Note: This page contains sample records for the topic features high mitotic from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Extragnathic odontogenic sinonasal myxoma with mitotic features  

PubMed Central

We present the first-ever documented evidence of mitotic figures in a case of sinonasal myxoma diagnosed in a 37 year-old gentleman. A 37 year-old gentleman was referred to the Otolaryngology clinic with left nasal discharge for six months. Preoperative images demonstrated obstruction of the left nasal airway with complete opacification of the left maxillary sinus, obscuration of the osteomeatal complex, as well as expansion and thinning of the medial wall of the maxillary antrum. The patient underwent diagnostic Funtional Endoscopic Sinus Surgery (FESS), therapeutic left Caldwell-Luc antrostomy, and revision FESS following recurrence. The patient was symptom-free at routine follow-up post-op. There has been much debate as to whether the absence of mitotic features in a specimen is absolutely necessary in order to confirm the diagnosis. We postulate that the presence of mitoses is an unusual diagnostic feature in extensive sinonasal myxoma.

Onyekwelu, O; DeZoysa, O; Watts, S

2012-01-01

2

A grading system combining architectural features and mitotic count predicts recurrence in stage I lung adenocarcinoma.  

PubMed

The International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) has recently proposed a new lung adenocarcinoma classification. We investigated whether nuclear features can stratify prognostic subsets. Slides of 485 stage I lung adenocarcinoma patients were reviewed. We evaluated nuclear diameter, nuclear atypia, nuclear/cytoplasmic ratio, chromatin pattern, prominence of nucleoli, intranuclear inclusions, mitotic count/10 high-power fields (HPFs) or 2.4?mm(2), and atypical mitoses. Tumors were classified into histologic subtypes according to the IASLC/ATS/ERS classification and grouped by architectural grade into low (adenocarcinoma in situ, minimally invasive adenocarcinoma, or lepidic predominant), intermediate (papillary or acinar), and high (micropapillary or solid). Log-rank tests and Cox regression models evaluated the ability of clinicopathologic factors to predict recurrence-free probability. In univariate analyses, nuclear diameter (P=0.007), nuclear atypia (P=0.006), mitotic count (P<0.001), and atypical mitoses (P<0.001) were significant predictors of recurrence. The recurrence-free probability of patients with high mitotic count (?5/10?HPF: n=175) was the lowest (5-year recurrence-free probability=73%), followed by intermediate (2-4/10?HPF: n=106, 80%), and low (0-1/10?HPF: n=204, 91%, P<0.001). Combined architectural/mitotic grading system stratified patient outcomes (P<0.001): low grade (low architectural grade with any mitotic count and intermediate architectural grade with low mitotic count: n=201, 5-year recurrence-free probability=92%), intermediate grade (intermediate architectural grade with intermediate-high mitotic counts: n=206, 78%), and high grade (high architectural grade with any mitotic count: n=78, 68%). The advantage of adding mitotic count to architectural grade is in stratifying patients with intermediate architectural grade into two prognostically distinct categories (P=0.001). After adjusting for clinicopathologic factors including sex, stage, pleural/lymphovascular invasion, and necrosis, mitotic count was not an independent predictor of recurrence (P=0.178). However, patients with the high architectural/mitotic grade remained at significantly increased risk of recurrence (high vs low: P=0.005) after adjusting for clinical factors. We proposed this combined architectural/mitotic grade for lung adenocarcinoma as a practical method that can be applied in routine practice. PMID:22499226

Kadota, Kyuichi; Suzuki, Kei; Kachala, Stefan S; Zabor, Emily C; Sima, Camelia S; Moreira, Andre L; Yoshizawa, Akihiko; Riely, Gregory J; Rusch, Valerie W; Adusumilli, Prasad S; Travis, William D

2012-04-13

3

Classification of mitotic figures with convolutional neural networks and seeded blob features  

PubMed Central

Background: The mitotic figure recognition contest at the 2012 International Conference on Pattern Recognition (ICPR) challenges a system to identify all mitotic figures in a region of interest of hematoxylin and eosin stained tissue, using each of three scanners (Aperio, Hamamatsu, and multispectral). Methods: Our approach combines manually designed nuclear features with the learned features extracted by convolutional neural networks (CNN). The nuclear features capture color, texture, and shape information of segmented regions around a nucleus. The use of a CNN handles the variety of appearances of mitotic figures and decreases sensitivity to the manually crafted features and thresholds. Results: On the test set provided by the contest, the trained system achieves F1 scores up to 0.659 on color scanners and 0.589 on multispectral scanner. Conclusions: We demonstrate a powerful technique combining segmentation-based features with CNN, identifying the majority of mitotic figures with a fair precision. Further, we show that the approach accommodates information from the additional focal planes and spectral bands from a multi-spectral scanner without major redesign.

Malon, Christopher D.; Cosatto, Eric

2013-01-01

4

High LET radiation enhances nocodazole Induced cell death in HeLa cells through mitotic catastrophe and apoptosis.  

PubMed

To understand how human tumor cells respond to the combined treatment with nocodazole and high LET radiation, alterations in cell cycle, mitotic disturbances and cell death were investigated in the present study. Human cervix carcinoma HeLa cells were exposed to nocodazole for 18 h immediately followed by high LET iron ion irradiation and displayed a sequence of events leading to DNA damages, mitotic aberrations, interphase restitution and endocycle as well as cell death. A prolonged mitotic arrest more than 10 h was observed following nocodazole exposure, no matter the irradiation was present or not. The occurrence of mitotic slippage following the mitotic arrest was only drug-dependent and the irradiation did not accelerate it. The amount of polyploidy cells was increased following mitotic slippage. No detectable G(2) or G(1) arrest was observed in cells upon the combined treatment and the cells reentered the cell cycle still harboring unrepaired cellular damages. This premature entry caused an increase of multipolar mitotic spindles and amplification of centrosomes, which gave rise to lagging chromosomal material, failure of cytokinesis and polyploidization. These mitotic disturbances and their outcomes confirmed the incidence of mitotic catastrophe and delayed apoptotic features displayed by TUNEL method after the combined treatment. These results suggest that the addition of high-LET iron ion irradiation to nocodazole enhanced mitotic catastrophe and delayed apoptosis in HeLa cells. These might be important cell death mechanisms involved in tumor cells in response to the treatment of antimitotic drug combined with high LET radiation. PMID:21785236

Li, Ping; Zhou, Libin; Dai, Zhongying; Jin, Xiaodong; Liu, Xinguo; Matsumoto, Yoshitaka; Furusawa, Yoshiya; Li, Qiang

2011-01-01

5

THE EFFECTS OF HIGH AND LOW TEMPERATURES ON THE EPIDERMAL MITOTIC ACTIVITY OF THE ADULT MALE MOUSE, MUS MUSCULUS L  

Microsoft Academic Search

The form of the diurnal cycles of epidermal mitotic activity in the adult male mouse has been shown to be determined by the times of sleeping and waking, high mitotic activity being associated with both natural and artificial sleep, and low mitotic activity with muscular exercise (Bullough, 1948 a, b). In order to define more closely the conditions which favour

W. S. BULLOUGH

6

Segmental chromosome aberrations converge on overexpression of mitotic spindle regulatory genes in high-risk neuroblastoma.  

PubMed

Integration of genome-wide profiles of DNA copy number alterations (CNAs) and gene expression variations (GEVs) could provide combined power to the identification of driver genes and gene networks in tumors. Here we merge matched genome and transcriptome microarray analyses from neuroblastoma samples to derive correlation patterns of CNAs and GEVs, irrespective of their genomic location. Neuroblastoma correlation patterns are strongly asymmetrical, being on average 10 CNAs linked to 1 GEV, and show the widespread prevalence of long range covariance. Functional enrichment and network analysis of the genes covarying with CNAs consistently point to a major cell function, the regulation of mitotic spindle assembly. Moreover, elevated expression of 14 key genes promoting this function is strongly associated to high-risk neuroblastomas with 1p loss and MYCN amplification in a set of 410 tumor samples (P < 0.00001). Independent CNA/GEV profiling on neuroblastoma cell lines shows that increased levels of expression of these genes are linked to 1p loss. By this approach, we reveal a convergence of clustered neuroblastoma CNAs toward increased expression of a group of prognostic and functionally cooperating genes. We therefore propose gain of function of the spindle assembly machinery as a lesion potentially offering new targets for therapy of high-risk neuroblastoma. PMID:22337647

Ooi, Wen Fong; Re, Angela; Sidarovich, Viktoryia; Canella, Valentina; Arseni, Natalia; Adami, Valentina; Guarguaglini, Giulia; Giubettini, Maria; Scaruffi, Paola; Stigliani, Sara; Lavia, Patrizia; Tonini, Gian Paolo; Quattrone, Alessandro

2012-02-15

7

CBFS: High Performance Feature Selection Algorithm Based on Feature Clearness  

PubMed Central

Background The goal of feature selection is to select useful features and simultaneously exclude garbage features from a given dataset for classification purposes. This is expected to bring reduction of processing time and improvement of classification accuracy. Methodology In this study, we devised a new feature selection algorithm (CBFS) based on clearness of features. Feature clearness expresses separability among classes in a feature. Highly clear features contribute towards obtaining high classification accuracy. CScore is a measure to score clearness of each feature and is based on clustered samples to centroid of classes in a feature. We also suggest combining CBFS and other algorithms to improve classification accuracy. Conclusions/Significance From the experiment we confirm that CBFS is more excellent than up-to-date feature selection algorithms including FeaLect. CBFS can be applied to microarray gene selection, text categorization, and image classification.

Seo, Minseok; Oh, Sejong

2012-01-01

8

Inhibitory effect of ethidium bromide on mitotic chromosome condensation and its application to high-resolution chromosome banding  

Microsoft Academic Search

Ethidium bromide (EB) is known to intercalate between stacked base pairs without specific base-pair preference. Its use in cultured human lymphocytes and Burkitt’s lymphoma cells resulted in the accumulation of cells in prophase and prometaphase stages. Inhibition of mitotic chromosome condensation as a possible mechanism involved in this phenomenon is discussed. A simple method for obtaining high-resolution banding patterns on

T. Ikeuchi

1984-01-01

9

Prognostic importance of the mitotic marker phosphohistone H3 in cutaneous nodular melanoma.  

PubMed

Mitotic count is a known prognostic predictor in cutaneous melanoma, and is included in the current American Joint Committee on Cancer tumor-node-metastasis (TNM) staging system. The mitotic marker phosphohistone H3 (PHH3) is considered to facilitate counting of mitosis, and the purpose of this study was to evaluate the prognostic significance and strength of PHH3 in comparison with standard mitotic counting in cutaneous malignant melanoma. A total of 457 consecutive cases of nodular cutaneous melanoma were initially included in this series. The mitotic count was assessed on hematoxylin and eosin sections, and PHH3 was then examined by immunohistochemistry on standard sections of paraffin-embedded tumor tissue. Both the mitotic count and the number of PHH3-stained mitotic figures were recorded in a minimum area of 1 mm(2). Increased mitotic count and PHH3 value were both associated with unfavorable features like tumor thickness and presence of ulceration. Univariate survival analysis showed a highly significant prognostic impact of mitotic count and PHH3, whereas multivariate analysis indicated PHH3 to be a stronger prognostic indicator than mitotic count. Assessment of mitotic activity by PHH3 immunostaining might have important practical advantages, and should be further studied to consider a place in routine examination of all cutaneous melanomas. PMID:22297638

Ladstein, Rita G; Bachmann, Ingeborg M; Straume, Oddbjørn; Akslen, Lars A

2012-02-02

10

CBFS: High Performance Feature Selection Algorithm Based on Feature Clearness  

Microsoft Academic Search

BackgroundThe goal of feature selection is to select useful features and simultaneously exclude garbage features from a given dataset for classification purposes. This is expected to bring reduction of processing time and improvement of classification accuracy.MethodologyIn this study, we devised a new feature selection algorithm (CBFS) based on clearness of features. Feature clearness expresses separability among classes in a feature.

Minseok Seo; Sejong Oh

2012-01-01

11

An automated fluorescence videomicroscopy assay for the detection of mitotic catastrophe  

PubMed Central

Mitotic catastrophe can be defined as a cell death mode that occurs during or shortly after a prolonged/aberrant mitosis, and can show apoptotic or necrotic features. However, conventional procedures for the detection of apoptosis or necrosis, including biochemical bulk assays and cytofluorometric techniques, cannot discriminate among pre-mitotic, mitotic and post-mitotic death, and hence are inappropriate to monitor mitotic catastrophe. To address this issue, we generated isogenic human colon carcinoma cell lines that differ in ploidy and p53 status, yet express similar amounts of fluorescent biosensors that allow for the visualization of chromatin (histone H2B coupled to green fluorescent protein (GFP)) and centrosomes (centrin coupled to the Discosoma striata red fluorescent protein (DsRed)). By combining high-resolution fluorescence videomicroscopy and automated image analysis, we established protocols and settings for the simultaneous assessment of ploidy, mitosis, centrosome number and cell death (which in our model system occurs mainly by apoptosis). Time-lapse videomicroscopy showed that this approach can be used for the high-throughput detection of mitotic catastrophe induced by three mechanistically distinct anti-mitotic agents (dimethylenastron (DIMEN), nocodazole (NDZ) and paclitaxel (PTX)), and – in this context – revealed an important role of p53 in the control of centrosome number.

Rello-Varona, S; Kepp, O; Vitale, I; Michaud, M; Senovilla, L; Jemaa, M; Joza, N; Galluzzi, L; Castedo, M; Kroemer, G

2010-01-01

12

High-Resolution Mapping of Spontaneous Mitotic Recombination Hotspots on the 1.1 Mb Arm of Yeast Chromosome IV  

PubMed Central

Although homologous recombination is an important pathway for the repair of double-stranded DNA breaks in mitotically dividing eukaryotic cells, these events can also have negative consequences, such as loss of heterozygosity (LOH) of deleterious mutations. We mapped about 140 spontaneous reciprocal crossovers on the right arm of the yeast chromosome IV using single-nucleotide-polymorphism (SNP) microarrays. Our mapping and subsequent experiments demonstrate that inverted repeats of Ty retrotransposable elements are mitotic recombination hotspots. We found that the mitotic recombination maps on the two homologs were substantially different and were unrelated to meiotic recombination maps. Additionally, about 70% of the DNA lesions that result in LOH are likely generated during G1 of the cell cycle and repaired during S or G2. We also show that different genetic elements are associated with reciprocal crossover conversion tracts depending on the cell cycle timing of the initiating DSB.

St. Charles, Jordan; Petes, Thomas D.

2013-01-01

13

In vivo localisation of the mitotic POLO kinase shows a highly dynamic association with the mitotic apparatus during early embryogenesis in Drosophila  

Microsoft Academic Search

The gene polo encodes a highly conserved serine\\/threonine protein kinase that has been implicated in several functions during cell division. Polo-like kinases are important positive regulators of cell cycle progression and have also been implicated in the exit from mitosis through the activation of the anaphase-promoting complex. Several data indicate that Plks are required for centrosome function, bipolar spindle organisation

Tatiana Moutinho-Santos; Paula Sampaio; Isabel Amorim; Madalena Costa; Claudio E Sunkel

1999-01-01

14

Autoreducibility, Mitoticity, and Immunity  

Microsoft Academic Search

We show the following results regarding complete sets. • NP-complete sets and PSPACE-complete sets are many-one autoreducible. • Complete sets of any level of PH, MODPH, or the Boolean hierarchy over NP are many-one autoreducible. • EXP-complete sets are many-one mitotic. • NEXP-complete sets are weakly many-one mitotic. • PSPACE-complete sets are weakly Turing-mitotic. • If one-way permutations and quick

Christian Glaßer; Mitsunori Ogihara; Aduri Pavan; Alan L. Selman; Liyu Zhang

2005-01-01

15

Autoreducibility, Mitoticity, and Immunity  

Microsoft Academic Search

We show the following results regarding complete sets. † NP-complete sets and PSPACE-complete sets are many-one autoreducible. † Complete sets of any level of PH, MODPH, or the Boolean hierarchy over NP are many-one autoreducible. † EXP-complete sets are many-one mitotic. † NEXP-complete sets are weakly many-one mitotic. † PSPACE-complete sets are weakly Turing-mitotic. † If one-way permutations and quick

Christian Gla; Alan L. Selmanx; Liyu Zhang

16

Modelling the mitotic apparatus  

Microsoft Academic Search

This bibliographical review of the modelling of the mitotic apparatus covers a period of one hundred and twenty years, from the discovery of the bipolar mitotic spindle up to the present day. Without attempting to be fully comprehensive, it will describe the evolution of the main ideas that have left their mark on a century of experimental and theoretical research.

Jean-Pierre Gourret

1995-01-01

17

Condensin: Architect of mitotic chromosomes  

Microsoft Academic Search

Condensin is a highly conserved pentameric complex consisting of two structural maintenance of chromosome (SMC) ATPase subunits\\u000a and three auxiliary components. While initially regarded as a key driver of mitotic chromosome condensation, condensin is\\u000a increasingly viewed as having a more subtle influence on chromosome architecture. The two condensin complexes are required\\u000a to direct the correct folding and organization of chromosomes

Damien F. Hudson; Kathryn M. Marshall; William C. Earnshaw

2009-01-01

18

Evidence of Activity-Specific, Radial Organization of Mitotic Chromosomes in Drosophila  

PubMed Central

The organization and the mechanisms of condensation of mitotic chromosomes remain unsolved despite many decades of efforts. The lack of resolution, tight compaction, and the absence of function-specific chromatin labels have been the key technical obstacles. The correlation between DNA sequence composition and its contribution to the chromosome-scale structure has been suggested before; it is unclear though if all DNA sequences equally participate in intra- or inter-chromatin or DNA-protein interactions that lead to formation of mitotic chromosomes and if their mitotic positions are reproduced radially. Using high-resolution fluorescence microscopy of live or minimally perturbed, fixed chromosomes in Drosophila embryonic cultures or tissues expressing MSL3-GFP fusion protein, we studied positioning of specific MSL3-binding sites. Actively transcribed, dosage compensated Drosophila genes are distributed along the euchromatic arm of the male X chromosome. Several novel features of mitotic chromosomes have been observed. MSL3-GFP is always found at the periphery of mitotic chromosomes, suggesting that active, dosage compensated genes are also found at the periphery of mitotic chromosomes. Furthermore, radial distribution of chromatin loci on mitotic chromosomes was found to be correlated with their functional activity as judged by core histone modifications. Histone modifications specific to active chromatin were found peripheral with respect to silent chromatin. MSL3-GFP-labeled chromatin loci become peripheral starting in late prophase. In early prophase, dosage compensated chromatin regions traverse the entire width of chromosomes. These findings suggest large-scale internal rearrangements within chromosomes during the prophase condensation step, arguing against consecutive coiling models. Our results suggest that the organization of mitotic chromosomes is reproducible not only longitudinally, as demonstrated by chromosome-specific banding patterns, but also radially. Specific MSL3-binding sites, the majority of which have been demonstrated earlier to be dosage compensated DNA sequences, located on the X chromosomes, and actively transcribed in interphase, are positioned at the periphery of mitotic chromosomes. This potentially describes a connection between the DNA/protein content of chromatin loci and their contribution to mitotic chromosome structure. Live high-resolution observations of consecutive condensation states in MSL3-GFP expressing cells could provide additional details regarding the condensation mechanisms.

Strukov, Yuri G.; Sural, Tuba H.; Kuroda, Mitzi I.; Sedat, John W.

2011-01-01

19

Continued Stabilization of the Nuclear Higher-Order Structure of Post-Mitotic Neurons In Vivo  

PubMed Central

Background Cellular terminal differentiation (TD) correlates with a permanent exit from the cell cycle and so TD cells become stably post-mitotic. However, TD cells express the molecular machinery necessary for cell proliferation that can be reactivated by experimental manipulation, yet it has not been reported the stable proliferation of any type of reactivated TD cells. Neurons become post-mitotic after leaving the ventricular zone. When neurons are forced to reenter the cell cycle they invariably undergo cell death. Wider evidence indicates that the post-mitotic state cannot solely depend on gene products acting in trans, otherwise mutations in the corresponding genes may lead to reentry and completion of the cell cycle in TD cells, but this has not been observed. In the interphase, nuclear DNA of metazoan cells is organized in supercoiled loops anchored to a nuclear nuclear matrix (NM). The DNA-NM interactions define a higher-order structure in the cell nucleus (NHOS). We have previously compared the NHOS of aged rat hepatocytes with that of early post-mitotic rat neurons and our results indicated that a very stable NHOS is a common feature of both senescent and post-mitotic cells in vivo. Principal Findings In the present work we compared the NHOS in rat neurons from different post-natal ages. Our results show that the trend towards further stabilization of the NHOS in neurons continues throughout post-natal life. This phenomenon occurs in absence of overt changes in the post-mitotic state and transcriptional activity of neurons, suggesting that it is independent of functional constraints. Conclusions Apparently the continued stabilization of the NHOS as a function of time is basically determined by thermodynamic and structural constraints. We discuss how the resulting highly stable NHOS of neurons may be the structural, non-genetic basis of their permanent and irreversible post-mitotic state.

Alva-Medina, Janeth; Maya-Mendoza, Apolinar; Dent, Myrna A. R.; Aranda-Anzaldo, Armando

2011-01-01

20

Mitotic Functions of Kinesin-5  

PubMed Central

In all eukaryotic cells, molecular motor proteins play essential roles in spindle assembly and function. The homotetrameric kinesin-5 motors in particular generate outward forces that establish and maintain spindle bipolarity and contribute to microtubule flux. Cell cycle dependent phosphorylation of kinesin-5 motors regulates their localization to the mitotic spindle. Analysis of live cells further shows that kinesin-5 motors are highly dynamic in the spindle. Understanding the interactions of kinesin-5 motors with microtubules and other spindle proteins is likely to broaden the documented roles of kinesin-5 motors during cell division.

Ferenz, Nick P.; Gable, Alyssa; Wadsworth, Pat

2010-01-01

21

Mitotic bookmarking by transcription factors  

PubMed Central

Mitosis is accompanied by dramatic changes in chromatin organization and nuclear architecture. Transcription halts globally and most sequence-specific transcription factors and co-factors are ejected from mitotic chromatin. How then does the cell maintain its transcriptional identity throughout the cell division cycle? It has become clear that not all traces of active transcription and gene repression are erased within mitotic chromatin. Many histone modifications are stable or only partially diminished throughout mitosis. In addition, some sequence-specific DNA binding factors have emerged that remain bound to select sites within mitotic chromatin, raising the possibility that they function to transmit regulatory information through the transcriptionally silent mitotic phase, a concept that has been termed “mitotic bookmarking.” Here we review recent approaches to studying potential bookmarking factors with regards to their mitotic partitioning, and summarize emerging ideas concerning the in vivo functions of mitotically bound nuclear factors.

2013-01-01

22

The Conserved N-Terminal Region of the Mitotic Checkpoint Protein BUBR1: A Putative TPR Motif of High Surface Activity  

PubMed Central

BUBR1, a key component of the mitotic spindle checkpoint, is a multidomain protein kinase that is activated in response to kinetochore tension. Although BUB1 and BUBR1 play an important role in cell division, very little is known about their structural characteristics. We show that the conserved N-terminal region of BUBR1, comprising residues 1–204, is a globular domain of high ?-helical content (?60%), stable in the pH range 4–9 and probably organized as a tetratricopeptide motif repeat (TPR), most closely resembling residues 16–181 of protein phosphatase 5. Because the latter presents a continuous amphipathic groove and is regulated by binding certain fatty acids, we compared the properties of BUBR1(1–204) and TPR-PP5(16–181) at air/water interfaces and found that both proteins exhibited a similar surface activity and formed stable, rigid monolayers. The deletion of a region that probably comprises several ?-helices of BUBR1 indicates that long-range interactions are essential for the stability of the N-terminal domain. The presence of the putative TPR motif strongly suggests that the N-terminal domain of BUBR1 is involved in direct protein-protein interactions and/or protein-lipid interactions.

Bolanos-Garcia, V. M.; Beaufils, S.; Renault, A.; Grossmann, J. G.; Brewerton, S.; Lee, M.; Venkitaraman, A.; Blundell, T. L.

2005-01-01

23

Highly sensitive feature detection for high resolution LC\\/MS  

Microsoft Academic Search

BACKGROUND: Liquid chromatography coupled to mass spectrometry (LC\\/MS) is an important analytical technology for e.g. metabolomics experiments. Determining the boundaries, centres and intensities of the two-dimensional signals in the LC\\/MS raw data is called feature detection. For the subsequent analysis of complex samples such as plant extracts, which may contain hundreds of compounds, corresponding to thousands of features – a

Ralf Tautenhahn; Christoph Böttcher; Steffen Neumann

2008-01-01

24

Mitotic Spindle Form and Function  

PubMed Central

The Saccharomyces cerevisiae mitotic spindle in budding yeast is exemplified by its simplicity and elegance. Microtubules are nucleated from a crystalline array of proteins organized in the nuclear envelope, known as the spindle pole body in yeast (analogous to the centrosome in larger eukaryotes). The spindle has two classes of nuclear microtubules: kinetochore microtubules and interpolar microtubules. One kinetochore microtubule attaches to a single centromere on each chromosome, while approximately four interpolar microtubules emanate from each pole and interdigitate with interpolar microtubules from the opposite spindle to provide stability to the bipolar spindle. On the cytoplasmic face, two to three microtubules extend from the spindle pole toward the cell cortex. Processes requiring microtubule function are limited to spindles in mitosis and to spindle orientation and nuclear positioning in the cytoplasm. Microtubule function is regulated in large part via products of the 6 kinesin gene family and the 1 cytoplasmic dynein gene. A single bipolar kinesin (Cin8, class Kin-5), together with a depolymerase (Kip3, class Kin-8) or minus-end-directed kinesin (Kar3, class Kin-14), can support spindle function and cell viability. The remarkable feature of yeast cells is that they can survive with microtubules and genes for just two motor proteins, thus providing an unparalleled system to dissect microtubule and motor function within the spindle machine.

Winey, Mark; Bloom, Kerry

2012-01-01

25

Micromechanical studies of mitotic chromosomes  

Microsoft Academic Search

Mitotic chromosomes respond elastically to forces in the nanonewton range, a property important to transduction of stresses\\u000a used as mechanical regulatory signals during cell division. In addition to being important biologically, chromosome elasticity\\u000a can be used as a tool for investigating the folding of chromatin. This paper reviews experiments studying stretching and bending\\u000a stiffness of mitotic chromosomes, plus experiments where

John F. Marko

2008-01-01

26

Exploring KM Features of High-Performance Companies  

NASA Astrophysics Data System (ADS)

For reacting to an increasingly rival business environment, many companies emphasize the importance of knowledge management (KM). It is a favorable way to explore and learn KM features of high-performance companies. However, finding out the critical KM features of high-performance companies is a qualitative analysis problem. To handle this kind of problem, the rough set approach is suitable because it is based on data-mining techniques to discover knowledge without rigorous statistical assumptions. Thus, this paper explored KM features of high-performance companies by using the rough set approach. The results show that high-performance companies stress the importance on both tacit and explicit knowledge, and consider that incentives and evaluations are the essentials to implementing KM.

Wu, Wei-Wen

2007-12-01

27

Advanced Induction Motor Endring Design Features for High Speed Applications  

Microsoft Academic Search

This paper presents advancements in induction motor endring design to overcome mechanical limitations and extend the operating speed range and joint reliability of induction machines. A novel endring design met the challenging mechanical requirements of this high speed, high temperature, power dense application, without compromising electrical performance. Analysis is presented of the advanced endring design features including a non uniform

Matthew Caprio; Vasileios Lelos; John Herbst; Jim Upshaw

2005-01-01

28

Unique Features of a Highly Pathogenic Campylobacter jejuni Strain†  

PubMed Central

Campylobacter jejuni, a major human enteric pathogen, exhibits significant strain-to-strain differences which result in differences in pathogenic potential. C. jejuni 81-176 is a highly virulent strain that exhibits unique pathogenic features and is used by many research laboratories. We have determined the nucleotide sequence of its genome and compared it to the genomes of other sequenced C. jejuni strains. We identified a number of unique genetic features which may confer specific metabolic and pathogenic properties on this strain. We have also identified regions of the C. jejuni genome that are hot spots for the integration of horizontally acquired genetic material. This information should help the understanding of the pathogenesis of C. jejuni and, in particular, the unique features of this highly pathogenic strain.

Hofreuter, Dirk; Tsai, Jennifer; Watson, Robert O.; Novik, Veronica; Altman, Bill; Benitez, Michelle; Clark, Christina; Perbost, Clotilde; Jarvie, Thomas; Du, Lei; Galan, Jorge E.

2006-01-01

29

The effects of high presentation levels on consonant feature transmission  

NASA Astrophysics Data System (ADS)

The effect of high speech presentation levels on consonant recognition and feature transmission was assessed in eight participants with normal hearing. Consonant recognition in noise (0 dB signal-to-noise ratio) was measured at five overall speech levels ranging from 65 to 100 dB SPL. Consistent with the work of others, overall percent correct performance decreased as the presentation level of speech increased [e.g., G. A. Studebaker, R. L. Sherbecoe, D. M. McDaniel, and C. A. Gwaltney, J. Acoust. Soc. Am. 105(4), 2431-2444 (1999)]. Confusion matrices were analyzed in terms of relative percent information transmitted at each speech presentation level, as a function of feature. Six feature sets (voicing, place, nasality, duration, frication, and sonorance) were analyzed. Results showed the feature duration (long consonant duration fricatives) to be most affected by increases in level, while the voicing feature was relatively unaffected by increases in level. In addition, alveolar consonants were substantially affected by level, while palatal consonants were not. While the underlying mechanisms responsible for decreases in performance with level increases are unclear, an analysis of common error patterns at high levels suggests that saturation of the neural response and/or a loss of neural synchrony may play a role.

Hornsby, Benjamin W. Y.; Trine, Timothy D.; Ohde, Ralph N.

2005-09-01

30

High-level feature extraction in JPEG compressed domain  

NASA Astrophysics Data System (ADS)

Traditional feature extraction techniques like the KLT, Harris and Wavelet work only in the uncompressed domain. Hence an additional step of decompression is required before any of them could be applied. We propose a two-level technique for extracting high-level feature points directly from JPEG compressed images. At the first level, the Discrete Cosine Transform (DCT) blocks having high activity content are filtered using a variance measure. At the next level, a DCT block centered at every pixel present in the filtered block is constructed from the neighboring DCT blocks. Feature points are then selected by analyzing the AC coefficients of the DCT block centered about it. The proposed method is simple and efficient. The extracted feature points were found to be rich in information content, which could be used for image registration. The results of this technique showed almost the same amount of repeatability between two images with 60% to 70% overlap, when compared with techniques available in the uncompressed domain. The features thus extracted can directly be used to calculate the motion parameters between two images in the compressed domain.

Narayanan, C. K.; Prakash, M. C.; Prabhakara Rao, G. V.

2004-11-01

31

The structural mechanisms that underpin mitotic kinase activation.  

PubMed

In eukaryotic cells, the peak of protein phosphorylation occurs during mitosis, switching the activities of a significant proportion of proteins and orchestrating a wholesale reorganization of cell shape and internal architecture. Most mitotic protein phosphorylation events are catalysed by a small subset of serine/threonine protein kinases. These include members of the Cdk (cyclin-dependent kinase), Plk (Polo-like kinase), Aurora, Nek (NimA-related kinase) and Bub families, as well as Haspin, Greatwall and Mps1/TTK. There has been steady progress in resolving the structural mechanisms that regulate the catalytic activities of these mitotic kinases. From structural and biochemical perspectives, kinase activation appears not as a binary process (from inactive to active), but as a series of states that exhibit varying degrees of activity. In its lowest activity state, a mitotic kinase may exhibit diverse autoinhibited or inactive conformations. Kinase activation proceeds via phosphorylation and/or association with a binding partner. These remodel the structure into an active conformation that is common to almost all protein kinases. However, all mitotic kinases of known structure have divergent features, many of which are key to understanding their specific regulatory mechanisms. Finally, mitotic kinases are an important class of drug target, and their structural characterization has facilitated the rational design of chemical inhibitors. PMID:23863175

Dodson, Charlotte A; Haq, Tamanna; Yeoh, Sharon; Fry, Andrew M; Bayliss, Richard

2013-08-01

32

Prognostic Significance of Mitotic Rate in Localized Primary Cutaneous Melanoma: An Analysis of Patients in the Multi-Institutional American Joint Committee on Cancer Melanoma Staging Database  

PubMed Central

Purpose The aim of this study was to assess the independent prognostic value of primary tumor mitotic rate compared with other clinical and pathologic features of stages I and II melanoma. Methods From the American Joint Committee on Cancer (AJCC) melanoma staging database, information was extracted for 13,296 patients with stages I and II disease who had mitotic rate data available. Results Survival times declined as mitotic rate increased. Ten-year survival ranged from 93% for patients whose tumors had 0 mitosis/mm2 to 48% for those with ? 20/mm2 (P < .001). Mean number of mitoses/mm2 increased as the primary melanomas became thicker (1.0 for melanomas ? 1 mm, 3.5 for 1.01 to 2.0 mm, 7.3 for 3.01 to 4.0 mm, and 9.6 for > 8 mm). Ulceration was also associated with a higher mitotic rate; 59% of ulcerated melanomas had ? 5 mitoses/mm2 compared with 16% of nonulcerated melanomas (P < .001). In a multivariate analysis of 10,233 patients, the independent predictive factors for survival in order of statistical significance were as follows: tumor thickness (?2 = 104.9; P < .001), mitotic rate (?2 = 67.0; P < .001), patient age (?2 = 48.2; P < .001), ulceration (?2 = 46.4; P < .001), anatomic site (?2 = 34.6; P < .001), and patient sex (?2 = 33.9; P < .001). Clark level of invasion was not an independent predictor of survival (?2 = 3.2; P = .37). Conclusion A high mitotic rate in a primary melanoma is associated with a lower survival probability. Among the independent predictors of melanoma-specific survival, mitotic rate was the strongest prognostic factor after tumor thickness.

Thompson, John F.; Soong, Seng-Jaw; Balch, Charles M.; Gershenwald, Jeffrey E.; Ding, Shouluan; Coit, Daniel G.; Flaherty, Keith T.; Gimotty, Phyllis A.; Johnson, Timothy; Johnson, Marcella M.; Leong, Stanley P.; Ross, Merrick I.; Byrd, David R.; Cascinelli, Natale; Cochran, Alistair J.; Eggermont, Alexander M.; McMasters, Kelly M.; Mihm, Martin C.; Morton, Donald L.; Sondak, Vernon K.

