Fractal dynamics of polarized bioelectrodes

This study is concerned with mathematical modelling of the fundamental relationship which exists between the current density and the overpotential across the metalsolution interface in the linear range using methods of system theory enhanced by ‘fractal’ concepts. A primer for both 1/f-type scaling and ‘anomalous’ relaxation/dispersion concepts is provided, followed by a brief review of the research history pertinent to the metal electrode polarization dynamics. Next, the ‘fractal relaxation systems’ approach is introduced to characterize, systems which attenuate with a fractional power-low dependence on frequency through a ‘scaling exponent’. The ‘singularity structure’ which is a scaling, rational system function is proposed to expand fractal systems in terms of basic subsystems individually representing elementary exponential relaxations and collectively exhibiting scaling properties. We stress that the ‘singularity structure’ carries scaling information identical to the conventional ‘distribution of relaxation times’ function. ‘Structure scale’ and ‘view scale’ concepts are presented in the due course to streamline the analysis of scaling phenomena in general and the polarization impedance in particular. System theory-wise, the notable result is that the fractional power function attenuation, or equivalently, the logarithmic nature of the distribution function translates into the ‘self-similar’ pattern replication of the system singularities in the s-plane. The singularity arrangement is governed by a recursive rule solely based on the knowledge of the fractional power factor or the scaling exponent.     

Development of optical probes for in vivo imaging of polarized macrophages during foreign body reactions

Plasticity of macrophage (MΦ) phenotypes exist in a spectrum from classically activated (M1) cells, to alternatively activated (M2) cells, contributing to both the normal healing of tissues and the pathogenesis of implant failure. Here, folate- and mannose-based optical probes were fabricated to simultaneously determine the degree of MΦ polarization. In vitro tests show the ability of these probes to specifically target M1 and M2 cells. In an in vivo murine model, they were able to distinguish between the M1-dominated inflammatory response to infection and the M2-dominated regenerative response to particle implants. Finally, the probes were used to assess the inflammatory/regenerative properties of biomaterial implants. Our results show that these probes can be used to monitor and quantify the dynamic processes of MΦ polarization and their role in cellular responses in real time.     

Influence of alloying elements on the corrosion stability of CoCrMo implant alloy in Hank's solution

The behavior of a CoCrMo alloy and its components was studied in simulated physiological solution (Hank’s solution) using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The passivation of all samples occurred spontaneously at the open circuit potential. The composition of the oxide films as a function of the solution components and the applied potential is discussed. The electrochemical properties of the spontaneously passivated electrodes at the open circuit potential were studied by EIS. The polarization resistance (R_p) and the electrode capacitance (C_dl) were determined. The higher R_p of the alloy than of the chromium pointed to the stabilizing effect of the other alloy components. The concentration of the metallic ions in a simulated physiological solution, measured by inductively coupled plasma-mass spectrometry, was in accordance with the values of both the R_p determined from EIS data and current densities measured with CV.     

肺结核患者外周血中Th细胞极化偏移及临床意义分析

目的:分析初诊肺结核患者外周血中CD4+T淋巴细胞及其亚型Th1和Th2细胞的改变,探讨其在肺结核病变过程中的临床意义。方法:取肝素抗凝全血,加RPMI1640培养液等体积混匀,依次加入1∶1 000稀释的PMA、1∶100稀释的Ion-omycin和1∶10稀释的Monensin,混匀后于37℃,5%CO2静置培养4小时或过夜。取100μl培养血细胞依次加入抗人CD3-Per-CP、CD8-APC、mIgG1-FITC、Rat IgG1-PE、IL-4-PE、IFN-γ-FITC抗体,按流式操作流程分别进行细胞膜和细胞浆内标记测定CD4+IL-4+(Th2)、CD4+IFN-γ+(Th1)两种细胞的水平。结果:初诊肺结核患者外周血中Th1水平均显著低于健康对照组(P0.01),而Th2水平则显著高于健康对照组(P0.05)。粟粒型肺结核患者外周血中Th1细胞含量显著低于浸润性肺结核患者(P0.05),而Th2水平显著高于浸润性肺结核和结核性胸膜炎(P0.05)。CD4+/CD3+T细胞比例在这三个病程中呈下降趋势,且粟粒型肺结核显著低于浸润性肺结核(P0.05)。糖尿病并肺结核患者Th1、CD4+/CD3+显著低于无糖尿病肺结核患者(P0.05),Th2含量则显著升高(P0.05)。15例重度肺结核患者经结核化疗与微卡治疗三个月后Th1、CD4+/CD3+水平较治疗前明显升高(P0.05),而Th2水平较治疗前显著降低(P0.01)。痰检或培养阳性与痰检阴性患者相比Th1、CD4+/CD3+水平呈下降趋势但无显著差异(P0.05),Th2细胞水平显著升高(P0.05)。结论:浸润性肺结核、结核性胸膜炎、粟粒型肺结核、糖尿病并肺结核患者存在着不同程度的免疫功能抑制,对Th1、Th2细胞水平与CD4+/CD3+比例测定有助于临床病情的判断和疗效观察。     

