关于动物组织声速频散的进一步研究

80年代以来,超声组织定征(Ultrasonic Tissue Characterization)已成为超声生物物理学研究中一项前沿课题.其明显的应用背景是寻求新的超声诊断参量,以开拓定量超声诊断的新途径.所谓超声组织定征,系指研究组织的各种声学参数(如声速、频散、声阻抗、声衰减、散射及非减性参量B/A等)的量值与组织状态之间的关系及相应的测试方法.近年来我们在这一领域已做了一系列研究工作.     

模拟生物组织非线性声参量B／A与其组分预测关系的研究

组织的非线性声参量A/B与组分有着密切的关系,许多学者根据不同的假设和物理关系,建立了各组分的声参量、混合物的声参量、以及各组分的体积含量三者之间的关系方程,即混合定则.通过对它们的比较发现,Apfel混合定则的约束条件少,具有典型性.     

两种除草剂对棉田节肢动物群落多样性指数的影响

系统地研究了棉田地面和棉株节肢动物群落及各亚群落施用克无踪(A)、高盖(B)与对照(CK)之间在群落生物多样性、丰富度和均匀度的差异.结果表明,对地面肉食动物群落生物多样性(H′)的A-CK的t值为3.099,B-CK的t值为2.449,t＞t_0.05=2.228,差异显著;地面植食动物亚群落的(H′)A-CK的t值为2.377,A-B为2.260,t＞t_0.05=2.228,差异均显著.棉株节肢动物群落及亚群落A-CK、B-CK和A-B之间差异不显著.地面节肢动物亚群落丰富度A-CK的t值为4.759,地面植食类节肢动物亚群落为4.359,地面肉食节肢动物亚群落为2.963,均t＞t0.0=2.228,表明A与CK之间差异显著;在均匀度上,A和B及A-CK、B与CK之间两类群落及亚群落上差异均不显著.A和B对棉株节肢动物群落影响很小.施用A和B及CK的生物多样性的变化总趋势一致.     

血清脂联素、载脂蛋白B/A1比值与颈总动脉内——中膜厚度和冠脉病变的相关性研究

目的:探讨血清脂联素、栽脂蛋白B/我脂蛋白A1比值与颈动脉内中膜厚度(IMT)的相关性,为冠心病的早期诊断提供简便、客观的指标.方法:入选经冠状动脉造影证实的冠心痛患者81例,其中单支病变组21例,多支病变组60例,另选冠状动脉造影正常者17例为对照组.采用高频超声探测双侧颈总动脉内中膜厚度(IMT),以及测定血清脂联素、载脂蛋白B/载脂蛋白A1水平,分析三者之间的相关性以及和冠心病的关系.结果:血清脂联素与颈动脉内中膜厚度呈负相关,载脂蛋白B/栽脂蛋白A1比值与颈动脉内中膜厚度呈正相关.与正常对照组相比,冠状动脉单支或多支病变组血清脂联素水平降低,而栽脂蛋白B/载脂蛋白A1比值、颈动脉内中膜厚度明显增高.结论:血清脂联素、载脂蛋白B/载脂蛋白A1比值与颈动脉内中膜厚度对于冠心痛的诊断有重要的预测价值.     

Stokes参量共焦显微术用于弱各向异性物质的成像研究

提出将基于Stokes参量的偏振共焦显微成像技术应用于弱各向异性物质的成像研究。通过将分振幅Stokes参量测量法与共焦扫描成像技术相结合的方法,得到了基于Stokes参量测量的偏振共焦显微成像系统。利用该系统对具有弱各向异性的生物组织样品进行逐点测量,通过四个通道同时测量获得全部的Stokes参量。再以计算得到的偏振参量作为成像物理量进行图像重建,获得对应Stokes参量、偏振度、相位差、方位角和椭率角的空间分布图像,从而对生物组织实现细胞水平的偏振显微成像研究。实验结果表明:基于Stokes参量的偏振共焦显微成像技术能够获得弱各向异性的生物组织样品的显微图像,并通过比较样品的Stokes参量及相关偏振参量的分布图像,提取样品全部的偏振信息,从而为生物组织的特性研究提供更丰富的信息。     

