Inexact three-dimensional reconstruction of a biological macromolecule from a restricted number of projections

A computer-generated three-dimensional model of Lumbricus terrestris hemoglobin has been obtained by reconstruction from four STEM low-dose computer-averaged micrographs. X-ray projections of a wooden model constructed from the calculated two-dimensional sections through the molecule were generally consistent with the original STEM projections of the hemoglobin and suggest the presence of large gaps between the central regions of adjacent 1/12th subunits of opposite tiers.     

Presence of a thermoregulatory hot spot in the prothorax of the large carpenter bee and the bumble bee

In both the large carpenter bee (Xylocopa pubescens) and the bumblebee (Bombus terrestris), a hot spot was detected in the center of the prothorax on its dorsal-external aspect. In both cases, the temperature in this hot spot was found to be greater than the ambient temperature and that at the tip of the gaster. In B. terrestris, it was higher by 9-10 degrees C from that at the gaster tip and by 15-16 degrees C from the ambient temperature, while in X. pubescens the corresponding differences were 11-20 degrees C and 18-19 degrees C, respectively. The recorded thermal differences were not fixed but were rather variable, temporally as well as individually, but invariably all individuals measured showed these temperature differences. Furthermore, in none of the studied specimens was a hot spot detected in any part of the body other than the prothorax. From this hot spot in the prothorax, there is a cascade of temperatures in both directions, that is, anteriorly towards the head and posteriorly towards the gaster, with a graded drop in temperature in either direction. This article discusses possible reasons for the existence of such a hot spot in this particular location (the prothorax), its role or function, and its mode of operation. The authors speculate that it is a thermoregulatory center (for heating or cooling) that might be present in possibly all Hymenoptera that spend a considerable part of their life flying, regardless of whether they are social, parasocial, or solitary.     

Histomorphological,immunohistochemical, and ultrastructural study on ontogeny of ileocaecal lymphoglandular complexes in prenatal and postnatal Indian buffalo: An innate mucosal immune barrier

The present study was conducted on prenatal and postnatal development of lymphoglandular complexes (LGCs) in ileocaecal region of buffalo fetuses (n = 15) ranging from 11.5 cm curved crown rump length (CVRL) (80 days) to 100 cm CVRL (299 days) and neonatal buffalo calves (n = 10). The fetuses were categorized into three groups based on their CVRL. LGC formation was not evident in ileocaecal junction up to 32 cm CVRL (145 days). At 35 cm CVRL (152 days), diffuse lymphocytes were scattered around the base of glands that encircled them. At 54 cm CVRL (195 days), lymphoid aggregates were present in submucosa around deep submucosal glands and formed primordia of LGCs in ileocaeccal orifice region. At 100 cm CVRL (299 days), these complexes were completely visible grossly. The distinguished lymphoid nodules in submucosa were invaded by submucosal extensions of overlying mucosal glands to form a large clear complex of glands and lymphoid nodules called as “Lymphoglandular complex” at this stage. It is the first report of prenatal development of LGCs in large intestine of buffaloes. Abundant CD3⁺ T cells were observed towards periphery of LGC. In neonates, these complexes were uniform, few with demarcation into dark and light zones that is, germinal center formation. Lymphocytes interspersed in lamina propria were mainly CD3⁺ T lymphocytes. In conclusion, the development of LGCs in ileocaecal region started prenatally in terms of all its cellular components into completely developed and immunocompetent to generate mucosal immunity.     

Influence of graphite nodules on the particles erosion of spheroidal graphite cast irons

The influence of graphite nodules on the normal angle erosion of the spheroidal graphite cast irons with four different matrices, namely ferrite, upper bainite, lower bainite and martensite, was investigated. The results indicate that, in the range investigated (10-15 area pet), graphite nodules (with variations in area percent and size) did not exert any influence in the irons with ferrite or upper bainite matrix. However, in the case of the spheroidal graphite cast iron with martensitic matrix, both increasing area percent and decreasing diameter of graphite nodules did in fact raise the erosion rate; moreover, those cast in metal molds consistently experienced higher erosion rate than those cast in sand molds. For the irons with a lower bainite matrix, increasing the amount of graphite nodules raises the erosion rate for those cast in sand molds, but did not affect the erosion rate for those cast in metal molds; furthermore, the erosion rate of the sanded-molded irons was consistently higher than their metal molded counterparts. The different roles of graphite nodules on the erosion rates of the spheroidal graphite cast irons are discussed.     