2011-01-01

33

Fusing high- and low-level features for speaker recognition  

Microsoft Academic Search

The area of automatic speaker recognition has been dominated by systems using only short-term, low-level acoustic information, such as cepstral features. While these systems have produced low error rates, they ignore higher levels of information beyond low-level acoustics that convey speaker information. Recently published works have demonstrated that such high-level information can be used successfully in automatic speaker recognition systems

Joseph P. Campbell; Douglas A. Reynolds; Robert B. Dunn

2003-01-01

34

Features of Nearest Neighbors Distances in High-Dimensional Space  

Microsoft Academic Search

Methods of nearest neighbors are essential in wide range of applications where it is necessary to estimate probability density (e.g. Bayes's classifier, problems of searching in large databases). This paper contemplates on features of distribution of nearest neighbors' distances in high-dimensional spaces. It shows that for uniform distribution of points in n-dimensional Euclidean space the distribution of the distance of

Marcel Jiina

35

Unique Features of a Highly Pathogenic Campylobacter jejuni Strain  

Microsoft Academic Search

Campylobacter jejuni, a major human enteric pathogen, exhibits significant strain-to-strain differences which result in differences in pathogenic potential. C. jejuni 81-176 is a highly virulent strain that exhibits unique pathogenic features and is used by many research laboratories. We have determined the nucleotide sequence of its genome and compared it to the genomes of other sequenced C. jejuni strains. We

Dirk Hofreuter; Jennifer Tsai; Robert O. Watson; Veronica Novik; Bill Altman; Michelle Benitez; Christina Clark; Clotilde Perbost; Thomas Jarvie; Lei Du; Jorge E. Galan

2006-01-01

36

Smurf2 as a novel mitotic regulator: From the spindle assembly checkpoint to tumorigenesis  

Microsoft Academic Search

The execution of the mitotic program with high fidelity is dependent upon precise spatiotemporal regulation of posttranslational protein modifications. For example, the timely polyubiquitination of critical mitotic regulators by Anaphase Promoting Complex\\/Cyclosome (APC\\/C) is essential for the metaphase to anaphase transition and mitotic exit. The spindle assembly checkpoint prevents unscheduled activity of APC\\/C-Cdc20 in early mitosis, allowing bipolar attachment of

Evan C Osmundson; Dipankar Ray; Finola E Moore; Hiroaki Kiyokawa

2009-01-01

37

A mitotic function for the high-mobility group protein HMG20b regulated by its interaction with the BRC repeats of the BRCA2 tumor suppressor  

PubMed Central

The inactivation of BRCA2, a suppressor of breast, ovarian and other epithelial cancers, triggers instability in chromosome structure and number, which are thought to arise from defects in DNA recombination and mitotic cell division, respectively. Human BRCA2 controls DNA recombination via eight BRC repeats, evolutionarily conserved motifs of ?35 residues, that interact directly with the recombinase RAD51. How BRCA2 controls mitotic cell division is debated. Several studies by different groups report that BRCA2 deficiency affects cytokinesis. Moreover, its interaction with HMG20b, a protein of uncertain function containing a promiscuous DNA-binding domain and kinesin-like coiled coils, has been implicated in the G2–M transition. We show here that HMG20b depletion by RNA interference disturbs the completion of cell division, suggesting a novel function for HMG20b. In vitro, HMG20b binds directly to the BRC repeats of BRCA2, and exhibits the highest affinity for BRC5, a motif that binds poorly to RAD51. Conversely, the BRC4 repeat binds strongly to RAD51, but not to HMG20b. In vivo, BRC5 overexpression inhibits the BRCA2–HMG20b interaction, recapitulating defects in the completion of cell division provoked by HMG20b depletion. In contrast, BRC4 inhibits the BRCA2–RAD51 interaction and the assembly of RAD51 at sites of DNA damage, but not the completion of cell division. Our findings suggest that a novel function for HMG20b in cytokinesis is regulated by its interaction with the BRC repeats of BRCA2, and separate this unexpected function for the BRC repeats from their known activity in DNA recombination. We propose that divergent tumor-suppressive pathways regulating chromosome segregation as well as chromosome structure may be governed by the conserved BRC motifs in BRCA2.

Lee, M; Daniels, M J; Garnett, M J; Venkitaraman, A R

2011-01-01

38

High Spatial Velocity Features in the Orion Nebula,  

NASA Astrophysics Data System (ADS)

We have used widely spaced in time Hubble Space Telescope images to determine tangential velocities of features associated with outflows from young stars. These observations were supplemented by ground-based telescope spectroscopy, and from the resultant radial velocities, space velocities were determined for many outflows. Numerous new moving features were found and grouped into known and newly assigned Herbig-Haro objects. It was found that stellar outflow is highly discontinuous, as frequently is the case, with long-term gaps of a few hundred years, and that these outflow periods are marked by staccato bursts over periods of about ten years. Although this has been observed in other regions, the Orion Nebula Cluster presents the richest display of this property. Most of the large-scale Herbig-Haro objects in the brightest part of the Orion Nebula appear to originate from a small region northeast of the strong Orion-S radio and infrared sources. With the possible exception of HH 203, we are not able to identify specific stellar sources, but do identify candidate sources for several other bright Herbig-Haro objects. We find that there are optical features in the BN-KL region that can be related to the known large-scale outflow that originates there. We find additional evidence for this outflow originating 500-1000 years ago. Based on observations at the San Pedro Martir Observatory operated by the Universidad Nacional Autónoma de México.

O'Dell, C. R.; Henney, W. J.

2008-10-01

39

Efficient learning and feature selection in high-dimensional regression.  

PubMed

We present a novel algorithm for efficient learning and feature selection in high-dimensional regression problems. We arrive at this model through a modification of the standard regression model, enabling us to derive a probabilistic version of the well-known statistical regression technique of backfitting. Using the expectation-maximization algorithm, along with variational approximation methods to overcome intractability, we extend our algorithm to include automatic relevance detection of the input features. This variational Bayesian least squares (VBLS) approach retains its simplicity as a linear model, but offers a novel statistically robust black-box approach to generalized linear regression with high-dimensional inputs. It can be easily extended to nonlinear regression and classification problems. In particular, we derive the framework of sparse Bayesian learning, the relevance vector machine, with VBLS at its core, offering significant computational and robustness advantages for this class of methods. The iterative nature of VBLS makes it most suitable for real-time incremental learning, which is crucial especially in the application domain of robotics, brain-machine interfaces, and neural prosthetics, where real-time learning of models for control is needed. We evaluate our algorithm on synthetic and neurophysiological data sets, as well as on standard regression and classification benchmark data sets, comparing it with other competitive statistical approaches and demonstrating its suitability as a drop-in replacement for other generalized linear regression techniques. PMID:20028222

Ting, Jo-Anne; D'Souza, Aaron; Vijayakumar, Sethu; Schaal, Stefan

2010-04-01

40

[Metabolism features of bacteria resistant to high concentrations of chromate].  

PubMed

Twenty strains of bacteria resistant to high concentrations of chromate were isolated from different ecological niches. They were able to reduce chromate to compounds of trivalent chromium--nonsoluble chromium hydroxide or soluble crystalline hydrates of trivalent chromium. The growth features of these microorganisms on media containing chromate at high concentrations (up to 20.0 g/l) are described. Besides chromate bacteria can reduce vanadate to compounds of V(4+) and Mo(6+) to Mo(5+). The best reduction takes place on the media where MPB. glucose or ethanol serves as the source of carbon. The growth and reduction of anion-in-study did not occur on organic acids. It was shown that tungstate, chlorate or perchlorate were not toxic for the studied bacteria up to concentrations of 10.0 g/l, however were not reduced by these microorganisms. The most active strains belong to genera Pseudomonas, Oerskovia, Bacillus, Micrococcus. PMID:23720958

Smirnova, G F; Podgorski?, V S

41

High-velocity features in Type Ia supernova spectra  

NASA Astrophysics Data System (ADS)

We use a sample of 58 low-redshift (z ? 0.03) Type Ia supernovae (SNe Ia) having well-sampled light curves and spectra near maximum light to examine the behaviour of high-velocity features (HVFs) in SN Ia spectra. We take advantage of the fact that Si II ?6355 is free of HVFs at maximum light in all SNe Ia, while HVFs are still strong in the Ca II near-infrared feature in many SNe, allowing us to quantify the strength of HVFs by comparing the structure of these two lines. We find that the average HVF strength increases with decreasing light-curve decline rate, and rapidly declining SNe Ia (?m15(B) ? 1.4 mag) show no HVFs in their maximum-light spectra. Comparison of HVF strength to the light-curve colour of the SNe Ia in our sample shows no evidence of correlation. We find a correlation of HVF strength with the velocity of Si II ?6355 at maximum light (vSi), such that SNe Ia with lower vSi have stronger HVFs, while those SNe Ia firmly in the `high-velocity' (i.e. vSi ? 12 000 km s-1) subclass exhibit no HVFs in their maximum-light spectra. While vSi and ?m15(B) show no correlation in the full sample of SNe Ia, we find a significant correlation between these quantities in the subset of SNe Ia having weak HVFs. In general, we find that slowly declining (low ?m15(B)) SNe Ia, which are more luminous and more energetic than average SNe Ia, tend to produce either high photospheric ejecta velocities (i.e. high vSi) or strong HVFs at maximum light, but not both. Finally, we examine the evolution of HVF strength for a sample of SNe Ia having extensive pre-maximum spectroscopic coverage and find significant diversity of the pre-maximum HVF behaviour.

Childress, Michael J.; Filippenko, Alexei V.; Ganeshalingam, Mohan; Schmidt, Brian P.

2013-10-01

42

How to be a mitotic chromosome  

Microsoft Academic Search

Proper mitotic chromosome structure is essential for faithful chromosome segregation. Mounting evidence suggests that mitotic\\u000a chromosome assembly is a progressive, dynamic process that requires topoisomerase II, condensins and cohesin and the activity\\u000a of several signalling molecules. Current results suggest how these different activities might interact to achieve the familiar\\u000a form of the mitotic chromosome.

Sandra C. Moser; Jason R. Swedlow

2011-01-01

43

Axin localizes to mitotic spindles and centrosomes in mitotic cells.  

PubMed

Wnt signaling plays critical roles in cell proliferation and carcinogenesis. In addition, numerous recent studies have shown that various Wnt signaling components are involved in mitosis and chromosomal instability. However, the role of Axin, a negative regulator of Wnt signaling, in mitosis has remained unclear. Using monoclonal antibodies against Axin, we found that Axin localizes to the centrosome and along mitotic spindles. This localization was suppressed by siRNA specific for Aurora A kinase and by Aurora kinase inhibitor. Interestingly, Axin over-expression altered the subcellular distribution of Plk1 and of phosphorylated glycogen synthase kinase (GSK3beta) without producing any notable changes in cellular phenotype. In the presence of Aurora kinase inhibitor, Axin over-expression induced the formation of cleavage furrow-like structures and of prominent astral microtubules lacking midbody formation in a subset of cells. Our results suggest that Axin modulates distribution of Axin-associated proteins such as Plk1 and GSK3beta in an expression level-dependent manner and these interactions affect the mitotic process, including cytokinesis under certain conditions, such as in the presence of Aurora kinase inhibitor. PMID:19331826

Kim, Shi-Mun; Choi, Eun-Jin; Song, Ki-Joon; Kim, Sewoon; Seo, Eunjeong; Jho, Eek-Hoon; Kee, Sun-Ho

2009-01-30

44

Mitotic and mitogenic Wnt signalling  

PubMed Central

Canonical Wnt signalling plays an important role in development, tissue homeostasis, and cancer. At the cellular level, canonical Wnt signalling acts by regulating cell fate, cell growth, and cell proliferation. With regard to proliferation, there is increasing evidence for a complex interaction between canonical Wnt signalling and the cell cycle. Mitogenic Wnt signalling regulates cell proliferation by promoting G1 phase. In mitosis, components of the Wnt signalling cascade function directly in spindle formation. Moreover, Wnt signalling is strongly activated in mitosis, suggesting that ‘mitotic Wnt signalling' plays an important role to orchestrate a cell division program. Here, we review the complex interplay between Wnt signalling and the cell cycle.

Niehrs, Christof; Acebron, Sergio P

2012-01-01

45

Mitotic and mitogenic Wnt signalling.  

PubMed

Canonical Wnt signalling plays an important role in development, tissue homeostasis, and cancer. At the cellular level, canonical Wnt signalling acts by regulating cell fate, cell growth, and cell proliferation. With regard to proliferation, there is increasing evidence for a complex interaction between canonical Wnt signalling and the cell cycle. Mitogenic Wnt signalling regulates cell proliferation by promoting G1 phase. In mitosis, components of the Wnt signalling cascade function directly in spindle formation. Moreover, Wnt signalling is strongly activated in mitosis, suggesting that 'mitotic Wnt signalling' plays an important role to orchestrate a cell division program. Here, we review the complex interplay between Wnt signalling and the cell cycle. PMID:22617425

Niehrs, Christof; Acebron, Sergio P

2012-05-22

46

Radar-anomalous, high-altitude features on Venus  

NASA Astrophysics Data System (ADS)

Over nearly all of the surface of Venus the reflectivity and emissivity at centimeter wavelengths are about 0.15 and 0.85 respectively. These values are consistent with moderately dense soils and rock populations, but the mean reflectivity is about a factor of 2 greater than that for the Moon and other terrestrial planets. Pettingill and Ford, using Pioneer Venus reflectivities and emissivities, found a number of anomalous features on Venus that showed much higher reflectivities and much lower emissivities with both values approaching 0.5. These include Maxwell Montes, a number of high regions in Aphrodite Terra and Beta Regio, and several isolated mountain peaks. Most of the features are at altitudes above the mean radius by 2 to 3 km or more. However, such features have been found in the Magellan data at low altitudes and the anomalies do not exist on all high structures, Maat Mons being the most outstanding example. A number of papers have been written that attempt to explain the phenomena in terms of the geochemistry balance of weathering effects on likely surface minerals. The geochemists have shown that the fundamentally basaltic surface would be stable at the temperatures and pressures of the mean radius in the form of magnetite, but would evolve to pyrite and/or pyrrhotite in the presence of sulfur-bearing compounds such as SO2. Pyrite will be stable at altitudes above 4 or 5 km on Venus. Although the geochemical arguments are rather compelling, it is vitally important to rationally look at other explanations for radar and radio emission measurements such as that presented by Tryka and Muhleman. The radar reflectivity values are retrieved from the raw Magellan backscatter measurements by fitting the Hagfors' radar scattering model in which a surface roughness parameters and a normal incidence electrical reflectivity are estimated. The assumptions of the theory behind the model must be considered carefully before the results can be believed. These include that the surface roughness exists only at horizontal scales large compared to the wavelength, the vertical deviations are gaussianly distributed, there is no shadowing, and that the reflection occurs at the interface of two homogeneous dielectric half-spaces. Probably all these conditions are violated at the anomalous features under discussion. The most important of these is the homogeneity of the near surface of Venus, particularly in highlands. Under the assumptions of the theory, all of the radio energy is reflected by the impedance jump at the very boundary. However, in heterogeneous soil some fraction of the illuminating energy is propagated into the soil and then scattered back out by impedance discontinuities such as rock, voids, and cracks. In light soils, the latter effect can overwhelm the scattering effects of the true surface and greatly enhance the backscatter power, suggesting a much higher value of an effective dielectric constant that would be estimated from Hagfors' model.

Muhleman, Duane O.; Butler, Bryan J.

1992-12-01

47

Mitotic force generators and chromosome segregation  

PubMed Central

The mitotic spindle uses dynamic microtubules and mitotic motors to generate the pico-Newton scale forces that are needed to drive the mitotic movements that underlie chromosome capture, alignment and segregation. Here, we consider the biophysical and molecular basis of force-generation for chromosome movements in the spindle, and, with reference to the Drosophila embryo mitotic spindle, we briefly discuss how mathematical modeling can complement experimental analysis to illuminate the mechanisms of chromosome-to-pole motility during anaphase A and spindle elongation during anaphase B.

Civelekoglu-Scholey, Gul

2010-01-01

48

Silencing of Nuclear Mitotic Apparatus protein (NuMA) accelerates the apoptotic disintegration of the nucleus  

Microsoft Academic Search

One main feature of apoptosis is the sequential degradation of the nuclear structure, including the fragmentation of chromatin\\u000a and caspase-mediated cleavage of various nuclear proteins. Among these proteins is the Nuclear Mitotic Apparatus protein (NuMA)\\u000a which plays a specific role in the organization of the mitotic spindle. The exact function of NuMA in the interphase nucleus\\u000a is unknown, but a

Pekka Taimen; Markku Kallajoki

2010-01-01

49

Feature selection for high-dimensional data in astronomy  

NASA Astrophysics Data System (ADS)

With an exponentially increasing amount of astronomical data, the complexity and dimension of astronomical data are likewise growing rapidly. Extracting information from such data becomes a critical and challenging problem. For example, some algorithms can only be employed in the low-dimensional spaces, so feature selection and feature extraction become important topics. Here we describe the difference between feature selection and feature extraction methods, and introduce the taxonomy of feature selection methods as well as the characteristics of each method. We present a case study comparing the performance and computational cost of different feature selection methods. For the filter method, ReliefF and fisher filter are adopted; for the wrapper method, improved CHAID, linear discriminant analysis (LDA), Naive Bayes (NB) and C4.5 are taken as learners. Applied on the sample, the result indicates that from the viewpoints of computational cost the filter method is superior to the wrapper method. Moreover, different learning algorithms combined with appropriate feature selection methods may arrive at better performance.

Zheng, Hongwen; Zhang, Yanxia

50

High-Dimensional Feature Descriptors to Characterize Volumetric Data  

Microsoft Academic Search

Volumetric data offer considerably more low-level information than the density and gradient values traditionally employed in transfer function-guided volume visualization. We propose the use of a richer set of low-level feature descriptors to allow a more sensitive and refined characterization of the data. The ensemble of these feature descriptors then forms a distinct data signature that can describe, classify, and

Julia EunJu Nam; Mauricio Mauer; Klaus Mueller

51

The Design of High-Level Features for Photo Quality Assessment  

Microsoft Academic Search

We propose a principled method for designing high level features forphoto quality assessment. Our resulting system can classify between high quality professional pho- tos and low quality snapshots. Instead of using the bag of low-level features approach, we first determine the per- ceptual factors that distinguish between professional photos and snapshots. Then, we design high level semantic features to measure

Yan Ke; Xiaoou Tang; Feng Jing

2006-01-01

52

Podocyte loss involves MDM2-driven mitotic catastrophe.  

PubMed

Podocyte apoptosis as a pathway of podocyte loss is often suspected but rarely detected. To study podocyte apoptosis versus inflammatory forms of podocyte death in vivo, we targeted murine double minute (MDM)-2 for three reasons. First, MDM2 inhibits p53-dependent apoptosis; second, MDM2 facilitates NF-?B signalling; and third, podocytes show strong MDM2 expression. We hypothesized that blocking MDM2 during glomerular injury may trigger p53-mediated podocyte apoptosis, proteinuria, and glomerulosclerosis. Unexpectedly, MDM2 blockade in early adriamycin nephropathy of Balb/c mice had the opposite effect and reduced intra-renal cytokine and chemokine expression, glomerular macrophage and T-cell counts, and plasma creatinine and blood urea nitrogen levels. In cultured podocytes exposed to adriamycin, MDM2 blockade did not trigger podocyte death but induced G2/M arrest to prevent aberrant nuclear divisions and detachment of dying aneuploid podocytes, a feature of mitotic catastrophe in vitro and in vivo. Consistent with these observations, 12 of 164 consecutive human renal biopsies revealed features of podocyte mitotic catastrophe but only in glomerular disorders with proteinuria. Furthermore, delayed MDM2 blockade reduced plasma creatinine levels, blood urea nitrogen, tubular atrophy, interstitial leukocyte numbers, and cytokine expression as well as interstitial fibrosis. Together, MDM2-mediated mitotic catastrophe is a previously unrecognized variant of podocyte loss where MDM2 forces podocytes to complete the cell cycle, which in the absence of cytokinesis leads to podocyte aneuploidy, mitotic catastrophe, and loss by detachment. MDM2 blockade with nutlin-3a could be a novel therapeutic strategy to prevent renal inflammation, podocyte loss, glomerulosclerosis, proteinuria, and progressive kidney disease. PMID:23749457

Mulay, Shrikant R; Thomasova, Dana; Ryu, Mi; Kulkarni, Onkar P; Migliorini, Adriana; Bruns, Hauke; Gröbmayr, Regina; Lazzeri, Elena; Lasagni, Laura; Liapis, Helen; Romagnani, Paola; Anders, Hans-Joachim

2013-07-01

53

Feature selection for tree species identification in very high resolution satellite images  

Microsoft Academic Search

The aim of this study was to provide an effective feature selection for tree species classifiers in mixed-species boreal forest, from a very high resolution optical satellite image. The 35 input features were the 5 input spectral bands (multispectral and panchromatic channels), 9 contextual features derived from the panchromatic channel and 21 segment-wise features computed at three segment sizes around

Matthieu Molinier; Heikki Astola

2011-01-01

54

High Resolution Urban Feature Extraction for Global Population Mapping using High Performance Computing  

SciTech Connect

The advent of high spatial resolution satellite imagery like Quick Bird (0.6 meter) and IKONOS (1 meter) has provided a new data source for high resolution urban land cover mapping. Extracting accurate urban regions from high resolution images has many applications and is essential to the population mapping efforts of Oak Ridge National Laboratory's (ORNL) LandScan population distribution program. This paper discusses an automated parallel algorithm that has been implemented on a high performance computing environment to extract urban regions from high resolution images using texture and spectral features

Vijayaraj, Veeraraghavan [ORNL; Bright, Eddie A [ORNL; Bhaduri, Budhendra L [ORNL

2007-01-01

55

Highly Nonrandom Features of Synaptic Connectivity in Local Cortical Circuits  

Microsoft Academic Search

How different is local cortical circuitry from a random network? To answer this question, we probed synaptic connections with several hundred simultaneous quadruple whole-cell recordings from layer 5 pyramidal neurons in the rat visual cortex. Analysis of this dataset revealed several nonrandom features in synaptic connectivity. We confirmed previous reports that bidirectional connections are more common than expected in a

Sen Song; Per Jesper Sjöström; Markus Reigl; Sacha Nelson; Dmitri B. Chklovskii

2005-01-01

56

NudC Deacetylation Regulates Mitotic Progression  

PubMed Central

Mitosis is largely driven by posttranslational modifications of proteins. Recent studies suggest that protein acetylation is prevalent in mitosis, but how protein acetylation/deacetylation regulates mitotic progression remains unclear. Nuclear distribution protein C (NudC), a conserved protein that regulates cell division, was previously shown to be acetylated. We found that NudC acetylation was decreased during mitosis. Using mass spectrometry analysis, we identified K39 to be an acetylation site on NudC. Reconstitution of NudC-deficient cells with wild-type or K39R acetylation-defective NudC rescued mitotic phenotypes, including chromosome misalignment, chromosome missegregation, and reduced spindle width, observed after NudC protein knockdown. In contrast, the K39Q acetylation-mimetic NudC was unable to rescue these mitotic phenotypes, suggesting that NudC deacetylation is important for mitotic progression. To examine proteins that may play a role in NudC deacetylation during mitosis, we found that NudC co-localizes on the mitotic spindle with the histone deacetylase HDAC3, an HDAC shown to regulate mitotic spindle stability. Further, NudC co-immunoprecipitates with HDAC3 and loss of function of HDAC3 either by protein knockdown or inhibition with a small molecule inhibitor increased NudC acetylation. These observations suggest that HDAC3 may be involved in NudC deacetylation during mitosis. Cells with NudC or HDAC3 knockdown exhibited overlapping mitotic abnormalities, including chromosomes arranged in a “dome-like” configuration surrounding a collapsed mitotic spindle. Our studies suggest that NudC acetylation/deacetylation regulates mitotic progression and NudC deacetylation, likely through HDAC3, is critical for spindle function and chromosome congression.

Chuang, Carol; Pan, Jing; Hawke, David H.; Lin, Sue-Hwa; Yu-Lee, Li-yuan

2013-01-01

57

NudC Deacetylation Regulates Mitotic Progression.  

PubMed

Mitosis is largely driven by posttranslational modifications of proteins. Recent studies suggest that protein acetylation is prevalent in mitosis, but how protein acetylation/deacetylation regulates mitotic progression remains unclear. Nuclear distribution protein C (NudC), a conserved protein that regulates cell division, was previously shown to be acetylated. We found that NudC acetylation was decreased during mitosis. Using mass spectrometry analysis, we identified K39 to be an acetylation site on NudC. Reconstitution of NudC-deficient cells with wild-type or K39R acetylation-defective NudC rescued mitotic phenotypes, including chromosome misalignment, chromosome missegregation, and reduced spindle width, observed after NudC protein knockdown. In contrast, the K39Q acetylation-mimetic NudC was unable to rescue these mitotic phenotypes, suggesting that NudC deacetylation is important for mitotic progression. To examine proteins that may play a role in NudC deacetylation during mitosis, we found that NudC co-localizes on the mitotic spindle with the histone deacetylase HDAC3, an HDAC shown to regulate mitotic spindle stability. Further, NudC co-immunoprecipitates with HDAC3 and loss of function of HDAC3 either by protein knockdown or inhibition with a small molecule inhibitor increased NudC acetylation. These observations suggest that HDAC3 may be involved in NudC deacetylation during mitosis. Cells with NudC or HDAC3 knockdown exhibited overlapping mitotic abnormalities, including chromosomes arranged in a "dome-like" configuration surrounding a collapsed mitotic spindle. Our studies suggest that NudC acetylation/deacetylation regulates mitotic progression and NudC deacetylation, likely through HDAC3, is critical for spindle function and chromosome congression. PMID:24069238

Chuang, Carol; Pan, Jing; Hawke, David H; Lin, Sue-Hwa; Yu-Lee, Li-Yuan

2013-09-19

58

Evolution and function of the mitotic checkpoint.  

PubMed

The mitotic checkpoint evolved to prevent cell division when chromosomes have not established connections with the chromosome segregation machinery. Many of the fundamental molecular principles that underlie the checkpoint, its spatiotemporal activation, and its timely inactivation have been uncovered. Most of these are conserved in eukaryotes, but important differences between species exist. Here we review current concepts of mitotic checkpoint activation and silencing. Guided by studies in model organisms and our phylogenomics analysis of checkpoint constituents and their functional domains and motifs, we highlight ancient and taxa-specific aspects of the core checkpoint modules in the context of mitotic checkpoint function. PMID:22898774

Vleugel, Mathijs; Hoogendoorn, Erik; Snel, Berend; Kops, Geert J P L

2012-08-14

59

Induction of mitotic gene conversion with nitrous acid, 1-methyl-3-nitro-1-nitrosoguanidine and other alkylating agents in Saccharomyces cerevisiae  

Microsoft Academic Search

1.Mitotic gene conversion was induced at three different hetero-allelic loci of the yeast Saccharomyces cerevisiae with nitrous acid, 1-methyl-3-nitro-1-nitrosoguanidine, N-nitroso-N-methylurethane, 1-nitroso-imidazolidone-2 and N-nitroso-N-methylcaproamide.2.All agents were already able to induce mitotic gene conversion at very high frequencies (1×10-3 and more) at doses of low toxicity.3.Induced mitotic gene conversion occurs in normal mitotic cells and does not result from a meiosis-like condition.4.Mitotic

F. K. Zimmermann; R. Schwaier

1967-01-01

60

High-speed, sub-15 nm feature size thermochemical nanolithography.  

PubMed

We report a nanolithography technique that allows simultaneous direct control of the local chemistry and topography of thin polymer films. Specifically, a heated atomic force microscope (AFM) tip can write sub-15 nm hydrophilic features onto a hydrophobic polymer at the rate of 1.4 mm per s. The thermally activated chemical reactions and topography changes depend on the chemical composition of the polymer, the raster speed, the temperature at the AFM tip/sample interface, and the normal load. This method is conceptually simple, direct, extremely rapid, achievable in a range of environments, and potentially adaptable to other materials systems. PMID:17385937

Szoszkiewicz, Robert; Okada, Takashi; Jones, Simon C; Li, Tai-De; King, William P; Marder, Seth R; Riedo, Elisa

2007-03-27

61

Mitotic regulation by NIMA-related kinases  

Microsoft Academic Search

The NIMA-related kinases represent a family of serine\\/threonine kinases implicated in cell cycle control. The founding member of this family, the NIMA kinase of Aspergillus nidulans, as well as the fission yeast homologue Fin1, contribute to multiple aspects of mitotic progression including the timing of mitotic entry, chromatin condensation, spindle organization and cytokinesis. Mammals contain a large family of eleven

Laura O'Regan; Joelle Blot; Andrew M Fry

2007-01-01

62

Furry promotes acetylation of microtubules in the mitotic spindle by inhibition of SIRT2 tubulin deacetylase.  

PubMed

The structure and function of microtubules (MTs) are regulated by post-translational modifications of tubulin subunits, such as acetylation of the Lys40 residue of ?-tubulin. Regulation of the organization and dynamics of MTs is essential for the precise formation of the mitotic spindle. Spindle MTs are highly acetylated, but the mechanism regulating this acetylation is largely unknown. Furry (Fry) is an evolutionarily conserved protein that binds to MTs and colocalizes with acetylated MTs in the mitotic spindle. In this study, we examined the role of Fry in the acetylation of MTs in the mitotic spindle. Depletion of Fry significantly reduced the level of MT acetylation in the mitotic spindle. Expression of the N-terminal fragment of Fry induced hyperacetylation of MTs in both mitotic and interphase cells. These results indicate that Fry promotes MT acetylation in the mitotic spindle. We also found that Fry binds to the tubulin deacetylase SIRT2, preferentially in mitotic cells. Cell-free experiments revealed that the N-terminal region of Fry is the domain responsible for binding to and inhibiting the tubulin-deacetylase activity of SIRT2. AGK2, a specific inhibitor of SIRT2, increased the level of MT acetylation in the mitotic spindle, indicating that SIRT2 is involved in the deacetylation of spindle MTs. Furthermore, AGK2 reversed the decrease in MT acetylation induced by Fry depletion. In summary, these results suggest that Fry plays a crucial role in promoting the level of MT acetylation in the mitotic spindle by inhibiting the tubulin-deacetylase activity of SIRT2. PMID:23886946

Nagai, Tomoaki; Ikeda, Masanori; Chiba, Shuhei; Kanno, Shin-Ichiro; Mizuno, Kensaku

2013-07-25

63

High-speed, sub-15 nm feature size thermochemical nanolithography  

NASA Astrophysics Data System (ADS)

The past decade has witnessed an explosion of techniques used to pattern materials on the nano and submicrometer scale, driven by a diversity of applications, such as molecular electronics, data storage, optoelectronics, displays, and all forms of sensors. However, there are many challenges to conventional techniques as they are approaching their fundamental size limit. Here we report a nanolithography technique that allows simultaneous direct control of the local chemistry and topography of thin polymer films. Specifically, a heated atomic force microscope tip can write sub-15 nanometer hydrophilic features over a hydrophobic polymer at the rate of 1.4 millimeters per second. This method is simple, direct, extremely rapid, achievable in a range of environments, and easily adaptable to other materials systems.

Riedo, Elisa; Szoszkiewicz, Robert; Okada, Takashi; Jones, Simon; Li, Tai-De; King, William; Marder, Seth

2007-03-01

64

Radar target recognition based on combined features of high range resolution profiles  

Microsoft Academic Search

This paper is focused on the feature extraction techniques of radar high range resolution profiles (HRRPs). In order to release the translational sensitivity of HRRPs, two translation invariant features, the central moments and distribution entropy, are extracted from the HRRPs and combined to form a new feature vector. Experiment on real data of three airplanes in flight is implemented to

Liu Mingjing; Zou Zhefeng; Hao Ming

2009-01-01

65

A Topology-Independent Similarity Measure for High-Dimensional Feature Spaces  

Microsoft Academic Search

In the field of computer vision feature matching in high di- mensional feature spaces is a commonly used technique for object recog- nition. One major problem is to find an adequate similarity measure for the particular feature space, as there is usually only little knowledge about the structure of that space. As a possible solution to this problem this paper

Jochen Kerdels; Gabriele Peters

2007-01-01

66

Architectures, features, and implementation of high-speed transport protocols  

Microsoft Academic Search

The results of a literature survey of the characteristics of high-speed protocols, new protocol architectures, and implementation techniques for these protocols are presented. A general description of transport protocol services is followed by a small sample of gigabit applications that might utilize a high-speed network. The applications considered are distributed processing, full-motion video, video-on-demand, and computer imaging. The problems with

T. F. La Porta; M. Schwartz

1991-01-01

67

RPA phosphorylation facilitates mitotic exit in response to mitotic DNA damage  

PubMed Central

Human replication protein A (RPA) becomes phosphorylated on the RPA2 subunit by cyclin B-Cdc2 during mitosis, although the functional role of this modification is unclear. We find that this modification stimulates RPA2 to become hyperphosphorylated in response to mitotic DNA damage caused by bleomycin treatment. Cells in which endogenous RPA2 was replaced by a mutant subunit lacking both Cdc2 sites had a significant defect in mitotic release into a 2N G1 phase after exposure to bleomycin. An increased percentage of these mutant cells also was positive initially for cyclin B expression and BubR1 chromatin staining, indicative of an extended spindle assembly checkpoint. The mutant cells that experienced mitotic DNA damage also underwent apoptosis at higher levels than cells expressing the WT subunit. Even so, we did not find the mutation had any dramatic effects on the level of DNA repair in mitosis. Cells lacking ATM (a checkpoint factor and RPA2 kinase) also were severely defective in mitotic exit and were unable to support RPA hyperphosphorylation after mitotic DNA damage. Although checkpoint 1 effector kinase (Chk1) had a more complex role, inhibition of Chk1 activity with UCN-01 also reduced mitotic exit. Chk1 activation and mitotic RPA hyperphosphorylation were found to be independent events. Our results demonstrate that mitotic RPA hyperphosphorylation facilitates release of cells from a damaged mitosis into a 2N G1 phase, thereby increasing cell viability.

Anantha, Rachel William; Sokolova, Elena; Borowiec, James A.

2008-01-01

68

Detecting Key Structural Features within Highly Recombined Genes  

PubMed Central

Many microorganisms exhibit high levels of intragenic recombination following horizontal gene transfer events. Furthermore, many microbial genes are subject to strong diversifying selection as part of the pathogenic process. A multiple sequence alignment is an essential starting point for many of the tools that provide fundamental insights on gene structure and evolution, such as phylogenetics; however, an accurate alignment is not always possible to attain. In this study, a new analytic approach was developed in order to better quantify the genetic organization of highly diversified genes whose alleles do not align. This BLAST-based method, denoted BLAST Miner, employs an iterative process that places short segments of highly similar sequence into discrete datasets that are designated “modules.” The relative positions of modules along the length of the genes, and their frequency of occurrence, are used to identify sequence duplications, insertions, and rearrangements. Partial alleles of sof from Streptococcus pyogenes, encoding a surface protein under host immune selection, were analyzed for module content. High-frequency Modules 6 and 13 were identified and examined in depth. Nucleotide sequences corresponding to both modules contain numerous duplications and inverted repeats, whereby many codons form palindromic pairs. Combined with evidence for a strong codon usage bias, data suggest that Module 6 and 13 sequences are under selection to preserve their nucleic acid secondary structure. The concentration of overlapping tandem and inverted repeats within a small region of DNA is highly suggestive of a mechanistic role for Module 6 and 13 sequences in promoting aberrant recombination. Analysis of pbp2X alleles from Streptococcus pneumoniae, encoding cell wall enzymes that confer antibiotic resistance, supports the broad applicability of this tool in deciphering the genetic organization of highly recombined genes. BLAST Miner shares with phylogenetics the important predictive quality that leads to the generation of testable hypotheses based on sequence data.

Wertz, John E; McGregor, Karen F; Bessen, Debra E

2007-01-01

69

Features of structure formation in high-viscosity paraffinic crudes  

SciTech Connect

In the design of petroleum refining processes for high-viscosity crudes and in solving problems associated with transportation of the crudes and increasing the recovery of oil from the formation, the viscosity characteristics and other rheological properties of the oil are of prime importance. These properties are governed to a considerable degree by associative interactions of the components of the crude. Here we are presenting results from an investigation of the viscosity properties of a number of crudes from fields in Ul`yanov Oblast, located in the Severo-Vostochnaya (Northeastern) and Filippovka groups of fields, and also its Yuzhnyi (Southern) pocket. These crudes differ among themselves in content of resins and asphaltenes and contain rather large amounts of high-molecular weight paraffin waxes; also, these crudes have high densities (up to 900 kg/cubic meter) and high viscosities (up to 600 mPa-sec). For this particular set of crudes, we have found certain correlations between rheological properties and composition.

Ratov, A.N.; Ashmyan, K.D.; Nemirovskaya, G.B. [and others

1995-09-01

70

Statistical Challenges with High Dimensionality: Feature Selection in Knowledge Discovery  

Microsoft Academic Search

Technological innovations have revolutionized the process of scientific research and knowledge discovery. The availability of massive data and challenges from frontiers of research and development have reshaped statistical thinking, data analysis and theoretical studies. The challenges of high-dimensionality arise in diverse fields of sciences and the humanities, ranging from computational biology and health studies to financial engineering and risk management.