ELISA与IFA检测鸡血清ALV-A/B特异性抗体相关性比较

为了研究ELISA和IFA检测鸡血清中ALV-A/B特异性抗体的相关性,将A/B亚群禽白血病病毒接种到DF1细胞上,用ELISA检测过的鸡血清作为一抗进行IFA检测,比较ELISA检测的S/P值与IFA检测的血清效价之间的相关性。结果表明ELISA检测鸡血清中ALV-A/B抗体的S/P值与IFA检测ALV-A/B的血清效价之间存在显著正相关(r=0.974 35;P﹤0.001)。由此可推测ELISA检测鸡血清的S/P值与IFA检测的血清效价之间存在显著相关性,且呈正相关。IFA检测血清阳性率与ELISA检测结果完全一致,因此当血清样品数量少时,可用IFA检测替代ELISA检测,既节约检测成本也提高了检测的准确性。     

猪苓甾酮类化合物的HPLC含量测定及指纹图谱研究

收集中国12个省区35个猪苓样品,利用高效液相色谱技术,测定5个甾酮类化合物含量,获得指纹图谱,利用相似度评价对图谱数据进行分析。共有28个样品能获得定量分析结果,其中25个样品中猪苓酮A和B的相对含量大于70%;经相关分析,猪苓酮A和B的含量之间呈极显著正相关(r=0.955,P0.01)。陕西省样品平均总甾酮含量以及猪苓酮A和B相对含量均最高,分别为182.70μg/g(C.V=82.4%)和92.3%(C.V=3.1%)。35个样品之间指纹图谱相似度0.412–0.943,标定了8个共有峰,指认了其中的3个色谱峰。11个陕西省样品之间指纹图谱相似度0.812–0.989,标定了17个共有峰,指认了其中的9个色谱峰。以上结果说明,猪苓酮A和B是猪苓主要甾酮类成分,对猪苓药材的质量控制有重要意义;陕西省的猪苓质量好且稳定。     

基于神经网络原理的荧光寿命成像研究

荧光寿命成像技术(fhlorescence lifetime imaging,FLIM)是一种新颖且功能强大的、能用于复杂生物组织和细胞结构与功能分析的生物组织成像技术。传统的时域荧光寿命成像数据分析方法,由于没有考虑荧光分子团之间以及他们与周围环境的相互作用,可能导致复杂的连续分布荧光寿命这一实际情况,因此对生物组织中自发荧光发光强度衰减过程的实验数据拟合效果欠佳。文章提出利用人工神经网络(artificial neural network,ANN)原理拟合算法来计算生物荧光分子团衰减动力过程,该方法能有效地建立生物荧光分子团衰减动力过程的非线性模型,并且具有处理非线性模型能力强、鲁棒性好、拟合精度高和所需计算时间少等优点。通过计算证明,相对于单参量指数与多参量指数衰减函数,这种数据拟合方法对于某些荧光分子团的多槽基面效价测定样品(multi-well plate assays)的数据有更好的一致性和更小的计算量。同时在文章中讨论了将该拟合算法应用于荧光寿命成像的前景。     

大兴安岭和长白山地区蜜环菌生物种的研究

从大兴安岭和长白山采集到30号蜜环菌(Armillaria mellea)标本,选其中有代表性的10个号的担子果获得单孢株。交配试验表明每一担子果都具有双因子异宗配合系。不同子实体交配型之间交配结果表明,在大兴安岭和长白山地区蜜环菌目前至少存在5个生物种,分别称为生物种A、B、C、D和E。将这5个生物种的单孢菌种与欧洲5个蜜环菌生物种的单孢菌株进行配合,生物种B与欧洲A.gallica,生物种E与欧洲A.ostoyae亲和交配,因此将生物种B和E分别定为A.gallica和A.ostoyae。生物种A、C和D则不与任何欧洲生物种交配。     

血清前白蛋白、总胆汁酸、AST/ALT比值在肝硬化分级中的诊断意义

目的 探讨肝硬化患者血清前白蛋白(PA)、总胆汁酸(TBA)、(天)门冬氨酸氨基转移酶(AST)/丙氨酸氨基转移酶(ALT)与肝硬化Child-Pugh分级的关系.方法 测定肝硬化患者的PA、TBA、AST和ALT水平.结果 血清PA在肝硬化A、B、C级之间比较明显降低;血清白蛋白在肝硬化患者中降低,A级与B、C级之间差异有统计学意义,而B、C级之间差异无统计学意义;TBA在肝硬化A、B、C级之间升高,但A、B级间比较差异无统计学意义,在B、C级之间差异有统计学意义;AST/ALT比值升高,A、B、C级之间比较,差异有统计学意义.结论 PA、TBA、AST/ALT比值对判断肝硬化程度具有重要的指导意义,可作为肝硬化患者病情诊断和预后判断的重要指标.     