Influence of surface topography and surface modifications on seizure initiation in lean lubricated sliding contacts

Seizure initiation in lean-lubricated contacts was experimentally studied using a transient test method of ball-on-disc type at two different sliding velocities, 2 and 3.8 m/s. Four different nodular cast iron surfaces were tested against a bearing ball of 100Cr6 steel: a fine-milled and roller-burnished surface, a ground and lapped surface, a ground and lapped laser-melted surface, and finally a ground surface. The results show that the ground surface, even though it is smoother than the fine-milled and roller-burnished surface, shows indications of seizure at a lower load. No graphite nodules from the nodular cast iron were visible in the surfaces on inspection with an optical light microscope. In contrast, the ground and lapped surface suffered no initial or total seizure in these tests. In this case, many graphite nodules were visible in the surface, and these nodules became detached in the contact zone, where they probably acted as a solid lubricant. Many graphite nodules were also visible in the ground and laser-melted surface, though in this case the graphite nodules did not become detached. This surface topography initiated seizure under a low normal load, and increased sliding velocity lowered the total seizure load significantly.     

基于PCA和改进的BP网络的肺结节识别研究

提出了一种基于PCA和改进的BP神经网络的CT影像肺结节检测方法。将已经获取的肺部影像中肺结节和血管的特征数据经PCA处理后,应用改进的BP神经网络进行分类,经过竞争选择,获得分类结果。实验证明该识别方法实现简单、识别率高、训练速度与识别速度较快,训练好的网络有很好的分类能力。     

A morphometric model to minimize subjectivity in the histological assessment of hepatocellular carcinoma and its precursors in cirrhosis

Objective: To explore how morphometry can minimize subjectivity in the assessment of liver nodules in cirrhosis using a novel classification tool. Study design: Ten hepatocellular carcinoma (HCC), 6 large regenerative nodules (LRN), and 34 regenerative (cirrhotic) nodules (RN), obtained from cirrhotic explant livers, were analyzed using a Kontron‐Zeiss KS400 image analyzer. We generated a morphometric model based on the analysis of volume fractions occupied by hepatocyte nuclei/cytoplasm, sinusoidal endothelium and lumen, neoplastic acini, fibrosis, centrilobular veins, portal arteries, veins and bile ducts, individual lesional arteries (smooth muscle actin), and capillarized sinusoids (CD34), and on surface fraction occupied by reticulin, and number in unit volume and size distribution of hepatocyte nuclei, and mean hepatocyte nucleus diameter and volume. Results: Volume fraction of capillarized sinusoids and of individual lesional arteries were more prominent in HCC and LRNs, when compared with RN, whereas surface fraction of reticulin was markedly decreased in HCC. The morphometric values of these three features were integrated into our classification tool to construct a hybrid system, which reclassified the nodules in the same categories. Conclusion: Our novel hybrid classification tool may minimize subjectivity in the histological assessment of nodular lesions in cirrhosis. Microsc. Res. Tech., 2008. © 2008 Wiley‐Liss, Inc.     

基于三维卷积神经网络的低剂量CT肺结节检测

为提高早期肺癌筛查过程中肺结节的检出率,提出利用三维卷积神经网络进行低剂量CT肺结节检测。首先采用多方向形态学滤波算法对低剂量序列CT图像进行预处理;接着,利用改进三维区域生长与凸包算法相结合进行肺实质分割;然后提取三维候选结节,为了解决卷积神经网络对样本不平衡的敏感问题,对三维候选结节正样本进行旋转和光照处理;最后在不同的网络参数下,对ELCAP数据库中50个序列低剂量肺癌筛查数据进行4组实验。实验结果表明,通过对网络参数的不断优化,准确度、灵敏度、特异度以及ROC曲线的AUC值分别达到了84.6%、88.89%、80.32%及0.924 4。该方法能够正确地对低剂量CT肺结节进行检测,与文献所提出肺结节检测算法相比,准确度、灵敏度和特异度分别平均提高了5.37%、5.6%和10.42%,综合性能较强,可以为肺癌筛查提供有效的帮助。     