Jianqing Fan; Runze Li

2006-01-01

71

Vibrational features of water's amorph at high pressures  

Microsoft Academic Search

The specific heat Cp and thermal conductivity kappa of water's high density amorph have been measured as a function of pressure up to 1.2GPa . Cp decreases on an increase in the pressure and kappa increases, both approaching a plateau value asymptotically. The decrease in Cp on an increase in pressure is shown to be due to increase in the

G. P. Johari; Ove Andersson

2006-01-01

72

Mitotic cytosol inhibits invagination of coated pits in broken mitotic cells.  

PubMed

Receptor-mediated endocytosis is inhibited during mitosis in mammalian cells and earlier work on A431 cells suggested that one of the sites inhibited was the invagination of coated pits (Pypaert, M., J. M. Lucocq, and G. Warren. 1987. Eur. J. Cell Biol. 45: 23-29). To explore this inhibition further, we have reproduced it in broken HeLa cells. Mitotic or interphase cells were broken by freeze-thawing in liquid nitrogen and warmed in the presence of mitotic or interphase cytosol. Using a morphological assay, we found invagination to be inhibited only when mitotic cells were incubated in mitotic cytosol. This inhibition was reversed by diluting the cytosol during the incubation. Reversal was sensitive to okadaic acid, a potent phosphatase inhibitor, showing that phosphorylation was involved in the inhibition of invagination. This was confirmed using purified cdc2 kinase which alone could partially substitute for mitotic cytosol. PMID:1910051

Pypaert, M; Mundy, D; Souter, E; Labbé, J C; Warren, G

1991-09-01

73

Physicochemical features of ultra-high viscosity alginates.  

PubMed

The physicochemical characteristics of the ultra-high viscosity and highly biocompatible alginates extracted from Lessonia nigrescens (UHV(N)) and Lessonia trabeculata (UHV(T)) were analyzed. Fluorescence and (1)H NMR spectroscopies, viscometry, and multi-angle light scattering (MALS) were used for elucidation of the chemical structure, molar mass, and coil size. The sequential structures from NMR spectroscopy showed high guluronate content for UHV(T), but low for UHV(N). Intrinsic viscosity [eta] measurements exhibited unusual high values (up to 2750 mL/g), whereas [eta] of a commercial alginate was only about 970 mL/g. MALS batch measurements of the UHV-alginates yielded ultra-high values of the weight average molar mass (M(w) up to 1.1x10(6) g/mol) and of the z-average gyration radius (R(G)(z) up to 191 nm). The M(w) and R(G)(z) distributions of UHV-alginates and of ultrasonically degraded fractions were determined using size exclusion chromatography combined with MALS and asymmetrical flow-field-flow fractionation. The M(w) dependency of [eta] and R(G)(z) could be described by [eta]=0.059xM(w)(0.78) and R(G)(z)=0.103xM(w)(x). (UHV(N): x=0.52; UHV(T): x=0.53) indicating that the monomer composition has no effect on coil expansion. Therefore, the equations can be used to calculate M(w) and R(G)(z) values of UHV(T)- and UHV(N)-alginate mixtures as used in immunoisolation. Furthermore, the simple and inexpensive capillary viscometry can be used for real-time validation of the extraction and purification process of the UHV-alginates. PMID:19394590

Storz, Henning; Müller, Kilian J; Ehrhart, Friederike; Gómez, Ivan; Shirley, Stephen G; Gessner, Petra; Zimmermann, Gertraud; Weyand, Esther; Sukhorukov, Vladimir L; Forst, Thomas; Weber, Matthias M; Zimmermann, Heiko; Kulicke, Werner-Michael; Zimmermann, Ulrich

2009-02-25

74

Unusual features in high statistics radar meteor studies at EISCAT  

NASA Astrophysics Data System (ADS)

We describe results of an experiment conducted with the European Incoherent Scatter (EISCAT) radars during three 8-h runs on consecutive nights in 2008 December aiming to detect and study the high-altitude meteor population along with the meteors detected at classical ~100-km altitudes. The experiment used coaxial ultra-high-frequency (UHF) and very high-frequency (VHF) radar beams pointed vertically to the zenith of Ramfjordmoen near Tromsø (Norway), and remote UHF receivers at Kiruna (Sweden) and Sodankylä (Finland) for tristatic observations of a very limited volume at an altitude of 170 km above the transmitter site. The EISCAT VHF radar detected during the 24-h period 22698 echoes identified as meteors. The number of UHF echoes in the same period was 2138, most detected also at VHF. Among the VHF meteors, 11 were detected at altitudes higher than 150 km. Of these, the record highest meteor was at 246.9 km. No high-altitude UHF echoes were detected, none was tristatic, and no echoes with a Doppler velocity above ~60 km s-1 were identified. Given the large number of echoes, which argues in favour of a highly significant characterization of the meteoroid population, we discuss the statistical properties of the detections and their possible physical nature. The average detection rate of VHF radar meteors was about 16 min-1. Comparing this high rate with that of the faintest optically detected meteors indicates that the radar detections originate from a meteoroid population that could be as optically faint as 13-14 mag. We did not observe a marked enhancement of the rates at the peak of the Geminid shower, confirming once again the proposal that most faint meteors, be these radar or optical, belong to the sporadic population and not to a specific shower. For a few meteors, our data show definite deceleration and possible fragmentation. A simple calculation indicates that one of the detected meteoroids was a submillimetre body that fragmented when the ram pressure reached about 0.5 pascal. This is much lower than the pressure that fragments brighter cometary meteors, which is at least two orders of magnitude higher.

Brosch, Noah; Häggström, Ingemar; Pellinen-Wannberg, Asta; Westman, Assar

2010-01-01

75

Vibrational features of water's amorph at high pressures  

NASA Astrophysics Data System (ADS)

The specific heat Cp and thermal conductivity ? of water’s high density amorph have been measured as a function of pressure up to 1.2GPa . Cp decreases on an increase in the pressure and ? increases, both approaching a plateau value asymptotically. The decrease in Cp on an increase in pressure is shown to be due to increase in the phonon frequency. The Debye temperature calculated from the available sound velocity data increases asymptotically with an increase in pressure and increases approximately linearly with an increase in the density of the amorph. The Grüneisen parameter of the high density amorph is 1.3. While the Debye theory explains the variation of Cp with pressure, it does not seem to do so for the variation of ? with pressure.

Johari, G. P.; Andersson, Ove

2006-03-01

76

Designing high performance DSM systems using InfiniBand features  

Microsoft Academic Search

Software DSM systems do not perform well because of the combined effects of increase in communication, slow networks and the large overhead associated with processing the coherence protocol. Modern interconnects like Myrinet, Quadrics and InfiniBand offer reliable, low latency (around 5.0 s point-to-point), and high-bandwidth (upto 10.0 Gbps in 4X InfiniBand). These networks also support efficient memory- based communication primitives

Ranjit Noronha; Dhabaleswar K. Panda

2004-01-01

77

Pair normalized channel feature and statistics-based learning for high-performance pedestrian detection  

NASA Astrophysics Data System (ADS)

High-performance pedestrian detection with good accuracy and fast speed is an important yet challenging task in computer vision. We design a novel feature named pair normalized channel feature (PNCF), which simultaneously combines and normalizes two channel features in image channels, achieving a highly discriminative power and computational efficiency. PNCF applies to both gradient channels and color channels so that shape and appearance information are described and integrated in the same feature. To efficiently explore the formidably large PNCF feature space, we propose a statistics-based feature learning method to select a small number of potentially discriminative candidate features, which are fed into the boosting algorithm. In addition, channel compression and a hybrid pyramid are employed to speed up the multiscale detection. Experiments illustrate the effectiveness of PNCF and its learning method. Our proposed detector outperforms the state-of-the-art on several benchmark datasets in both detection accuracy and efficiency.

Zeng, Bobo; Wang, Guijin; Ruan, Zhiwei; Lin, Xinggang; Meng, Long

2012-07-01

78

Absorption features of high-redshift galactic winds  

NASA Astrophysics Data System (ADS)

The environment of high-redshift galaxies is characterized by both wind-driven outflowing gas and gravitationally infalling streams. To investigate such galaxy-IGM interplay we have generated synthetic optical absorption line spectra piercing the volume surrounding a starbursting analog of a Lyman Break Galaxy selected in a z ? 3 output from a SPH simulation, including a detailed treatment of mechanical feedback from winds. Distributions for several observable species (Hi, Ciii, Civ, Siii, Siiii, Siiv, Ovi, Ovii, and Oviii) have been derived by post-processing the simulation outputs. The hot wind material is characterized by the presence of high-ionization species such as Ovi, Ovii, and Oviii (the latter two observable only in X-ray bands); the colder (T < 105.5 K) infalling streams can be instead identified by the combined presence of Siii, Siiii, and Ciii optical absorption together with Ovi that surrounds the cooler gas clumps. Considering both line profile and Pixel Optical Depth analysis of the synthetic spectra. We conclude that it may be difficult to clearly identify wind-blowing galaxies and their complex gaseous environment at high redshift in optical QSO absorption-line spectra based solely on the observed ion absorption patterns.

Fangano, A. P. M.; Ferrara, A.; Richter, P.

2012-09-01

79

Pretreatment in a high-pressure microwave processor for MIB-1 immunostaining of cytological smears and paraffin tissue sections to visualize the various phases of the mitotic cycle.  

PubMed

In many pathology laboratories, both microwave ovens and pressure cookers are used for pretreatment of cytologic smears and paraffin sections to allow MIB-1 staining. For both methods there are two problems. First, the results cannot be used for quantitation because standardization is impossible. Second, the staining results are often suboptimal, resulting in negative staining of cells in the G(1)- and S-phases. When pretreatment is performed in a microwave processor, allowing microwave heating under pressure, precise temperature monitoring becomes possible. In addition, the importance of the pH of the buffer was studied using a test battery series. Optimal staining is achieved at a temperature of 115C, 10 min, pH 6. This method proved to be highly reproducible. Because the immunostaining results are optimal, the various phases of the cell cycle can be defined in the sections and smears. In addition, the perinucleolar staining of the late G(1)-phase is optimally visualized and nuclei of the stable pKi-67 pathway can be identified. Under suboptimal conditions, in particular, the number of cells in the late G(1)-phase are underestimated in the MIB-1 counts. PMID:10424885

Suurmeijer, A J; Boon, M E

1999-08-01

80

High-Dimensional Feature Matching: Employing the Concept of Meaningful Nearest Neighbors  

Microsoft Academic Search

Matching of high-dimensional features using nearest neighbors search is an important part of image matching methods which are based on local invariant features. In this work we highlight effects pertinent to high-dimensional spaces that are significant for matching, yet have not been explicitly accounted for in previous work. In our approach, we require every nearest neighbor to be meaningful, that

Dusan Omercevic; Ondrej Drbohlav; Ales Leonardis

2007-01-01

81

Sound insulating element featuring high stiffness and low weight  

SciTech Connect

This paper describes a new approach to the problem of combining good sound insulation with high stiffness, low weight and limited thickness. A typical application is shipboard partitions where weight and thickness are essential cost factors and where specified demands on sound insulation are made at an increasing rate. A single leaf wall will as we know under favorable conditions give sound insulation according to the mass law. When a panel is stiffened the coincidence frequency moves to lower frequency and for typical dimensions and material properties it will be found within the interesting frequency region (100 to 3150 Hz). A double leaf wall must have weak connections between the leaves for good sound insulation, which in turn makes the stiffness performance poor. Optimizing stiffness with available space and material will result in a construction with a sandwich cross section.

Einarsson, S.; Soederquist, J.

1982-01-01

82

Large-scale mitotic cell synchronization.  

PubMed

Understanding cell growth and cell division involves the study of regulatory events that occur in a cell cycle phase-dependent manner. Studies analyzing cell cycle regulatory mechanisms and cell cycle progression invariably require synchronization of cell populations at specific cell cycle stages. Several methods have been established to synchronize cells, including serum deprivation, contact inhibition, centrifugal elutriation, and drug-dependent synchronization. Despite potential adverse cellular consequences of synchronizing cells by pharmacological agents, drug-dependent methods can be advantageous when studying later cell cycle events to ensure specific enrichment at selected mitotic stages. This chapter describes protocols used in our laboratory for isolating mitotic mammalian cells in a large-scale manner. In particular, we discuss the technical aspects of adherent or suspension cell isolation, the methods necessary to enrich cells at different mitotic stages and the optimized culture conditions. PMID:21755441

Dulla, Kalyan; Santamaria, Anna

2011-01-01

83

The Drosophila Microtubule-Associated Protein Mars Stabilizes Mitotic Spindles by Crosslinking Microtubules through Its N-Terminal Region  

PubMed Central

Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs) are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs) have been reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function. Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs.

Zhang, Gang; Beati, Hamze; Nilsson, Jakob; Wodarz, Andreas

2013-01-01

84

Atypical features in pleomorphic adenoma—a clinicopathologic study and implications for management  

Microsoft Academic Search

Pleomorphic adenoma is the most common salivary gland neoplasm and infrequently undergoes malignant transformation. Carcinoma ex pleomorphic adenoma is typically an infiltrative neoplasm with features of cellular pleomorphism, high mitotic activity, peri-neural and vascular invasion. More recently, sub-groups of pleomorphic adenoma have been described exhibiting vascular invasion and features of malignancy without evidence of extra-capsular extension. There is little information

M. Ethunandan; R. Witton; G. Hoffman; A. Spedding; P. A. Brennan

2006-01-01

85

High sensitive and high resolution investigations of the Jovian S-burst emission modulation features  

NASA Astrophysics Data System (ADS)

In spite of the long history of studying, the Jovian S-burst radiation still represents an event which needs to be investigated in detail. Many questions concerning this complex phenomenon are opened. One of the interesting problems is the different modulation features appearing on the dynamic spectra in dependence on the time resolution achieved in the experiment and also on the visualization time scale. It seems that in every concrete case the physical mechanism of the modulation is different. In connection to this the following statistical sets need to be fully collected and analyzed for each modulation effects: 1) observed conditions: dependence or independence on Jupiter - Io - observer position, season time, day-night time, the Solar activity; 2) observed parameters: sign and value of the frequency drift, lane's curvature, modulation depth, distances between the nearest lanes and their variety, scale of the modulation; 3) polarization properties. During the last years the new high sensitive recording facilities, such as the digital spectro-polarimiter (DSP) and waveform receiver (WFR) were created and installed into the largest decameter band antenna array UTR-2 (Kharkov, Ukraine). It can be noted that in the present time this combination (antenna + equipments) gives the best sensitiveness, band of analysis, dynamic range, time and frequency resolutions. The using of mentioned above technique allowed detecting new time-frequency features of the Jovian S-bursts. Several bright new results concerning the modulations were obtained. With the creation of new giant low frequency antenna array (LOFAR) and low wavelength array (LWA) the new possibilities of high level study of the Jovian DAM emission will appear. For instance, the combination of LOFAR and already existing instruments (max base in order of 2000 km) will permit to determine the spatial parameters and localization of an emission source. Future results may prove useful for the general understanding of the still unclear origin of the sporadic Jovian decametre emission.

Litvinenko, G. V.; Konovalenko, A. A.; Rucker, H. O.; Lecacheux, A.; Vinogradov, V. V.

2007-08-01

86

Stability of feature selection algorithms: a study on high-dimensional spaces  

Microsoft Academic Search

With the proliferation of extremely high-dimensional data , feature selection algorithms have become indispensable c om- ponents of the learning process. Strangely, despite extens ive work on the stability of learning algorithms, the stabil ity of feature selection algorithms has been relatively neglecte d. This study is an attempt to fill that gap by quantifying the s ensi- tivity of

Alexandros Kalousis; Julien Prados; Melanie Hilario

2007-01-01

87

The Hybrid Tree: An Index Structure for High Dimensional Feature Spaces  

Microsoft Academic Search

Feature based similarity search is emerging as an important search paradigm in database systems. The technique used is to map the data items as points into a high dimensional feature space which is indexed using a multidimensional data structure. Similarity search then corresponds to a range search over the data structure. Although several data structures have been pro- posed for

Kaushik Chakrabarti; Sharad Mehrotra

1999-01-01

88

Opening the Black Box of Feature Extraction: Incorporating Visualization into High-Dimensional Data Mining Processes  

Microsoft Academic Search

Feature extraction techniques have been used to handle high-dimensional data and experimental studies often show improved classification accuracies. Unfortunately very few studies provide concrete evidences on the effectiveness of these feature extraction techniques and they largely remain to be black boxes. In this study, we design and implement a visualization prototype system that allows users to look into the classification

Jianting Zhang; Le Gruenwald

2006-01-01

89

Zygotic development without functional mitotic centrosomes  

Microsoft Academic Search

The centrosome is the dominant microtubule-organizing center in animal cells. At the onset of mitosis, each cell normally has two centrosomes that lie on opposite sides of the nucleus. Centrosomes nucleate the growth of microtubules and orchestrate the efficient assembly of the mitotic spindle. Recent studies in vivo and in vitro have shown that the spindle can form even in

Timothy L Megraw; Ling-Rong Kao; Thomas C Kaufman

2001-01-01

90

Death through a tragedy: mitotic catastrophe  

Microsoft Academic Search

Mitotic catastrophe (MC) has long been considered as a mode of cell death that results from premature or inappropriate entry of cells into mitosis and can be caused by chemical or physical stresses. Whereas it initially was depicted as the main form of cell death induced by ionizing radiation, it is today known to be triggered also by treatment with

H Vakifahmetoglu; M Olsson; B Zhivotovsky

2008-01-01

91

Optical high-performance computing: introduction to the JOSA A and Applied Optics feature.  

PubMed

The feature issues in both Applied Optics and the Journal of the Optical Society of America A focus on topics of immediate relevance to the community working in the area of optical high-performance computing. PMID:19649027

Caulfield, H John; Dolev, Shlomi; Green, William M J

2009-08-01

92

Mitotic errors, aneuploidy and micronuclei in Hodgkin lymphoma pathogenesis  

PubMed Central

The Reed-Sternberg (RS) cell is the driving force behind Hodgkin lymphoma (HL), a unique malignancy in which the rare RS cell creates an inflammatory microenvironment that recruits a reactive tumor infiltrate. Well-known oncogenic factors such as nuclear factor kappa B (NF?B) signaling and Epstein-Barr virus infection are linked to HL pathogenesis but do not adequately explain the RS cell’s key pathologic features of multi-nucleation, abnormalities of centrosome function and number and aneuploidy. Chromosomal instability is also considered a key pathway in the origin of the RS cell, though the molecular mechanisms have largely been a “black box.” We demonstrated that the midbody kelch domain protein KLHDC8B protects against mitotic errors, centrosomal amplification and chromosomal instability. Here we discuss how the new findings linking KLHDC8B to mitotic integrity and faithful chromosomal segregation are providing mechanistic explanations for the origin of the RS cell and the molecular pathogenesis of chromosomal instability in HL.

Krem, Maxwell M.; Horwitz, Marshall S.

2013-01-01

93

A study of directional instability during mitotic chromosome movement  

NASA Astrophysics Data System (ADS)

Mitotic chromosome movements are responsible for the correct segregation of duplicated chromosomes into the daughter cells. Errors in this process are known to play a role in some of the serious diseases such as cancer, and the little understood process of aging. A thorough comprehension of the physical basis of this process is therefore necessary. An intriguing aspect of chromosome movements during mitosis is "directional instability": runs with approximately constant speed punctuated by abrupt reversal in direction of motion. I have constructed a mechanistic model that views chromosome movement as a result of interplay between poleward and antipoleward or polar ejection forces (PEF) on a chromosome; and microtubule (MT) depolymerization-coupled movement of the chromosome. Computer simulations based on this model using a single set of parameters accurately and quantitatively predict: the force, character, speed, and duration of chromosome movements, oscillations of chromosomes associated with only one spindle pole, the larger force during anaphase, the effect of MT-depolymerizing drugs on chromosome movements, and the decreased turnover of kinetochore-MTs during anaphase. The model also predicts how chromosome behavior should respond to perturbations of the PEF. These predictions could be unequivocally tested if it were possible to destroy structures smaller than the light resolution limit with minimal collateral damage. To address these requirements, I developed a methodology for ultrahigh resolution microsurgery with tightly-focused, ultrafast lasers pulses. This entailed an in-depth study of optical breakdown in dielectrics. Characterization of the single pulse damage in test dielectric materials ranging from silicon and glass to cell walls and membranes has shown that in the target regions where the laser intensity exceeds critical intensity, optical breakdown proceeds by tunneling ionization followed by a runaway avalanche ionization that ends with the ionization of all the valence electrons. Highly reproducible features on the nanometer size-scale indicate that the valence electron density is the central factor determining the critical intensity, implying that high precision can be maintained in a wide range of solids. Along with the new understanding optical breakdown, this technique will find potential applications in diverse fields ranging from MEMS fabrication to nano-fluidics, as well as cellular nanosurgery.

Joglekar, Ajit P.

94

Multiple phosphorylation events control mitotic degradation of the muscle transcription factor Myf5  

PubMed Central

Background The two myogenic regulatory factors Myf5 and MyoD are basic helix-loop-helix muscle transcription factors undergoing differential cell cycle dependent proteolysis in proliferating myoblasts. This regulated degradation results in the striking expression of these two factors at distinct phases of the cell cycle, and suggests that their precise and alternated disappearance is an important feature of myoblasts, maybe connected to the maintenance of the proliferative status and/or commitment to the myogenic lineage of these cells. One way to understand the biological function(s) of the cyclic expression of these proteins is to specifically alter their degradation, and to analyze the effects of their stabilization on cells. To this aim, we undertook the biochemical analysis of the mechanisms governing Myf5 mitotic degradation, using heterologous systems. Results We show here that mitotic degradation of Myf5 is conserved in non-myogenic cells, and is thus strictly under the control of the cell cycle apparatus. Using Xenopus egg extracts as an in vitro system to dissect the main steps of Myf5 mitotic proteolysis, we show that (1) Myf5 stability is regulated by a complex interplay of phosphorylation/dephosphorylation, probably involving various kinases and phosphatases, (2) Myf5 is ubiquitylated in mitotic extracts, and this is a prerequisite to its degradation by the proteasome and (3) at least in the Xenopus system, the E3 responsible for its mitotic degradation is not the APC/C (the major E3 during mitosis). Conclusion Altogether, our data strongly suggest that the mitotic degradation of Myf5 by the ubiquitin-proteasome system is precisely controlled by multiple phosphorylation of the protein, and that the APC/C is not involved in this process.

Doucet, Christine; Gutierrez, Gustavo J; Lindon, Catherine; Lorca, Thierry; Lledo, Gwendaline; Pinset, Christian; Coux, Olivier

2005-01-01

95

Mad2 inhibits the mitotic kinesin MKlp2  

PubMed Central

We identified the mitotic kinesin-like protein 2 (MKlp2), a kinesin required for chromosome passenger complex (CPC)–mediated cytokinesis, as a target of the mitotic checkpoint protein Mad2. MKlp2 possesses a consensus Mad2-binding motif required for Mad2 binding. Mad2 prevents MKlp2 from loading onto the mitotic spindle, a prerequisite step for its function as a mitotic kinesin. Furthermore, Mad2 inhibits the ability of MKlp2 to relocate the CPC from centromeres, an essential step to promote cytokinesis. An MKlp2 mutant that is refractory to Mad2-mediated inhibition prematurely translocates to the mitotic spindle and mislocalizes the CPC component Aurora B from the midbody of dividing cells. This correlates with an increased incidence of cytokinesis failure. Together, these findings reveal that MKlp2 is a novel mitotic target of Mad2 necessary for proper mitotic progression and cytokinesis.

McCormick, Frank

2010-01-01

96

Centrosomes promote timely mitotic entry in C. elegans embryos.  

PubMed

Several mitotic regulators, including Cyclin B1/Cdk1, are present at centrosomes prior to mitosis onset, but it is unclear whether centrosomes promote mitotic entry in vivo. Here we developed a sensitive assay in C. elegans embryos for the temporal analysis of mitotic entry, in which the male and female pronuclei undergo asynchronous entry into mitosis when separated from one another. Using this assay, we found that centrosome integrity is necessary for timing mitotic entry. Centrosomes do not function in this instance through their ability to nucleate microtubules. Instead, centrosomes serve to focus the Aurora A kinase AIR-1, which is essential for timely mitotic entry. Furthermore, analysis of embryos in which centrosomes and pronuclei are detached from one another demonstrates that centrosomes are sufficient to promote mitosis onset. Together, our findings support a model in which centrosomes serve as integrative centers for mitotic regulators and thus trigger mitotic entry in a timely fashion. PMID:17419992

Hachet, Virginie; Canard, Coralie; Gönczy, Pierre

2007-04-01

97

Hybrid feature detection and information accumulation using high-resolution LC-MS metabolomics data.  

PubMed

Feature detection is a critical step in the preprocessing of liquid chromatography-mass spectrometry (LC-MS) metabolomics data. Currently, the predominant approach is to detect features using noise filters and peak shape models based on the data at hand alone. Databases of known metabolites and historical data contain information that could help boost the sensitivity of feature detection, especially for low-concentration metabolites. However, utilizing such information in targeted feature detection may cause large number of false positives because of the high levels of noise in LC-MS data. With high-resolution mass spectrometry such as liquid chromatograph-Fourier transform mass spectrometry (LC-FTMS), high-confidence matching of peaks to known features is feasible. Here we describe a computational approach that serves two purposes. First it boosts feature detection sensitivity by using a hybrid procedure of both untargeted and targeted peak detection. New algorithms are designed to reduce the chance of false-positives by nonparametric local peak detection and filtering. Second, it can accumulate information on the concentration variation of metabolites over large number of samples, which can help find rare features and/or features with uncommon concentration in future studies. Information can be accumulated on features that are consistently found in real data even before their identities are found. We demonstrate the value of the approach in a proof-of-concept study. The method is implemented as part of the R package apLCMS at http://www.sph.emory.edu/apLCMS/ . PMID:23362826

Yu, Tianwei; Park, Youngja; Li, Shuzhao; Jones, Dean P

2013-02-12

98

Local-Learning-Based Feature Selection for High-Dimensional Data Analysis  

PubMed Central

This paper considers feature selection for data classification in the presence of a huge number of irrelevant features. We propose a new feature-selection algorithm that addresses several major issues with prior work, including problems with algorithm implementation, computational complexity, and solution accuracy. The key idea is to decompose an arbitrarily complex nonlinear problem into a set of locally linear ones through local learning, and then learn feature relevance globally within the large margin framework. The proposed algorithm is based on well-established machine learning and numerical analysis techniques, without making any assumptions about the underlying data distribution. It is capable of processing many thousands of features within minutes on a personal computer while maintaining a very high accuracy that is nearly insensitive to a growing number of irrelevant features. Theoretical analyses of the algorithm’s sample complexity suggest that the algorithm has a logarithmical sample complexity with respect to the number of features. Experiments on 11 synthetic and real-world data sets demonstrate the viability of our formulation of the feature-selection problem for supervised learning and the effectiveness of our algorithm.

Sun, Yijun; Todorovic, Sinisa; Goodison, Steve

2012-01-01

99

Three-dimensional segmentation of nuclei and mitotic chromosomes for the study of cell divisions in live Drosophila embryos.  

PubMed

Drosophila embryogenesis is an established model to investigate mechanisms and genes related to cell divisions in an intact multicellular organism. Progression through the cell cycle phases can be monitored in vivo using fluorescently labeled fusion proteins and time-lapse microscopy. To measure cellular properties in microscopic images, accurate and fast image segmentation methods are a critical prerequisite. To quantify static and dynamic features of interphase nuclei and mitotic chromosomes, we developed a three-dimensional (3D) segmentation method based on multiple level sets. We tested our method on 3D time-series images of live embryos expressing histone-2Av-green fluorescence protein. Our method is robust to low signal-to-noise ratios inherent to high-speed imaging, fluorescent signals in the cytoplasm, and dynamic changes of shape and texture. Comparisons with manual ground-truth segmentations showed that our method achieves more than 90% accuracy on the object as well as voxel levels and performs consistently throughout all cell cycle phases and developmental stages from syncytial blastoderm to postblastoderm mitotic domains. PMID:22069299

Chinta, Rambabu; Wasser, Martin

2011-11-08

100

On the CQE Phase Signature Feature in High-Resolution Spectro-Interferometry of Be Stars  

NASA Astrophysics Data System (ADS)

We analyse a feature that is detectable at the differential phases of high-resolution spectro-interferometry of Be stars. The origin of this feature (dubbed CQE-PS, Central Quasi Emission Phase Signature) lies in the differential absorption of photospheric radiation by the circumstellar disk, which is spectroscopically detected as a CQE line profile in shell stars. This phenomenon has great diagnostic potential for Be star disks, revealing properties of these disks on the scale of a few stellar radii.

Faes, D. M.; Carciofi, A. C.; Rivinius, Th.; Štefl, S.; Baade, D.; Domiciano de Souza, A.

2012-12-01

101

Sequential phosphorylation of GRASP65 during mitotic Golgi disassembly  

PubMed Central

Summary GRASP65 phosphorylation during mitosis and dephosphorylation after mitosis are required for Golgi disassembly and reassembly during the cell cycle. At least eight phosphorylation sites on GRASP65 have been identified, but whether they are modified in a coordinated fashion during mitosis is so far unknown. In this study, we raised phospho-specific antibodies that recognize phosphorylated T220/T224, S277 and S376 residues of GRASP65, respectively. Biochemical analysis showed that cdc2 phosphorylates all three sites, while plk1 enhances the phosphorylation. Microscopic studies using these antibodies for double and triple labeling demonstrate sequential phosphorylation and dephosphorylation during the cell cycle. S277 and S376 are phosphorylated from late G2 phase through metaphase until telophase when the new Golgi is reassembled. T220/224 is not modified until prophase, but is highly modified from prometaphase to anaphase. In metaphase, phospho-T220/224 signal localizes on both Golgi haze and mitotic Golgi clusters that represent dispersed Golgi vesicles and Golgi remnants, respectively, while phospho-S277 and S376 labeling is more concentrated on mitotic Golgi clusters. Expression of a phosphorylation-resistant GRASP65 mutant T220A/T224A inhibited mitotic Golgi fragmentation to a much larger extent than the expression of the S277A and S376A mutants. In cytokinesis, T220/224 dephosphorylation occurs prior to that of S277, but after S376. This study provides evidence that GRASP65 is sequentially phosphorylated and dephosphorylated during mitosis at different sites to orchestrate Golgi disassembly and reassembly during cell division, with phosphorylation of the T220/224 site being most critical in the process.

Tang, Danming; Yuan, Hebao; Vielemeyer, Ole; Perez, Franck; Wang, Yanzhuang

2012-01-01

102

Prevalence and features of migraine in Japanese junior high school students aged 12–15 yr  

Microsoft Academic Search

Migraine is the most common cause of recurrent headache among children and adolescents resulting in missing of school and disabling their daily life. The purpose of this study is to determine the prevalence and clinical features of headache in junior high school children in Japan. In December 2004, questionnaires were sent to 14 junior high schools. There were multiple-choice type

Naoki Ando; Shinji Fujimoto; Tatsuya Ishikawa; Jun Teramoto; Satoru Kobayashi; Ayako Hattori; Hajime Togari

2007-01-01

103

Orderly inactivation of the key checkpoint protein mitotic arrest deficient 2 (MAD2) during mitotic progression.  

PubMed

Anaphase is promoted by the ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C) only when all the chromosomes have achieved bipolar attachment to the mitotic spindles. Unattached kinetochores or the absence of tension between the paired kinetochores activates a surveillance mechanism termed the spindle-assembly checkpoint. A fundamental principle of the checkpoint is the activation of mitotic arrest deficient 2 (MAD2). MAD2 then forms a diffusible complex called mitotic checkpoint complex (designated as MAD2(MCC)) before it is recruited to APC/C (designated as MAD2(APC/C)). Large gaps in our knowledge remain on how MAD2 is inactivated after the checkpoint is satisfied. In this study, we have investigated the regulation of MAD2-containing complexes during mitotic progression. Using selective immunoprecipitation of checkpoint components and gel filtration chromatography, we found that MAD2(MCC) and MAD2(APC/C) were regulated very differently during mitotic exit. Temporally, MAD2(MCC) was broken down ahead of MAD2(APC/C). The inactivation of the two complexes also displayed different requirements of proteolysis; although APC/C and proteasome activities were dispensable for MAD2(MCC) inactivation, they are required for MAD2(APC/C) inactivation. In fact, the degradation of CDC20 is inextricably linked to the breakdown of MAD2(APC/C). These data extended our understanding of the checkpoint complexes during checkpoint silencing. PMID:21335556

Ma, Hoi Tang; Poon, Randy Y C

2011-02-18

104

Tissue-specific Mitotic Bookmarking by Hematopoietic Transcription Factor GATA1  

PubMed Central

Summary Tissue-specific transcription patterns are preserved throughout cell divisions to maintain lineage fidelity. We investigated whether transcription factor GATA1 plays a role in transmitting hematopoietic gene expression programs through mitosis when transcription is transiently silenced. Live cell imaging revealed that a fraction of GATA1 is retained focally within mitotic chromatin. ChIP-seq of highly purified mitotic cells uncovered that key hematopoietic regulatory genes are occupied by GATA1 in mitosis. The GATA1 co-regulators FOG1 and TAL1 dissociate from mitotic chromatin, suggesting that GATA1 functions as platform for their postmitotic recruitment. Mitotic GATA1 target genes tend to re-activate more rapidly upon entry into G1 than genes from which GATA1 dissociates. Mitosis-specific destruction of GATA1 delays reactivation selectively of genes that retain GATA1 during mitosis. These studies suggest a requirement of mitotic “bookmarking” by GATA1 for the faithful propagation of cell type-specific transcription programs through cell division.

Kadauke, Stephan; Udugama, Maheshi I.; Pawlicki, Jan M.; Achtman, Jordan C.; Jain, Deepti P.; Cheng, Yong; Hardison, Ross C.; Blobel, Gerd A.

2012-01-01

105

Spectral Features of the Tunneling Density of States in High-Tc Superconductors  

NASA Astrophysics Data System (ADS)

An overview is presented of the tunneling density of states in several cuprate superconductors including Tl-2201, La-214 and underdoped, optimally-doped and overdoped Bi-2212. Both SIN and SIS junction geometries are obtained using a point contact method with a Au tip. It is demonstrated that the high bias spectral features known as the dip and hump are universal to cuprates. The doping dependence of the dip/hump features in Bi-2212 have allowed a systematic and detailed analysis, including a direct correspondence to similar effects in ARPES, and which clearly demonstrate that these features are tied to the underlying interactions responsible for superconductivity. This is shown by correlation between dip/hump energies and the superconducting gap magnitude. However, deviations from this plot are found in SIS junctions with particularly sharp features in which case the dip is more consistent with a collective mode picture.

Ozyuzer, L.; Zasadzinski, J. F.; Miyakawa, N.; Oda, M.; Kendziora, C.; Sha, J.; Hinks, D. G.; Gray, K. E.

2000-03-01

106

Nanometer-size surface features produced by single, low energy, highly charged ions  

SciTech Connect

We have studied the interaction of ions with solid surfaces in the limit of slow, highly charged ions (Xe{sup 44+} 0.1--20 keV/{ital q}). Using atomic force microscopy we are able to see individual ion impact sites on mica, approximately one site per incident ion. Such features are typically circular with {similar_to}20 nm diameter. This damage may be caused by local charge depletion and conversion of the 50 keV Coulomb potential energy of the ions. Contact mode microscopy shows the features to be either pits or blisters depending on scanning direction and force between tip and substrate. By using lateral force microscopy we see the features to be regions of increased friction. The observed surface damage is independent of the ion kinetic energy. Repeated scanning over the same region causes erasure of the observed features. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

Parks, D.C. [Kansas State University, Manhattan, Kansas 66506-2601 (United States); Bastasz, R.; Schmieder, R.W. [Sandia National Laboratories, Livermore, California 94551-0969 (United States); Stoeckli, M. [Kansas State University, Manhattan, Kansas 66506-2601 (United States)

1995-05-01

107

The application of graph diffusion in high-level feature extraction  

NASA Astrophysics Data System (ADS)

In this paper, a new graph diffusion method is presented to improve the high-level feature extraction performance. In this method, we construct a semantic graph by describe the concepts as nodes and the concept affinities as the weights of edges, then we use the training set and its corresponding label matrix to estimate the concept relationship, where the relationship of two concepts were measured by the inner product of its corresponding row vector. We test the method on the high-level feature extraction task of TRECVID 2009 and the experimental results show the effectiveness of the method.