生物组织散射元平均间距估计的一种新方法

生物组织散射元平均间中划描述生物组织微观结构特性和生物组织超微散射特性的重要参数。本文在对生物组织超声背向散射随机模的基础上,提出了基于生物组织超声背向散射信号突变点检测的工用射元平均间距估计的新方法。该方法是生物组织超声散射分析的有效方法。     

Heavy ion induced membrane damage: Hemolysis of erythrocytes and changes in erythrocyte membrane fluidity

Human erythrocytes were irradiated with heavy ions of energies between 4 and 18 MeV/u having linear energy transfer (LET) values between 92 and 14000 keV/µm. Hemolysis has been studied as a macroscopic parameter for membrane damage and changes of the fluidity as a more microscopic parameter. The membrane fluidity changed in a characteristic dose-dependent manner as detected by electron spin resonance employing 12-doxylstearic acid methyl ester spin label (SL 12). Lysis cross sections and RBE values were determined from dose effect curves. The results demonstrate a high hemolytic efficiency of heavy ions compared to X rays. With increasing LET values the measured relative biological efficiency (RBE) values increase continuously. In the complete LET range the cross sections formed one common curve as function of LET and no saturation effects are observed. This is in direct contrast to other biological endpoints such as cell inactivation or DNA damage.     

Modeling of esterase production from Saccharomyces cerevisiae

A suitable simple model tested by experiments is required to address complex biological reactions like esterase synthesis by Saccharomyces cerevisiae. Such an approach might be the answer to a proper bioprocessing strategy. In this regard, a logistic model for esterase production from Saccharomyces cerevisiae has been developed, which predicts well the cell mass, the carbon source (glucose) consumption, and the esterase activity. The accuracy of the model has been statistically examined by using the Student's t-test. The parameter sensitivity analysis showed that all five parameters (microm, Ks, Xm, Yx/s, and Yp/x) have significant influence on the predicted values of esterase activity.     

Learning scoring schemes for sequence alignment from partial examples

When aligning biological sequences, the choice of parameter values for the alignment scoring function is critical. Small changes in gap penalties, for example, can yield radically different alignments. A rigorous way to compute parameter values that are appropriate for aligning biological sequences is through inverse parametric sequence alignment. Given a collection of examples of biologically correct alignments, this is the problem of finding parameter values that make the scores of the example alignments close to those of optimal alignments for their sequences. We extend prior work on inverse parametric alignment to partial examples, which contain regions where the alignment is left unspecified, and to an improved formulation based on minimizing the average error between the score of an example and the score of an optimal alignment. Experiments on benchmark biological alignments show we can find parameters that generalize across protein families and that boost the accuracy of multiple sequence alignment by as much as 25%.     

Computer modelling study on the compatibility of PEO–PMMA block copolymers

The compatibility of six kinds of designed poly(ethylene oxide)-block-poly(methyl methacrylate) (PEO-b-PMMA) copolymers was studied at 270, 298 and 400 K by mesoscopic modelling. The values of order parameter depended on both the structures of block copolymers and the simulation temperatures, while the values of order parameter of the long chains were higher than those of the short ones; temperature showed a more obvious effect on long chains than on short ones. These plain copolymers doped with PEO or PMMA homopolymer showed different order parameter values. When the triblock copolymer was composed of the same component at both ends and was doped with a homopolymer with the same component as that in the middle or the end of triblock copolymer, the values of order parameter depended on the simulation temperature, such as A5B6A5 doped with B6 at 400 K and A5B6A5 doped with A5 at 270 K, it showed the highest order parameter values. The study of copolymers doped with nanoparticles showed that the mesoscopic phase was influenced by not only the properties of the nanoparticles, such as the size and density, but also the compositions of copolymers. Among them, increasing the size of doped nanoparticles was the most significant effect on changing the phase morphologies.     

Effects of nanoparticles on the compatibility of PEO-PMMA block copolymers

The compatibility of six kinds of designed poly(ethylene oxide)-block-poly(methyl methacrylate) (PEO-b-PMMA) copolymers was studied at 270, 298 and 400 K via mesoscopic modeling. The values of the order parameters depended on both the structures of the block copolymers and the simulation temperature, while the values of the order parameters of the long chains were higher than those of the short ones; temperature had a more obvious effect on long chains than on the short ones. Plain copolymers doped with poly(ethylene oxide) (PEO) or poly(methyl methacrylate) (PMMA) homopolymer showed different order parameter values. When a triblock copolymer had the same component at both ends and was doped with one of its component polymers as a homopolymer (such as A5B6A5 doped with B6 or A5 homopolymer), the value of its order parameter depended on the simulation temperature. The highest order parameter values were observed for A5B6A5 doped with B6 at 400 K and for A5B6A5 doped with A5 at 270 K. A study of copolymers doped with nanoparticles showed that the mesoscopic phase was influenced by not only the properties of the nanoparticles, such as the size and density, but also the compositions of the copolymers. Increasing the size of the nanoparticles used as a dopant had the most significant effect on the phase morphologies of the copolymers.     