球铁中石墨球径尺寸对铁素体化率影响

本文按炭扩散牛眼状铁素体生产模型定量地描述石墨球径尺寸对铁素体化率影响规律,对球径均方根值为2.20μm、3.42μm、5.56μm,三种情况下铁素体化率实验结果与理论曲线所作的对比表明：在曲线中部大部分区域内实验与理论计算结果定量符合;在曲线开头小部分区域内理论计算结果高于实验值;在曲线末端理论计算结果低于实验值。球径愈小理论与实验符合愈好。分析表明：在曲线开头小部分区域内理论与实验之间的差异归因于铁素体成核需要一定的孕育期;在曲线末端理论与实验不符归因于石墨——奥氏体共晶团范围内分成分偏析。     

Role of TGF-beta in immune-evasion of cancer

One of the major obstacles in tumor-immunology is the outgrowth of malignant tumors despite their immunogenicity and recognition by the immune-system. Multiple mechanisms for this phenomenon have been proposed. We review the possible involvement of transforming growth factor beta (TGF-beta) in this context. TGF-beta is a cytokine with pleiotropic functions, involved in multiple physiologic processes including immunoregulation. Immune elimination of most cancers ultimately depends on cytolytic T cells (CTL). We propose a mechanism of specific suppression of cytolytic T cell (CTL)-responses mediated through immunoglobulin-bound TGF-beta (IgG-TGF-beta), secreted by activated B cells, and a cell of myeloid origin. This mononuclear "Veto" cell presumably binds IgG-TGF-beta through Fc-receptors and activates latent TGF-beta. The suggestion that B cell responses can inhibit tumor rejection is supported by observations in B cell-deficient mice. Ways for enhancing effective cancer immunity by interfering with the network of interactions involving IgG-TGF-beta are discussed.     

Improved method of preparation of supported planar lipid bilayers as artificial membranes for antigen presentation

T cell activation is the result of direct cell-cell contact between T cells and antigen presenting cells (APCs), and of interactions between membrane-bound ligands and receptors at the contact interface, the "immunological synapse." Model APCs based upon supported fluid lipid bilayers have been used to dissect these complex molecular interactions and to facilitate real-time microscopic observations. Nearly all studies have used liposome fusion-based methods to make supported bilayers, and the biophysical properties of these membranes were not characterized in detail. Here, using both Langmuir-Blodgett and liposome fusion techniques, we explored five different methods of lipid bilayer preparation on glass, mica, or dextran cushion substrates and characterized the stability, homogeneity, and fluidity of the bilayers with fluorescence microscopy and fluorescence recovery after photobleaching (FRAP). Most combinations of techniques and substrates led to unsatisfactory results, notably, a lack of homogeneity for liposome fusion on glass, low stability of bilayers on mica, and loss of fluidity of dextran-cushioned bilayers in solutions containing protein. To overcome these deficits, we developed a technique that combines liposome fusion on glass and thermally enhanced bilayer expansion. The newly expanded pristine bilayer showed high degrees of stability, homogeneity, and fluidity. MHC and ICAM-1 molecules anchored on the bilayer diffused freely and stimulated T cell calcium flux and adhesion, respectively.     

桥本甲状腺炎的超声诊断研究进展

随着超声技术的不断发展,超声在桥本甲状腺炎的诊断中发挥出越来越重要的作用。利用超声检查不仅可直观提供病灶形态信息、血流分布信息、组织硬度信息,同时还可以引导穿刺活检,做出定性诊断,为早期鉴别甲状腺结节良恶性提供帮助。本文就桥本甲状腺炎的超声诊断研究进展予以综述。     

Gustatory ultrastructures of an amphihaline migratory fish hilsa Tenualosa ilisha

This study was conducted with the tongue samples of different life stages of hilsa, that is, adult Marine hilsa, adult Riverine hilsa, and Riverine juvenile hilsa, respectively. Three types of taste buds (Types I, II, and III based on their elevation from the epithelium at different levels) of the tongue, which may be to ensure full utilization of the gustatory ability of the fish were rocorded. Presence of specific taste buds indicate that the fish hilsa dwells in turbid waters with a possible preference toward diatom like planktonic food source. Enhanced expression of taste receptors (T1R1 and T1R3) and associated stimulatory G‐proteins subunits on tongue also indicate occurrence of amino acid like substances that guided sensory cues for feeding by this fish. A firm regularity or stringency of the free surface of the epithelial cells may be attributed to compactly arranged microridges. These structures protect against physical abrasions potentially caused during food manoeuvring and swallowing. In our present observations, the surface architectures of the tongue of hilsa are discussed within the background of migratory adaptation of the species in the context of feeding and habitat preferences.     