Du, Xiaohan; Zhang, Honggang; Guo, Jun; Xu, Xiaojun

2013-03-01

108

Epidemiological Features of High School Baseball Injuries in the United States, 2005-2007  

Microsoft Academic Search

OBJECTIVES.The goals were to calculate injury rates among high school baseball players and to characterize the general epidemiological features of high school baseball injuries and, more specifically, injuries attributed to being hit by a batted ball. METHODS.We analyzed baseball exposure and injury data collected over the 2005-2006 and 2006-2007 school years from a nationally representative sample of 100 US high

Christy L. Collins; R. Dawn Comstock

2008-01-01

109

Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen Interacts with Bromodomain Protein Brd4 on Host Mitotic Chromosomes  

Microsoft Academic Search

The latency-associated nuclear antigen (LANA) of Kaposi's sarcoma-associated herpesvirus (KSHV) is required for viral episome maintenance in host cells during latent infection. Two regions of the protein have been implicated in tethering LANA\\/viral episomes to the host mitotic chromosomes, and LANA chromosome- binding sites are subjects of high interest. Because previous studies had identified bromodomain protein Brd4 as the mitotic

Jianxin You; Viswanathan Srinivasan; Gerald V. Denis; William J. Harrington; M. E. Ballestas; K. M. Kaye; P. M. Howley

2006-01-01

110

Antitumour imidazoacridone C-1311 induces cell death by mitotic catastrophe in human colon carcinoma cells.  

PubMed

In this study, we investigated the cell death process induced by imidazoacridone C-1311 (Symadex) in HT-29 human colon carcinoma cells which have been shown to be preferentially sensitive to this compound in experimental tumour models both in vitro and in nude mice. Compound C-1311 at the EC(99) dose delayed progression of cells through the S phase which was followed by G2 arrest. At 48-96 h after drug exposure, an increasing fraction of cells rounded up and detached from the substratum which suggested the induction of cell death. This was confirmed by the induction of DNA fragmentation as revealed by pulse field electrophoresis and DNA strand breaks by the TUNEL assay. The dying cells had also mitotic features which were evidenced by various biochemical and morphological criteria such as activation of Cdk1 kinase, presence of the mitotic epitope MPM-2 and condensation of chromatin into mitotic chromosomes in drug-treated cells. These results show that C-1311 does not induce rapid apoptosis in HT-29 cells, instead drug exposure leads to prolonged G2 arrest followed by G2 to M transit and cell death during mitosis in the process of mitotic catastrophe. PMID:15710357

Hyzy, Magdalena; Bozko, Przemyslaw; Konopa, Jerzy; Skladanowski, Andrzej

2005-01-18

111

Revertant somatic mosaicism by mitotic recombination in dyskeratosis congenita.  

PubMed

Revertant mosaicism is an infrequently observed phenomenon caused by spontaneous correction of a pathogenic allele. We have observed such reversions caused by mitotic recombination of mutant TERC (telomerase RNA component) alleles in six patients from four families affected by dyskeratosis congenita (DC). DC is a multisystem disorder characterized by mucocutaneous abnormalities, dystrophic nails, bone-marrow failure, lung fibrosis, liver cirrhosis, and cancer. We identified a 4 nt deletion in TERC in a family with an autosomal-dominant form of DC. In two affected brothers without bone-marrow failure, sequence analysis revealed pronounced overrepresentation of the wild-type allele in blood cells, whereas no such skewing was observed in the other tissues tested. These observations suggest that this mosaic pattern might have resulted from somatic reversion of the mutated allele to the normal allele in blood-forming cells. SNP-microarray analysis on blood DNA from the two brothers indeed showed independent events of acquired segmental isodisomy of chromosome 3q, including TERC, indicating that the reversions must have resulted from mitotic recombination events. Subsequently, after developing a highly sensitive method of detecting mosaic homozygosity, we have found four additional cases with a mosaic-reversion pattern in blood cells; these four cases are part of a cohort of 17 individuals with germline TERC mutations. This shows that revertant mosaicism is a recurrent event in DC. This finding has important implications for improving diagnostic testing and understanding the variable phenotype of DC. PMID:22341970

Jongmans, Marjolijn C J; Verwiel, Eugene T P; Heijdra, Yvonne; Vulliamy, Tom; Kamping, Eveline J; Hehir-Kwa, Jayne Y; Bongers, Ernie M H F; Pfundt, Rolph; van Emst, Liesbeth; van Leeuwen, Frank N; van Gassen, Koen L I; Geurts van Kessel, Ad; Dokal, Inderjeet; Hoogerbrugge, Nicoline; Ligtenberg, Marjolijn J L; Kuiper, Roland P

2012-02-16

112

Differential Mitotic Stability of Yeast Disomes Derived from Triploid Meiosis  

PubMed Central

The frequencies of recovered disomy among the meiotic segregants of yeast (Saccharomyces cerevisiae) triploids were assessed under conditions in which all 17 yeast chromosomes were monitored simultaneously. The studies employed inbred triploids, in which all homologous centromeres were identical by descent, and single haploid testers carrying genetic markers for all 17 linkage groups. The principal results include: (1) Ascospores from triploid meiosis germinate at frequencies comparable to those from normal diploids, but most fail to produce visible colonies due to the growth-retarding effects of high multiple disomy. (2) The probability of disome formation during triploid meiosis is the same for all chromosomes; disomy for any given chromosome does not exclude simultaneous disomy for any other chromosome. (3) The 17 yeast chromosomes fall into three frequency classes in terms of disome recovery. The results support the idea that multiply disomic meiotic segregants of the triploid experience repeated, nonrandom, post-germination mitotic chromosome losses (N+1?N) and that the observed variations in individual disome recovery are wholly attributable to inherent differences in disome mitotic stability.

Campbell, Douglas; Doctor, John S.; Feuersanger, Jeane H.; Doolittle, Mark M.

1981-01-01

113

Loops Determine the Mechanical Properties of Mitotic Chromosomes  

PubMed Central

We introduce a new polymer model for mitotic chromosomes. The key assumption of the model is the ability of the chromatin fibre to cross-link to itself due to binding proteins. These protein-chromatin interactions are included by a probabilistic and dynamic mechanism. The hypothesis is motivated by the observation of high repulsive forces between ring polymers. We performed computer simulations to validate our model. Our results show that the presence of loops leads to a tight compaction and contributes significantly to the bending rigidity of chromosomes. Moreover, our qualitative prediction of the force elongation behaviour is close to experimental findings. The Dynamic Loop Model presented here indicates that the internal structure of mitotic chromosomes is based on self-organization of the chromatin fibre rather than attachment of chromatin to a protein scaffold. It also shows that the number and size of loops have a strong influence on the mechanical properties. We suggest that changes in the mechanical characteristics of chromosomes in different stages of the cell cycle, for example, can be explained by an altered internal loop structure.

Zhang, Yang; Heermann, Dieter W.

2011-01-01

114

High-accuracy real-time pedestrian detection system using 2D and 3D features  

NASA Astrophysics Data System (ADS)

We present a real time stereo-vision pedestrian detector implementation with a very high accuracy, the 2D component of which attains 99% recall with less than 10-6 false positives per window on the INRIA persons dataset. We utilize a sequence of classifiers which use different features, beginning with Haar-like features and a Haar-like feature implementation adapted to disparity images, and performing a final verification with Histogram-of-Oriented Gradient (HOG) features. We present a 2D Haar-like feature implementation that utilizes 2x2 kernel filters at multiple scales rather than integral images, and combines a quickly trained preliminary adaBoost classifier with a more accurate SVM classifier. We also show how these Haar-like features may be computed from a partially incomplete stereo disparity image in order to make use of 3-dimensional data. Finally, we discuss how these features, along with the HOG features, are computed rapidly and how the classifiers are combined in such a way as to enable real-time implementation with higher detection rates and lower false positive rates than typical systems. Our overall detector is a practical combination of speed and detection performance, operating on 544x409 image (10,425 windows) at a frame rate of 10-20fps, depending on scene complexity. The detector's overall false positive rate is less than 10-6, corresponding to about one false positive every 10-60s when testing on our non-training data. Additionally, the detector has shown usefulness for detecting other object types, and has been implemented for traffic cones, telephone poles, and vehicles.

Chambers, David R.; Flannigan, Clay; Wheeler, Benjamin

2012-05-01

115

Automatic Mapping of Linear Woody Vegetation Features in Agricultural Landscapes Using Very High Resolution Imagery  

Microsoft Academic Search

Automatic mapping and monitoring of agricultural landscapes using remotely sensed imagery has been an important research problem. This paper describes our work on developing automatic methods for the detection of target landscape features in very high spatial resolution images. The target objects of interest consist of linear strips of woody vegetation that include hedgerows and riparian vegetation that are important

Selim Aksoy; H. GÖkhan Akcay; Tom Wassenaar

2010-01-01

116

Inverse kinematics based on high-order moments of feature points and their Jacobian matrices  

Microsoft Academic Search

In this paper, we propose the inverse kinematics method based on high-order moment features and their Jaco- bian matrices, which can use an arbitrary information source about the shape of the targeted kinematic chain as reference input. The method is especially useful to generate the motion of humanoid robots and human figures, and we can generate the whole body pose

Ko Ayusawa; Yoshihiko Nakamura

2011-01-01

117

Assessing Motor Skills as a Differentiating Feature between High Functioning Autism and Asperger's Disorder  

ERIC Educational Resources Information Center

|The purpose of this research was to investigate if motor skills could be used as a differentiating feature between Asperger's Disorder (AD) and High Functioning (HFA) in children under the age of 9 years, 0 months, in order to provide additional information regarding the usefulness and validity of distinguishing these two disorders. There is…

Cid, Maria R.

2011-01-01

118

Ultrastructural features of highly active antiretroviral therapy-associated partial lipodystrophy  

Microsoft Academic Search

Chronic treatment with highly active antiretroviral therapy (HAART) results in a novel variety of partial lipodystrophy, combining lipoatrophic and hypertrophic areas. We have previously reported the histopathological features of this disease and have also shown that adipocyte apoptosis is involved in its origin. With the aim of further elucidating the mechanisms underlying this peculiar disorder, we performed an ultrastructural study

Josep Lloreta; Pere Domingo; Ramón M. Pujol; Juan A. Arroyo; Núria Baixeras; Xavier Matias-Guiu; Montserrat Gilaberte; Maria A. Sambeat; Sergi Serrano

2002-01-01

119

Thermal theory based feature extraction method for high noise PET images  

Microsoft Academic Search

We propose an image feature extraction method based on the thermal theory for high noise PET images. The PET imaging, which records physiological activities of tissues, is broadly used to provide diagnostic information for investigating clinical disorders. To extract desired regions of interest (ROIs) from noisy PET images for clinical applications is an important issue. The proposed method hypothesizes an

Hong-Dun Lin; Kang-Ping Lin; Being-Tau Chung; Liang-Chih Wu; Ren-Shyan Liu

2003-01-01

120

Feature Extraction in Land Use Changes of the Gyeongan River basin Using High Resolution Aerial Photographs  

Microsoft Academic Search

The goal of this study was to investigate the feature extraction in lad use change dynamics using high resolution aerial photographs and GIS (Geographical information system) in the Kyungan River Basin where there are rapid land use changes by recent reckless developments. A land use\\/land cover map was made using aerial orthophotography and land use change dynamics was analyzed using

Park So-Young; Kwang-Woo NAM; Young-Seup KIM; Chul-Uong CHOI

121

Dynamics and inherent safety features of small modular high temperature gas-cooled reactors  

Microsoft Academic Search

Investigations were made at Oak Ridge National Laboratory to characterize the dynamics and inherent safety features of various modular high temperature gas-cooled reactor (HTGR) designs. This work was sponsored by the US Nuclear Regulatory Commission's HTGR Safety Research program. The US Department of Energy (DOE) and the Gas Cooled Reactor Associates (GCRA) have sponsored studies of several modular HTGR concepts,

R. M. Harrington; S. J. Ball; J. C. Cleveland

1986-01-01

122

High resolution speech feature parametrization for monophone-based stressed speech recognition  

Microsoft Academic Search

This letter investigates the impact of stress on monophone speech recognition accuracy and proposes a new set of acoustic parameters based on high resolution wavelet analysis. The two parameter schemes are entitled wavelet packet parameters (WPP) and subband-based cepstral parameters (SBC). The performance of these features is compared to traditional Mel-frequency cepstral coefficients (MFCC) for stressed speech monophone recognition. The

Ruhi Sarikaya; John H. L. Hansen

2000-01-01

123

Features of the measurement of high-frequency ac voltage with electronic voltmeters  

Microsoft Academic Search

The features of the measurement of a high-frequency ac voltage with electronic voltmeters are considered for cases when the\\u000a measured ac voltage is normalized at the input of the electronic-voltmeter probe or at the input of a special connector to\\u000a which the voltmeter probe is connected.

V. V. Krestovskii; G. P. Telitchenko; V. I. Shevtsov

2011-01-01

124

Histone deacetylase 3 localizes to the mitotic spindle and is required for kinetochore-microtubule attachment  

PubMed Central

Protein acetylation and deacetylation play key roles in multiple physiological functions. Histone deacetylase 3 (HDAC3) is a highly conserved, ubiquitously expressed protein that forms multiprotein corepressor complexes to repress gene transcription. Recent studies show that HDAC3 may play a role in cell proliferation. Altered HDAC3 level increases G2/M cells, but the mechanism remains unknown. Here we show for the first time, to our knowledge, that the HDAC3 complex, including nuclear receptor corepressor (N-CoR), transducin-?-like protein 1 (TBL1), and TBL1-related protein 1 (TBLR1), is localized on the mitotic spindle. Knockdown of HDAC3 or N-CoR resulted in a collapsed mitotic spindle that was surrounded by chromosomes arranged in a dome-like configuration. Treatment of mitotic cells with Trichostatin A, an HDAC inhibitor, resulted in similar spindle defects independent of transcriptional regulation. In addition, wild-type HDAC3 but not a deacetylase-dead mutant HDAC3 rescued the phenotypes of HDAC3-depleted cells, suggesting that the enzymatic activity of HDAC3 is important for proper spindle function. Whereas the kinetochores and the spindle assembly checkpoint appeared intact in HDAC3-deficient cells, kinetochore–microtubule attachments were impaired because spindle microtubules were unstable in response to cold treatment. These data suggest that the HDAC3 complex is involved in the formation of functional mitotic spindles and proper kinetochore–microtubule attachment. The level or distribution of acetylated ?-tubulin was not altered in HDAC3-deficient cells. Taken together, our studies raise the interesting possibility that acetylation–deacetylation of mitotic spindle components may be essential for mitotic spindle function.

Ishii, Sumiyasu; Kurasawa, Yasuhiro; Wong, Jiemin; Yu-Lee, Li-yuan

2008-01-01

125

Phosphorylation of linker histones by cAMP-dependent protein kinase in mitotic micronuclei of Tetrahymena  

Microsoft Academic Search

Linker histones (LHs) in transcriptionally inretive, mitotically dividing micronuclei of Tetrahymena thermophila, a, ß, ? and d, are highly phosphorylated in vivo. Analysis of the derived sequences of these LHs suggests that none of these polypeptides contain sites of phosphorylation by p34cdc2, the kinase thought to play an essential role governing the entry of all cells into mitosis. Suprisingly a,

Melody T. Sweet; C. David Allis

1993-01-01

126

Grading of Well-differentiated Pancreatic Neuroendocrine Tumors Is Improved by the Inclusion of Both Ki67 Proliferative Index and Mitotic Rate.  

PubMed

The grading system for pancreatic neuroendocrine tumors (PanNETs) adopted in 2010 by the World Health Organization (WHO) mandates the use of both mitotic rate and Ki67/MIB-1 index in defining the proliferative rate and assigning the grade. In cases when these measures are not concordant for grade, it is recommended to assign the higher grade, but specific data justifying this approach do not exist. Thus, we counted mitotic figures and immunolabeled, using the Ki67 antibody, 297 WHO mitotic grade 1 and 2 PanNETs surgically resected at a single institution. We quantified the Ki67 proliferative index by marking at least 500 cells in "hot spots" and by using digital image analysis software to count each marked positive/negative cell and then compared the results with histologic features and overall survival. Of 264 WHO mitotic grade 1 PanNETs, 33% were WHO grade 2 by Ki67 proliferative index. Compared with concordant grade 1 tumors, grade-discordant tumors were more likely to have metastases to lymph node (56% vs. 34%) (P<0.01) and to distant sites (46% vs. 12%) (P<0.01). Discordant mitotic grade 1 PanNETs also showed statistically significantly more infiltrative growth patterns, perineural invasion, and small vessel invasion. Overall survival was significantly different (P<0.01), with discordant mitotic grade 1 tumors showing a median survival of 12 years compared with 16.7 years for concordant grade 1 tumors. Conversely, mitotic grade 1/Ki67 grade 2 PanNETs showed few significant differences from tumors that were mitotic grade 2 and either Ki67 grade 1 or 2. Our data demonstrate that mitotic rate and Ki67-based grades of PanNETs are often discordant, and when the Ki67 grade is greater than the mitotic grade, clinical outcomes and histopathologic features are significantly worse than concordant grade 1 tumors. Patients with discordant mitotic grade 1/Ki67 grade 2 tumors have shorter overall survival and larger tumors with more metastases and more aggressive histologic features. These data strongly suggest that Ki67 labeling be performed on all PanNETs in addition to mitotic rate determination to define more accurately tumor grade and prognosis. PMID:24121170

McCall, Chad M; Shi, Chanjuan; Cornish, Toby C; Klimstra, David S; Tang, Laura H; Basturk, Olca; Mun, Liew Jun; Ellison, Trevor A; Wolfgang, Christopher L; Choti, Michael A; Schulick, Richard D; Edil, Barish H; Hruban, Ralph H

2013-11-01

127

WAVENET feature extraction of high-range resolution radar profiles for automatic target recognition  

NASA Astrophysics Data System (ADS)

We propose a WAVENET method for feature extraction of high-range resolution (HRR) radar profiles. Because HRR signals constantly vary with incremental changes in time and target aspect, the inverse problem we address is that of extracting a subset of discriminatory features from a set of HRR profiles that are unique to each target class. Based on, we construct a neural net technique built on wavelets for determining the discriminating features separating each target class. The method involves choosing a suitable set of child wavelets, such that the transformation of the original data (the training set of HRR profiles) will enhance the nonlinear separability of different classes of target signals while significantly reducing the dimension of the data.

Morris, Hedley C.; De Pass, Monica M.

2005-03-01

128

High resolution urban feature extraction for global population mapping using high performance computing  

Microsoft Academic Search

The advent of high spatial resolution satellite imagery like Quick Bird (0.6 meter) and IKONOS (1 meter) has provided a new data source for high resolution urban land cover mapping. Extracting accurate urban regions from high resolution images has many applications and is essential to the population mapping efforts of Oak Ridge National Laboratory's (ORNL) LandScan population distribution program. This

Veeraraghavan Vijayaraj; Eddie A Bright; Budhendra L Bhaduri

2007-01-01

129

A PLANETARY LENSING FEATURE IN CAUSTIC-CROSSING HIGH-MAGNIFICATION MICROLENSING EVENTS  

SciTech Connect

Current microlensing follow-up observations focus on high-magnification events because of the high efficiency of planet detection. However, central perturbations of high-magnification events caused by a planet can also be produced by a very close or a very wide binary companion, and the two kinds of central perturbations are not generally distinguished without time consuming detailed modeling (a planet-binary degeneracy). Hence, it is important to resolve the planet-binary degeneracy that occurs in high-magnification events. In this paper, we investigate caustic-crossing high-magnification events caused by a planet and a wide binary companion. From this investigation, we find that because of the different magnification excess patterns inside the central caustics induced by the planet and the binary companion, the light curves of the caustic-crossing planetary-lensing events exhibit a feature that is discriminated from those of the caustic-crossing binary-lensing events, and the feature can be used to immediately distinguish between the planetary and binary companions. The planetary-lensing feature appears in the interpeak region between the two peaks of the caustic-crossings. The structure of the interpeak region for the planetary-lensing events is smooth and convex or boxy, whereas the structure for the binary-lensing events is smooth and concave. We also investigate the effect of a finite background source star on the planetary-lensing feature in the caustic-crossing high-magnification events. From this, we find that the convex-shaped interpeak structure appears in a certain range that changes with the mass ratio of the planet to the planet-hosting star.

Chung, Sun-Ju; Hwang, Kyu-Ha; Ryu, Yoon-Hyun; Lee, Chung-Uk, E-mail: sjchung@kasi.re.kr, E-mail: kyuha@kasi.re.kr, E-mail: yhryu@kasi.re.kr, E-mail: leecu@kasi.re.kr [Korea Astronomy and Space Science Institute, Hwaam-Dong, Yuseong-Gu, Daejeon 305-348 (Korea, Republic of)

2012-05-20

130

Feature Selection for high Dimensional DNA Microarray data using hybrid approaches.  

PubMed

Feature selection from DNA microarray data is a major challenge due to high dimensionality in expression data. The number of samples in the microarray data set is much smaller compared to the number of genes. Hence the data is improper to be used as the training set of a classifier. Therefore it is important to select features prior to training the classifier. It should be noted that only a small subset of genes from the data set exhibits a strong correlation with the class. This is because finding the relevant genes from the data set is often non-trivial. Thus there is a need to develop robust yet reliable methods for gene finding in expression data. We describe the use of several hybrid feature selection approaches for gene finding in expression data. These approaches include filtering (filter out the best genes from the data set) and wrapper (best subset of genes from the data set) phases. The methods use information gain (IG) and Pearson Product Moment Correlation (PPMC) as the filtering parameters and biogeography based optimization (BBO) as the wrapper approach. K nearest neighbour algorithm (KNN) and back propagation neural network are used for evaluating the fitness of gene subsets during feature selection. Our analysis shows that an impressive performance is provided by the IG-BBO-KNN combination in different data sets with high accuracy (>90%) and low error rate. PMID:24143053

Kumar, Ammu Prasanna; Valsala, Preeja

2013-09-23

131

CBIR: from low-level features to high-level semantics  

NASA Astrophysics Data System (ADS)

The performance of a content-based image retrieval (CBIR) system is inherently constrained by the features adopted to represent the images in the database. Use of low-level features can not give satisfactory retrieval results in many cases; especially when the high-level concepts in the user's mind is not easily expressible in terms of the low-level features. Therefore whenever possible, textual annotations shall be added or extracted and/or processed to improve the retrieval performance. In this paper a hybrid image retrieval system is presented to provide the user with the flexibility of using both the high-level semantic concept/keywords as well as low-level feature content in the retrieval process. The emphasis is put on a statistical algorithm for semantic grouping in the concept space through relevance feedback in the image space. Under this framework, the system can also incrementally learn the user's search habit/preference in terms of semantic relations among concepts; and uses this information to improve the performance of subsequent retrieval tasks. This algorithm can eliminate the need for a stand-alone thesaurus, which may be too large in size and contain too much redundant information to be of practical use. Simulated experiments are designed to test the effectiveness of the algorithm. An intelligent dialogue system, to which this algorithm can be a part of the knowledge acquisition module, is also described as a front end for the CBIR system.

Zhou, Xiang S.; Huang, Thomas S.

2000-04-01

132

Feature Selection for high Dimensional DNA Microarray data using hybrid approaches  

PubMed Central

Feature selection from DNA microarray data is a major challenge due to high dimensionality in expression data. The number of samples in the microarray data set is much smaller compared to the number of genes. Hence the data is improper to be used as the training set of a classifier. Therefore it is important to select features prior to training the classifier. It should be noted that only a small subset of genes from the data set exhibits a strong correlation with the class. This is because finding the relevant genes from the data set is often non-trivial. Thus there is a need to develop robust yet reliable methods for gene finding in expression data. We describe the use of several hybrid feature selection approaches for gene finding in expression data. These approaches include filtering (filter out the best genes from the data set) and wrapper (best subset of genes from the data set) phases. The methods use information gain (IG) and Pearson Product Moment Correlation (PPMC) as the filtering parameters and biogeography based optimization (BBO) as the wrapper approach. K nearest neighbour algorithm (KNN) and back propagation neural network are used for evaluating the fitness of gene subsets during feature selection. Our analysis shows that an impressive performance is provided by the IG-BBO-KNN combination in different data sets with high accuracy (>90%) and low error rate.

Kumar, Ammu Prasanna; Valsala, Preeja

2013-01-01

133

The Energy Relations of Mitotic Activity in Adult Mouse Epidermis  

Microsoft Academic Search

The theory that epidermal mitotic activity in the mouse involves significant quantities of energy has been examined in the relatively simple conditions of a saline tissue-culture medium. It is shown that an adequate oxygen supply is of the highest importance, both oxygen intake and mitotic activity varying directly with oxygen tension. In anaerobic conditions cell division ceases. Sufficient quantities of

W. S. Bullough; Monica Johnson

1951-01-01

134

On the Spatial Configuration of the Mitotic Spindle  

NASA Astrophysics Data System (ADS)

An experimental simulation using electrorheological (ER) fluid is developed to investigate the spatial configuration of the mitotic spindle. In the presence of two different kinds of electric field, the structures of particle arrangement in ER fluid are similar to the configuration of the mitotic spindle of the animal and plant cells respectively.

Wen, Weijia; Sun, Limin; Lu, Kunquan; Tang, Xiaowei

1995-03-01

135

On the road to cancer: aneuploidy and the mitotic checkpoint  

Microsoft Academic Search

Abnormal chromosome content — also known as aneuploidy — is the most common characteristic of human solid tumours. It has therefore been proposed that aneuploidy contributes to, or even drives, tumour development. The mitotic checkpoint guards against chromosome mis-segregation by delaying cell-cycle progression through mitosis until all chromosomes have successfully made spindle-microtubule attachments. Defects in the mitotic checkpoint generate aneuploidy

Beth A. A. Weaver; Geert J. P. L. Kops; Don W. Cleveland

2005-01-01

136

High-Velocity Features: A Ubiquitous Property of Type Ia Supernovae  

Microsoft Academic Search

Evidence of high-velocity features (HVFs) such as those seen in the near-maximum spectra of some Type Ia supernovae (SNe Ia; e.g., SN 2000cx) has been searched for in the available SN Ia spectra observed earlier than 1 week before B maximum. Recent observational efforts have doubled the number of SNe Ia with very early spectra. Remarkably, all SNe Ia with

P. A. Mazzali; S. Benetti; G. Altavilla; G. Blanc; E. Cappellaro; N. Elias-Rosa; G. Garavini; A. Goobar; A. Harutyunyan; R. Kotak; B. Leibundgut; P. Lundqvist; S. Mattila; J. Mendez; S. Nobili; R. Pain; A. Pastorello; F. Patat; G. Pignata; Ph. Podsiadlowski; P. Ruiz-Lapuente; M. Salvo; B. P. Schmidt; J. Sollerman; V. Stanishev; M. Stehle; C. Tout; M. Turatto; W. Hillebrandt

2005-01-01

137

The Effect of High vs Low Density Barium Preparations on the Quantitative Features of Swallowing  

Microsoft Academic Search

We compared the effect of high-density and low-density barium preparations on the quantitative features of swallowing. The two barium preparations differed primarily in density but also differed somewhat in viscosity. Concurrent videofluoroscopic and manometric studies were done in nine healthy control subjects. Videofluoroscopy was recorded in the lateral projection at 30 frames\\/sec while concurrent manometry was done with five intraluminal

Wylie J. Dodds; Benson T. Massey; Mark K. Kern

1989-01-01

138

Spectral Features of the Tunneling Density of States in High-Tc Superconductors  

Microsoft Academic Search

An overview is presented of the tunneling density of states in several cuprate superconductors including Tl-2201, La-214 and underdoped, optimally-doped and overdoped Bi-2212. Both SIN and SIS junction geometries are obtained using a point contact method with a Au tip. It is demonstrated that the high bias spectral features known as the dip and hump are universal to cuprates. The

L. Ozyuzer; J. F. Zasadzinski; N. Miyakawa; M. Oda; C. Kendziora; J. Sha; D. G. Hinks; K. E. Gray

2000-01-01

139

Nanometer-size surface features produced by single, low energy, highly charged ions  

Microsoft Academic Search

We have studied the interaction of ions with solid surfaces in the limit of slow, highly charged ions (Xe{sup 44+} 0.1--20 keV\\/{ital q}). Using atomic force microscopy we are able to see individual ion impact sites on mica, approximately one site per incident ion. Such features are typically circular with â¼20 nm diameter. This damage may be caused by local

D. C. Parks; R. Bastasz; R. W. Schmieder; M. Stoeckli

1995-01-01

140

Evaluation of Graylevel-Features for Printing Technique Classification in High-Throughput Document Management Systems  

Microsoft Academic Search

The detection of altered or forged documents is an important tool in large scale office automation. Printing technique examination\\u000a can therefore be a valuable source of information to determine a questioned documents authenticity. A study of graylevel features\\u000a for high throughput printing technique recognition was undertaken. The evaluation included printouts generated by 49 different\\u000a laser and 13 different inkjet printers.

Christian Schulze; Marco Schreyer; Armin Stahl; Thomas M. Breuel

2008-01-01

141

Imprint lithography with sub-10 nm feature size and high throughput  

Microsoft Academic Search

Nanoimprint lithography, a high-throughput, low-cost, nonconventional lithographic method proposed and demonstrated recently, has been developed and investigated. Nanoimprint lithography has demonstrated 10 nm feature size, 40 nm pitch, vertical and smooth sidewalls, and nearly 90° corners. Further experimental study indicates that the ultimate resolution of nanoimprint lithography could be sub-10 nm, the imprint process is repeatable, and the mold is

Stephen Y. Chou; Peter R. Krauss

1997-01-01

142

RESEARCH ON CHANGE DETECTION OF OUTDATED MAP ROAD FEATURE BASED ON UPDATED HIGH-RESOLUTION REMOTE SENSING IMAGE  

Microsoft Academic Search

This paper researched on change detection of outdated map road feature based on updated high-resolution satellite remote sensing (RS) image. The change of road feature was divided into two parts: one is disappear or partial change; the other is new added. To detect disappear or partial changed road, based on outdated map road feature, this paper put forward methods of

Ming DONG Haitao ZHANG

143

A Novel Pathway that Coordinates Mitotic Exit with Spindle Position  

PubMed Central

In budding yeast, the spindle position checkpoint (SPC) delays mitotic exit until the mitotic spindle moves into the neck between the mother and bud. This checkpoint works by inhibiting the mitotic exit network (MEN), a signaling cascade initiated and controlled by Tem1, a small GTPase. Tem1 is regulated by a putative guanine exchange factor, Lte1, but the function and regulation of Lte1 remains poorly understood. Here, we identify novel components of the checkpoint that operate upstream of Lte1. We present genetic evidence in agreement with existing biochemical evidence for the molecular mechanism of a pathway that links microtubule-cortex interactions with Lte1 and mitotic exit. Each component of this pathway is required for the spindle position checkpoint to delay mitotic exit until the spindle is positioned correctly.

Nelson, Scott A.

2007-01-01

144

Random mitotic activities across human embryonic stem cell colonies.  

SciTech Connect

A systemic and quantitative study was performed to examine whether different levels of mitotic activities, assessed by the percentage of S-phase cells at any given time point, existed at different physical regions of human embryonic stem (hES) cell colonies at 2, 4, 6 days after cell passaging. Mitotically active cells were identified by the positive incorporation of 5-bromo-2-deoxyuridine (BrdU) within their newly synthesized DNA. Our data indicated that mitotically active cells were often distributed as clusters randomly across the colonies within the examined growth period, presumably resulting from local deposition of newly divided cells. This latter notion was further demonstrated by the confined growth of enhanced green florescence protein (EGFP) expressing cells amongst non-GFP expressing cells. Furthermore, the overall percentage of mitotically active cells remained constantly at about 50% throughout the 6-day culture period, indicating mitotic activities of hES cell cultures were time-independent under current growth conditions.

Jin, Q.; Duggan, R.; Dasa, S.; Li, F.; Chen, L. (Biosciences Division)

2010-08-01

145

Inhibition of Cdc42 during mitotic exit is required for cytokinesis.  

PubMed

The role of Cdc42 and its regulation during cytokinesis is not well understood. Using biochemical and imaging approaches in budding yeast, we demonstrate that Cdc42 activation peaks during the G1/S transition and during anaphase but drops during mitotic exit and cytokinesis. Cdc5/Polo kinase is an important upstream cell cycle regulator that suppresses Cdc42 activity. Failure to down-regulate Cdc42 during mitotic exit impairs the normal localization of key cytokinesis regulators-Iqg1 and Inn1-at the division site, and results in an abnormal septum. The effects of Cdc42 hyperactivation are largely mediated by the Cdc42 effector p21-activated kinase Ste20. Inhibition of Cdc42 and related Rho guanosine triphosphatases may be a general feature of cytokinesis in eukaryotes. PMID:23878274

Atkins, Benjamin D; Yoshida, Satoshi; Saito, Koji; Wu, Chi-Fang; Lew, Daniel J; Pellman, David

2013-07-22

146

Centromere fragmentation is a common mitotic defect of S and G2 checkpoint override.  

PubMed

DNA damaging agents, including those used in the clinic, activate cell cycle checkpoints, which blocks entry into mitosis. Given that checkpoint override results in cell death via mitotic catastrophe, inhibitors of the DNA damage checkpoint are actively being pursued as chemosensitization agents. Here we explored the effects of gemcitabine in combination with Chk1 inhibitors in a panel of pancreatic cancer cell lines and found variable abilities to override the S phase checkpoint. In cells that were able to enter mitosis, the chromatin was extensively fragmented, as assessed by metaphase spreads and Comet assay. Notably, electron microscopy and high-resolution light microscopy showed that the kinetochores and centromeres appeared to be detached from the chromatin mass, in a manner reminiscent of mitosis with unreplicated genomes (MUGs). Cell lines that were unable to override the S phase checkpoint were able to override a G2 arrest induced by the alkylator MMS or the topoisomerase II inhibitors doxorubicin or etoposide. Interestingly, checkpoint override from the topoisomerase II inhibitors generated fragmented kinetochores (MUGs) due to unreplicated centromeres. Our studies show that kinetochore and centromere fragmentation is a defining feature of checkpoint override and suggests that loss of cell viability is due in part to acentric genomes. Furthermore, given the greater efficacy of forcing cells into premature mitosis from topoisomerase II-mediated arrest as compared with gemcitabine-mediated arrest, topoisomerase II inhibitors maybe more suitable when used in combination with checkpoint inhibitors. PMID:23624842

Beeharry, Neil; Rattner, Jerome B; Caviston, Juliane P; Yen, Tim

2013-04-24

147

Development of a virtual probe tip with an application to high aspect ratio microscale features  

SciTech Connect

Nondestructive measurement of microscale features remains a challenging metrology problem. For example, to assess a high aspect ratio small hole it is currently common to cut a cross section and measure the features of interest using an atomic force microscope, scanning probe microscope, or scanning electron microscope. Typically, these metrology tools may be suitable for surface finish measurement but often lack the capability for dimensional metrology. The aim of this article is to discuss the development of a high aspect-ratio microscale probe for measurement of microscale features. A 700:1 high aspect ratio probe shank is fabricated with a 7 {mu}m diameter, and attached at one end to an oscillator. The oscillator produces a standing wave in the oscillating probe shank as opposed to conventional probes that use a microscale sphere on the end of a comparatively rigid shank. As a result of the standing wave formed in steady state vibration, the free end of the shank generates an amplitude of oscillation greater than the probe shank diameter. Thus, the probe does not require a spherical ball to serve as the contact point and simply uses the contact diameter of the free end of the vibrating shank. This methodology is referred to as a virtual probe tip. The virtual probe tip in conjunction with a nanopositioning scanner is used to measure surface profile measurements over traverse lengths of 130 {mu}m. In this article, results from profiles of a 500 nm step height and a ruby sphere of diameter 1 mm are presented. Experiments in this article indicate the ability to repeatedly resolve surface features of less than 5 nm while maintaining bandwidths greater than 1 kHz. Furthermore, adhesion problems often encountered with micrometer scaled probes were not observed during profile measurements with this virtual probe.

