Susceptibility, field inhomogeneity, and chemical shift-corrected NMR microscopy: Application to the human finger in vivo

Spectroscopic proton image data recorded with the aid of a gradient-echo spectroscopic imaging pulse sequence are reported. A postdetection processing method is suggested which permits correction of artifacts due to inhomogeneity, susceptibility, and chemical-shift resonance offsets. That is, apart from the spectral information available in this way, better spatial resolutions can be achieved. The method is demonstrated by resonance-offset corrected images of the human finger in vivo. Moreover, resonance-line selective and spectroscopically resolved diffusion-weighted images and diffusivity maps rendered with the aid of the same postdetection procedure are shown.     

Modelling CreA protein–DNA recognition determinants. A molecular dynamics study of fully charged CreA–DNA model in water

CreA, the negative regulator mediating carbon catabolism repression in Aspergillus nidulans, is a protein that contains a DNA-binding domain comprising two zinc finger motifs. A 3D model for the CreA–G4 (5′-GCGGGGGCGT-3′) complex is constructed on the basis of the structure of the Zif268–DNA crystal complex [Science 252 (1991) 809] and using similarity analysis and computer assisted modelling techniques. The CreA–G4 model was then subjected to a set of molecular dynamics (MD) studies. Based on our previous nano second long Zif268–DNA MD simulation, a 170 ps long trajectory was deemed sufficient to test possible DNA–protein interactions. A screening of the static model and of the trajectory was performed for protein amino acids, nucleotide bases, phosphates backbone and water molecules mediating protein–DNA contacts. Energy, root mean square deviation (RMSD), principal inertial moment and distances were analysed. For this time span, the stability shown in fluctuation patterns reveals the presence of a complex behaving in a manner similar to Zif268–DNA.

An unambiguous characterisation of the amino acids involved in DNA-binding was obtained. These results could contribute towards the establishment of a code of protein–DNA recognition for this class of DNA-binding motifs.     

Expression of integrin beta1 and its roles on adhesion between different cell cycle hepatocellular carcinoma cells (SMMC-7721) and human umbilical vein endothelial cells

To investigate expression of integrin β₁ and its roles on adhesion between different cell cycle hepatocellular carcinoma cell (HCC) and human umbilical vein endothelial cells (HUVEC), the synchronous G₁ and S phase HCC were achieved through thymine-2-deoxyriboside and colchicines sequential blockage method and double thymine-2-deoxyriboside blockage method, respectively. Expression of integrin β₁ on hepatocellular carcinoma cells was detected with flow cytometer. Further, the adhesive force of HCC to HUVEC and the role of integrin β₁ in this adhesive course were studied by micropipette aspiration technique. The results showed that percentage of each cyclic phases of the controlled HCC (non-synchronous) are: G₂+M phase, 11%; G₁ phase, 54%; S phase, 36%; the synchronous rates of G₁ and S phase HCC amount to 74 and 98%, respectively. The expressive fluorescent intensity of integrin β₁ in G₁ phase HCC is depressed significantly than the values of S phase and controlled HCC. Accordingly, the adhesive forces of G₁ phase HCC to HUVEC was significantly lower than the value of S phase cells (P<0.01), but it has no remarkable difference when compared the adhesive force values of S phase HCC with control; the contribution of integrin β₁ was about 50% in the adhesion of HCC to HUVEC. It suggested that HCC would be synchronized preferably in G₁ and S phase with thymine-2-deoxyriboside and colchicines, the adhesive molecule integrin β₁ expressed in a high lever in HCC and presented differences in vary cell cycle, and integrin β₁ played an important roles in adhesion of HCC to HUVEC. Possibly, S phase HCC take a great action in this adhesive course.     

On a Saffman–Taylor problem in an infinite wedge

We consider a zero-surface-tension two-dimensional Hele–Shaw flow in an infinite wedge. There exists a self-similar interface evolution in this wedge, an analogue of the famous Saffman–Taylor finger in a channel, exact shape of which has been given by Kadanoff. One of the main features of this evolution is its infinite time of existence and stability for the Hadamard ill-posed problem. We derive several exact solutions existing infinitely by generalizing and perturbing the one given by Kadanoff.     

Identification of efferent flow in the superior vena cava and azygos vein confluence using cine phase-contrast MRI: speculation of the role of the azygos arch valves

Purpose

We aimed to evaluate flow patterns in the superior vena cava (SVC) and azygos vein confluence with cine phase-contrast magnetic resonance imaging with consideration for the role played by the azygos arch valves.

Materials and Methods

Two-dimensional cine phase-contrast magnetic resonance images of the SVC and azygos vein confluence were prospectively acquired in 10 healthy volunteers. Flow directions during the cardiac cycle were evaluated quantitatively using sequential flow profile graphs obtained from each orthogonal image and affirmed visually by two radiologists from the oblique sagittal cine images.