Two-dimensional and three-dimensional time-lapse microscopic magnetic resonance imaging of Xenopus gastrulation movements using intrinsic tissue-specific contrast.

The amphibian embryo undergoes radical tissue transformations during blastula and gastrula stages, but live observation of internal morphogenetic events by optical microscopy is not feasible due to the opacity of the early embryo. Here, we report on the use of microscopic magnetic resonance imaging (MRI) to directly follow morphogenetic movements during blastula and gastrula stages of the Xenopus laevis embryo. We compare three different MRI modalities that take advantage of the intrinsic contrast present in embryonic tissues: three-dimensional (3D) fat-imaging, 3D water-imaging, and 2D high-speed high-resolution imaging of early embryonic stages. We show that the features revealed by the intrinsic contrast correlate with the histological structure of the embryo. Using this tissue specific intrinsic contrast, the main embryonic tissues and internal tissue movements as well as archenteron invagination can be differentiated without cell labeling. We present 2D and 3D time-lapse sequences of early Xenopus embryonic development, spanning the stages from early blastula to the end of gastrula, which show the complex internal rearrangements of gastrulation in essentially real-time.     

用单表位合成肽抗原荧光偏振免疫法检测抗幽门螺旋杆菌尿素酶的抗体

目的:应用单表位合成肽抗原,建立一种新的基于荧光偏振技术(fluorescencepolarization,FP)的抗体检测方法。方法:用幽门螺旋杆菌(Helicobacterpylori,Hp)尿素酶B(UreB)的单表位合成分支肽抗原免疫小鼠,以ELISA法分析免疫的效果。分析FITC标记的合成肽抗原在不同浓度时的FP值,用FP技术分析抗原表位的抗原性以及不同稀释比例的血清样品对FP检测的影响。分别应用FPIA法和ELISA法,对126例样品进行Hp感染检测,对FPIA的检测数据进行受试者工作特征曲线(receiveroperatingcharacteristiccurve,ROC)分析。结果:UreB的单表位抗原肽具有较强的抗原性和免疫原性;1.0nmol/L的FITC标记肽可用于FPIA检测,血清样品做1∶25稀释时可明显区分阳性和阴性检测结果。与ELISA方法检测的结果相比较,用基于UreB单表位合成肽抗原的FPIA法检测Hp感染的灵敏度为85.7%,特异度为98%。结论:应用UreB单表位合成肽抗原,可对抗UreB的抗体进行快速FPIA检测,用此法检测抗体在疾病的临床诊断中具有广阔的应用前景。     

Optimization of artificial urine formula for in vitro cellular study compared with native urine

Several artificial urine (AU) formulas have been developed to mimic the normal urine. Most of them are protein-free, particularly when secreted proteins (secretome) is to be analyzed. However, the normal urine actually contains a tiny amount of proteins. We hypothesized that urinary proteins at physiologic level play a role in preservation of renal cell biology and function. This study evaluated the effects from supplementation of 0-10% fetal bovine serum (FBS) into the well-established AU-Siriraj protocol on MDCK renal tubular cells. Time to deformation (T_D) was reduced by both native urine and AU-Siriraj without/with FBS compared with complete culture medium (control). Among the native urine and AU-Siriraj without/with FBS, the cells in AU-Siriraj+2.5% FBS had the longest T_D. Supplementation of FBS increased cell death in a dose-dependent manner (but still <10%). Transepithelial electrical resistance (TER) of the polarized cells in the native urine was comparable to the control, whereas that of the cells in AU-Siriraj+2.5% FBS had the highest TER. These data indicate that supplementation of 2.5% FBS into AU-Siriraj can prolong time to deformation and enhance polarization of renal tubular cells. Therefore, AU-Siriraj+2.5% FBS is highly recommended for in vitro study of cell biology and function (when secretome is not subjected to analysis).     