Bauza, Marcin B.; Hocken, Robert J.; Smith, Stuart T.; Woody, Shane C. [InsituTec Inc., 2750 East W.T. Harris Boulevard, Suite 103, Charlotte, North Carolina 28213 and Center for Precision Metrology, UNCC, 9201 University City Boulevard, Charlotte, North Carolina 28213 (United States); Center for Precision Metrology, UNCC, 9201 University City Boulevard, Charlotte, North Carolina 28213 (United States); InsituTec Inc., 2750 East W.T. Harris Boulevard, Suite 103, Charlotte, North Carolina 28213 (United States)

2005-09-15

148

Development of a virtual probe tip with an application to high aspect ratio microscale features  

NASA Astrophysics Data System (ADS)

Nondestructive measurement of microscale features remains a challenging metrology problem. For example, to assess a high aspect ratio small hole it is currently common to cut a cross section and measure the features of interest using an atomic force microscope, scanning probe microscope, or scanning electron microscope. Typically, these metrology tools may be suitable for surface finish measurement but often lack the capability for dimensional metrology. The aim of this article is to discuss the development of a high aspect-ratio microscale probe for measurement of microscale features. A 700:1 high aspect ratio probe shank is fabricated with a 7 ?m diameter, and attached at one end to an oscillator. The oscillator produces a standing wave in the oscillating probe shank as opposed to conventional probes that use a microscale sphere on the end of a comparatively rigid shank. As a result of the standing wave formed in steady state vibration, the free end of the shank generates an amplitude of oscillation greater than the probe shank diameter. Thus, the probe does not require a spherical ball to serve as the contact point and simply uses the contact diameter of the free end of the vibrating shank. This methodology is referred to as a virtual probe tip. The virtual probe tip in conjunction with a nanopositioning scanner is used to measure surface profile measurements over traverse lengths of 130 ?m. In this article, results from profiles of a 500 nm step height and a ruby sphere of diameter 1 mm are presented. Experiments in this article indicate the ability to repeatedly resolve surface features of less than 5 nm while maintaining bandwidths greater than 1 kHz. Furthermore, adhesion problems often encountered with micrometer scaled probes were not observed during profile measurements with this virtual probe.

Bauza, Marcin B.; Hocken, Robert J.; Smith, Stuart T.; Woody, Shane C.

2005-09-01

149

Distinctive Features of Novel Superconducting Transitions in Underdoped and Overdoped HIGH-Tc Cuprates  

NASA Astrophysics Data System (ADS)

It is argued that the new theory that combines the precursor BCS-like non-superconducting (SC) pairing and the Cooper-pair condensation into a superfluid Bose-liquid state is more plausible than the standard SC fluctuation approach in describing the distinctive features of the underdoped and overdoped high-Tc cuprates. We show that the scenarios for high-Tc superconductivity in these materials are quite different on the character of the Cooper-pair formation and SC phase transitions.

Dzhumanov, S.; Fan, J. D.

150

The flavonoid eupatorin inactivates the mitotic checkpoint leading to polyploidy and apoptosis.  

PubMed

The spindle assembly checkpoint (SAC) is a conserved mechanism that ensures the fidelity of chromosome distribution in mitosis by preventing anaphase onset until the correct bipolar microtubule-kinetochore attachments are formed. Errors in SAC function may contribute to tumorigenesis by inducing numerical chromosome anomalies (aneuploidy). On the other hand, total disruption of SAC can lead to massive genomic imbalance followed by cell death, a phenomena that has therapeutic potency. We performed a cell-based high-throughput screen with a compound library of 2000 bioactives for novel SAC inhibitors and discovered a plant-derived phenolic compound eupatorin (3',5-dihydroxy-4',6,7-trimethoxyflavone) as an anti-mitotic flavonoid. The premature override of the microtubule drug-imposed mitotic arrest by eupatorin is dependent on microtubule-kinetochore attachments but not interkinetochore tension. Aurora B kinase activity, which is essential for maintenance of normal SAC signaling, is diminished by eupatorin in cells and in vitro providing a mechanistic explanation for the observed forced mitotic exit. Eupatorin likely has additional targets since eupatorin treatment of pre-mitotic cells causes spindle anomalies triggering a transient M phase delay followed by impaired cytokinesis and polyploidy. Finally, eupatorin potently induces apoptosis in multiple cancer cell lines and suppresses cancer cell proliferation in organotypic 3D cell culture model. PMID:22227008

Salmela, Anna-Leena; Pouwels, Jeroen; Kukkonen-Macchi, Anu; Waris, Sinikka; Toivonen, Pauliina; Jaakkola, Kimmo; Mäki-Jouppila, Jenni; Kallio, Lila; Kallio, Marko J

2011-12-29

151

PIASy mediates SUMO-2 conjugation of Topoisomerase-II on mitotic chromosomes  

PubMed Central

Here we show that the PIASy protein is specifically required for mitotic modification of Topoisomerase-II by SUMO-2 conjugation in Xenopus egg extracts. PIASy was unique among the PIAS family members in its capacity to bind mitotic chromosomes and recruit Ubc9 onto chromatin. These properties were essential, since PIASy mutants that did not bind chromatin or failed to recruit Ubc9 were functionally inactive. We observed that PIASy depletion eliminated essentially all chromosomal accumulation of EGFP–SUMO-2-conjugated species, suggesting that it is the primary E3-like factor for mitotic chromosomal substrates of SUMO-2. PIASy-dependent SUMO-2-conjugated species were highly concentrated on the inner centromere, and inhibition of PIASy blocked anaphase sister chromatid segregation in egg extracts. Taken together, our observations suggest that PIASy is a critical regulator of mitotic SUMO-2 conjugation for Topoisomerase-II and other chromosomal substrates, and that its activity may have particular relevance for centromeric functions required for proper chromosome segregation.

Azuma, Yoshiaki; Arnaoutov, Alexei; Anan, Tadashi; Dasso, Mary

2005-01-01

152

Mitotic spindle destabilization and genomic instability in Shwachman-Diamond syndrome  

PubMed Central

Deficiencies in the SBDS gene result in Shwachman-Diamond syndrome (SDS), an inherited bone marrow failure syndrome associated with leukemia predisposition. SBDS encodes a highly conserved protein previously implicated in ribosome biogenesis. Using human primary bone marrow stromal cells (BMSCs), lymphoblasts, and skin fibroblasts, we show that SBDS stabilized the mitotic spindle to prevent genomic instability. SBDS colocalized with the mitotic spindle in control primary BMSCs, lymphoblasts, and skin fibroblasts and bound to purified microtubules. Recombinant SBDS protein stabilized microtubules in vitro. We observed that primary BMSCs and lymphoblasts from SDS patients exhibited an increased incidence of abnormal mitoses. Similarly, depletion of SBDS by siRNA in human skin fibroblasts resulted in increased mitotic abnormalities and aneuploidy that accumulated over time. Treatment of primary BMSCs and lymphoblasts from SDS patients with nocodazole, a microtubule destabilizing agent, led to increased mitotic arrest and apoptosis, consistent with spindle destabilization. Conversely, SDS patient cells were resistant to taxol, a microtubule stabilizing agent. These findings suggest that spindle instability in SDS contributes to bone marrow failure and leukemogenesis.

Austin, Karyn M.; Gupta, Mohan L.; Coats, Scott A.; Tulpule, Asmin; Mostoslavsky, Gustavo; Balazs, Alejandro B.; Mulligan, Richard C.; Daley, George; Pellman, David; Shimamura, Akiko

2008-01-01

153

Cloud field classification based upon high spatial resolution textural features. 2. Simplified vector approaches  

NASA Astrophysics Data System (ADS)

The huge volume of data being collected in global climate studies makes it necessary to develop efficient automatic data analysis methods. While most cloud classification algorithms are based upon multispectral signatures, there is growing use of textural features. The results given in Part 1 of this study demonstrate that textural features computed from the Gray Level Cooccurrence Matrix (GLCM) approach produce high cloud classification accuracies. The present study compares classification results derived from two vector approaches, Sum and Difference Histogram (SADH) and Gray Level Difference Vector (GLDV), with those from the GLCM approach. It is found that the SADH approach produces accuracies equivalent to those obtained using GLCM, but with greater ability to resolve error clusters; also, there is a 30% savings in run time and a 50% savings in storage requirements. The GLDV approach suffers a slight degradation in classification accuracy but has a 40% savings in run time and an 87% savings in storage requirements. Textural features are not highly sensitive to moderate variations in cloud threshold selection. However, the whole cloud, rather than only the brightest portions of the cloud, produce the highest classification accuracies. A very important result is that spatial information content and classification accuracy are preserved even at lower radiometric resolutions with effective gray levels of 16. means that significantly low resolution digitized versions of satellite imagery retain essentially the full spatial information content of the original digital data. Substitution of digitized imagery can significantly reduce the expense of many remote sensing studies.

Chen, D. W.; Sengupta, S. K.; Welch, R. M.

1989-10-01

154

Relationships among Repetitive Behaviors, Sensory Features, and Executive Functions in High Functioning Autism.  

PubMed

This study examined the relationship between repetitive behaviors and sensory processing issues in school-aged children with high functioning autism (HFA). Children with HFA (N = 61) were compared to healthy, typical controls (N = 64) to determine the relationship between these behavioral classes and to examine whether executive dysfunction explained any relationship between the variables. Particular types of repetitive behavior (i.e., stereotypy and compulsions) were related to sensory features in autism; however, executive deficits were only correlated with repetitive behavior. This finding suggests that executive dysfunction is not the shared neurocognitive mechanism that accounts for the relationship between restricted, repetitive behaviors and aberrant sensory features in HFA. Group status, younger chronological age, presence of sensory processing issues, and difficulties with behavior regulation predicted the presence of repetitive behaviors in the HFA group. PMID:21475640

Boyd, Brian A; McBee, Matthew; Holtzclaw, Tia; Baranek, Grace T; Bodfish, James W

2009-10-01

155

Relationships among Repetitive Behaviors, Sensory Features, and Executive Functions in High Functioning Autism  

PubMed Central

This study examined the relationship between repetitive behaviors and sensory processing issues in school-aged children with high functioning autism (HFA). Children with HFA (N = 61) were compared to healthy, typical controls (N = 64) to determine the relationship between these behavioral classes and to examine whether executive dysfunction explained any relationship between the variables. Particular types of repetitive behavior (i.e., stereotypy and compulsions) were related to sensory features in autism; however, executive deficits were only correlated with repetitive behavior. This finding suggests that executive dysfunction is not the shared neurocognitive mechanism that accounts for the relationship between restricted, repetitive behaviors and aberrant sensory features in HFA. Group status, younger chronological age, presence of sensory processing issues, and difficulties with behavior regulation predicted the presence of repetitive behaviors in the HFA group.

Boyd, Brian A.; McBee, Matthew; Holtzclaw, Tia; Baranek, Grace T.; Bodfish, James W.

2009-01-01

156

NAD(P)H:Quinone Oxidoreductase 1 (NQO1) Localizes to the Mitotic Spindle in Human Cells  

PubMed Central

NAD(P)H:quinone oxidoreductase 1 (NQO1) is an FAD containing quinone reductase that catalyzes the 2-electron reduction of a broad range of quinones. The 2-electron reduction of quinones to hydroquinones by NQO1 is believed to be a detoxification process since this reaction bypasses the formation of the highly reactive semiquinone. NQO1 is expressed at high levels in normal epithelium, endothelium and adipocytes as well as in many human solid tumors. In addition to its function as a quinone reductase NQO1 has been shown to reduce superoxide and regulate the 20 S proteasomal degradation of proteins including p53. Biochemical studies have indicated that NQO1 is primarily located in the cytosol, however, lower levels of NQO1 have also been found in the nucleus. In these studies we demonstrate using immunocytochemistry and confocal imaging that NQO1 was found associated with mitotic spindles in cells undergoing division. The association of NQO1 with the mitotic spindles was observed in many different human cell lines including nontransformed cells (astrocytes, HUVEC) immortalized cell lines (HBMEC, 16HBE) and cancer (pancreatic adenocarcinoma, BXPC3). Confocal analysis of double-labeling experiments demonstrated co-localization of NQO1with alpha-tubulin in mitotic spindles. In studies with BxPc-3 human pancreatic cancer cells the association of NQO1 with mitotic spindles appeared to be unchanged in the presence of NQO1 inhibitors ES936 or dicoumarol suggesting that NQO1 can associate with the mitotic spindle and still retain catalytic activity. Analysis of archival human squamous lung carcinoma tissue immunostained for NQO1 demonstrated positive staining for NQO1 in the spindles of mitotic cells. The purpose of this study is to demonstrate for the first time the association of the quinone reductase NQO1 with the mitotic spindle in human cells.

Siegel, David; Kepa, Jadwiga K.; Ross, David

2012-01-01

157

NAD(P)H:quinone oxidoreductase 1 (NQO1) localizes to the mitotic spindle in human cells.  

PubMed

NAD(P)H:quinone oxidoreductase 1 (NQO1) is an FAD containing quinone reductase that catalyzes the 2-electron reduction of a broad range of quinones. The 2-electron reduction of quinones to hydroquinones by NQO1 is believed to be a detoxification process since this reaction bypasses the formation of the highly reactive semiquinone. NQO1 is expressed at high levels in normal epithelium, endothelium and adipocytes as well as in many human solid tumors. In addition to its function as a quinone reductase NQO1 has been shown to reduce superoxide and regulate the 20 S proteasomal degradation of proteins including p53. Biochemical studies have indicated that NQO1 is primarily located in the cytosol, however, lower levels of NQO1 have also been found in the nucleus. In these studies we demonstrate using immunocytochemistry and confocal imaging that NQO1 was found associated with mitotic spindles in cells undergoing division. The association of NQO1 with the mitotic spindles was observed in many different human cell lines including nontransformed cells (astrocytes, HUVEC) immortalized cell lines (HBMEC, 16HBE) and cancer (pancreatic adenocarcinoma, BXPC3). Confocal analysis of double-labeling experiments demonstrated co-localization of NQO1with alpha-tubulin in mitotic spindles. In studies with BxPc-3 human pancreatic cancer cells the association of NQO1 with mitotic spindles appeared to be unchanged in the presence of NQO1 inhibitors ES936 or dicoumarol suggesting that NQO1 can associate with the mitotic spindle and still retain catalytic activity. Analysis of archival human squamous lung carcinoma tissue immunostained for NQO1 demonstrated positive staining for NQO1 in the spindles of mitotic cells. The purpose of this study is to demonstrate for the first time the association of the quinone reductase NQO1 with the mitotic spindle in human cells. PMID:22984577

Siegel, David; Kepa, Jadwiga K; Ross, David

2012-09-11

158

Mitotic centromere-associated kinesin (MCAK): a potential cancer drug target.  

PubMed

The inability to faithfully segregate chromosomes in mitosis results in chromosome instability, a hallmark of solid tumors. Disruption of microtubule dynamics contributes highly to mitotic chromosome instability. The kinesin-13 family is critical in the regulation of microtubule dynamics and the best characterized member of the family, the mitotic centromere-associated kinesin (MCAK), has recently been attracting enormous attention. MCAK regulates microtubule dynamics as a potent depolymerizer of microtubules by removing tubulin subunits from the polymer end. This depolymerizing activity plays pivotal roles in spindle formation, in correcting erroneous attachments of microtubule-kinetochore and in chromosome movement. Thus, the accurate regulation of MCAK is important for ensuring the faithful segregation of chromosomes in mitosis and for safeguarding chromosome stability. In this review we summarize recent data concerning the regulation of MCAK by mitotic kinases, Aurora A/B, Polo-like kinase 1 and cyclin-dependent kinase 1. We propose a molecular model of the regulation of MCAK by these mitotic kinases and relevant phosphatases throughout mitosis. An ever-increasing quantity of data indicates that MCAK is aberrantly regulated in cancer cells. This deregulation is linked to increased malignance, invasiveness, metastasis and drug resistance, most probably due to increased chromosomal instability and remodeling of the microtubule cytoskeleton in cancer cells. Most interestingly, recent observations suggest that MCAK could be a novel molecular target for cancer therapy, as a new cancer antigen or as a mitotic regulator. This collection of new data indicates that MCAK could be a new star in the cancer research sky due to its critical roles in the control of genome stability and the cytoskeleton. Further investigations are required to dissect the fine details of the regulation of MCAK throughout mitosis and its involvements in oncogenesis. PMID:22249213

Sanhaji, Mourad; Friel, Claire T; Wordeman, Linda; Louwen, Frank; Yuan, Juping

2011-12-01

159

The 'Double-Edged Sword' of high-feature products: an explorative study of the business impact  

Microsoft Academic Search

In high-technology consumer markets, manufacturers integrate a growing number of technologies and features to satisfy consumers' preference for high-feature products. At the same time, companies report an increasing number of consumer complaints and even product returns, not due to product faults but to usability problems and the product's inability to meet customer expectations. To investigate the potential business impact of

Jeroen Keijzers; Ouden den PH; Yuan Lu

2008-01-01

160

Dynamics and inherent safety features of small modular high temperature gas-cooled reactors  

SciTech Connect

Investigations were made at Oak Ridge National Laboratory to characterize the dynamics and inherent safety features of various modular high temperature gas-cooled reactor (HTGR) designs. This work was sponsored by the US Nuclear Regulatory Commission's HTGR Safety Research program. The US Department of Energy (DOE) and the Gas Cooled Reactor Associates (GCRA) have sponsored studies of several modular HTGR concepts, each having it own unique advantageous economic and inherent safety features. The DOE design team has recently choses a 350-MW(t) annular core with prismatic, graphite matrix fuel for its reference plant. The various safety features of this plant and of the pebble-bed core designs similar to those currently being developed and operated in the Federal Republic of Germany (FRG) are described. A varity of postulated accident sequences involving combinations of loss of forced circulation of the helium primary coolant, loss of primary coolant pressurization, and loss of normal and backup heat sinks were studied and are discussed. Results demonstrate that each concept can withstand an uncontrolled heatup accident without reaching excessive peak fuel temperatures. Comparisons of calculated and measured response for a loss of forced circulation test on the FRG reactor, AVR, are also presented. 10 refs.

Harrington, R.M.; Ball, S.J.; Cleveland, J.C.

1986-01-01

161

Cyclic development of igneous features and their relationship to high-temperature hydrothermal features in the Henderson porphyry molybdenum deposit, Colorado  

USGS Publications Warehouse

The Henderson porphyry molybdenum deposit was formed by the superposition of coupled alteration and mineralization events, of varying intensity and size, that were associated with each of at least 11 intrusions. Deposition of molybdenite was accompanied by time-equivalent silicic and potassic alteration. High-temperature alteration and mineralization are spatially and temporally linked to the crystallization of compositionally zoned magma in the apex of stocks. Differences in hydrothermal features associated with each intrusion (e.g., mass of ore, orientation and type of veins, density of veins, and intensity of alteration) correlate with differences in primary igneous features (e.g., composition, texture, morphology, and size). The systematic relations between hydrothermal and magmatic features suggest that primary magma compositions, including volatile contents, largely control the geometry, volume, level of emplacement, and mechanisms of crystallization of stocks. These elements in turn govern the orientations and densities of fractures, which ultimately determine the distribution patterns of hydrothermal alteration and mineralization. -from Authors

Carten, R. B.; Geraghty, E. P.; Walker, B. M.

1988-01-01

162

Mitotic spindle assembly by two different pathways in vitro  

PubMed Central

We have used Xenopus egg extracts to study spindle morphogenesis in a cell-free system and have identified two pathways of spindle assembly in vitro using methods of fluorescent analogue cytochemistry. When demembranated sperm nuclei are added to egg extracts arrested in a mitotic state, individual nuclei direct the assembly of polarized microtubule arrays, which we term half-spindles; half-spindles then fuse pairwise to form bipolar spindles. In contrast, when sperm nuclei are added to extracts that are induced to enter interphase and arrested in the following mitosis, a single sperm nucleus can direct the assembly of a complete spindle. We find that microtubule arrays in vitro are strongly biased towards chromatin, but this does not depend on specific kinetochore-microtubule interactions. Indeed, although we have identified morphological and probably functional kinetochores in spindles assembled in vitro, kinetochores appear not to play an obligate role in the establishment of stable, bipolar microtubule arrays in either assembly pathway. Features of the two pathways suggest that spindle assembly involves a hierarchy of selective microtubule stabilization, involving both chromatin-microtubule interactions and antiparallel microtubule-microtubule interactions, and that fundamental molecular interactions are probably the same in both pathways. This in vitro reconstitution system should be useful for identifying the molecules regulating the generation of asymmetric microtubule arrays and for understanding spindle morphogenesis in general.

1991-01-01

163

DESIGN SAFETY FEATURES OF THE BNL HIGH-TEMPERATURE COMBUSTION FACILITY  

SciTech Connect

The Brookhaven National Laboratory (BNL) High-Temperature Combustion Facility (HTCF) was used to perform hydrogen deflagration and detonation experiments at temperatures to 650 K. Safety features that were designed to ensure safe and reliable operation of the experimental program are described. Deflagration and detonation experiments have been conducted using mixtures of hydrogen, air, and steam. Detonation cell size measurements were made as a function of mixture composition and thermodynamic gas conditions. Deflagration-to-detonation transition experiments were also conducted. Results of the experimental program are presented, and implications with respect to hydrogen safety are discussed.

GINSBERG,T.; CICCARELLI,G.; BOCCIO,J.

2000-06-11

164

Topoisomerase II does not play a scaffolding role in the organization of mitotic chromosomes assembled in Xenopus egg extracts  

PubMed Central

We have investigated the role of topoisomerase II (topo II) in mitotic chromosome assembly and organization in vitro using Xenopus egg extracts. When sperm chromatin was incubated with mitotic extracts, the highly compact chromatin rapidly swelled and concomitantly underwent local condensation. Further incubation induced the formation of entangled thin chromatin fibers that eventually resolved into highly condensed individual chromosomes. This in vitro system made it possible to manipulate mitotic chromosomes in their assembly condition without any isolation or stabilization steps. Two complementary approaches, immunodepletion and antibody blocking, demonstrated that topo II activity is required for chromosome assembly and condensation. Once condensation was completed, however, blocking of topo II activity had little effect on the chromosome morphology. Immunofluorescent studies showed that topo II was uniformly distributed throughout the condensed chromosomes and was not restricted to the chromosomal axis. Surprisingly, all detectable topo II molecules were easily extracted from the chromosomes under mild conditions where the shape of chromosomes was well preserved. Our results show that topo II is essential for mitotic chromosome assembly, but does not play a scaffolding role in the structural maintenance of chromosomes assembled in vitro. We also present evidence that changes of DNA topology affect the distribution of topo II in mitotic chromosomes in our system.

1993-01-01

165

Automatic Genre Classification Using Large High-Level Musical Feature Sets  

Microsoft Academic Search

This paper presents a system that extracts 109 musical features from symbolic recordings (MIDI, in this case) and uses them to classify the recordings by genre. The features used here are based on instrumentation, texture, rhythm, dynamics, pitch statistics, melody and chords. The classification is performed hierarchically using different sets of features at different levels of the hierarchy. Which features

Cory Mckay; Ichiro Fujinaga

2004-01-01

166

Cephalalgiaphobia as a feature of high-frequency migraine: a pilot study  

PubMed Central

Background Cephalalgiaphobia is the fear of having a headache attack during a pain-free period that may induce patients to use analgesic in the absence of pain to prevent headache and to improve their performances. This study aims at assessing if cephalalgiaphobia is related to migraine frequency or medication overuse, and if it is per se a predictor of increase in migraine frequency. Methods This is a pilot prospective cohort study on 126 consecutive migraineurs referred to a tertiary Headache Centre. A headache specialist collected data regarding migraine features, frequency and medications at baseline (T0) and 2 years later (T1). Cephalalgiaphobia was investigated at T0 and T1 through a score determined by a 4 items questionnaire. Results Moderate-high migraine frequency was associated with higher risk of cephalalgiaphobia (p?high-frequency migraine feature and may play a role in chronicization. Therefore, it should be better investigated by clinicians and treated or prevented in order to reduce the risk of disability and the increase in migraine frequency.

2013-01-01

167

Improved feature extraction from high-resolution remotely sensed imagery using object geometry  

NASA Astrophysics Data System (ADS)

Information extraction from high spatial resolution imagery is sometimes hampered by the limited number of spectral channels available from these systems. Standard supervised classification algorithms found in commercial software packages may misclassify different features with similar spectral characteristics; leading to a high occurrence of false positives. An additional step in the information extraction process was developed incorporating the concept of object geometry. Objects are defined as a contiguous group of pixels identified as belonging to a single class in the spectral classification. Using results from the spectral classification, a supervised approach was developed using genetic programming to select and mathematically combine feature-specific shape descriptors from a larger set of shape descriptors, to form a new classifier. This investigation focused on extraction of residential housing from QuickBird and IKONOS imagery of the Mississippi Gulf Coast before and immediately after hurricane Katrina. Use of genetic programming significantly reduced false positives caused by asphalt pavement and isolated roofing material scattered throughout the image.

Momm, H. G.; Gunter, Bryan; Easson, Greg

2010-04-01

168

Structural features of the behavior of a high-carbon pearlitic steel upon cyclic loading  

NASA Astrophysics Data System (ADS)

The structural evolution upon high-cycle fatigue (tension with the magnitude of stress in a cycle below the macroscopic yield stress) of the hypereutectoid steel U10 (1.03 wt % C), in which pearlite of different morphology (fine-lamellar, coarse-lamellar, and partially spheroidized pearlite) was formed, has been investigated by scanning and transmission electron microscopy. Based on the fractographic analysis, features of fracture of these structural states have been considered. At a significant distance (10 mm) from the fatigue fracture, features of structural transformations caused by cyclic loading have been revealed. It has been shown that upon high-cycle fatigue in the steel U10 with structures of lamellar and partially spheroidized pearlite, substantial structural changes occur, namely, fragmentation and partial dissolution of cementite plates, and in fine pearlite, additionally, spheroidizing of cementite and polygonization of the ferritic component are observed. A dependence of the character of fracture on the type of structure formed upon fatigue loading has been established. In the steel with a nonequilibrium structure of unannealed fine pearlite, an enhanced elasticity modulus, as compared to other more stable structures (coarse-lamellar, annealed fine, and spheroidized pearlite), and a reduction in the magnitude of the elasticity modulus under the action of cyclic loading have been found. It has been established that the structural changes in fine pearlite of laboratory specimens of the steel U10 upon cyclic tension are qualitatively similar to those in a railroad wheel of the steel 65G under the service conditions.

Makarov, A. V.; Savrai, R. A.; Schastlivtsev, V. M.; Tabatchikova, T. I.; Yakovleva, I. L.; Egorova, L. Yu.

2011-01-01

169

High Order Linguistic Features Such as Ambiguity Processing as Relevant Diagnostic Markers for Schizophrenia  

PubMed Central

Due to the deficits of schizophrenic patients regarding the understanding of vague meanings (D. Ketteler and S. Ketteler (2010)) we develop a special test battery called HOLF (high order linguistic function test), which should be able to detect subtle linguistic performance deficits in schizophrenic patients. HOLF was presented to 40 schizophrenic patients and controls, focussing on linguistic features such as ambiguity, synonymy, hypero-/hyponymy, antinomy, and adages. Using the HOLF test battery we found that schizophrenic patients showed significant difficulties in discriminating ambiguities, hypero- and hyponymy, or synonymy compared to healthy controls. Antonyms and adages showed less significant results in comparing both groups. The more difficult a linguistic task was, the more confusion was measured in the schizophrenic group while healthy controls did not show significant problems in processing high order language tasks.

Ketteler, Daniel; Theodoridou, Anastasia; Ketteler, Simon; Jager, Matthias

2012-01-01

170

High order linguistic features such as ambiguity processing as relevant diagnostic markers for schizophrenia.  

PubMed

Due to the deficits of schizophrenic patients regarding the understanding of vague meanings (D. Ketteler and S. Ketteler (2010)) we develop a special test battery called HOLF (high order linguistic function test), which should be able to detect subtle linguistic performance deficits in schizophrenic patients. HOLF was presented to 40 schizophrenic patients and controls, focussing on linguistic features such as ambiguity, synonymy, hypero-/hyponymy, antinomy, and adages. Using the HOLF test battery we found that schizophrenic patients showed significant difficulties in discriminating ambiguities, hypero- and hyponymy, or synonymy compared to healthy controls. Antonyms and adages showed less significant results in comparing both groups. The more difficult a linguistic task was, the more confusion was measured in the schizophrenic group while healthy controls did not show significant problems in processing high order language tasks. PMID:23304500

Ketteler, Daniel; Theodoridou, Anastasia; Ketteler, Simon; Jäger, Matthias

2012-12-11

171

New fabrication methodology for fine-feature high-aspect-ratio structures made from high-Z materials  

NASA Astrophysics Data System (ADS)

Radiological imagin relies heavily on collimators to achieve diagnostic x-ray images. These collimating structures are required due to the lack of efficient x-ray reflectors or refractors needed to make lenses or mirrors. In order to achieve higher resolution x-ray images, finer collimator geometries are needed. The two critical parameters that define the fineness of a collimator are the length of the collimator structure and the aperture size. Current collimator fabrication technology provides structures with coarse cell sizes, which require long structural lengths, to achieve image optimization. Finer collimator geometries would help reduce the overall length of collimating structures. Tecomet, of Woburn, MA has developed a new technology to fabricate fine-featured, high aspect ratio structures made from high Z materials. These collimating structures have been made from tungsten with aspect ratios above 50:1 and geometry features less than 20 microns. This technology has enabled advancements in the design of x-ray coded apertures. This has opened the door to new ideas for x-ray imaging. Optimization coders, made from tungsten, can now be designed and fabricated to achieve very high angular resolution. Significant reduction in weight is realized due to the reduction in collimator thickness. The collimators made using these fabrication methods also provide greater long-term structural stability compared to collimators used in diagnostic x-ray imaging using lead.

Desai, Upendra D.; Orwig, Larry E.; Clark, David; Appleby, Michael

1999-08-01

172

Imaging protein dynamics in live mitotic cells  

PubMed Central

To ensure that genetic material is accurately segregated during mitosis, eukaryotic cells assemble a mitotic spindle, a dynamic structure composed of microtubules and associated regulatory, structural and motor proteins. Although much has been learned in the past decades from direct observations of live cells expressing fluorescently tagged spindle proteins, a complete understanding of spindle assembly requires a detailed analysis of the dynamic behavior of component parts. Proteins tagged with conventional fluorophores, however, make such an analysis difficult because all of the molecules are uniformly fluorescent. To alleviate this problem, we have tagged proteins with a photoactivatable variant of GFP (PA-GFP), thereby allowing one to follow the behavior of a subset of tagged molecules in the cell. Here, we describe methods to tag and express proteins with PA-GFP, locally photoactivate the recombinant protein and record the dynamic behavior of the photoactivated molecules in live cells. We provide examples of photoactivable proteins in mammalian and yeast cells to illustrate the power of this approach to examine the dynamics of spindle formation and function in diverse cells.

Ferenz, Nick P.; Ma, Nan; Lee, Wei-Lih; Wadsworth, Patricia

2010-01-01

173

Specific Endogenous Mitotic Inhibitors of Human Lymphocyte Transformation.  

National Technical Information Service (NTIS)

On the basis of investigations into the control of epidermal proliferation, and maturation, Bullough and Laurence proposed that epithelial cells make a specific and endogenous mitotic inhibitor ('chalone') which functions to preclude mitosis in the epider...

J. C. Houck H. Iruasquin S. Leikin

1972-01-01

174

TOPK and PTEN participate in CHFR mediated mitotic checkpoint.  

PubMed

Mitotic progression is regulated by co-ordinated action of several proteins and is crucial for the maintenance of genomic stability. CHFR (Check point protein with FHA and RING domains) is an E3 ubiquitin ligase and a checkpoint protein that regulates entry into mitosis. But the molecular players involved in CHFR mediated mitotic checkpoint are not completely understood. In this study, we identified TOPK/PBK, a serine/threonine kinase and PTEN, a lipid phosphatase to play an important role in CHFR mediated mitotic transitions. We demonstrated that CHFR ubiquitinates and regulates TOPK levels, which is essential for its checkpoint function. Moreover, TOPK phosphorylates and inactivates PTEN, which in turn activates Akt that leads to proper G2/M progression. Collectively, our results reveal TOPK and PTEN as new players in CHFR mediated mitotic checkpoint. PMID:24012691

Shinde, Swapnil R; Gangula, Narmadha Reddy; Kavela, Sridhar; Pandey, Vimal; Maddika, Subbareddy

2013-09-03

175

The role of clathrin in mitotic spindle organisation  

PubMed Central

Summary Clathrin, a protein best known for its role in membrane trafficking, has been recognised for many years to localise to the spindle apparatus during mitosis but its function at the spindle remained unclear. Recent work has better defined the role of clathrin in the function of the mitotic spindle and proposed that it crosslinks microtubules (MTs) of the kinetochore fibres (K-fibres) in the mitotic spindle. This mitotic function is unrelated to clathrin’s role in membrane trafficking and occurs in partnership with two other spindle proteins: transforming acidic coiled-coil protein 3 (TACC3) and colonic hepatic tumour overexpressed gene (ch-TOG). This review summarises the role of clathrin in mitotic spindle organisation with an emphasis on the recent discovery of the TACC3/ch-TOG/clathrin complex.

Royle, Stephen J.

2012-01-01

176

Selective detachment of mitotic cells by hypotonic salt solution  

Microsoft Academic Search

Summary  A method has been developed to obtain synchronous populations from a human cell line which previously resisted the use of\\u000a the selective harvest technique. A concentration of Colcemid was determined which reversibly enriched the mitotic population\\u000a but avoided delays in cell cycle progression. Mitotic cells were then detached from monolayer cultures by brief treatment\\u000a with hypotonic salt solutions. The resulting

Edwin V. Gaffney; Edward G. McElwain

1973-01-01

177

Chromosome shattering: a mitotic catastrophe due to chromosome condensation failure  

Microsoft Academic Search

Chromosome shattering has been described as a special form of mitotic catastrophe, which occurs in cells with unrepaired DNA\\u000a damage. The shattered chromosome phenotype was detected after application of a methanol\\/acetic acid (MAA) fixation protocol\\u000a routinely used for the preparation of metaphase spreads. The corresponding phenotype in the living cell and the mechanism\\u000a leading to this mitotic catastrophe have remained

B. Hübner; H. Strickfaden; S. Müller; M. Cremer; T. Cremer

2009-01-01

178

Loss of heterozygosity and mitotic linkage maps in the mouse.  

PubMed Central

Loss of heterozygosity is a significant oncogenetic mechanism and can involve a variety of mechanisms including chromosome loss, deletion, and homologous interchromosomal mitotic recombination. Analysis of H-2 antigen-loss variants from heterozygous murine cell lines provides an experimental system to estimate the relative contributions of different mechanisms for allele loss and to compare the chromosomal patterns of mitotic and meiotic recombination. Cytotoxic anti-H-2D antibodies and complement were used to isolate 161 independent target antigen-negative clones from H-2d/H-2b heterozygous cell lines; of these, 131 (84.5%) lost the allele encoding the target antigen. Allele-loss variants were typed and scored as either heterozygous or homozygous for six H-2D-proximal chromosome 17 markers and for one distal marker by restriction enzyme-site variations and Southern analysis. A single mitotic crossover could account for 50 clones (37%), with heterozygosity for at least one proximal marker and loss of heterozygosity for all markers distal to the putative recombination site. Eighty-two allele-loss variants (60%) were homozygous for all markers; the origin of these clones could be either chromosome loss or mitotic recombination between the centromere and the most proximal marker. Only 4 clones (3%) arose through more complex events such as multiple crossovers or deletion. A mitotic linkage map for mouse chromosome 17 was constructed, and the gene order deduced from somatic recombination was identical to that obtained by conventional transmission genetics. These results demonstrate that mitotic recombination is a common event leading to allele loss, in spite of the lack of evidence for frequent somatic pairing of homologous chromosomes. Mitotic mapping provides a defined system for comparison of mitotic and meiotic recombination and may lead to practical advances for elucidating somatic mechanisms of oncogenesis and for gene therapy in targeting mutations to specific sites through homologous recombination. Images

Henson, V; Palmer, L; Banks, S; Nadeau, J H; Carlson, G A

1991-01-01

179

Subcellular redistribution and mitotic inheritance of transition metals in proliferating mouse fibroblast cells.  