Results

Although the blood in the SVC and azygos vein confluence had an afferent flow during the systolic phase, a slight temporal efferent flow during the diastolic phase was quantitatively observed in all cases. Flow in the SVC can also be confirmed visually. The average velocity, average maximum afferent velocity during the systolic phase and average maximum efferent velocity during the diastolic phase of the SVC were 8.7±2.4, 19.9±3.7 and −1.0±3.2 cm/s, respectively; for the azygos vein confluence, these values were 2.2±1.5, 7.1±2.6 and −1.5±1.1 cm/s, respectively.

Conclusion

We verified that a slight temporal efferent flow exists in the SVC and azygos vein confluence during the diastolic phase, which suggests that the usual role of the azygos arch valves is to prevent this physiological retrograde flow.     

残膜清理滚筒凸轮轴的应力测试及其分析

应用动态、静态应变分析仪对残膜清理滚筒凸轮轴进行了静、动应力实地测试及其分析,并深入地研究了凸轮轴、挑膜齿在正常工作条件下的受力情况,为下一轮改进设计提供必要的依据.     

下肢静脉曲张腔内激光治疗与传统剥脱手术治疗的远期疗效对比研究

目的 比较静脉腔内激光治疗（EVLT）和传统剥脱手术治疗下肢静脉曲张（VVLE）的远期疗效。方法 选取VVLE患者120例,随机分为EVLT 组与对照组,每组各60例。EVLT组采用EVLT治疗,对照组采用传统剥脱手术治疗。分别对两组患者手术并发症、术后1、2、3 年复发率以及术后生活质量进行对比评价。结果 术后3 个月EVLT 组患者生活质量调查表（CIVIQ）评分显著高于对照组（P＜0.05）,术后6 个月两组患者CIVIQ 评分比较则无统计学差异（P＞0.05）。EVLT 组患者术后皮下瘀血、感觉麻木、硬结、皮下脂肪液化感染的发生率均显著低于对照组（均P＜0.01）,皮肤灼伤的发生率则高于对照组（P＜0.05）,两组患者静脉炎的发生率无统计学差异（P＞0.05）;两组患者术后1、2、3年复发率比较均无统计学差异（均P＞0.05）。结论 应用EVLT治疗VVLE 手术并发症少,患者术后恢复较快,远期疗效理想,值得临床推广应用。     

Automatic polymerase chain reaction product detection system for food safety monitoring using zinc finger protein fused to luciferase

An automatic polymerase chain reaction (PCR) product detection system for food safety monitoring using zinc finger (ZF) protein fused to luciferase was developed. ZF protein fused to luciferase specifically binds to target double stranded DNA sequence and has luciferase enzymatic activity. Therefore, PCR products that comprise ZF protein recognition sequence can be detected by measuring the luciferase activity of the fusion protein. We previously reported that PCR products from Legionella pneumophila and Escherichia coli (E. coli) O157 genomic DNA were detected by Zif268, a natural ZF protein, fused to luciferase. In this study, Zif268–luciferase was applied to detect the presence of Salmonella and coliforms. Moreover, an artificial zinc finger protein (B2) fused to luciferase was constructed for a Norovirus detection system. In the luciferase activity detection assay, several bound/free separation process is required. Therefore, an analyzer that automatically performed the bound/free separation process was developed to detect PCR products using the ZF–luciferase fusion protein. By means of the automatic analyzer with ZF–luciferase fusion protein, target pathogenic genomes were specifically detected in the presence of other pathogenic genomes. Moreover, we succeeded in the detection of 10 copies of E. coli BL21 without extraction of genomic DNA by the automatic analyzer and E. coli was detected with a logarithmic dependency in the range of 1.0 × 10 to 1.0 × 10⁶ copies.     

Modelling spray impingement using linear stability theories for droplet shattering

This paper compares several linear‐theory‐based models for droplet shattering employed for simulations of spray impingement on flat wall surface or a circular cylinder. Numerical simulations are conducted using a stochastic separated flow (SSF) technique that includes sub‐models for droplet dynamics and impact. Results for spray impingement over a flat wall indicate that the linear theory applicable for a single droplet impact over‐predicts the number of satellite (or secondary) droplets upon shattering when compared to experimental data. The causes for the observed discrepancies are discussed. Numerical simulation results for spray impingement over a circular cylinder in cross flow are obtained and discussed. Copyright © 2005 John Wiley & Sons, Ltd.     

Optical properties of frustrated cholesteric liquid crystals in planar cell

ABSTRACT

We investigated the alignment director of a frustrated cholesteric liquid crystal (CLC) confined in a planar cell. Three cells with different confinement ratio (c?=?d/p) (where p is the pitch and d is the cell thickness) are prepared. Under an electric field, the CLC planar texture is transformed into a cholesteric fingerprint (CF). The results showed that CF contrast depends on c. When c?≈?2, CLC stripes are formed by a periodic CF, with a period equal to the CLC pitch. The CF is developed and slowly extended to the whole cell surface along the rubbing direction and the contrast of the grating stripes keeps unchangeable. Yet, the CLC finger borders have a different light intensity. However, when c?≈?1, the CF contrast increases with time. When c?θ between the polarizer and the CFs.