肿瘤显像剂S^11C-甲基-L-半胱氨酸的细胞摄取机制研究

目的探讨肿瘤细胞摄取S^11C-甲基-L-半胱氨酸（^11C-MCYS）的机制。方法将Hepal-6肝癌细胞分为Na^＋依赖组（NaCl组）及非Na^＋依赖组（氯化胆碱组）进行氨基酸转运实验。每组又分为对照组、L-氨基酸转运载体抑制剂2-氨基二环．2,2,1-庚烷-2-羧酸（BCH）组、转运系统A和ASC的抑制剂α-甲基-氨基异丁酸（MeAIB）组、MeAIB＋丝氨酸组,分别加入^11C-MCYS（400μl0．925MBq／ml）、^11C—MCYS（200μl1．85MBq／ml）＋阻滞剂BCH（200μl 15mmol／L）、^11C-MCYS（200μl1．85MBq／ml）＋阻滞剂MeAIB（200Ixl15mmol／L）以及“C．MCYS（200斗11．85MBq／ml）＋阻滞剂MeAIB＋丝氨酸（200斗l15mmol／L）。作用4min后终止培养应用1计数仪测量细胞放射性活度。将Hepal一6肝癌细胞分为5组,各组均加入200μl^11C—MCYS（1．85MBq／ml）后分别加入50、100、200、300、350μmol／L浓度不等的MCYS进行竞争抑制实验。培养4min后终止培养应用γ计数仪测量细胞放射性活度。结果无论是否有Na^＋存在,对照组、BCH组、MeAIB及MeAIB＋丝氨酸组对^11C—MCYS摄取的差异均无统计学意义（均P〉0．05）。MeAIB组和MeAIB＋丝氨酸组中的NaCl组细胞放射性活性与氯化胆碱组相比差异均无统计学意义（18958．18±97．32比20582．27±196．32,18385．24±122．96比21620比±131．41,均P〉0．05）,两者均不能抑制Na^＋非依赖性氨基酸转运载体的转运。而BCH组中的NaCl组细胞放射性活性高于氯化胆碱组（2587．21±＋30．25比2340．61±21．09,P〈0．05）,可见BCH能明显抑制Na^＋非依赖性氨基酸转运体对^11C-MCYS的转运。不同浓度MCYS（50～350μmol／L）作用下肿瘤细胞对^11C-MCYS摄取差异无统计学意义（均P〉0．05）。结论肿瘤细胞摄取^11C-MCYS是通过非Na^＋依赖的L-氨基酸转运系统进行转运的,极少涉及氨基酸转运系统A和ASC。     

应用计算流体动力学方法研究人工心脏流场

目的探讨计算流体动力学（CFD）方法在人工心脏设计中的应用。方法应用CFD Fluent6．1软件模拟不同状态下自制螺旋和轴流2种叶轮血泵泵腔、出人流口的流场状态．内部流场采用三维彩图显示。结果得到2种血泵在不同转速下压力流量情况和内部流场及剪切应力分布状态。结论模拟计算结果与体外实验结果对照显示CFD分析结果很好地提示血泵实际工作状态。CFD方法可以有效地提示设计血泵的血液相容性能，是血泵研制的可靠手段。     