PubMed

Synchrotron X-ray fluorescence microscopy of non-synchronized NIH 3T3 fibroblasts revealed an intriguing redistribution dynamics that defines the inheritance of trace metals during mitosis. At metaphase, the highest density areas of Zn and Cu are localized in two distinct regions adjacent to the metaphase plate. As the sister chromatids are pulled towards the spindle poles during anaphase, Zn and Cu gradually move to the center and partition into the daughter cells to yield a pair of twin pools during cytokinesis. Colocalization analyses demonstrated high spatial correlations between Zn, Cu, and S throughout all mitotic stages, while Fe showed consistently different topographies characterized by high-density spots distributed across the entire cell. Whereas the total amount of Cu remained similar compared to interphase cells, mitotic Zn levels increased almost 3-fold, suggesting a prominent physiological role that lies beyond the requirement of Zn as a cofactor in metalloproteins or messenger in signaling pathways. PMID:23212029

McRae, Reagan; Lai, Barry; Fahrni, Christoph J

2013-01-01

180

A Mitotic GlcNAcylation/Phosphorylation Signaling Complex Alters the Posttranslational State of the Cytoskeletal Protein Vimentin  

PubMed Central

O-linked ?-N-acetylglucosamine (O-GlcNAc) is a highly dynamic intracellular protein modification responsive to stress, hormones, nutrients, and cell cycle stage. Alterations in O-GlcNAc addition or removal (cycling) impair cell cycle progression and cytokinesis, but the mechanisms are not well understood. Here, we demonstrate that the enzymes responsible for O-GlcNAc cycling, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) are in a transient complex at M phase with the mitotic kinase Aurora B and protein phosphatase 1. OGT colocalized to the midbody during telophase with Aurora B. Furthermore, these proteins coprecipitated with each other in a late mitotic extract. The complex was stable under Aurora inhibition; however, the total cellular levels of O-GlcNAc were increased and the localization of OGT was decreased at the midbody after Aurora inhibition. Vimentin, an intermediate filament protein, is an M phase substrate for both Aurora B and OGT. Overexpression of OGT or OGA led to defects in mitotic phosphorylation on multiple sites, whereas OGT overexpression increased mitotic GlcNAcylation of vimentin. OGA inhibition caused a decrease in vimentin late mitotic phosphorylation but increased GlcNAcylation. Together, these data demonstrate that the O-GlcNAc cycling enzymes associate with kinases and phosphatases at M phase to regulate the posttranslational status of vimentin.

Slawson, Chad; Lakshmanan, T.; Knapp, Spencer

2008-01-01

181

Timeless links replication termination to mitotic kinase activation.  

PubMed

The mechanisms that coordinate the termination of DNA replication with progression through mitosis are not completely understood. The human Timeless protein (Tim) associates with S phase replication checkpoint proteins Claspin and Tipin, and plays an important role in maintaining replication fork stability at physical barriers, like centromeres, telomeres and ribosomal DNA repeats, as well as at termination sites. We show here that human Tim can be isolated in a complex with mitotic entry kinases CDK1, Auroras A and B, and Polo-like kinase (Plk1). Plk1 bound Tim directly and colocalized with Tim at a subset of mitotic structures in M phase. Tim depletion caused multiple mitotic defects, including the loss of sister-chromatid cohesion, loss of mitotic spindle architecture, and a failure to exit mitosis. Tim depletion caused a delay in mitotic kinase activity in vivo and in vitro, as well as a reduction in global histone H3 S10 phosphorylation during G2/M phase. Tim was also required for the recruitment of Plk1 to centromeric DNA and formation of catenated DNA structures at human centromere alpha satellite repeats. Taken together, these findings suggest that Tim coordinates mitotic kinase activation with termination of DNA replication. PMID:21573113

Dheekollu, Jayaraju; Wiedmer, Andreas; Hayden, James; Speicher, David; Gotter, Anthony L; Yen, Tim; Lieberman, Paul M

2011-05-06

182

Qualitative Features of Cyclones triggering high precipitation events in the Island of Crete, Eastern Mediterranean.  

NASA Astrophysics Data System (ADS)

There are many cases where high precipitation or even worse flood events are provoked by cyclonic atmospheric circulation patterns of similar characteristics. In this study, an attempt was made to investigate the features of the cyclones related to these high precipitation events as well as possible correlation of the precipitation characteristics to these cyclones. A statistical analysis of the features of cyclones affecting Crete was performed over a 30-year period (1979-2011). The cyclones identification and characteristics were extracted with the aid of the Melbourne University automatic cyclone finding and tracking scheme (CTS) based on ERA Interim reanalysis datasets. A number of high precipitation events were defined with a threshold criterion based on a dataset of 53 daily precipitation records over the Island of Crete. Track selection was performed using as second criterion the cyclone distance from the study area. The track points of cyclones affecting Crete found to be related to specific rain events where further analyzed in terms of origination, direction and position. Average values of characteristics were also estimated such as the radius, pressure, depth and East/North velocity for the cyclones affecting Crete. The analysis was also extended concerning seasonality (winter, spring, autumn) and locality (eastern, central or western part of the study site) of the events. In all cases cyclones affecting Crete seem to originate mostly Northwest (~55%) and Southwest (~15%) of Crete having a Southeast (~55%) and Northeast (~15%) direction, correspondingly. Also for the majority of the events (>65%) cyclones are mainly attributed to the characteristics of a strong closed system of relatively long duration and track length.

Iordanidou, Vasiliki; Koutroulis, Aristeidis; Tsanis, Ioannis; Flocas, Helena

2013-04-01

183

Scanning electron microscopy imaging of ultra-high aspect ratio hole features  

NASA Astrophysics Data System (ADS)

In-line, non-destructive process control metrology of high aspect ratio (HAR) holes and trenches has long been a known gap in metrology. Imaging the bottoms of at-node size contact holes in oxide with aspect rations beyond 10:1 has not yet been demonstrated. Nevertheless, holes and trenches of 30:1, 40:1, or even 60:1 will soon enter production, with these etches being applied to various homogeneous and multi-layer stacks of Si and SiO2. The need comes from Moore's Law and increasing functional density on microchips, on which true 3D memory devices will soon be manufactured. These can take many different forms, but a common building block will be these ultra-HAR etched features. In this work, we show experimental results and simulations from the NIST JMONSEL program to assess the feasibility of measuring such features using both conventional low voltage scanning electron microscopy (SEM) and higher beam energies and low vacuum conditions to ameliorate charging. In our measurements, higher voltage SEM did not improve upon conventional critical dimension (CD)-SEM. Simulations suggest the reason is a failure to overcome a negative oxide potential. Although a signal can in principle be detected from the bottom of contact holes in typical imaging conditions in the CD-SEM, it is likely that it will be very small and possibly below the noise floor.

Cepler, Aron J.; Bunday, Benjamin; Thiel, Bradley L.; Villarrubia, John S.

2012-03-01

184

The Potential of GLAST in Observing Features in the High-Energy Spectra of GRBs  

NASA Astrophysics Data System (ADS)

GLAST is a gamma-ray mission which will be launched in November 2007. It is equipped with the GLAST Burst Monitor (GBM) which detects Gamma-Ray Bursts (GRBs) with high reliability and provides a position and energy spectrum in the range between 10 keV and 30 MeV. The Large Area Telescope (LAT) will observe photons with energies from 20 MeV up to more than 300 GeV. With GLAST it will be possible to study the spectra of GRBs over 7 orders of magnitude in energy and for the first time in the energy band above several tens of GeV. From the high-energy part of GRB spectra new insights into the bursts physics can be expected. Emission due to Inverse Compton scattering of electrons or due to interactions of hadrons would point to particles accelerated in the jets of the GRBs. A cut-off of the spectrum would allow to study internal absorption of gamma-rays in the burst and external attenuation in interaction with the EBL. We will present the study of simulated GRBs with respect to features in the high-energy spectrum. We will discuss the performance of GLAST of detecting cut-offs and additional high-energy emission.

Komin, Nu.; Piron, F.; Pelassa, V.

185

Leakage Reduction Effect by Multiple Cracking Feature of High Performance Fiber Reinforced Cement Composite  

NASA Astrophysics Data System (ADS)

In a kind of concrete canal, repair materials are applied for recovery of the deteriorated functions. However, due to the re-cracking of the repair material caused by the fluctuations of the crack width, there is a great possibility that the functional deterioration reoccurs after the repair. In this research, High Performance Fiber Reinforced Cement Composite (HPFRCC), which has multiple cracking feature, was evaluated as a repair material to prevent the functional deterioration after the repair. HPFRCC and mortar specimens were cracked and examined by permeability test. As a result, it was clarified that the leakage from the HPFRCC specimen was very little compared with the leakage from the mortar specimen. Moreover, it was confirmed that the leakage from the narrow cracks were gradually decreased.

Ueno, Kazuhiro; Natsuka, Isamu; Ishii, Masayuki

186

Civilian ship classification based on structure features in high resolution SAR images  

NASA Astrophysics Data System (ADS)

With the globalization there is an increasing degree of concern on the ship traffic monitoring. Civilian ship classification is an important research area, as it can help to improve sea traffic surveillance and control activities. By making use of the new generation SAR satellites like COSMO-SkyMed, civilian ship classification in high resolution SAR images is a hotspot and preceding problem in SAR applications. This paper presents a ship classification method that uses single-pol COSMO-SkyMed images to categorize civilian ships into three types, including bulk carriers, container ships and oil tankers. The experimental results based on ship structure features show that the whole classification accuracy is above 80%.

Jiang, Shaofeng; Wang, Chao; Zhang, Hong; Wu, Fan; Zhang, Bo

2012-10-01

187

Design features of a high-intensity, cesium-sputter/plasma-sputter negative ion source  

SciTech Connect

A versatile, high-intensity, negative ion source has been designed and is now under construction which can be operated in either the cesium-sputter or plasma-sputter mode. The cesium-sputter mode can be effected by installation of a newly designed conical-geometry cesium-surface ionizer; for operation in the plasma-sputter mode, the surface ionizer is removed and either a hot-filament or RIF antenna plasma-discharge igniter is installed. A multicusp magnetic field is specifically provided confining the plasma in the radial direction when the plasma-sputter mode is selected. This arrangement allows comparison of the two modes of operation. Brief descriptions of the design features, ion optics, and anticipated performances of the two source geometries will be presented in this report.

Alton, G.D.; Mills, G.D. [Oak Ridge National Lab., TN (United States); Dellwo, J. [ORNL and Joint Institute for Heavy Ion Research, Oak Ridge, TN (United States)

1993-12-31

188

MULTIPLE HIGH-VELOCITY SiO MASER FEATURES FROM THE HIGH-MASS PROTOSTAR W51 NORTH  

SciTech Connect

We present the detection of multiple high-velocity silicon monoxide (SiO v = 1, 2, J = 1-0) maser features in the high-mass protostar W51 North which are distributed over an exceedingly large velocity range from 105 to 230 km s{sup -1}. The SiO v = 1, J = 1-0 maser emission shows 3-5 narrow components which span a velocity range from 154 to 230 km s{sup -1} according to observational epochs. The SiO v = 2, J = 1-0 maser also shows 3-5 narrow components that do not correspond to the SiO v = 1 maser and span a velocity range from 105 to 154 km s{sup -1}. The multiple maser components show significant changes on very short timescales (<1 month) from epoch to epoch. We suggest that the high-velocity SiO masers may be emanated from massive star-forming activity of the W51 North protostar as SiO maser jets and will be a good probe of the earliest evolutionary stages of high-mass star formation via an accretion model. Further high angular resolution observations will be required for confirmation.

Cho, Se-Hyung; Kim, Jaeheon; Byun, Do-Young, E-mail: cho@kasi.re.kr, E-mail: jhkim@kasi.re.kr, E-mail: bdy@kasi.re.kr [Korean VLBI Network, Korea Astronomy and Space Science Institute, P. O. Box 88, Yonsei University, Seongsan-ro 262, Seodaemun, Seoul 120-749 (Korea, Republic of)

2011-02-01

189

The Impact of Mitotic versus Interphase Chromatin Architecture on the Molecular Flow of EGFP by Pair Correlation Analysis  

PubMed Central

Here we address the impact nuclear architecture has on molecular flow within the mitotic nucleus of live cells as compared to interphase by the pair correlation function method. The mitotic chromatin is found to allow delayed but continuous molecular flow of EGFP in and out of a high chromatin density region, which, by pair correlation function analysis, is shown as a characteristic arc shape that appears upon entry and exit. This is in contrast to interphase chromatin, which regulates flow between different density chromatin regions by means of a mechanism which turns on and off intermittently, generating discrete bursts of EGFP. We show that the interphase bursts are maintained by metabolic energy, whereas the mitotic mechanism of regulation responsible for the arc is not sensitive to ATP depletion. These two distinct routes of molecular flow were concomitantly measured in the Caenorhabditis elegans germ line, which indicates a conservation of mechanism on a scale more widespread than cell type or organism.

Hinde, Elizabeth; Cardarelli, Francesco; Digman, Michelle A.; Kershner, Aaron; Kimble, Judith; Gratton, Enrico

2011-01-01

190

Aurora A kinase regulates mammary epithelial cell fate by determining mitotic spindle orientation in a Notch-dependent manner.  

PubMed

Cell fate determination in the progeny of mammary epithelial stem/progenitor cells remains poorly understood. Here, we have examined the role of the mitotic kinase Aurora A (AURKA) in regulating the balance between basal and luminal mammary lineages. We find that AURKA is highly expressed in basal stem cells and, to a lesser extent, in luminal progenitors. Wild-type AURKA expression promoted luminal cell fate, but expression of an S155R mutant reduced proliferation, promoted basal fate, and inhibited serial transplantation. The mechanism involved regulation of mitotic spindle orientation by AURKA and the positioning of daughter cells after division. Remarkably, this was NOTCH dependent, as NOTCH inhibitor blocked the effect of wild-type AURKA expression on spindle orientation and instead mimicked the effect of the S155R mutant. These findings directly link AURKA, NOTCH signaling, and mitotic spindle orientation and suggest a mechanism for regulating the balance between luminal and basal lineages in the mammary gland. PMID:23810554

Regan, Joseph L; Sourisseau, Tony; Soady, Kelly; Kendrick, Howard; McCarthy, Afshan; Tang, Chan; Brennan, Keith; Linardopoulos, Spiros; White, Donald E; Smalley, Matthew J

2013-06-27

191

Design features and performance of the LAMPF high-intensity beam area  

SciTech Connect

LAMPF is a multi-purpose high-intensity meson factory capable of producing a 1 mA beam of 800-MeV protons. The three target cells and the beam stop facilities in the high intensity area have many special design features that are required for operation in the presence of high heat loads and intense radiation fields where accessibility is extremely limited. Reliable targets, beam windows, beam stops, beam transport and diagnostic components, vacuum enclosures, and auxiliary systems have been developed. Sophisticated remote-handling systems are employed for maintenance. Complex protection systems have been developed to guard against damage caused by errant beam. Beam availability approaching 90% has been achieved at currents of 600 to 700 ..mu..A. A new facility for direct proton and neutron radiation effects studies will be installed in 1985. The new facility will provide an integrated spallation neutron flux of up to 5 x 10/sup 17/ m/sup -2/s/sup -1/ and will anable proton irradiation studies in the primary beam.

Agnew, L.; Grisham, D.; Macek, R.J.; Sommer, W.F.; Werbeck, R.D.

1983-01-01

192

High resolution (SE-I) scanning electron microscopy features of primate cerebellar cortex.  

PubMed

This paper provides an exploration into the outer and inner surfaces of primate cerebellar neurons using secondary electron-I (SE-I) topographic contrast. SE-I enriched, chromium coated, cryofractured cerebellum staged within the condenser/objective lens stage of SEMs, equipped with high brightness LaB6 and field emission emitter, generated quality images of intact and fractured nerve cells studied at intermediate and high magnifications. Granule and Golgi cell surfaces revealed smooth, accurately delineated profiles of the true cell surface features, which lacked the SE-III dominated brilliance of conventional gold or gold-palladium decorated images. Fractured non synaptic segments of parallel fibers in the molecular layer showed interconnected anastomotic networks of ER tubules, vesicles and cisterns, whereas cross fractured presynaptic "en passant" endings of these fibers exhibited spheroidal synaptic vesicles and SE-I edge brightness contrast delineated their limiting plasma membranes. Parallel fiber fractured synaptic endings showed a homogeneous extravesicular material surrounding the synaptic vesicles. The neuroglial cytoplasm ensheathing nerve processes exhibited a smooth discontinuous surface. The high mass density surface of the myelin sheath showed a mixed population of globular structures, 10-30 nm, corresponding to protein and phospholipid microdomains. PMID:7873989

Castejón, O J; Castejón, H V; Apkarian, R P

1994-12-01

193

Automated feature detection and imaging for high-resolution screening of zebrafish embryos.  

PubMed

The development of automated microscopy platforms has enabled large-scale observation of biological processes, thereby complementing genome scale biochemical techniques. However, commercially available systems are restricted either by fixed-field-of-views, leading to potential omission of features of interest, or by low-resolution data of whole objects lacking cellular detail. This limits the efficiency of high-content screening assays, especially when large complex objects are used as in whole-organism screening. Here we demonstrate a toolset for automated intelligent high-content screening of whole zebrafish embryos at cellular resolution on a standard wide-field screening microscope. Using custom-developed algorithms, predefined regions of interest-such as the brain-are automatically detected. The regions of interest are subsequently imaged automatically at high magnification, enabling rapid capture of cellular resolution data. We utilize this approach for acquiring 3-D datasets of embryonic brains of transgenic zebrafish. Moreover, we report the development of a mold design for accurate orientation of zebrafish embryos for dorsal imaging, thereby facilitating standardized imaging of internal organs and cellular structures. The toolset is flexible and can be readily applied for the imaging of different specimens in various applications. PMID:21548893

Peravali, Ravindra; Gehrig, Jochen; Giselbrecht, Stefan; Lütjohann, Dominic S; Hadzhiev, Yavor; Müller, Ferenc; Liebel, Urban

2011-05-01

194

Feasibility of Using Optical Power Spectrum Analysis Techniques for Automatic Feature Classification from High Resolution Thermal, Radar, and Panchromatic Imagery.  

National Technical Information Service (NTIS)

The objective of this study was to determine experimentally the feasibility of using optical power spectrum analysis techniques for automatic topographic feature classification from high resolution radar, panchromatic and thermal imagery. A data base of r...

H. L. Kasdan

1979-01-01

195

Morphological features of Triassic and Late Cretaceous high-latitude radiolarian assemblages (comparative analysis)  

NASA Astrophysics Data System (ADS)

High-latitude radiolarian assemblages of Mesozoic represent particular interest for Boreal-Tethyan correlation of Mesozoic as well as for their paleobiogeography. Radiolarians are the only planktonic protists that present both in low- and high-latitude Mesozoic sections, therefore they have high importance. The aim of this work is to distinguish common and different features of Triassic and Late Cretaceous high-latitude assemblages of Radiolaria during their comparative analysis. We use material from Triassic of Omolon Massif (NE Siberia) (Bragin, Egorov, 2001) and Kotel'nyi Island (Arctic) (Bragin, Bragina, 2009; Bragin, in press) and Late Cretaceous of Western Siberia (Amon, 2000) and Kamchatka Peninsula (Vishnevskaya, 2005; Bragina, 1991). The main trends of radiolarian assemblages from these sections are: quantitative domination of some taxa, presence of characteristic high-latitude taxa that are absent or very rare in low-latitude regions, and relatively low taxonomic diversity with absence of many high taxa and many morphotypes. We made following conclusions after comparative analysis: 1. Triassic assemblages are dominated by morphotypes with bipolar main spines (Pseudostylosphaera and similar forms), and by pylomate forms (Glomeropyle). Genus Glomeropyle has bipolar distribution pattern and it is typically high-latitude taxon. Late Cretaceous assemblages are dominated by forms with bipolar three-bladed main spines (Amphisphaera, Protoxiphotractus, Stylosphaera), by prunoid morphotypes (Amphibrachium, Prunobrachium), discoid spongy forms (Orbiculiforma, Spongodiscus) by three-rayed (Paronaella, Spongotripus), four-rayed (Crucella, Histiastrum) and multirayed stauraxon forms (Pentinastrum, Multastrum). Pylomate forms (Spongopyle) are present in the Late Cretaceous high-latitude assemblages but not so common. 2. Spherical forms with spines that possess apophyses (Kahlerosphaera, Dumitricasphaera) are common for Triassic high-latitude areas, but not present in the Cretaceous assemblages. Spherical forms with hollow, commonly twisted spines (Capnuchosphaera) and with two-bladed spines (Zhamojdasphaera) are present only in the Triassic assemblages. 3. Saturnalids are present both in Triassic and Late Cretaceous high-latitude assemblages but not common. 4. Stauraxon three-rayed forms (like Paronaella) are very rare in the Triassic high-latitude assemblages but very common in the Late Cretaceous ones. Some Late Cretaceous morphotypes of this type have bipolar distribution pattern (Spongotripus). 5. Discoidal forms in the Triassic high-latitude assemblages are represented by Tetraspongodiscus - small forms with 4 radial spines. Cretaceous discoids are highly more diverse and are represented by numerous taxa with variable morphology. 6. Multicyrtoid nassellarians with longitudinal ridges are very rare in the Triassic (Whalenella), but very common in the Late Cretaceous (Pseudodictyomitra, Dictyomitra). Multicyrtoid Stichomitra-type specimens are present both in the Triassic and Cretaceous assemblages. 7. Hat-shaped and highly ornamented Nassellaria are almost absent in the high-latitude Triassic and Late Cretaceous assemblages. 8. During long evolutionary history of Radiolaria typically boreal forms strongly differ, and only morphotypes with bipolar main spines and pylomate forms retain their significance as high-latitude indicators.

Bragin, Nikita; Bragina, Liubov

2010-05-01

196

Mutagenic analysis of the destruction signal of mitotic cyclins and structural characterization of ubiquitinated intermediates.  

PubMed Central

Mitotic cyclins are abruptly degraded at the end of mitosis by a cell-cycle-regulated ubiquitin-dependent proteolytic system. To understand how cyclin is recognized for ubiquitin conjugation, we have performed a mutagenic analysis of the destruction signal of mitotic cyclins. We demonstrate that an N-terminal cyclin B segment as short as 27 residues, containing the 9-amino-acid destruction box, is sufficient to destabilize a heterologous protein in mitotic Xenopus extracts. Each of the three highly conserved residues of the cyclin B destruction box is essential for ubiquitination and subsequent degradation. Although an intact destruction box is essential for the degradation of both A- and B-type cyclins, we find that the Xenopus cyclin A1 destruction box cannot functionally substitute for its B-type counterpart, because it does not contain the highly conserved asparagine necessary for cyclin B proteolysis. Physical analysis of ubiquitinated cyclin B intermediates demonstrates that multiple lysine residues function as ubiquitin acceptor sites, and mutagenic studies indicate that no single lysine residue is essential for cyclin B degradation. This study defines the key residues of the destruction box that target cyclin for ubiquitination and suggests there are important differences in the way in which A- and B-type cyclins are recognized by the cyclin ubiquitination machinery. Images

King, R W; Glotzer, M; Kirschner, M W

1996-01-01

197

A phospho/methyl switch at histone H3 regulates TFIID association with mitotic chromosomes  

PubMed Central

Histone methylation patterns are correlated with eukaryotic gene transcription. High-affinity binding of the plant homeodomain (PHD) of TFIID subunit TAF3 to trimethylated lysine-4 of histone H3 (H3K4me3) is involved in promoter recruitment of this basal transcription factor. Here, we show that for transcription activation the PHD of TAF3 can be replaced by PHDs of other high-affinity H3K4me3 binders. Interestingly, H3K4me3 binding of TFIID and the TAF3-PHD is decreased by phosphorylation of the adjacent threonine residue (H3T3), which coincides with mitotic inhibition of transcription. Ectopic expression of the H3T3 kinase haspin repressed TAF3-mediated transcription of endogenous and of reporter genes and decreased TFIID association with chromatin. Conversely, immunofluorescence and live-cell microscopy studies showed an increased association of TFIID with mitotic chromosomes upon haspin knockdown. Based on our observations, we propose that a histone H3 phospho–methyl switch regulates TFIID-mediated transcription during mitotic progression of the cell cycle.

Varier, Radhika A; Outchkourov, Nikolay S; de Graaf, Petra; van Schaik, Frederik M A; Ensing, Henk Jan L; Wang, Fangwei; Higgins, Jonathan M G; Kops, Geert J P L; Timmers, HTh Marc

2010-01-01

198

Detailed Hydrographic Feature Extraction from High-Resolution LiDAR Data  

SciTech Connect

Detailed hydrographic feature extraction from high-resolution light detection and ranging (LiDAR) data is investigated. Methods for quantitatively evaluating and comparing such extractions are presented, including the use of sinuosity and longitudinal root-mean-square-error (LRMSE). These metrics are then used to quantitatively compare stream networks in two studies. The first study examines the effect of raster cell size on watershed boundaries and stream networks delineated from LiDAR-derived digital elevation models (DEMs). The study confirmed that, with the greatly increased resolution of LiDAR data, smaller cell sizes generally yielded better stream network delineations, based on sinuosity and LRMSE. The second study demonstrates a new method of delineating a stream directly from LiDAR point clouds, without the intermediate step of deriving a DEM. Direct use of LiDAR point clouds could improve efficiency and accuracy of hydrographic feature extractions. The direct delineation method developed herein and termed “mDn”, is an extension of the D8 method that has been used for several decades with gridded raster data. The method divides the region around a starting point into sectors, using the LiDAR data points within each sector to determine an average slope, and selecting the sector with the greatest downward slope to determine the direction of flow. An mDn delineation was compared with a traditional grid-based delineation, using TauDEM, and other readily available, common stream data sets. Although, the TauDEM delineation yielded a sinuosity that more closely matches the reference, the mDn delineation yielded a sinuosity that was higher than either the TauDEM method or the existing published stream delineations. Furthermore, stream delineation using the mDn method yielded the smallest LRMSE.

Danny L. Anderson

2012-05-01

199

Retrieval Using Texture Features in High Resolution Multi-spectral Satellite Imagery  

SciTech Connect

Texture features have long been used in remote sensing applications to represent and retrieve image regions similar to a query region. Various representations of texture have been proposed based on the Fourier power spectrum, spatial co-occurrence, wavelets, Gabor filters, etc. These representations vary in their computational complexity and their suitability for representing different region types. Much of the work done thus far has focused on panchromatic imagery at low to moderate spatial resolutions, such as images from Landsat 1-7 which have a resolution of 15-30 m/pixel, and from SPOT 1-5 which have a resolution of 2.5-20 m/pixel. However, it is not clear which texture representation works best for the new classes of high resolution panchromatic (60-100 cm/pixel) and multi-spectral (4 bands for red, green, blue, and near infra-red at 2.4-4 m/pixel) imagery. It is also not clear how the different spectral bands should be combined. In this paper, we investigate the retrieval performance of several different texture representations using multi-spectral satellite images from IKONOS. A query-by-example framework, along with a manually chosen ground truth dataset, allows different combinations of texture representations and spectral bands to be compared. We focus on the specific problem of retrieving inhabited regions from images of urban and rural scenes. Preliminary results show that (1) the use of all spectral bands improves the retrieval performance, and (2) co-occurrence, wavelet and Gabor texture features perform comparably.

Newsam, S D; Kamath, C

2004-01-22

200

High surface porosity as the origin of emissivity features in asteroid spectra  

NASA Astrophysics Data System (ADS)

Emission features in the mid-IR domain (7-25 ?m) are quite ubiquitous among large asteroids and therefore offer the potential to uncover their surface composition. However, when comparing these spectra with the actual laboratory spectra of both minerals and meteorites, they do not necessarily match. Here, and in a companion paper by King et al. (in preparation, 2012), we show that by modifying the sample preparation - typically by suspending meteorite and/or mineral powder (<30 ?m) in IR-transparent KBr (potassium bromide) powder - we are able to reproduce the spectral behavior of those main-belt asteroids with emissivity features. This resulting good match between KBr-diluted meteorite spectra and asteroid spectra suggests an important surface porosity (>90%) for the first millimeter for our asteroid sample. It therefore appears that mid-IR emission spectra of asteroids do not only carry information about their surface composition but they can also help us constraining their surface structure (under-dense versus compact surface structure), as suggested by Emery et al. (Emery, J.P., Cruikshank, D.P., van Cleve, J. [2006]. Icarus 182, 496-512) in the case of the Jupiter Trojans. The large surface porosity inferred from the mid-IR spectra of certain asteroids is also implied by two other independent measurements, namely their thermal inertia and their radar albedo. We further clarified how much compositional information can be retrieved from the mid-IR range by focusing our analysis on a single object, 624 Hektor. We showed that the mid-IR range provides critical constraints (i) on its origin and of that of the red Trojans that we locate in the formation regions of the comets, and (ii) on the primordial composition of the dust present in the outer region (>10 AU) of the Solar System's protoplanetary disk. Future investigations should focus on finding the mechanism responsible for creating such high surface porosity.

Vernazza, P.; Delbo, M.; King, P. L.; Izawa, M. R. M.; Olofsson, J.; Lamy, P.; Cipriani, F.; Binzel, R. P.; Marchis, F.; Merín, B.; Tamanai, A.

2012-11-01

201

High altitude pulmonary edema-clinical features, pathophysiology, prevention and treatment.  

PubMed

High altitude pulmonary edema (HAPE) is a noncardiogenic pulmonary edema which typically occurs in lowlanders who ascend rapidly to altitudes greater than 2500-3000 m. Early symptoms of HAPE include a nonproductive cough, dyspnoea on exertion and reduced exercise performance. Later, dyspnoea occurs at rest. Clinical features are cyanosis, tachycardia, tachypnoea and elevated body temperature generally not exceeding 38.5°C. Rales are discrete initially and located over the middle lung fields. HAPE mainly occurs due to exaggerated hypoxic pulmonary vasoconstriction and elevated pulmonary artery pressure. It has been observed that HAPE is a high permeability type of edema occurring also due to leaks in the capillary wall ('stress failure'). Slow descent is the most effective method for prevention; in addition, graded ascent and time for acclimatization, low sleeping altitudes, avoidance of alcohol and sleeping pills, and avoidance of exercise are the key to preventing HAPE. Treatment of HAPE consists of immediate improvement of oxygenation either by supplemental oxygen, hyperbaric treatment, or by rapid descent. PMID:23580834

Paralikar, Swapnil J

2012-05-01

202

Molecular origin of mitotic aneuploidies in preimplantation embryos.  

PubMed

Mitotic errors are common in human preimplantation embryos. The occurrence of mitotic errors is highest during the first three cleavages after fertilization and as a result about three quarters of human preimplantation embryos show aneuploidies and are chromosomally mosaic at day three of development. The origin of these preimplantation mitotic aneuploidies and the molecular mechanisms involved are being discussed in this review. At later developmental stages the mitotic aneuploidy rate is lower. Mechanisms such as cell arrest, apoptosis, active correction of the aneuploidies and preferential allocation of the aneuploid cells to the extra-embryonic tissues could underlie this lower rate. Understanding the mechanisms that cause mitotic aneuploidies in human preimplantation embryos and the way human preimplantation embryos deal with these aneuploidies might lead to ways to limit the occurrence of aneuploidies, in order to ultimately increase the quality of embryos and with that the likelihood of a successful pregnancy in IVF/ICSI. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure. PMID:22771499

Mantikou, Eleni; Wong, Kai Mee; Repping, Sjoerd; Mastenbroek, Sebastiaan

2012-07-03

203

Robust mitotic entry is ensured by a latching switch.  

PubMed

Cell cycle events are driven by Cyclin dependent kinases (CDKs) and by their counter-acting phosphatases. Activation of the Cdk1:Cyclin B complex during mitotic entry is controlled by the Wee1/Myt1 inhibitory kinases and by Cdc25 activatory phosphatase, which are themselves regulated by Cdk1:Cyclin B within two positive circuits. Impairing these two feedbacks with chemical inhibitors induces a transient entry into M phase referred to as mitotic collapse. The pathology of mitotic collapse reveals that the positive circuits play a significant role in maintaining the M phase state. To better understand the function of these feedback loops during G2/M transition, we propose a simple model for mitotic entry in mammalian cells including spatial control over Greatwall kinase phosphorylation. After parameter calibration, the model is able to recapture the complex and non-intuitive molecular dynamics reported by Potapova et al. (Potapova et al., 2011). Moreover, it predicts the temporal patterns of other mitotic regulators which have not yet been experimentally tested and suggests a general design principle of cell cycle control: latching switches buffer the cellular stresses which accompany cell cycle processes to ensure that the transitions are smooth and robust. PMID:24143279

Tuck, Chloe; Zhang, Tongli; Potapova, Tamara; Malumbres, Marcos; Novák, Béla

2013-07-26

204

Robust mitotic entry is ensured by a latching switch  

PubMed Central

Summary Cell cycle events are driven by Cyclin dependent kinases (CDKs) and by their counter-acting phosphatases. Activation of the Cdk1:Cyclin B complex during mitotic entry is controlled by the Wee1/Myt1 inhibitory kinases and by Cdc25 activatory phosphatase, which are themselves regulated by Cdk1:Cyclin B within two positive circuits. Impairing these two feedbacks with chemical inhibitors induces a transient entry into M phase referred to as mitotic collapse. The pathology of mitotic collapse reveals that the positive circuits play a significant role in maintaining the M phase state. To better understand the function of these feedback loops during G2/M transition, we propose a simple model for mitotic entry in mammalian cells including spatial control over Greatwall kinase phosphorylation. After parameter calibration, the model is able to recapture the complex and non-intuitive molecular dynamics reported by Potapova et al. (Potapova et al., 2011). Moreover, it predicts the temporal patterns of other mitotic regulators which have not yet been experimentally tested and suggests a general design principle of cell cycle control: latching switches buffer the cellular stresses which accompany cell cycle processes to ensure that the transitions are smooth and robust.

Tuck, Chloe; Zhang, Tongli; Potapova, Tamara; Malumbres, Marcos; Novak, Bela

2013-01-01

205

A mitotic role for GSK-3beta kinase in Drosophila.  

PubMed

Glycogen synthase kinase-3beta (GSK-3beta) is involved in a wide variety of cellular processes, and implicated in a growing list of human diseases. Recent drug inhibition studies have suggested a role for GSK-3beta in mitosis in animals. Here, we take an alternative approach to understanding GSK-3beta function in mitosis by genetic mutational analysis in Drosophila. GSK-3beta function is well conserved between Drosophila (Zw3) and humans, frequently operating similarly in pathways, as diverse as the Wnt signaling and circadian rhythm pathways, and sharing a key role in the development of the neuromuscular junction. Unlike drug inhibitor studies, we find that loss of function mutations of zw3 result in markedly curved, or bent, metaphase spindles that exhibit metaphase delay. These defects do not routinely result in mitotic catastrophe, and argue that Zw3 plays a role in the maintenance of the mitotic spindle, rather than an essential role in spindle morphogenesis. Consistent with a mitotic function, we observe a complex and dynamic localization of Zw3 during cell division. These studies provide genetic data that validate and extend drug inhibition studies on a novel mitotic role for glycogen synthase kinase in the maintenance of the mitotic spindle. PMID:19029800

Wojcik, Edward J

2008-12-13

206

Development of an ultrasensitive in vitro assay to monitor growth of primary cell cultures with reduced mitotic activity  

Microsoft Academic Search

Primary cell cultures, such as isolated epithelial cells, neuronal cells, or hepatocytes are characterized by a very low mitotic activity. Monitoring of small changes in cell numbers requires staining with a DNA-specific dye with an extremely high sensitivity and a low inter- and intraassay variability. For this purpose, an ultrasensitive in vitro assay has been developed based on the fluorescent

Roman A. Blaheta; Bernd Kronenberger; Dirk Woitaschek; Stephan Weber; Martin Scholz; Horst Schuldes; Albrecht Encke; Bernd H. Markus

1998-01-01

207

Universal features in the photoemission spectroscopy of high-temperature superconductors.  