基于xPC Target的深海采矿升沉补偿控制系统的研究

针对深海多金属锰结核的开采,以水力流体提升式采矿系统中的扬矿管的升沉补偿为研究对象,提出了一种基于SIMULINK中xPC Target模块环境下的实时在线控制系统,开发过程简单易行,支持在线参数修改,实现了在线实时控制功能,工作稳定,精度高。     

结合多尺度圆形滤波与MS聚类 的疑似结节分割

肺部CT图像中疑似病灶感兴趣区域(ROI)的准确分割是肺部计算机辅助检测/诊断(CAD)的重要环节。本文提出结合Hessian矩阵滤波的均值漂移聚类肺部疑似病灶ROI区域分割算法。对原图像进行多尺度Hessian矩阵圆形滤波,图像中圆形的疑似结节病灶区域得到滤波增强、直线形的气管/血管区域得到抑制,将Hessian矩阵滤波后的形状特征、灰度、空间位置3种信息引入特征空间,将均值漂移聚类的核函数分解为3种特征信息所分别对应的核函数乘积形式,最后采用自适应计算带宽的方法确定每个待分割疑似区域的带宽进行均值漂移聚类分割。对来自LIDC等127个包含不同类型肺结节的病例进行实验,实验结果表明引入Hessian矩阵圆形滤波信息的均值漂移聚类能够分割出与血管或气管相连或者交叉的结节区域,去除ROI中包含的非结节区域,能有效分割出基于灰度信息难以分割的毛玻璃型(GGO)结节;对于3种类型的结节区域:血管相连结节(VPN)、毛玻璃型结节(GG0)、孤立性结节(SPN)分割平均准确率分别为92.80%、86.13%、95.08%。     

Abrasive-assisted Nickel Electroforming Process with Moving Cathode

In traditional electroforming process for revolving parts with complex profiles, the drawbacks on surface of deposits, such as pinholes and nodules, will lead to varying physical and mechanical properties on different parts of electroformed components. To solve the problem, compositely moving cathode is employed in abrasive-assisted electroforming of revolving parts with complicated profiles. The cathode translates and rotates simultaneously to achieve uniform friction effect on deposits without drawbacks. The influences of current density and translation speed on the microstructure and properties of the electroformed nickel layers are investigated. It is found that abrasive-assisted electroforming with compound cathode motion can effectively remove the pinholes and nodules, positively affect the crystal nucleation, and refine the grains of layer. The increase of current density will lead to coarse microstructure and lower micro hardness, from 325 HV down to 189 HV. While, faster translational linear speed produces better surface quality and higher micro hardness, from 236 HV up to 283 HV. The weld-ability of the electroformed layers are also studied through the metallurgical analysis of welded joints between nickel layer and 304 stainless steel. The electrodeposited nickel layer shows fine performance in welding. The novel compound motion of cathode promotes the mechanical properties and refines the microstructure of deposited layer.     

Interfacial interactions between diamond disk and granite during vertical spindle grinding

The present work was undertaken to experimentally elucidate the interfacial interactions between diamond disk and workpiece during vertical spindle grinding of three natural granites. Measurements were made of the spindle power and the disk-granite interfacial temperatures using a pair of grindable foil thermocouples. The energy partition to the granite was subsequently estimated by using a temperature matching method. The ground granite surfaces were examined using SEM and XRD at each separate stage ranging from rough to fine grinding. The experimental results showed that maximum temperature rise at the disk-granite interface was unlikely to be a significant factor governing the formation of high gloss on the ground granite surfaces. New composition was not detected on the ground granite surfaces. SEM observations indicated that the granite workpieces were removed mainly by ductile mechanism, with some evidence of brittle fracture especially for rough grinding and to a much lesser extent for fine grinding. The gloss of a ground granite surface was found to be directly associated with the relative amount of ductile flow on the surface.     