肿瘤显像剂S-11C-甲基-L-半胱氨酸的细胞摄取机制研究

目的 探讨肿瘤细胞摄取S-11C-甲基-L-半胱氨酸(11C-MCYS)的机制.方法 将Hepa1-6肝癌细胞分为Na+依赖组(NaCl组)及非Na+依赖组(氯化胆碱组)进行氨基酸转运实验.每组又分为对照组、L-氨基酸转运载体抑制剂2-氨基二环-2,2,1-庚烷-2-羧酸(BCH)组、转运系统A和ASC的抑制剂α-甲基-氨基异丁酸(MeAIB)组、MeAIB+丝氨酸组,分别加入11C-MCYS(400μ1 0.925 MBq/ml)、11C-MCYS(200μl 1.85 MBq/ml)+阻滞剂BCH(200μl 15 mmol/L)、11C-MCYS(200μl 1.85 MBq/ml)+阻滞剂MeAIB(200μl 15 mmol/L)以及11C-MCYS (200μl 1.85 MBq/ml)+阻滞剂MeAIB+丝氨酸(200μl15 mmol/L).作用4 min后终止培养应用γ计数仪测量细胞放射性活度.将Hepal-6肝癌细胞分为5组,各组均加入200 μl11C-MCYS( 1.85 MBq/ml)后分别加入50、100、200、300、350μmol/L浓度不等的MCYS进行竞争抑制实验.培养4 min后终止培养应用γ计数仪测量细胞放射性活度.结果 无论是否有Na+存在,对照组、BCH组、MeAlB及MeAIB+丝氨酸组对11C-MCYS摄取的差异均无统计学意义(均P＞0.05).MeAIB组和MeAIB+丝氨酸组中的NaC1组细胞放射性活性与氯化胆碱组相比差异均无统计学意义(18 958.18±97.32比20 582.27±196.32,18 385.24±122.96比21 620.54±131.41,均P＞0.05),两者均不能抑制Na+非依赖性氨基酸转运载体的转运.而BCH组中的NaC1组细胞放射性活性高于氯化胆碱组(2587.21±30.25比2340.61±21.09,P＜0.05),可见BCH能明显抑制Na+非依赖性氨基酸转运体对11C-MCYS的转运.不同浓度MCYS(50 ～ 350 μmol/L)作用下肿瘤细胞对11C-MCYS摄取差异无统计学意义(均P＞0.05).结论 肿瘤细胞摄取11C-MCYS是通过非Na+依赖的L-氨基酸转运系统进行转运的,极少涉及氨基酸转运系统A和ASC.     

Effect of the distribution of adsorbed proteins on cellular adhesion behaviors using surfaces of nanoscale phase-reversed amphiphilic block copolymers

In order to create suitable biocompatible materials for various tissue engineering applications, it is important to be able to understand protein adsorption and cell adhesion behaviors on the material’s surfaces. It is known that the nanoscale distribution of adsorbed proteins affects cell adhesion behaviors. However, how nanoscale structures affect cell adhesion behaviors is still unclear. Therefore, in this study, we investigate the effect of the distribution of adsorbed proteins by the phase reversal of amphiphilic block copolymers composed of protein-non-adsorptive poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and protein-adsorptive poly(3-methacryloyloxy propyltris(trimethylsilyloxy) silane) (PMPTSSi) on cell adhesion behaviors. The nanodomain structures of phase-separated block copolymers were successfully confirmed using transmission electron microscopy and atomic force microscopy. Surfaces that had PMPC dot-like domains (23 ± 4 nm) and ones that had PMPTSSi dot-like domains (25 ± 6 nm) were made. From protein adsorption and L929 cell adhesion measurements, it was found that even on surfaces with equal quantities of protein adsorption, the number of cells on surfaces with PMPC dot-like domains was larger than those with PMPTSSi dot-like domains. This suggests that the simple phase-reversal of the distribution of adsorbed proteins can be used to affect cell adhesion behaviors for designing biomaterial surfaces for tissue engineering applications.     

The influence of cellular source on periodontal regeneration using calcium phosphate coated polycaprolactone scaffold supported cell sheets

Cell-based therapy is considered a promising approach to achieving predictable periodontal regeneration. In this study, the regenerative potential of cell sheets derived from different parts of the periodontium (gingival connective tissue, alveolar bone and periodontal ligament) were investigated in an athymic rat periodontal defect model. Periodontal ligament (PDLC), alveolar bone (ABC) and gingival margin-derived cells (GMC) were obtained from human donors. The osteogenic potential of the primary cultures was demonstrated in vitro. Cell sheets supported by a calcium phosphate coated melt electrospun polycaprolactone (CaP-PCL) scaffold were transplanted to denuded root surfaces in surgically created periodontal defects, and allowed to heal for 1 and 4 weeks. The CaP-PCL scaffold alone was able to promote alveolar bone formation within the defect after 4 weeks. The addition of ABC and PDLC sheets resulted in significant periodontal attachment formation. The GMC sheets did not promote periodontal regeneration on the root surface and inhibited bone formation within the CaP-PCL scaffold. In conclusion, the combination of either PDLC or ABC sheets with a CaP-PCL scaffold could promote periodontal regeneration, but ABC sheets were not as effective as PDLC sheets in promoting new attachment formation.     