PubMed

The energy gap for electronic excitations is one of the most important characteristics of the superconducting state, as it directly reflects the pairing of electrons. In the copper-oxide high-temperature superconductors (HTSCs), a strongly anisotropic energy gap, which vanishes along high-symmetry directions, is a clear manifestation of the d-wave symmetry of the pairing. There is, however, a dramatic change in the form of the gap anisotropy with reduced carrier concentration (underdoping). Although the vanishing of the gap along the diagonal to the square Cu-O bond directions is robust, the doping dependence of the large gap along the Cu-O directions suggests that its origin might be different from pairing. It is thus tempting to associate the large gap with a second-order parameter distinct from superconductivity. We use angle-resolved photoemission spectroscopy to show that the two-gap behavior and the destruction of well-defined electronic excitations are not universal features of HTSCs, and depend sensitively on how the underdoped materials are prepared. Depending on cation substitution, underdoped samples either show two-gap behavior or not. In contrast, many other characteristics of HTSCs, such as the dome-like dependence of on doping, long-lived excitations along the diagonals to the Cu-O bonds, and an energy gap at the Brillouin zone boundary that decreases monotonically with doping while persisting above (the pseudogap), are present in all samples, irrespective of whether they exhibit two-gap behavior or not. Our results imply that universal aspects of high- superconductivity are relatively insensitive to differences in the electronic states along the Cu-O bond directions. PMID:24101464

Zhao, Junjing; Chatterjee, Utpal; Ai, Dingfei; Hinks, David G; Zheng, Hong; Gu, G D; Castellan, John-Paul; Rosenkranz, Stephan; Claus, Helmut; Norman, Michael R; Randeria, Mohit; Campuzano, Juan Carlos

2013-10-07

208

Transcriptional response to stress in the dynamic chromatin environment of cycling and mitotic cells  

PubMed Central

Heat shock factors (HSFs) are the master regulators of transcription under protein-damaging conditions, acting in an environment where the overall transcription is silenced. We determined the genomewide transcriptional program that is rapidly provoked by HSF1 and HSF2 under acute stress in human cells. Our results revealed the molecular mechanisms that maintain cellular homeostasis, including HSF1-driven induction of polyubiquitin genes, as well as HSF1- and HSF2-mediated expression patterns of cochaperones, transcriptional regulators, and signaling molecules. We characterized the genomewide transcriptional response to stress also in mitotic cells where the chromatin is tightly compacted. We found a radically limited binding and transactivating capacity of HSF1, leaving mitotic cells highly susceptible to proteotoxicity. In contrast, HSF2 occupied hundreds of loci in the mitotic cells and localized to the condensed chromatin also in meiosis. These results highlight the importance of the cell cycle phase in transcriptional responses and identify the specific mechanisms for HSF1 and HSF2 in transcriptional orchestration. Moreover, we propose that HSF2 is an epigenetic regulator directing transcription throughout cell cycle progression.

Vihervaara, Anniina; Sergelius, Christian; Vasara, Jenni; Blom, Malin A. H.; Elsing, Alexandra N.; Roos-Mattjus, Pia; Sistonen, Lea

2013-01-01

209

Computational analysis of the spatial distribution of mitotic spindle angles in mouse developing airway  

NASA Astrophysics Data System (ADS)

Investigating the spatial information of cellular processes in tissues during mouse embryo development is one of the major technical challenges in development biology. Many imaging methods are still limited to the volumes of tissue due to tissue opacity, light scattering and the availability of advanced imaging tools. For analyzing the mitotic spindle angle distribution in developing mouse airway epithelium, we determined spindle angles in mitotic epithelial cells on serial sections of whole airway of mouse embryonic lungs. We then developed a computational image analysis to obtain spindle angle distribution in three dimensional airway reconstructed from the data obtained from all serial sections. From this study, we were able to understand how mitotic spindle angles are distributed in a whole airway tube. This analysis provides a potentially fast, simple and inexpensive alternative method to quantitatively analyze cellular process at subcellular resolution. Furthermore, this analysis is not limited to the size of tissues, which allows to obtain three dimensional and high resolution information of cellular processes in cell populations deeper inside intact organs.

Tang, Nan; Marshall, Wallace F.

2013-02-01

210

Insulin growth factors regulate the mitotic cycle in cultured rat sympathetic neuroblasts  

SciTech Connect

While neuronal mitosis is uniquely restricted to early development, the underlying regulation remains to be defined. The authors have now developed a dissociated, embryonic sympathetic neuron culture system that uses fully defined medium in which cells enter the mitotic cycle. The cultured cells expressed two neuronal traits, tyrosine hydroxylase and the neuron-specific 160-kDa neurofilament subunit protein, but were devoid of glial fibrillary acidic protein, a marker for non-myelin-forming Schwann cells in ganglia. Approximately one-third of the tyrosine hydroxylase-positive cells synthesized DNA in culture, specifically incorporating ({sup 3}H)thymidine into their nuclei. They used this system to define factors regulating the mitotic cycle in sympathetic neuroblasts. Members of the insulin family of growth factors, including insulin and insulin-like growth factors I and II, regulated DNA synthesis in the presumptive neuroblasts. Insulin more than doubled the proportion of tyrosine hydroxylase-positive cells entering the mitotic cycle, as indicated by autoradiography of ({sup 3}H)thymidine incorporation into nuclei. Scintillation spectrometry was an even more sensitive index of DNA synthesis. In contrast, the trophic protein nerve growth factor exhibited no mitogenic effect, suggesting that the mitogenic action of insulin growth factors is highly specific. The observations are discussed in the context of the detection of insulin growth factors and receptors in the developing brain.

DiCicco-Bloom, E.; Black, I.B. (Cornell Univ. Medical College, New York, NY (USA))

1988-06-01

211

Mitotic phosphorylation of rab4 prevents binding to a specific receptor on endosome membranes.  

PubMed Central

Phosphorylation of the monomeric GTPase rab4 in mitotic cells leads to its relocalization from endosome membranes to the cytosol. To determine the mechanism underlying this change in distribution, we established an in vitro assay that reconstituted specific binding of rab4 when endosome-containing membranes were incubated with rab4 complexed with its cytosolic chaperone, GDP dissociation inhibitor (GDI). rab4 was found to bind to a saturable receptor associated with highly purified endosomes. Membrane binding and nucleotide exchange were physically distinct, since an active soluble fragment of the rab4 receptor, but not rab4 nucleotide exchange activity, could be released from membranes by elastase cleavage. Interestingly, the soluble fragment could be used to fully reconstitute rab4 membrane binding. In vitro phosphorylation of rab4 by cdc2/cyclin B kinase did not affect formation of rab4-GDI complexes, but did completely inhibit rab4 binding to its receptor. In contrast, in vitro phosphorylation of membranes did not result in the dissociation of bound rab4, nor were mitotic membranes deficient with respect to binding non-phosphorylated rab4. Thus, mitotic cells appear to accumulate rab4 in the cytosol by phosphorylating rab4 during the soluble phase of its normal activity cycle, thereby preventing membrane attachment.

Ayad, N; Hull, M; Mellman, I

1997-01-01

212

APC2 and Axin promote mitotic fidelity by facilitating centrosome separation and cytoskeletal regulation.  

PubMed

To ensure the accurate transmission of genetic material, chromosome segregation must occur with extremely high fidelity. Segregation errors lead to chromosomal instability (CIN), with deleterious consequences. Mutations in the tumor suppressor adenomatous polyposis coli (APC) initiate most colon cancers and have also been suggested to promote disease progression through increased CIN, but the mechanistic role of APC in preventing CIN remains controversial. Using fly embryos as a model, we investigated the role of APC proteins in CIN. Our findings suggest that APC2 loss leads to increased rates of chromosome segregation error. This occurs through a cascade of events beginning with incomplete centrosome separation leading to failure to inhibit formation of ectopic cleavage furrows, which result in mitotic defects and DNA damage. We test several hypotheses related to the mechanism of action of APC2, revealing that APC2 functions at the embryonic cortex with several protein partners, including Axin, to promote mitotic fidelity. Our in vivo data demonstrate that APC2 protects genome stability by modulating mitotic fidelity through regulation of the cytoskeleton. PMID:24026117

Poulton, John S; Mu, Frank W; Roberts, David M; Peifer, Mark

2013-09-11

213

Disruption of IFT complex A causes cystic kidneys without mitotic spindle misorientation.  

PubMed

Intraflagellar transport (IFT) complexes A and B build and maintain primary cilia. In the mouse, kidney-specific or hypomorphic mutant alleles of IFT complex B genes cause polycystic kidneys, but the influence of IFT complex A proteins on renal development is not well understood. In the present study, we found that HoxB7-Cre-driven deletion of the complex A gene Ift140 from collecting ducts disrupted, but did not completely prevent, cilia assembly. Mutant kidneys developed collecting duct cysts by postnatal day 5, with rapid cystic expansion and renal dysfunction by day 15 and little remaining parenchymal tissue by day 20. In contrast to many models of polycystic kidney disease, precystic Ift140-deleted collecting ducts showed normal centrosomal positioning and no misorientation of the mitotic spindle axis, suggesting that disruption of oriented cell division is not a prerequisite to cyst formation in these kidneys. Precystic collecting ducts had an increased mitotic index, suggesting that cell proliferation may drive cyst expansion even with normal orientation of the mitotic spindle. In addition, we observed significant increases in expression of canonical Wnt pathway genes and mediators of Hedgehog and tissue fibrosis in highly cystic, but not precystic, kidneys. Taken together, these studies indicate that loss of Ift140 causes pronounced renal cystic disease and suggest that abnormalities in several different pathways may influence cyst progression. PMID:22282595

Jonassen, Julie A; SanAgustin, Jovenal; Baker, Stephen P; Pazour, Gregory J

2012-01-26

214

Pores and Ridges: High-Resolution Fingerprint Matching Using Level 3 Features  

Microsoft Academic Search

Fingerprint friction ridge details are generally described in a hierarchical order at three different levels, namely, level 1 (pattern), level 2 (minutia points), and level 3 (pores and ridge contours). Although latent print examiners frequently take advantage of level 3 features to assist in identification, automated fingerprint identification systems (AFIS) currently rely only on level 1 and level 2 features.

Anil K. Jain; Yi Chen; Meltem Demirkus

2007-01-01

215

Pores and Ridges: High-Resolution Fingerprint Matching Using Level 3 Features  

Microsoft Academic Search

Fingerprint friction ridge details are generally described in a hierarchical order at three different levels, namely, Level 1 (pattern), Level 2 (minutia points), and Level 3 (pores and ridge contours). Although latent print examiners frequently take advantage of Level 3 features to assist in identification, Automated Fingerprint Identification Systems (AFIS) currently rely only on Level 1 and Level 2 features.In

Anil K. Jain; Yi Chen; Meltem Demirkus

2007-01-01

216

Special features of a substorm during high solar wind dynamic pressure  

SciTech Connect

A substorm on July 24, 1986, exhibiting a rather unusual auroral morphology is analyzed with data from spacecraft (Viking; DMSP F6 and F7; GOES 5 and 6; three LANL geosynchronous satellites; CCE; and IMP 8). This substorm occurred during high solar wind dynamic pressure (>5 nPa). Several notable features for this substorm are: (1) the substorm onset activity was preceded by prominent auroral activations in the morning sector with spatial separations between adjacent bright regions ranging from {approximately}160 to 640 km, and their intensity was modulated at {approximately}3.2-min intervals; (2) the initial substorm activity was concentrated in the morning sector, followed by a sudden activation in the dusk sector, leaving the midnight sector relatively undisturbed, in sharp contrast to the traditional substorm development; (3) while a substorm injection was observed at a geocentric distance of {approximately}8.4 R{sub E} by CCE in association with the substorm onset, particle injections (detectable with three LANL geosynchronous satellites) and dipolarization signatures (detectable by the two GOES satellites) were not observed until subsequent intensifications; (4) timing subsequent substorm intensifications from injections at the geosynchronous altitude differed from timing intensifications based on Viking auroral images by as much as {approximately}3 min; (5) the polar cap boundary was at a significantly higher latitude than the poleward boundary delineated by detectable auroral luminosity in the auroral oval. Detailed timing analysis suggests the substorm onset to be associated with southward interplanetary magnetic field (IMF), possibly with the crossing of an IMF sector boundary (interplanetary current sheet). The dimming of auroral luminosity in the midnight region was associated with a sudden northward turning of the IMF during high solar wind dynamic pressure condition. 36 refs., 14 figs.

Lui, A.T.Y.; Ohtani, S.; Newell, P.T. [Johns Hopkins Univ., Laurel, MD (United States)] [and others

1995-10-01

217

Highly Accurate Geometric Correction for NOAA AVHRR Data Considering Elevation Effect and Coastline Features  

NASA Astrophysics Data System (ADS)

In recent years, the images captured by AVHRR (Advanced Very High Resolution Radiometer) on the NOAA (National Oceanic and Atmospheric Administration) series of satellites have been used very widely for environment and land cover monitoring. In order to use NOAA images, they need to be accurately transformed from the image coordinate system into map coordinate system. This paper proposes a geometric correction method that corrects the errors caused by this transformation. In this method, the errors in NOAA image are corrected in the image coordinate system before transforming into the map coordinate system. First, the elevation values, which are read from GTOPO30 database, are verified to divide data into flat and rough blocks. Next, in order to increase the number of GCPs (Ground Control Points), besides the GCPs in the database, more GCPs are generated based on the feature of the coastline. After using reference images to correct the missing lines and noise pixels in the top and bottom parts of the image, the elevation errors of the GCP templates are corrected and GCP template matching is applied to find the residual errors for the blocks that match GCP templates. Based on these blocks, the residual errors of other flat and rough blocks are calculated by affine and Radial Basis Function transform respectively. According to the residual errors, all pixels in the image are moved to their correct positions. Finally, data is transformed from image into map by bilinear interpolation. With the proposed method, the average values of the error after correction are smaller than 0.2 pixels on both latitude and longitude directions. This result proved that the proposed method is a highly accurate geometric correction method.

van, An Ngoc; Nakazawa, Mitsuru; Aoki, Yoshimitsu

218

Microorganisms in small patterned ground features and adjacent vegetated soils in the High Arctic, Canada  

NASA Astrophysics Data System (ADS)

We compared 1) microbial biomass C (MBC), 2) number of bacteria (MPN), 3) diversity of fungal isolates (FI), and 4) the composition of the bacterial community in patterned ground features (PGFs) and adjacent vegetated soils (AVS) in study sites from three islands (Ellef Ringnes, Prince Patrick and Banks Islands) located along a bioclimatic gradient in the High Arctic of Canada. Soil samples were collected from PGFs and AVS located along transects in zonal (mesic) sites, and within a range of topographic conditions (drier and wetter areas at each island). FI and MPN inoculates were grown at two temperatures (7 vs. 25°C). MBC at the mesic position was greatest in Green Cabin, intermediate in Mould Bay, and lowest in Isachsen. MBC was higher in AVS than in PGFs in Green Cabin and Mould Bay but when we compared other topographic position within the study sites (islands), we found that microbial biomass C was also higher in AVS than in PGF in the dry position in Isachsen and Green Cabin. MPN were different among study sites and locations but not between incubation temperatures. MPN were higher in AVS than in PGF. FI were greater in AVS than in PGF but not different among sites. We conclude that MBC decreased with increasing latitude in these High Arctic islands. In addition, heterotrophic bacteria, some fungal genera and the number of TRFLP phylophytes vary along the gradient. Further, microbial activities are lower in PGFs as compared to AVS; and this effect could be decoupled by the effect of topographic position and temperature.

González, G.; Rivera-Figueroa, F. J.; Gould, W. A.; Cantrell, S. A.; Perez Jimenez, J. R.

2008-12-01

219

Robustness of features for automatic target discrimination in high resolution polarimetric SAR data  

NASA Astrophysics Data System (ADS)

We have studied the robustness of features against aspect variability for the purpose of target discrimination using polarimetric 35 Ghz ISAR data. Images at a resolution of 10 cm and 30 cm have been used for a complete aspect range of 360 degrees. The data covered four military targets: T72, ZSU23/4, T62, and BMP2. For the study we composed several feature vectors out of individual features extracted from the images. The features are divided into three categories: radiometric, geometric and polarimetric. We found that individual features show a strong variability as a function of aspect angle and cannot be used to discriminate between the targets irrespectively of the aspect angle. Using feature vectors and a maximum likelihood classifier reasonable discrimination (about 80%) between the four targets irrespective of the aspect angle was obtained at 10 cm resolution. At 30 cm resolution less significant discrimination (less than 70%) was found irrespective of the kind of feature vector used. In addition we investigated target discrimination per 30-degree aspect interval. In order to determine the aspect angle of targets we used a technique based on the Radon transformation, which gave an accuracy of about 5 degrees in aspect angle. We found that in this case good discrimination (more than 90%) was obtained at 10 cm resolution and reasonable discrimination (about 80%) at 30 cm resolution. The results are compared with analogous results from MSTAR data (30 cm resolution) of comparable targets.

van den Broek, Albertus C.; Dekker, Rob J.; Steeghs, Phillippe

2003-09-01

220

Delayed cell death associated with mitotic catastrophe in ?-irradiated stem-like glioma cells  

PubMed Central

Background and Purpose Stem-like tumor cells are regarded as highly resistant to ionizing radiation (IR). Previous studies have focused on apoptosis early after irradiation, and the apoptosis resistance observed has been attributed to reduced DNA damage or enhanced DNA repair compared to non-stem tumor cells. Here, early and late radioresponse of patient-derived stem-like glioma cells (SLGCs) and differentiated cells directly derived from them were examined for cell death mode and the influence of stem cell-specific growth factors. Materials and methods Primary SLGCs were propagated in serum-free medium with the stem-cell mitogens epidermal growth factor (EGF) and fibroblast growth factor-2 (FGF-2). Differentiation was induced by serum-containing medium without EGF and FGF. Radiation sensitivity was evaluated by assessing proliferation, clonogenic survival, apoptosis, and mitotic catastrophe. DNA damage-associated ?H2AX as well as p53 and p21 expression were determined by Western blots. Results SLGCs failed to apoptose in the first 4 days after irradiation even at high single doses up to 10 Gy, but we observed substantial cell death later than 4 days postirradiation in 3 of 6 SLGC lines treated with 5 or 10 Gy. This delayed cell death was observed in 3 of the 4 SLGC lines with nonfunctional p53, was associated with mitotic catastrophe and occurred via apoptosis. The early apoptosis resistance of the SLGCs was associated with lower ?H2AX compared to differentiated cells, but we found that the stem-cell culture cytokines EGF plus FGF-2 strongly reduce ?H2AX levels. Nonetheless, in two p53-deficient SLGC lines examined ?IR-induced apoptosis even correlated with EGF/FGF-induced proliferation and mitotic catastrophe. In a line containing CD133-positive and -negative stem-like cells, the CD133-positive cells proliferated faster and underwent more ?IR-induced mitotic catastrophe. Conclusions Our results suggest the importance of delayed apoptosis, associated mitotic catastrophe, and cellular proliferation for ?IR-induced death of p53-deficient SLGCs. This may have therapeutic implications. We further show that the stem-cell culture cytokines EGF plus FGF-2 activate DNA repair and thus confound in vitro comparisons of DNA damage repair between stem-like and more differentiated tumor cells.

2011-01-01

221

High-Throughput Detection of Linear Features: Selected Applications in BiologicalImaging  

Microsoft Academic Search

\\u000a Psychovisual experiments support the notion that a considerable amount of information is contained in region boundaries such\\u000a as edges and linear features [1]. Thus, as long as these elements are preserved, it is possible to simplify images drastically\\u000a with no apparent loss of content. Linear features also underlie the organization of many structures of interest in biology,\\u000a remote sensing, medicine,

Luke Domanski; Changming Sun; Ryan Lagerstrom; Dadong Wang; Leanne Bischof; Matthew Payne; Pascal Vallotton

222

Profiles of US and CT imaging features with a high probability of appendicitis  

PubMed Central

Objectives To identify and evaluate profiles of US and CT features associated with acute appendicitis. Methods Consecutive patients presenting with acute abdominal pain at the emergency department were invited to participate in this study. All patients underwent US and CT. Imaging features known to be associated with appendicitis, and an imaging diagnosis were prospectively recorded by two independent radiologists. A final diagnosis was assigned after 6 months. Associations between appendiceal imaging features and a final diagnosis of appendicitis were evaluated with logistic regression analysis. Results Appendicitis was assigned to 284 of 942 evaluated patients (30%). All evaluated features were associated with appendicitis. Imaging profiles were created after multivariable logistic regression analysis. Of 147 patients with a thickened appendix, local transducer tenderness and peri-appendiceal fat infiltration on US, 139 (95%) had appendicitis. On CT, 119 patients in whom the appendix was completely visualised, thickened, with peri-appendiceal fat infiltration and appendiceal enhancement, 114 had a final diagnosis of appendicitis (96%). When at least two of these essential features were present on US or CT, sensitivity was 92% (95% CI 89–96%) and 96% (95% CI 93–98%), respectively. Conclusion Most patients with appendicitis can be categorised within a few imaging profiles on US and CT. When two of the essential features are present the diagnosis of appendicitis can be made accurately.

Lameris, W.; van Es, H. W.; ten Hove, W.; Bouma, W. H.; van Leeuwen, M. S.; van Keulen, E. M.; van der Hulst, V. P. M.; Henneman, O. D.; Bossuyt, P. M.; Boermeester, M. A.; Stoker, J.

2010-01-01

223

Extraventricular neurocytoma with atypical features and ganglionic differentiation.  

PubMed

Extraventricular neurocytoma (EVN) is an unusual variant of central neurocytoma located outside the ventricular system. Both tumours share a similar histology characterised by monotonous populations of round-to-oval cells with scanty cytoplasm separated by neuropil and branching capillaries. We report an EVN arising from the right frontal lobe near the olfactory tract in a 34-year-old male with worsening chronic epilepsy. Our patient's tumour exhibited many uncommon features including ganglionic differentiation, increased mitotic activity and a high proliferative index. We discuss the important differential diagnoses given the site of the tumour as well as the differentiating features from olfactory neuroblastoma, oligodendroglioma, anaplastic ganglioglioma and supra-tentorial primitive neuroectodermal tumour. PMID:20399667

Chou, Shaun; Varikatt, Winny; Dexter, Mark; Ng, Thomas

2010-07-01

224

The 21 micron feature in the circumstellar envelopes around highly evolved stars  

NASA Astrophysics Data System (ADS)

The origin of the so-called 21 micron feature which is prominent in the infrared (IR) spectra of some carbon-rich proto-planetary nebular (PPNe) has been a mystery since its first detection in 1989. So far, this feature has been detected in 12 PPNe (and possibly in two planetary nebulae associated with Wolf-Rayet central stars). This feature has a similar intrinsic spectral shape and peaks at the same wavelength (20.1 ?m) in all PPNe sources. These sources have quite uniform properties: they are mostly metal-poor, carbon-rich F and G supergiants with IR excesses and overabundant s-process elements. A large number of candidate carriers for this feature have been proposed in the past decade, including hydrogenated fullerenes, polycyclic aromatic hydrocarbon, hydrogenated amorphous carbon, diamonds, synthetic carbonaceous macromolecules, amides (especially urea), iron oxides (?-Fe2O3, Fe3O4, FeO), SiS2, titanium carbide nanoclusters, doped SiC, and SiC core-SiO2 mantle particles. But none of them has been widely accepted. In this paper we review the observational characteristics of this feature and the proposed candidate materials.

Zhang, Ke; Jiang, Bi-Wei; Li, Ai-Gen

2006-03-01

225

Sequence of centromere separation: Analysis of mitotic chromosomes in man  

Microsoft Academic Search

Mitotic chromosomes from human peripheral lymphocytes studied at the junction of metaphase and anaphase show that the centromeres of various chromosomes separate in a nonrandom, apparently genetically controlled sequence. It does not depend upon the position of the centromere in the chromosome, the length of the chromosome or total amount of detectable C-chromatin. In man, several chromosomes e.g. 18, 17,

Baldev K. Vig

1981-01-01

226

Mitotic recombination and segregation of satellites in Bloom's syndrome  

Microsoft Academic Search

Mitotic recombination in satellite stalks — a phenomenon often difficult to distinguish from satellite association — was studied in a sister and a brother with Bloom's syndrome. Segregation after recombination was analyzed in the lymphocytes of the sister who had Q-bright satellites. Her cells varied greatly both in regard to the acrocentrics which displayed Q-bright satellites and the number of

Eeva Therman; Priscila G. Otto; Nasrollah T. Shahidi

1981-01-01

227

Changes in mitotic indices in roots of Vicia faba  

Microsoft Academic Search

Roots of Vicia faba were treated with solutions of colchicine or IAA or both. Mitotic indices and the frequencies of the different stages of mitosis were determined immediately after a three hour treatment or following a 24 hour period of recovery. Roots scored after treatment with colchicine for three hours showed several effects, none of which were reversed by simultaneous

D. Davidson; R. D. MacLeod

1966-01-01

228

Use of N-Acetylcolchamine as a Mitotic Poison.  

National Technical Information Service (NTIS)

The anti-mitotic activity of N-acetylcolchamine on Ehrlich ascites cancer cells has been studied in vivo in mice. It has been established that N-acetylcolchamine is an inhibitor of mitosis which, like colchicine, is able to block cell division at the stag...

V. I. Khmelevskii F. Y. Zusman O. V. Khmelevskii N. N. Myshkin

1969-01-01

229

The ultrastructure of mitotic nuclei of Blastocrithidia triatomae  

Microsoft Academic Search

The fine structure of mitotic nuclei of the flagellateBlastocrithidia triatomae has been studied by serial thin sections and three-dimensional reconstructions. The sequence of changes during the four stages of mitosis are described. A set of three dense plaques is constantly found in the equatorial stage of mitosis. The microtubular spindle is organized around these plaques. The plaques split into halves

Alberto J. Solari

1983-01-01

230

Mitotic lamin disassembly is triggered by lipid-mediated signaling  

PubMed Central

Disassembly of the nuclear lamina is a key step during open mitosis in higher eukaryotes. The activity of several kinases, including CDK1 (cyclin-dependent kinase 1) and protein kinase C (PKC), has been shown to trigger mitotic lamin disassembly, yet their precise contributions are unclear. In this study, we develop a quantitative imaging assay to study mitotic lamin B1 disassembly in living cells. We find that CDK1 and PKC act in concert to mediate phosphorylation-dependent lamin B1 disassembly during mitosis. Using ribonucleic acid interference (RNAi), we showed that diacylglycerol (DAG)-dependent PKCs triggered rate-limiting steps of lamin disassembly. RNAi-mediated depletion or chemical inhibition of lipins, enzymes that produce DAG, delayed lamin disassembly to a similar extent as does PKC inhibition/depletion. Furthermore, the delay of lamin B1 disassembly after lipin depletion could be rescued by the addition of DAG. These findings suggest that lipins activate a PKC-dependent pathway during mitotic lamin disassembly and provide evidence for a lipid-mediated mitotic signaling event.

Mall, Moritz; Walter, Thomas; Gorjanacz, Matyas; Davidson, Iain F.; Nga Ly-Hartig, Thi Bach; Ellenberg, Jan

2012-01-01

231

Mitotic phosphorylation of nucleoporins: dismantling NPCs and beyond.  

PubMed

Recently reporting in Cell, Laurell et al. (2011) demonstrate that the hyperphosphorylation of vertebrate Nup98 by distinct mitotic kinases contributes to its release from nuclear pores, drives nuclear envelope permeabilization, and may provide a molecular switch coordinating nuclear envelope breakdown and spindle formation. PMID:21397836

Doye, Valérie

2011-03-15

232

A roller coaster ride with the mitotic cyclins  

Microsoft Academic Search

Cyclins are discovered as proteins that accumulate progressively through interphase and disappear abruptly at mitosis during each cell cycle. In mammalian cells, cyclin A accumulates from late G1 phase and is destroyed before metaphase, and cyclin B is destroyed slightly later at anaphase. The abundance of the mitotic cyclins is mainly regulated at the levels of transcription and proteolysis. Transcription

Tsz Kan Fung; Randy Y. C. Poon

2005-01-01

233

Molecular Dissection of Mitotic Recombination in the Yeast Saccharomyces cerevisiae  

Microsoft Academic Search

Recombination plays a central role in the repair of broken chromosomes in all eukaryotes. We carried out a systematic study of mitotic recombination. Using several assays, we established the chronological sequence of events necessary to repair a single double-strand break. Once a chromosome is broken, yeast cells become immediately committed to recombinational repair. Recombination is completed within an hour and

Yael Aylon; Batia Liefshitz; Gili Bitan-Banin; Martin Kupiec

2003-01-01

234

Mlh1 mediates tissue-specific regulation of mitotic recombination  

Microsoft Academic Search

Mitotic recombination (MR) between chromosome homologs in somatic cells is a major pathway to the loss of heterozygosity (LOH), which may cause cancer if tumor suppressor genes are involved. MR can be suppressed by DNA sequence heterology (homeology) in hybrid mice from matings between species or between subspecies. We now report that MR is relatively suppressed in F1 hybrids between

Changshun Shao; Li Deng; Yanping Chen; Raju Kucherlapati; Peter J Stambrook; Jay A Tischfield; C Shao

2004-01-01

235

Mitotic bookmarking of genes: a novel dimension to epigenetic control  

Microsoft Academic Search

Regulatory machinery is focally organized in the interphase nucleus. The information contained in these focal nuclear microenvironments must be inherited during cell division to sustain physiologically responsive gene expression in progeny cells. Recent results suggest that focal mitotic retention of phenotypic transcription factors at promoters together with histone modifications and DNA methylation — a mechanism collectively known as gene bookmarking

Sayyed K. Zaidi; Daniel W. Young; Martin A. Montecino; Jane B. Lian; Andre J. van Wijnen; Janet L. Stein; Gary S. Stein

2010-01-01

236

Role of senescence and mitotic catastrophe in cancer therapy  

Microsoft Academic Search

Senescence and mitotic catastrophe (MC) are two distinct crucial non-apoptotic mechanisms, often triggered in cancer cells and tissues in response to anti-cancer drugs. Chemotherapeuticals and myriad other factors induce cell eradication via these routes. While senescence drives the cells to a state of quiescence, MC drives the cells towards death during the course of mitosis. The senescent phenotype distinguishes tumor

Richa Singh; Jasmine George; Yogeshwer Shukla

2010-01-01

237

New insights into the pathology of podocyte loss: mitotic catastrophe.  

PubMed

Podocytes represent an essential component of the kidney's glomerular filtration barrier. They stay attached to the glomerular basement membrane via integrin interactions that support the capillary wall to withstand the pulsating filtration pressure. Podocyte structure is maintained by a dynamic actin cytoskeleton. Terminal differentiation is coupled with permanent exit from the cell cycle and arrest in a postmitotic state. Postmitotic podocytes do not have an infinite life span; in fact, physiologic loss in the urine is documented. Proteinuria and other injuries accelerate podocyte loss or induce death. Mature podocytes are unable to replicate and maintain their actin cytoskeleton simultaneously. By the end of mitosis, cytoskeletal actin forms part of the contractile ring, rendering a round shape to podocytes. Therefore, when podocyte mitosis is attempted, it may lead to aberrant mitosis (ie, mitotic catastrophe). Mitotic catastrophe implies that mitotic podocytes eventually detach or die; this is a previously unrecognized form of podocyte loss and a compensatory mechanism for podocyte hypertrophy that relies on post-G1-phase cell cycle arrest. In contrast, local podocyte progenitors (parietal epithelial cells) exhibit a simple actin cytoskeleton structure and can easily undergo mitosis, supporting podocyte regeneration. In this review we provide an appraisal of the in situ pathology of mitotic catastrophe compared with other proposed types of podocyte death and put experimental and renal biopsy data in a unified perspective. PMID:24007883

Liapis, Helen; Romagnani, Paola; Anders, Hans-Joachim

2013-09-03

238

Canine lymphomas: association of classification type, disease stage, tumor subtype, mitotic rate, and treatment with survival.  

PubMed

Canine lymphoma is the neoplasm most often treated by chemotherapy, yet there are few data to correlate response to therapy with its different subtypes. This study is based on biopsy specimens from 992 dogs for which lymphoma was the clinical diagnosis. All cases were phenotyped by immunohistochemistry for CD3 and CD79alpha. Cases with histiocytic proliferation were evaluated immunohistochemically for CD18. Clonality was verified in 12 cases by polymerase chain reaction (PCR). Survival (event time) data and complete survival information (cause of death or time to last follow-up) were available on 456 dogs. Additional covariate information when available included size, age, sex, phenotype, stage and grade of lymphoma, mitotic index, and treatment protocol. Because of the many subtypes of B- and T-cell lymphoma, the cases were grouped into 7 diagnostic categories: (1) benign hyperplasia; (2) low-grade B-cell; (3) high-grade B- and T-cell; (4) low-grade T-cell; (5) centroblastic large B-cell of all mitotic grades (subdivided by clinical stage); (6) immunoblastic large B-cell of all mitotic grades, and (7) high-grade peripheral T-cell. Grouping was determined by histological grade (based on mitotic rate/400× field, with low-grade 0-5, intermediate 6-10, and high-grade >10) and stage for survival function estimation. No association with survival was found for size (based on breed of dog) or sex. All diagnostic categories of indolent or low-grade type had low mitotic rates, whereas those with clinically high grades had high mitotic rates. The diagnostic category with the most cases was centroblastic large B-cell lymphoma. Compared with dogs in this largest represented group of lymphomas, dogs with high-grade lymphomas had significantly higher mortality rates, and dogs with low-grade T-cell lymphomas had significantly lower mortality rates. Treatments for high-, intermediate-, and low-grade lymphomas were divided into 4 groups: absence of treatment, chemotherapy with or without hydroxydaunorubicin, and only prednisone. Dogs with low-grade T-cell (T-zone) lymphomas had the longest median survival (622 days), whereas the shortest median survival was in dogs with T-cell high-grade (peripheral T-cell) subtype (162 days). The dogs with centroblastic large B-cell lymphomas had a median survival of 127 days with low stage, 221 days with intermediate stage, and 215 days with advanced stage. Dogs with T-zone lymphoma were probably diagnosed in later stages of disease because of the lack of signs associated with progression. As with human lymphomas, a histological diagnosis with immunophenotyping is a minimal requirement for diagnosis of a specific subtype. PMID:23444036

Valli, V E; Kass, P H; Myint, M San; Scott, F

2013-02-26

239

Bhlhb5 Regulates the Post-Mitotic Acquisition of Area Identities in Layers II-V of the Developing Neocortex  

PubMed Central

SUMMARY While progenitor-restricted factors broadly specify area identities in developing neocortex, the downstream regulatory elements involved in acquisition of those identities in post-mitotic neurons are largely unknown. Here, we identify Bhlhb5, a transcription factor expressed in layers II–V, as a post-mitotic regulator of area identity. Bhlhb5 is initially expressed in a high caudomedial to low rostrolateral gradient that transforms into a sharp border between sensory and rostral motor cortices. Bhlhb5-null mice exhibit aberrant expression of area-specific genes and structural organization in the somatosensory and caudal motor cortices. In somatosensory cortex, Bhlhb5-null mice display post-synaptic disorganization of vibrissal barrels. In caudal motor cortex, Bhlhb5-null mice exhibit anomalous differentiation of corticospinal motor neurons, accompanied by failure of corticospinal tract formation. Together, these results demonstrate Bhlhb5’s function as an area-specific transcription factor that regulates the post-mitotic acquisition of area identities and elucidate the genetic hierarchy between progenitors and post-mitotic neurons driving neocortical arealization.