Ultrastructural alterations in liver of mice exposed chronically and transgenerationally to aqueous extract of betel nut: Implications in betel nut‐induced carcinogenesis

The aqueous extract of betel nut (AEBN) induces the formation of preneoplastic nodules in the liver of Swiss Albino mice and leads to increased predisposition to cancer when administered transgenerationally. The aim of this investigation was to elucidate the alterations in ultrastructure of subcellular organelles in the liver nodules using transmission electron microscopy and to determine whether these alterations have implications in AEBN‐induced carcinogenesis. Male and female Swiss Albino mice were exposed to AEBN chronically and transgenerationally at a dose of 2 mg/mL in drinking water for 24 weeks. Extensive polymorphism was noted in nuclear shape and heterochromatin organization. Heterochromatin aggregation and marginalization were observed in the nuclei of chronically exposed mice, whereas transgenerationally exposed mice exhibited dispersion or loss of heterochromatin. The nuclear envelope was disrupted, and the nucleoli were enlarged in chronically exposed mice, whereas in transgenerationally exposed mice the nucleoli were reduced in size or totally absent. The cisternae of the rough endoplasmic reticulum were dilated and disrupted, and a large number of autophagic vesicles were observed in both chronically and transgenerationally exposed mice. Atypical mitochondria that underwent extensive cristolysis and progressively declined in size and number from the chronically exposed mice to the different generations of transgenerationally exposed mice were also observed. Thus, exposure to AEBN resulted in severe loss of ultrastructural integrity of cells in the liver nodules, and the progressive loss of mitochondrial function appeared to play a significant role in increasing the predisposition to cancer of mice exposed transgenerationally to AEBN. Microsc. Res. Tech. 2010. © 2009 Wiley‐Liss, Inc.     

Velocity measurement of the liquid–solid flow in a vertical pipeline using gamma-ray absorption and weighted cross-correlation

Developing technology for the deep-sea mining of polymetallic nodules requires, theoretical analyses, simulation and numerous experimental studies. In this paper authors focused on nuclear methods adoption to velocity of solid phase measurement in an extremely hard and varying environment. Selected results of the experimental studies of two-phase liquid–solid particles flow in a vertical pipeline obtained by probing with photon beams are presented. With the use of the sealed ²⁴¹Am isotopes emitting gamma radiation of 59.5 keV, and the scintillation probes with NaI(TI) detectors, the average transport velocity for ceramic models representing natural polymetallic nodules were determined. In the paper for analysis of the signals coming from the probes, the cross correlation function (CCF) and its modifications consisting in the combination of the CCF with such procedures as the average square difference function (ASDF) and the average magnitude difference function (AMDF) were used. An example of measurement is presented and its resulting uncertainties determined. In described experiment the relative values of the combined uncertainty of solid particles average velocity estimation are equal to: 3.2% for the CCF, 3.0% for the CCF/AMDF and 2.8% for the CCF/ASDF.     

Vascular remodelling during the normal and malignant life cycle of the mammary gland

The mammary gland life cycle is exemplified by massive, physiologically dictated changes in cell number and composition, architecture, and functionality. These drastic upheavals, by necessity, also involve the mammary endothelium, which undergoes angiogenic expansion during pregnancy and lactation followed by ordered regression during involution. In this review, we summarise data obtained using the Mercox methyl methacrylate corrosion cast technique to analyse the mammary gland vasculature during normal development and carcinogenesis. Concomitant with epithelial cell expansion, the mammary vasculature grows during the first half of pregnancy by sprouting angiogenesis whereas the last half of pregnancy and lactation are characterised by the non-proliferative intussusceptive angiogenesis. The vasculature of the lactating gland is composed of a well-developed capillary meshwork enveloping the secretory alveoli with basket-like honeycomb structures. During involution, regression of the vasculature is achieved by regional collapse of the honeycomb structures, capillary retraction, and endothelial attenuation. This process appears partly to involve apoptosis. However, an additional mechanism involving remodelling without cell death, which we have termed angiomeiosis, must exist to explain the morphological observations. Interestingly, in mammary tumours of neuT transgenic mice, both sprouting and intussusceptive angiogenesis was observed simultaneously in the same nodules, a finding with potential implications for cancer therapy. The underlying molecular mechanisms controlling angiogenic modulation in the mammary gland, particularly angiogenic regression and the endothelial:parenchymal interplay, are poorly understood. However, the data summarised in this review indicate that precisely these molecular mechanisms offer novel alternatives for specific and effective treatment of breast cancer.