Effects of chamber shape and fiber orientation on relations between fiber dynamics and chamber dynamics

The function of a chamber depends on its hydrodynamic properties: isometric pressures it can exert in the operating range of distensions, compliances in the operating range of distensions, and wall-displacement resistances in the operating range of distensions. Wall-displacement resistance is the departure of pressure from isometric pressure relative to rate of cavity-volume change. The dependence of pressure on average stress and wall/cavity volume ratio is indifferent to chamber shape, which suggests that the volume-based compliance-elastance and resistance-viscosity equations would be only moderately shape dependent. The present study shows that this supposition is correct. If the wall is thin, these relations are shape indifferent. At higher wall/cavity volume ratio, cylindricity increases slightly the P-V-curve slope relative to elastance and either increases slightly or does not affect resistance relative to viscosity. The compliance-elastance and resistance-viscosity relations also depend only slightly on fiber orientation. Therefore, with the sphere equations, one can account accurately for normal and abnormal function of a prolate spheroid in terms of volume dimensions of the wall and apparent average fiber properties.     

Simultaneous imaging and restoration of cell function using cell permeable peptide probe

Targeting tissues/cells using probing materials to detect diseases such as cancer and inflammatory disease has been attempted with some success. Most of the molecular targets used in diagnosis and therapy were identified through the discovery of intracellular signaling pathways. Among intracellular signaling processes, the ubiquitination of proteins, and thereby their proteasomal degradation, is important because it plays a role in most diseases involving alterations to a component of the ubiquitination system, particularly E3 ligases, which have selective target-binding affinity and are key to the success of regulating the disorder. The regulation and monitoring of E3 ligases can be achieved using peptides containing protein–protein binding motifs. We generated a human protein-derived peptide that could target Smurf1, a member of the E3 ligase family, by competitively binding to osteo-Smads. To effectively deliver it into cells, the peptide was further modified with a cell-penetrating peptide. The peptide contains two fluorescent dyes: fluorescein isothiocyanate (FITC; absorbance/emission wavelengths: 495/519 nm) as a fluorophore and black hole quencher-1 (BHQ-1) as a fluorescence quencher. When the target Smurf1 combined with complementary sequences in the peptide probe, the distance between the fluorophore and BHQ-1 increased via a conformational change, resulting in the recovery of the fluorescence signal. Simultaneously, the degradation of Smad1/5/8 was blocked by the binding of the peptide probe to Smurf1, leading to the potentiation of the osteogenic pathway, which was reflected by an increase in the expression of osteoinductive genes, such as alkaline phosphatase and osteocalcin. Possible future applications of the peptide probe include its integration into imaging tools for the diagnosis of Smurf1-overexpressing diseases.     

Functional insights on the polarized redistribution of leukocyte integrins and their ligands during leukocyte migration and immune interactions

Summary:  Cell–cell and cell–matrix interactions are of critical importance in immunobiology. Leukocytes make extensive use of a specialized repertoire of receptors to mediate such processes. Among these receptors, integrins are known to be of crucial importance. This review deals with the central role of integrins and their counterreceptors during the establishment of leukocyte–endothelium contacts, interstitial migration, and final encounter with antigen-presenting cells to develop an appropriate immune response. Particularly, we have addressed the molecular events occurring during these sequential processes, leading to the dynamic subcellular redistribution of adhesion receptors and the reorganization of the actin cytoskeleton, which is reflected in changes in cytoarchitecture, including leukocyte polarization, endothelial docking structure formation, or immune synapse organization. The roles of signaling and structural actin cytoskeleton-associated proteins and organized membrane microdomains in the regulation of receptor adhesiveness are also discussed.     