Probing protein-sugar interactions

We have investigated the partial specific volumes (2) (ml/g), hydration, and cosolvent interactions of rabbit muscle aldolase by equilibrium sedimentation in the analytical ultracentrifuge and by direct density increment (partial differential/partial differentialc(2))(mu) measurements over a range of sugar concentrations and temperature. In a series of sugars increasing in size, glucose, sucrose, raffinose, and alpha-cyclodextrin, (partial differential/ partial differentialc(2))(mu) decreases linearly with the solvent density rho(0). These sugar cosolvents do not interact with the protein; however, the interaction parameter B(1) (g water/g protein) mildly increases with increasing sugar size. The experimental B(1) values are smaller than values calculated by excluded volume (rolling ball) considerations. B(1) relates to hydration in this and in other instances studied. It decreases with increasing temperature, leading to an increase in (2) due to reduced water of hydration electrostriction. The density increments (partial differential/ partial differentialc(2))(mu), however, decrease in concave up form in the case of glycerol and in concave down form for trehalose, leading to more complex behavior in the case of carbohydrates playing a biological role as osmolytes and antifreeze agents. A critical discussion, based on the thermodynamics of multicomponent solutions, is presented.     

Ionic liquid based ultrasonic assisted extraction of isoflavones from Iris tectorum Maxim and subsequently separation and purification by high-speed counter-current chromatography

We developed an ionic liquid based ultrasonic assisted extraction (ILUAE) method for the extraction of the three isoflavones, namely tectoridin, iristectorin B and iristectorin A from Iris tectorum Maxim of the Iridaceae family. Three kinds of 1-alkyl-3-methylimidazolium ionic liquids with different alkyl chain and anion were investigated. The results indicated that ionic liquids (ILs) showed remarkable effects on the extraction yield of isoflavones. In addition, the ILUAE, including several ultrasonic parameters, such as the concentration, extraction time and solvent to solid ratio have been optimized. Under these optimal conditions (e.g., with 30 min extraction time and the solvent to solid ratio of 30 ml/g), this approach gained the highest extraction yields of tectoridin (37.45 mg/g), iristectorin B (2.88 mg/g) and iristectorin A (5.28 mg/g). Meanwhile, tectoridin, iristectorin B and iristectorin A in the ILUAE extract were separated and purified successfully through the high-speed counter-current chromatography (HSCCC) with a two-phase solvent system consisting of n-butanol-water (1:1, v/v). The additional advantage of this approach is that 60.21 mg tectoridin, 4.33 mg iristectorin B and 8.24 mg iristectorin A with more than 95.0% purities have been obtained from 400 mg ILUAE extract of I. tectorum within 5 h and one-step elution under the most optimized conditions (e.g., a flow rate of 2.0 ml/min, 900 rpm and the wavelengh of 280 nm). The obtained fractions were successfully analyzed by HPLC and identified by (1)H-NMR and (13)C-NMR.     

Application of logistic curve fitting to cell-mediated cytotoxicity tests

Blood mononuclear cells from 6 healthy adults were examined for LAK activity against 16 cell lines derived from human malignant tumors. The cytotoxicity curves obtained from a linear plot of the log of E/T ratio versus the percentage of the target cells killed were found to well fit the logistic curves. As the logistic distribution is known to approximate to the normal distribution, and the K/2 value is the function value for the representative, the K/2 value is reasonably selected as the % lysis value for the lytic unit calculation. Values of the three parameters, K as the maximum cytotoxicity, A as the scale parameter and B as the shape parameter, were analyzed using the experimental data. Eleven targets had three or more significantly fitted curves. Six among them were selected as highly sensitive cell lines to LAK activity, because the average values for K were higher than 80% (coefficients of variation were from 0.02 to 0.11) and analyzed further. The average values for B were relatively constant (range: 1.09-1.56) and the average values for A varied from 3.5 to 20.3 (conefficients of variation were from 0.26 to 0.71). The shape of the curves were nearly the same. These results indicate that the 6 cell lines are useful as the targets for the LAK activity.