, flag leaf length. days to maturity, number of fertile spikelet/panicle, number of effective tillers/hill, grain yield/10-hill, and 1000-grain weight. In general the hybrids performed significantly better than the respective parents. Significant heterosis was observed for most of the studied characters. Among the 10 hybrids, four hybrids viz., 17A×45R, 25A×37R, 27A×39R, 31A×47R, and 35A×47R showed highest heterosis in 10-hill grain yield/10-hill. Inbreeding depression of F₂ progeny was also studied for 11 characters of 10 hybrids. Both positive and negative inbreeding depression were found in many crosses for the studied characters, but none was found significant. Selection of good parents was found to be the most important for developing high yielding hybrid rice varieties. Project supported by the Foundation of Ministry of Science and Information and Communication Technology, People's Republic of Bangladesh     

Modeling for the diffusion limitation of free radical polymerization

A new model was developed to describe the diffusion limitation on free radical polyme-rization. In this model the termination rate coefficient (k _t) and propagation rate coefficient (k _p) were expressed as a function of bulk viscosity (η). This model was used to simulate the batch thermal polymerization of styrene (St) and the continuous thermal bulk copolymerization of St (monomer 1) and maleic anhydride (MAH, monomer 2) in a CSTR with on-line monitor of the rheological behavior. The simulated results on polymerization conversion, copolymer composition, molecular weight and its distributions were compared with the experimental data, and the results calculated by two previous gel-effect models i.e. Martin-Hamielec and Tulig-Tirrell models. It was found that the present model produces better prediction than that of the Tulig-Tirrell model and has the same accuracy as that of the Martin-Hamielec model, but is much simpler. Project (29734130) supported by Natural Science Foundation of China.     

Optimization of conditions for supercritical fluid extraction of flavonoids from hops (Humulus lupulus L.)

Waste hops are good sources of flavonoids. Extraction of flavonoids from waste hops (SC-CO₂ extracted hops) using supercritical fluids technology was investigated. Various temperatures, pressures and concentrations of ethanol (modifier) and the ratio (w/w) of solvent to material were tested in this study. The results of single factor and orthogonal experiments showed that at 50°C, 25 MPa, the ratio of solvent to material (50%), ethanol concentration (80%) resulted in maximum extraction yield flavonoids (7.8 mg/g). HPLC-MS analysis of the extracts indicated that flavonoids obtained were xanthohumol, the principal prenylflavonoid in hops. Project (No. Y304203) supported by the Natural Science Foundation of Zhejiang Province, China     

Electrical conductivity and corrosion resistance of ZnFe2O4-based materials used as intert anode for aluminum electrolysis

ZnFe₂O₄ and ZnFe₂O₄-based materials were tested to obtain the electrical conductivity and corrosion resistance in melting bath for aluminum electrolysis. The results proved that adequate additives, such as Ni₂O₃ CuO, Cu, ZnO and CeO₂ would increase the electrical conductivity, and the ZnFe₂O₄-based anodes with these additives were of good corrosion resistance. The current density on anode, the mole ratio of NaF/AlF₃ (MR) and the content of alumina in the bath effect the anode corrosion rate in different way. Project supported by the Science Foundation of Liaoning Province, P. R. China (95 – 156)     

关于T凸函数的不等式

In this paper, the Tφ-convex functions were introduced as a generalizations of convex functions. Then the characteristics of the Tφ-convex functions were discussed. Furthermore, some new inequalities for the Tφ-convex functions were derived.     

The kinetics of hydrogen diffusion in Ti3Al-based alloy

The process of gaseous hydrogen charging into a Ti₃Al-based alloy in the temperature range of 500–650°C is investigated. The results showe that the relationship between the average hydrogen concentration at constant temperature and charging time reveals a parabolic rate law. Applying the theory of lattice diffusion to analyze the hydrogen diffusion in the alloy, we find that the apparent activation energy of hydrogen diffusion is 90.40 kJ/mol, and the equilibrium hydrogen content in the alloy depends on the temperature of the gaseous hydrogen charging process. Project supported by the Natural Science Foundation of Shanghai (93QE14002)     

Effects of N source and nitrification pretreatment on growth of Arthrospiraplatensis in human urine

Culture of Arthrospira platensis (Spirulina platensis) in human urine was investigated to get valuable biomass. NO3-N was the proper N source, in comparison with other N source, including urea, NH4-N and NO2-N. As a result, aerobic nitrification of human urine was performed, with above 93.6% nitrification percentage finally achieved with total-N (TN) load of 46.52 mg/(L·d), in which Arthrospira platensis was successfully grown. The main compositions of the obtained biomass are close to those in Zarrouk medium. Thus, it is possible to culture Arthrospira platensis in nitrified human urine for food production within bioregenerative life support systems (BLSSs).     

Optimization of fermentation conditions for P450 BM-3 monooxygenase production by hybrid design methodology

INTRODUCTION P450 enzymes are found throughout nature and can catalyze the oxidation of various chemicals (Ortiz de Montellano, 1995). Because of their important roles in these processes, numerous systems have been developed for the expression of P450s in vitro (Helvig and Capdevila, 2000; Nakamura et al., 2001; Deeni, 2001). But P450 enzymes fermentation levels in the microbial system are too low to catalyze the reactions for industrial preparations. Therefore, it is necessary to impr…     

Optimization of cultural conditions for thermostable β-1, 3-1, 4-glucanase production byBacillus subtilis ZJF-1A5

The optimization of cultural conditions for β-glucanase production byBacillus subtilis ZJF-1A5 was investigated in flask trials. Temperature had great effect on β-glucanase production which maximized at optimal temperature of 37°C and decreased significantly when temperature was over 37°C. Charge quantity affected β-glucanase production significantly. Adding oxygen vector N-dodecane or acetic ether benefited β-glucanase production, but it depended on the concentration and charge quantity. The results of fractional factorial design showed that age and size of inoculum and shaking speed were the key factors affecting β-glucanase production and the cultivation time span to reach the highest β-glucanase activity. The optimal cultural conditions for β-glucanase production obtained with CCD were as follows: inoculum age and size (16 h, 3.82% (v/v)), shaking speed 210 r/min, charge quantity of 30 mL in 250 mL flask and initial pH 7.0, cultured at 37°C for 50 h. Repeated experimental results accorded with those predicted by a second-order polynomial model. The amount of β-glucanase, α-amylase and neutral protease produced byB subtilis ZJF-1A5 was associated partially with cell growth. Those three enzymes' activities increased following the cell growth and increased significantly when cells entered the stationary phase. Project (No. B0608) supported by the National Natural Science Foundation of China and a grant (2001121B25) from Hangzhou Science and Technology Development Project of Zhejiang Province, China     

Scaling behavior of nucleotide cluster in DNA sequences

In this paper we study the scaling behavior of nucleotide cluster in 11 chromosomes of Encephalitozoon cuniculi Genome. The statistical distribution of nucleotide clusters for 11 chromosomes is characterized by the scaling behavior of P（S） ∝ e^-αs＇ where S represents nucleotide cluster size. The cluster-size distribution P（S1＋S2） with the total size of sequential C-G cluster and A-T cluster S1＋S2 were also studied. P（S1＋S2） follows exponential decay. There does not exist the case of large C-G cluster following large A-T cluster or large A-T cluster following large C-G cluster. We also discuss the relatively random walk length function L（n） and the local compositional complexity of nucleotide sequences based on a new model. These investigations may provide some insight into nucleotide cluster of DNA sequence.