Effects of Nucleus on Leukocyte Recovery

The rheological properties of a leukocyte significantly affect its biological and mechanical characteristics. To date, existing physical models of leukocyte are not capable of quantitatively explaining the wide range of deformation and recovery behaviors observed in experiment. However, a compound drop model has gained some success. In the present work, we investigate the effect of nucleus size and position, and the relative rheological properties of cytoplasm and nucleus, on cell recovery dynamics. Two nucleus sizes corresponding to that of neutrophil and lymphocyte are considered. Direct comparison between numerical simulations and experimental observation is made. Results indicate that the time scale ratio between the nucleus and cytoplasm plays an important role in cell recovery characteristics. Comparable time scales between the two cell components yield favorable agreement in recovery rates between numerical and experimental observations; disparate time scales, on the other hand, result in recovery behavior and cell shapes inconsistent with experiments. Furthermore, it is found that the nucleus eccentricity exhibits minimum influence on all major aspects of the cell recovery characteristics. The present work offers additional evidence in support of the compound cell model for predicting the rheological behavior of leukocytes. © 1999 Biomedical Engineering Society. PAC99: 8717-d, 8719Tt     

Magnetic resonance imaging using hemagglutinating virus of Japan-envelope vector successfully detects localization of intra-cardially administered microglia in normal mouse brain

Although the therapeutic use of microglia has received some attention for the treatment of brain diseases, few non-invasive techniques exist for monitoring the cells after administration. Here, we present a technique using magnetic resonance imaging (MRI) to track microglia injected intra-cardially. We labeled microglia expressing enhanced green fluorescent protein with superparamagnetic iron oxide (Resovist) using the hemagglutinating virus of Japan-envelope vector. We injected labeled microglia into the left ventricle of the heart of mice. After monitoring exogenously administered microglia in the mouse brain in vivo using T(2)*-weighted MRI at a magnetic field of 7T, we compared the MR images with histochemical localization of exogenous microglia in vitro. MRI revealed clear signal changes attributable to Resovist-containing microglia in the mouse brain. Histochemistry demonstrated the presence of exogenous microglia in the brain at the same locations shown by MRI. This study demonstrates the usefulness of MRI for non-invasive monitoring of exogenous microglia, and suggests a promising future for microglia/macrophages as therapeutic tools for brain disease.     

Use of fluorescent quantum dot bioconjugates for cellular imaging of immune cells,cell organelle labeling,and nanomedicine: surface modification regulates biological function,including cytotoxicity

With the development of nanotechnology, nanoscale products that are smaller than several hundred nanometers have been applied to all areas of science and technology. Nanoscale products, including carbon nanotubes, fullerene derivatives, and nanocrystal quantum dots (QDs), are wide spread as novel tools in various fields, not only in materials engineering, electronics, plastics, and the automobile and aerospace industries, but also in molecular biology and medicine. At present, QDs have been widely used in biological and medical studies because of their superior photoemission and photostability. Although the physical and chemical properties of QDs have been circumstantially investigated, little is known about any harmful effects of QDs on human health. Here we report on the toxicity and biological behavior of QDs in vitro and in vivo. The toxicity of the core constituent chemicals such as cadmium and selenium has been identified. Recently, the surface molecules surrounding QDs have been intensively investigated. Accumulating evidence that toxic surface-covering molecules showed their cytotoxicity and biomolecules conjugated with QDs maintained their biological effects indicates that at least the biological properties of QDs are attributable to the QD-capping material rather than to the core metalloid complex itself.     

Study of cellular responses to polymeric biomaterials using the differential display method

In this study, we attempted to detect altered gene expressions in the cells that had adhered to various surfaces using the differential display method. Thioglycollate-elicited peritoneal exudate cells (PEC) and mouse fibroblast (L929) cells were cultured on the polymer films. After a predetermined time, the total RNA was isolated from cells and the differential mRNA expressions were evaluated by RT-PCR method. As a result, in the differential display of amplified cDNA from PEC, the different patterns of cDNA fragments among the samples were obtained. This indicates that there were many different mRNA expressions depending on the polymer surfaces. The use of differential method was proven to be useful for studying cell-polymer interaction.