Joshi, Pushkar S.; Molyneaux, Bradley J.; Feng, Liang; Xie, Xiaoling; Macklis, Jeffrey D.; Gan, Lin

2008-01-01

240

Ribbon plastic optical fiber linked optical transmitter and receiver modules featuring a high alignment tolerance.  

PubMed

Ribbon plastic optical fiber (POF) linked four-channel optical transmitter (Tx) and receiver (Rx) modules have been proposed and realized featuring an excellent alignment tolerance. The two modules share a common configuration involving an optical sub-assembly (OSA) with vertical cavity surface emitting lasers (VCSELs)/photodetectors (PDs), and their driver ICs, which are integrated onto a single printed circuit board (PCB) substrate. The OSA includes an alignment structure, a beam router and a fiber guide, which were produced by using plastic injection molding. We have accomplished a fully passive alignment between the VCSELs/PDs and the ribbon POF by taking advantage of the alignment structure that serves as a reference during the alignment of the constituent parts of the OSA. The electrical link, which largely determines the operation speed, has been remarkably shortened, due to a direct wire-bonding between the VCSELs/PDs and the driver circuits. The light sources and the detectors can be individually positioned, thereby overcoming the pitch limitations of the ribbon POF, which is made up of perfluorinated graded-index (GI) POF with a 62.5 ?m core diameter. The overall alignment tolerance was first assessed by observing the optical coupling efficiency in terms of VCSEL/PD misalignment. The horizontal and vertical 3-dB alignment tolerances were about 20 ?m and 150 ?m for the Tx and 50 ?m and over 200 ?m for the Rx, respectively. The VCSEL-to-POF coupling loss for the Tx and the POF-to-PD loss for the Rx were 3.25 dB and 1.35 dB at a wavelength of 850 nm, respectively. Subsequently, a high-speed signal at 3.2 Gb/s was satisfactorily delivered via the Tx and Rx modules over a temperature range of -30 to 70°C with no significant errors; the channel crosstalk was below -30 dB. Finally, the performance of the prepared modules was verified by transmitting a 1080p HDMI video supplied by a Bluelay player to an LCD TV. PMID:21369260

Lee, Hak-Soon; Park, Jun-Young; Cha, Sang-Mo; Lee, Sang-Shin; Hwang, Gyo-Sun; Son, Yung-Sung

2011-02-28

241

A Feature-based Sampling Method to Detect Anomalous Patterns in High Dimensional Datasets  

Microsoft Academic Search

We introduce a feature-based sampling method to detect anomalous patterns. By recognizing that an observation is considered normal because there are many observations similar to it, we formally define the problem of anomalous pattern detection. The properties of normal and anoma- lous patterns allow us to devise a generic framework using the sampling method to quickly prune the normal observa-

Minh Quoc Nguyen; Leo Mark; Edward Omiecinski

242

The high prevalence of “Soft” bipolar (II) features in atypical depression  

Microsoft Academic Search

Seventy-two percent of 86 major depressive patients with atypical features as defined by the DSM-IV and evaluated systematically were found to meet our criteria for bipolar 11 and related “soft” bipolar disorders; nearly 60% had antecedent cyclothymic or hyperthymic temperaments. The family history for bipolar disorder validated these clinical findings. Even if we limit the diagnosis of bipolar II to

G Perugi; H. S Akiskal; L Lattanzi; D Cecconi; C Mastrocinque; A Patronelli; S Vignoli; E Bemi

1998-01-01

243

Pharicin A, a novel natural ent-kaurene diterpenoid, induces mitotic arrest and mitotic catastrophe of cancer cells by interfering with BubR1 function  

PubMed Central

In this study, we report the functional characterization of a new ent-kaurene diterpenoid termed pharicin A, which was originally isolated from Isodon, a perennial shrub frequently used in Chinese folk medicine for tumor treatment. Pharicin A induces mitotic arrest in leukemia and solid tumor-derived cells identified by their morphology, DNA content and mitotic marker analyses. Pharicin A-induced mitotic arrest is associated with unaligned chromosomes, aberrant BubR1 localization and deregulated spindle checkpoint activation. Pharicin A directly binds to BubR1 in vitro, which is correlated with premature sister chromatid separation in vivo. Pharicin A also induces mitotic arrest in paclitaxel-resistant Jurkat and U2OS cells. Combined, our study strongly suggests that pharicin A represents a novel class of small molecule compounds capable of perturbing mitotic progression and initiating mitotic catastrophe, which merits further preclinical and clinical investigations for cancer drug development.

Huang, Ying; Wu, Ying-Li; Zhao, Yong; Xiao, Wei-Lie; Lin, Qi-Shan; Sun, Han-Dong

2010-01-01

244

High cadence spectropolarimetry of moving magnetic features observed around a pore  

NASA Astrophysics Data System (ADS)

Context. Moving magnetic features (MMFs) are small-size magnetic elements that are seen to stream out from sunspots, generally during their decay phase. Several observational results presented in the literature suggest them to be closely related to magnetic filaments that extend from the penumbra of the parent spot. Nevertheless, few observations of MMFs streaming out from spots without penumbra have been reported. The literature still lacks analyses of the physical properties of these features. Aims: We investigate physical properties of monopolar MMFs observed around a small pore that had developed penumbra in the days preceding our observations and compare our results with those reported in the literature for features observed around sunspots. Methods: We analyzed NOAA 11005 during its decay phase with data acquired at the Dunn Solar Telescope in the Fe i 617.3 nm and the Ca ii 854.2 nm spectral lines with IBIS, and in the G-band. The field of view showed monopolar MMFs of both polarities streaming out from the leading negative polarity pore of the observed active region. Combining different analyses of the data, we investigated the temporal evolution of the relevant physical quantities associated with the MMFs as well as the photospheric and chromospheric signatures of these features. Results: We show that the characteristics of the investigated MMFs agree with those reported in the literature for MMFs that stream out from spots with penumbrae. Moreover, observations of at least two of the observed features suggest them to be manifestations of emerging magnetic arches. Appendices A and B, and a movie are available in electronic form at http://www.aanda.org

Criscuoli, S.; Del Moro, D.; Giannattasio, F.; Viticchié, B.; Giorgi, F.; Ermolli, I.; Zuccarello, F.; Berrilli, F.

2012-10-01

245

Serum high mobility group box-1 (HMGB1) is closely associated with the clinical and pathologic features of gastric cancer  

Microsoft Academic Search

BACKGROUND: High mobility group box-1 (HMGB1) is a newly recognized factor regulating cancer cell tumorigenesis, expansion and invasion. We investigated the correlation between the serum HMGB1 levels and the clinical and pathologic features of gastric cancer and evaluated the validity of HMGB1 as a potential biomarker for the early diagnosis of gastric cancer. METHODS: A total of 227 subjects were

Hye Won Chung; Sang-Guk Lee; Heejung Kim; Duck Jin Hong; Jae Bock Chung; David Stroncek; Jong-Baeck Lim

2009-01-01

246

Structural and motional features of benzene-solvated C 60 as revealed by high-resolution solid state NMR  

Microsoft Academic Search

Structural and motional features of C60 · 4C6H6 solvate has been investigated by high-resolution 13C solid-state NMR spectroscopy. 13C line shape analysis of the cross-polarization spectrum for the static sample at 293 K shows an unusual motional restriction of benzene molecules in this solvate. The existence of highly anisotropic motion of benzene fraction is visualized also by the detection of

P. Tekely; P Palmas; P Mutzenhardt; F Masin; A.-S Grell; I Messari; M Gelbcke

1998-01-01

247

RHAMM Promotes Interphase Microtubule Instability and Mitotic Spindle Integrity through MEK1/ERK1/2 Activity*  

PubMed Central

An oncogenic form of RHAMM (receptor for hyaluronan-mediated motility, mouse, amino acids 163–794 termed RHAMM?163) is a cell surface hyaluronan receptor and mitotic spindle protein that is highly expressed in aggressive human cancers. Its regulation of mitotic spindle integrity is thought to contribute to tumor progression, but the molecular mechanisms underlying this function have not previously been defined. Here, we report that intracellular RHAMM?163 modifies the stability of interphase and mitotic spindle microtubules through ERK1/2 activity. RHAMM?/? mouse embryonic fibroblasts exhibit strongly acetylated interphase microtubules, multi-pole mitotic spindles, aberrant chromosome segregation, and inappropriate cytokinesis during mitosis. These defects are rescued by either expression of RHAMM or mutant active MEK1. Mutational analyses show that RHAMM?163 binds to ?- and ?-tubulin protein via a carboxyl-terminal leucine zipper, but in vitro analyses indicate this interaction does not directly contribute to tubulin polymerization/stability. Co-immunoprecipitation and pulldown assays reveal complexes of RHAMM?163, ERK1/2-MEK1, and ?- and ?-tubulin and demonstrate direct binding of RHAMM?163 to ERK1 via a D-site motif. In vitro kinase analyses, expression of mutant RHAMM?163 defective in ERK1 binding in mouse embryonic fibroblasts, and blocking MEK1 activity collectively confirm that the effect of RHAMM?163 on interphase and mitotic spindle microtubules is mediated by ERK1/2 activity. Our results suggest a model wherein intracellular RHAMM?163 functions as an adaptor protein to control microtubule polymerization during interphase and mitosis as a result of localizing ERK1/2-MEK1 complexes to their tubulin-associated substrates.

Tolg, Cornelia; Hamilton, Sara R.; Morningstar, Lyndsey; Zhang, Jing; Zhang, S.; Esguerra, Kenneth V.; Telmer, Patrick G.; Luyt, Len G.; Harrison, Rene; McCarthy, James B.; Turley, Eva A.

2010-01-01

248

Formation of coastline features by large-scale instabilities induced by high-angle waves.  

PubMed

Along shore sediment transport that is driven by waves is generally assumed to smooth a coastline. This assumption is valid for small angles between the wave crest lines and the shore, as has been demonstrated in shoreline models. But when the angle between the waves and the shoreline is sufficiently large, small perturbations to a straight shoreline will grow. Here we use a numerical model to investigate the implications of this instability mechanism for large-scale morphology over long timescales. Our simulations show growth of coastline perturbations that interact with each other to produce large-scale features that resemble various kinds of natural landforms, including the capes and cuspate forelands observed along the Carolina coast of southeastern North America. Wind and wave data from this area support our hypothesis that such an instability mechanism could be responsible for the formation of shoreline features at spatial scales up to hundreds of kilometres and temporal scales up to millennia. PMID:11713526

Ashton, A; Murray, A B; Arnault, O

2001-11-15

249

Extracting building features from high resolution aerial imagery for natural hazards risk assessment  

Microsoft Academic Search

Natural hazards risk assessment requires data on the built environment. This paper reports an image analysis method that can extract building features, mainly roof plan areas, for potential vulnerability analysis. Both pixel- and object-based image processing methods are adopted. First, red\\/green\\/blue colour bands and image textures are incorporated in a supervised artificial neural network classifier to achieve good classification results

Keping Chen; Russell Blong

2002-01-01

250

Down-modulation of nucleoporin RanBP2/Nup358 impaired chromosomal alignment and induced mitotic catastrophe.  

PubMed

Chromosomal missegregation is a common feature of many human tumors. Recent studies have indicated a link between nucleoporin RanBP2/Nup358 and chromosomal segregation during mitosis; however, the molecular details have yet to be fully established. Observed through live cell imaging and flow cytometry, here we show that RNA interference-mediated knockdown of RanBP2 induced G2/M phase arrest, metaphase catastrophe and mitotic cell death. Furthermore, RanBP2 down-modulation disrupted importin/karyopherin ?1 as well as the expression and localization of the Ran GTPase activating protein 1. We found that N-terminal of RanBP2 interacted with the N-terminal of importin ?1. Moreover, at least a portion of RanBP2 partially localizes at the centrosome during mitosis. Notably, we also found that GTPase Ran is also involved in the regulation of RanBP2-importin ?1 interaction. Overall, our results suggest that mitotic arrest and the following cell death were caused by depletion of RanBP2. Our findings point to a crucial role for RanBP2 in proper mitotic progression and faithful chromosomal segregation. PMID:24113188

Hashizume, C; Kobayashi, A; Wong, R W

2013-10-10

251

Ubiquitin and SUMO systems in the regulation of mitotic checkpoints  

PubMed Central

Proteolysis mediated by the ubiquitin–proteasome system is a crucial regulatory mechanism in signal transduction cascades of temporal cellular processes such as cell division. Two principal subtypes of modular ubiquitin ligase, the anaphase-promoting complex or cyclosome (APC/C) and the Skp1/Cullin-1/F-box protein complex, have emerged as essential regulators of key events in the cell cycle. The importance of these ligases is best illustrated by their roles in the checkpoint and repair pathways or in response to multiple stresses, where they affect activation of the M-phase-promoting factor or proper formation and/or maintenance of the mitotic spindle. Recent studies have considerably improved our understanding of the function of the concerted action of the phosphorylation and ubiquitin or SUMO systems in the regulation of the stability and activity of key components of the mitotic checkpoint.

Gutierrez, Gustavo J.; Ronai, Ze'ev

2011-01-01

252

Ubiquitin and SUMO systems in the regulation of mitotic checkpoints.  

PubMed

Proteolysis mediated by the ubiquitin-proteasome system is a crucial regulatory mechanism in signal transduction cascades of temporal cellular processes such as cell division. Two principal subtypes of modular ubiquitin ligase, the anaphase-promoting complex or cyclosome (APC/C) and the Skp1/Cullin-1/F-box protein complex, have emerged as essential regulators of key events in the cell cycle. The importance of these ligases is best illustrated by their roles in the checkpoint and repair pathways or in response to multiple stresses, where they affect activation of the M-phase-promoting factor or proper formation and/or maintenance of the mitotic spindle. Recent studies have considerably improved our understanding of the function of the concerted action of the phosphorylation and ubiquitin or SUMO systems in the regulation of the stability and activity of key components of the mitotic checkpoint. PMID:16647857

Gutierrez, Gustavo J; Ronai, Ze'ev

2006-05-02

253

Cancer predisposition caused by elevated mitotic recombination in Bloom mice.  

PubMed

Bloom syndrome is a disorder associated with genomic instability that causes affected people to be prone to cancer. Bloom cell lines show increased sister chromatid exchange, yet are proficient in the repair of various DNA lesions. The underlying cause of this disease are mutations in a gene encoding a RECQ DNA helicase. Using embryonic stem cell technology, we have generated viable Bloom mice that are prone to a wide variety of cancers. Cell lines from these mice show elevations in the rates of mitotic recombination. We demonstrate that the increased rate of loss of heterozygosity (LOH) resulting from mitotic recombination in vivo constitutes the underlying mechanism causing tumour susceptibility in these mice. PMID:11101838

Luo, G; Santoro, I M; McDaniel, L D; Nishijima, I; Mills, M; Youssoufian, H; Vogel, H; Schultz, R A; Bradley, A

2000-12-01

254

Surface feature characterization test plan: Conceptual design of a high level nuclear waste repository in salt  

SciTech Connect

This report presents the Surface Feature Characterization Test Plan for conceptual design. The Test Plan is part of the surface feature characterization program for conceptual design which will obtain information on site topography, hydrology, stratigraphy, and soil and rock engineering properties. The information will be obtained by the Geologic Project Manager (GPM). This Test Plan provides guidance to the GPM as to (1) the kinds of data to be collected, (2) anticipated methods, (3) the level of detail required, (4) interpretation to be made, and (5) the format for presentation. Based on this Test Plan and on conditions at the site that is selected, the GPM will develop an Activity Plan describing the methods to be used in obtaining the needed information. For each item of information, the Test Plan describes those facilities which require it for their design. The GPM can then determine the appropriate methods and level of effort for obtaining the information, taking into account its use and conditions at the selected site. 7 figs., 3 tabs.

Not Available

1984-06-01

255

Vesicular stomatitis virus inhibits mitotic progression and triggers cell death  

Microsoft Academic Search

Vesicular stomatitis virus (VSV) infects and kills a wide range of cell types; however, the mechanisms involved in VSV-mediated cell death are not fully understood. Here we show that VSV infection interferes with mitotic progression, resulting in cell death. This effect requires the interaction of VSV matrix (M) protein with the Rae1–Nup98 complex in mitosis, which is associated with a

Papia Chakraborty; Joachim Seemann; Ram K Mishra; Jen-Hsuan Wei; Lauren Weil; Daniel R Nussenzveig; Joshua Heiber; Glen N Barber; Mary Dasso; Beatriz M A Fontoura

2009-01-01

256

Timing and Checkpoints in the Regulation of Mitotic Progression  

Microsoft Academic Search

Accurate chromosome segregation relies on the precise regulation of mitotic progression. Regulation involves control over the timing of mitosis and a spindle assembly checkpoint that links anaphase onset to the completion of chromosome-microtubule attachment. In this paper, we combine live-cell imaging of HeLa cells and protein depletion by RNA interference to examine the functions of the Mad, Bub, and kinetochore

Patrick Meraldi; Viji M. Draviam; Peter K. Sorger

2004-01-01

257

Pattern formation in stochastic systems: Magnetized billiards and mitotic spindles  

NASA Astrophysics Data System (ADS)

Physical systems that exhibit chaotic behavior or are subject to thermal noise are treated as random processes, especially if the state of the system cannot be measured precisely. Here we examine two such systems. The first is a single electron confined to a wedge-shaped section of a disk, called a billiard, in the presence of a uniform transverse magnetic field. The system exhibits a mixture of chaotic and nonchaotic behavior at different values of the magnetic field strength. If the size of the billiard is on the order of micrometers, as in a quantum dot, both quantum and classical analyses are necessary. The second system is a collection of stiff fibers, called microtubules, suspended in a fluid called the cytoplasm, and lying over chromosomes in a cell. The cytoplasm supplies molecular motors and fuel for the motors. The chromosomes supply motor attachment points. The combination causes the microtubules to self-assemble into a coherent structure called the mitotic spindle. This structure is vital to cell division in plants and animals. Elements of the mitotic spindle have sizes ranging from nanometers to micrometers, and all are subject to considerable thermal agitation. Mitotic spindle self-assembly occurs despite the randomizing effect of this thermal motion. We studied both systems by constructing physical models described by mathematical equations. From these we were able to perform computer simulations. For the billiard problem, we made innovative use of geometric symmetries. These symmetries allowed us to construct efficient representations of both classical and quantum systems. We found a new region of integrable trajectories for a magnetic field above that required to produce completely chaotic orbits. For the mitotic spindle, we were the first to demonstrate spindle self-assembly in a model that matches conditions reported by experimental biologists. Our simulations have shed significant light on which of the many elements in this complex system are vital for spindle formation.

Schaffner, Stuart C.

258

Dissociation of Cytokinesis Initiation from Mitotic Control in a Eukaryote  

Microsoft Academic Search

Cytokinesis is initiated only after mitotic exit in eukaryotes. However, in the insect (procyclic) form of an ancient protist, Trypanosoma brucei, a blockade at the G2\\/M checkpoint results in an enrichment of anucleate cells (zoids), suggesting separated regulations between mitosis and cytokinesis (X. Tu and C. C. Wang, J. Biol. Chem. 279:20519-20528, 2004). Polo-like kinases (Plks) are known to play

Praveen Kumar; C. C. Wang

2006-01-01

259

Structure of the complex of a mitotic kinesin with its calcium binding regulator.  

PubMed

Much of the transport, tension, and movement in mitosis depends on kinesins, the ATP-powered microtubule-based motors. We report the crystal structure of a kinesin complex, the mitotic kinesin KCBP bound to its principal regulator KIC. Shown to be a Ca(2+) sensor, KIC works as an allosteric trap. Extensive intermolecular interactions with KIC stabilize kinesin in its ADP-bound conformation. A critical component of the kinesin motile mechanism, called the neck mimic, switches its association from kinesin to KIC, stalling the motor. KIC denies access of the motor to its track by steric interference. Two major features of this regulation, allosteric trapping and steric blocking, are likely to be general for all kinesins. PMID:19416847

Vinogradova, Maia V; Malanina, Galina G; Reddy, Anireddy S N; Fletterick, Robert J

2009-05-05

260

Semi-automatic methodologies for landslide features extraction: new opportunities but also challenges from high resolution topography  

NASA Astrophysics Data System (ADS)

In recent years new remotely sensed technologies, such as airborne and terrestrial laser scanner, have improved the detail, and the quality of topographic data with notable advantages over traditional survey techniques (Tarolli et al., 2009). A new generation of high resolution (?3 m) Digital Terrain Models (DTMs) are now available for different areas, and widely used by researchers, offering new opportunities for the scientific community. These data call for the development of the new generation of methodologies for objective extraction of geomorphic features, such as channel heads, channel networks, landslide scars, etc. A high resolution DTM, for example, is able to detect in detail the divergence/convergence areas related to unchannelized/channelized processes respect to a coarse DTM. In last few years different studies used the landform curvature as a useful measure for the interpretation of dominant landform processes (Tarolli and Dalla Fontana, 2009). Curvature has been used to analyze landslide morphology and distribution, and to objectively extract the channel network. In this work, we test the performances of some of these new methodologies for geomorphic features extraction, in order to provide a semi-automatic method to recognize landslide scars in a complex mountainous terrain. The analysis has been carried out using a very high resolution DTM (0.5 m), and different sizes of the moving window for the landform curvature calculation. Statistical dispersion measures (standard deviation, interquartile range, mean and median absolute deviation), and probability plots (quantile-quantile plot) were adopted to objectively define the thresholds of curvature for landslide features extraction. The study was conducted on a study area located in the Eastern Italian Alps, where recent accurate field surveys by DGPS on landslide scars, and a high quality set of airborne laser scanner elevation data are available. The results indicate that curvature maps derived by small moving window sizes are not so representative of local morphology. They do not explore a sufficient range at which landslide features occur. The curvature maps derived by larger moving window sizes overcome this problem, resulting more appropriate for the extraction of surveyed features. The results of our work highlight the capability, but also the challenges of adopted analysis in automated methodologies for geomorphic feature extraction. References Tarolli, P., J R. Arrowsmith, and E. R. Vivoni (2009), Understanding earth surface processes from remotely sensed digital terrain models, Geomorphology, doi:10.1016/j.geomorph.2009.07.005. Tarolli, P., and G. Dalla Fontana (2009), Hillslope-to-valley transition morphology: new opportunities from high resolution DTMs, Geomorphology, doi:10.1016/j.geomorph.2009.02.006.

Tarolli, P.; Sofia, G.; Dalla Fontana, G.

2009-12-01

261

The overlooked greatwall: a new perspective on mitotic control  

PubMed Central

The role of the dual specificity protein phosphatase, Cdc25, in activating the cyclin-dependent kinase-cyclin B complex (Cdk1-CycB) by overcoming the inhibitory Wee1 kinase is a long-established principle for mitotic entry. Recently, however, evidence has emerged of a regulatory network that facilitates Cdk1-CycB activity by inhibiting the form of protein phosphatase 2A having a B55 regulatory subunit (PP2A-B55). Here, I review the genetic and biochemical evidence for Greatwall kinase and its substrate Endosulphine as the key components of this previously obscure regulatory network. Not only is the inhibition of PP2A-B55 by phospho-endosulphine required to prevent dephosphorylation of Cdk1-CycB substrates until mitotic exit, but it is also required to promote Cdc25 activity and inhibit Wee1 at mitotic entry. I discuss how these alternating states of preferential PP2A-B55 or Cdk1-CycB activity can have an impact upon the regulation of Polo kinase and its ability to bind different partner proteins as mitosis progresses.

Glover, David M.

2012-01-01

262

A roller coaster ride with the mitotic cyclins.  

PubMed

Cyclins are discovered as proteins that accumulate progressively through interphase and disappear abruptly at mitosis during each cell cycle. In mammalian cells, cyclin A accumulates from late G1 phase and is destroyed before metaphase, and cyclin B is destroyed slightly later at anaphase. The abundance of the mitotic cyclins is mainly regulated at the levels of transcription and proteolysis. Transcription is stimulated and repressed by several transcription factors, including B-MYB, E2F, FOXM1, and NF-Y. Elements in the promoter, including CCRE/CDE and CHR, are in part responsible for the cell cycle oscillation of transcription. Destruction of the mitotic cyclins is carried out by the ubiquitin ligases APC/C(CDC20) and APC/C(CDH1). Central to our knowledge is the understanding of how APC/C is turned on from anaphase to early G1 phase, and turned off from late G1 till the spindle-assembly checkpoint is deactivated in metaphase. Reciprocal actions of cyclin-dependent kinases (CDKs) on APC/C, as well as on the SCF complexes ensure that the mitotic cyclins are destroyed only at the proper time. PMID:15840442

Fung, Tsz Kan; Poon, Randy Y C

2005-06-01

263

The overlooked greatwall: a new perspective on mitotic control.  

PubMed

The role of the dual specificity protein phosphatase, Cdc25, in activating the cyclin-dependent kinase-cyclin B complex (Cdk1-CycB) by overcoming the inhibitory Wee1 kinase is a long-established principle for mitotic entry. Recently, however, evidence has emerged of a regulatory network that facilitates Cdk1-CycB activity by inhibiting the form of protein phosphatase 2A having a B55 regulatory subunit (PP2A-B55). Here, I review the genetic and biochemical evidence for Greatwall kinase and its substrate Endosulphine as the key components of this previously obscure regulatory network. Not only is the inhibition of PP2A-B55 by phospho-endosulphine required to prevent dephosphorylation of Cdk1-CycB substrates until mitotic exit, but it is also required to promote Cdc25 activity and inhibit Wee1 at mitotic entry. I discuss how these alternating states of preferential PP2A-B55 or Cdk1-CycB activity can have an impact upon the regulation of Polo kinase and its ability to bind different partner proteins as mitosis progresses. PMID:22754657

Glover, David M

2012-03-01

264

Daxx regulates mitotic progression and prostate cancer predisposition.  

PubMed

Mitotic progression of mammalian cells is tightly regulated by the E3 ubiquitin ligase anaphase promoting complex (APC)/C. Deregulation of APC/C is frequently observed in cancer cells and is suggested to contribute to chromosome instability and cancer predisposition. In this study, we identified Daxx as a novel APC/C inhibitor frequently overexpressed in prostate cancer. Daxx interacts with the APC/C coactivators Cdc20 and Cdh1 in vivo, with the binding of Cdc20 dependent on the consensus destruction boxes near the N-terminal of the Daxx protein. Ectopic expression of Daxx, but not the D-box deleted mutant (Daxx?D-box), inhibited the degradation of APC/Cdc20 and APC/Cdh1 substrates, leading to a transient delay in mitotic progression. Daxx is frequently upregulated in prostate cancer tissues; the expression level positively correlated with the Gleason score and disease metastasis (P = 0.027 and 0.032, respectively). Furthermore, ectopic expression of Daxx in a non-malignant prostate epithelial cell line induced polyploidy under mitotic stress. Our data suggest that Daxx may function as a novel APC/C inhibitor, which promotes chromosome instability during prostate cancer development. PMID:23239745

Kwan, Pak Shing; Lau, Chi Chiu; Chiu, Yung Tuen; Man, Cornelia; Liu, Ji; Tang, Kai Dun; Wong, Yong Chuan; Ling, Ming-Tat

2012-12-13

265

Proteomic analysis of mitotic RNA polymerase II reveals novel interactors and association with proteins dysfunctional in disease.  

PubMed

RNA polymerase II (RNAPII) transcribes protein-coding genes in eukaryotes and interacts with factors involved in chromatin remodeling, transcriptional activation, elongation, and RNA processing. Here, we present the isolation of native RNAPII complexes using mild extraction conditions and immunoaffinity purification. RNAPII complexes were extracted from mitotic cells, where they exist dissociated from chromatin. The proteomic content of native complexes in total and size-fractionated extracts was determined using highly sensitive LC-MS/MS. Protein associations with RNAPII were validated by high-resolution immunolocalization experiments in both mitotic cells and in interphase nuclei. Functional assays of transcriptional activity were performed after siRNA-mediated knockdown. We identify >400 RNAPII associated proteins in mitosis, among these previously uncharacterized proteins for which we show roles in transcriptional elongation. We also identify, as novel functional RNAPII interactors, two proteins involved in human disease, ALMS1 and TFG, emphasizing the importance of gene regulation for normal development and physiology. PMID:22199231

Möller, André; Xie, Sheila Q; Hosp, Fabian; Lang, Benjamin; Phatnani, Hemali P; James, Sonya; Ramirez, Francisco; Collin, Gayle B; Naggert, Jürgen K; Babu, M Madan; Greenleaf, Arno L; Selbach, Matthias; Pombo, Ana

2011-12-22

266

Mapping epibenthic assemblages and their relations to sedimentary features in shallow-water, high-energy environments  

Microsoft Academic Search

Knowledge of spatial relationships among benthic biota and sedimentary features in shallow-water (<30m) high-energy environments has been severely limited by sampling technology. We describe and report tests of a SCUBA-diving mapping method specifically for this region. Underwater acoustic location is used to achieve meter-scale resolution over kilometer-scale regions of the sea floor. A triad of acoustic transponders is bottom-mounted at

John D. Sisson; Jeff Shimeta; Cheryl Ann Zimmer; Peter Traykovski

2002-01-01

267

Brochothrix thermosphacta Bacteriophages Feature Heterogeneous and Highly Mosaic Genomes and Utilize Unique Prophage Insertion Sites ? †  

PubMed Central

Brochothrix belongs to the low-GC branch of Gram-positive bacteria (Firmicutes), closely related to Listeria, Staphylococcus, Clostridium, and Bacillus. Brochothrix thermosphacta is a nonproteolytic food spoilage organism, adapted to growth in vacuum-packaged meats. We report the first genome sequences and characterization of Brochothrix bacteriophages. Phage A9 is a myovirus with an 89-nm capsid diameter and a 171-nm contractile tail; it belongs to the Spounavirinae subfamily and shares significant homologies with Listeria phage A511, Staphylococcus phage Twort, and others. The A9 unit genome is 127 kb long with 11-kb terminal redundancy; it encodes 198 proteins and 6 tRNAs. Phages BL3 and NF5 are temperate siphoviruses with a head diameter of 56 to 59 nm. The BL3 tail is 270 nm long, whereas NF5 features a short tail of only 94 nm. The NF5 genome (36.95 kb) encodes 57 gene products, BL3 (41.52 kb) encodes 65 products, and both are arranged in life cycle-specific modules. Surprisingly, BL3 and NF5 show little relatedness to Listeria phages but rather demonstrate relatedness to lactococcal phages. Peptide mass fingerprinting of viral proteins indicate programmed ?1 translational frameshifts in the NF5 capsid and the BL3 major tail protein. Both NF5 and BL3 feature circularly permuted, terminally redundant genomes, packaged by a headful mechanism, and integrases of the serine (BL3) and tyrosine (NF5) types. They utilize unique target sequences not previously described: BL3 inserts into the 3? end of a RNA methyltransferase, whereas NF5 integrates into the 5?-terminal part of a putative histidinol-phosphatase. Interestingly, both genes are reconstituted by phage sequence.

Kilcher, Samuel; Loessner, Martin J.; Klumpp, Jochen

2010-01-01

268

Geomorphic features extraction from high-resolution topography: landslide crowns and bank erosion  

Microsoft Academic Search

In recent years, new remote-sensed technologies, such as airborne and terrestrial laser scanner, have improved the detail\\u000a and the quality of topographic information, providing topographical high-resolution and high-quality data over larger areas\\u000a better than other technologies. A new generation of high-resolution (?3 m) digital terrain models (DTMs) is now available\\u000a for different areas and is widely used by researchers, offering new

Paolo Tarolli; Giulia Sofia; Giancarlo Dalla Fontana

269

Speaker Verification Using Support Vector Machines and High-Level Features  

Microsoft Academic Search

High-level characteristics such as word usage, pronunciation, phonotactics, prosody, etc., have seen a resurgence for automatic speaker recognition over the last several years. With the availability of many conversation sides per speaker in current corpora, high-level systems now have the amount of data needed to sufficiently characterize a speaker. Although a significant amount of work has been done in finding

William M. Campbell; Joseph P. Campbell; Terry P. Gleason; Douglas A. Reynolds; Wade Shen

2007-01-01

270

A better insight into the performance of silicon BJTs featuring highly nonuniform collector doping profiles  

Microsoft Academic Search

This paper investigates the effects of highly nonuniform collector doping profiles on the speed and breakdown performance of silicon bipolar transistors. Monte Carlo and drift diffusion simulation results point out that a thin highly doped layer adjacent to the base collector junction can improve the device cut off frequency without deteriorating significantly the maximum oscillation frequency and the breakdown voltage,

Pierpaolo Palestri; Claudio Fiegna; Luca Selmi; Michael S. Peter; G. A. M. Hurkx; Jan W. Slotboom; Enrico Sangiorgi

2000-01-01

271

Experimental Examination of Diode Features in a High-Power Magnetron with a Transparent Cathode  

Microsoft Academic Search

A Magnetron is a high efficiency microwave source, although the energy conversion efficiency of a pulsed- power magnetron with a relativistic electron beam is less than that of a non-relativistic magnetron. We studied the possibility of increasing the energy conversion efficiency of a high-power magnetron using a transparent cathode. The conversion efficiency is controlled by the resonance efficiency between the

Hoshiyuki Yamazaki; Weihua Jiang

2008-01-01

272

Risk factors for psychosis in an ultra high-risk group: psychopathology and clinical features  

Microsoft Academic Search

The identification of individuals at high risk of developing a psychotic disorder has long been a goal of clinicians because it is thought that early treatment of this group may prevent onset of the disorder. However, little is known of predictive factors of psychosis, even within a high-risk group. This study followed up 104 young people thought to be at

Alison R Yung; Lisa J Phillips; Hok Pan Yuen; Patrick D McGorry

2004-01-01

273

Directional instability of kinetochore motility during chromosome congression and segregation in mitotic newt lung cells: a push-pull mechanism  

Microsoft Academic Search

Most models of mitotic congression and segregation assume that only poleward pulling forces occur at kinetochores. However, there are reports for several different cell types that both mono-oriented and bi-oriented chromosomes oscillate toward and away from the pole throughout mitosis. We used new methods of high resolution video microscopy and computer-assisted tracking techniques to measure the positions over time of

Robert V. Skibbens; Victoria Petrie Skeen; E. D. Salmon

1993-01-01

274

A Novel RING Finger Protein, Human Enhancer of Invasion 10, Alters Mitotic Progression through Regulation of Cyclin B Levels  

Microsoft Academic Search

The process of cellular morphogenesis is highly conserved in eukaryotes and is dependent upon the function of proteins that are centrally involved in specification of the cell cycle. The human enhancer of invasion clone 10 (HEI10) protein was identified from a HeLa cell library based on its ability to promote yeast agar invasion and filamentation. Through two-hybrid screening, the mitotic

Garabet G. Toby; Wahiba Gherraby; Thomas R. Coleman; Erica A. Golemis

2003-01-01

275

The Effect of Three Agricultural Chemicals on Mitotic Division and Total Seed Protein Banding Profiles of Alfalfa (Vicia faba)  

Microsoft Academic Search

Treatments of alfalfa (Vicia faba L.) seeds with gibberellic acid (GA3), fertilizer, potassium oxide (K2O) and the auxin inhibitor N-meta-tolyl-phathalamic acid (Tomaset) showed a decrease in mitotic index and increased the percentage of the chromosomal abnormalities. The harmful effect was high with the use of tomaset, moderate with K2O and low in plants treated with GA3. SDS-PAGE studies revealed qualitative

MEKKI LAILA

276

Fission yeast pkl1 is a kinesin-related protein involved in mitotic spindle function.  

PubMed Central

We have used anti-peptide antibodies raised against highly conserved regions of the kinesin motor domain to identify kinesin-related proteins in the fission yeast Schizosaccharomyces pombe. Here we report the identification of a new kinesin-related protein, which we have named pkl1. Sequence homology and domain organization place pkl1 in the Kar3/ncd subfamily of kinesin-related proteins. Bacterially expressed pkl1 fusion proteins display microtubule-stimulated ATPase activity, nucleotide-sensitive binding, and bundling of microtubules. Immunofluorescence studies with affinity-purified antibodies indicate that the pkl1 protein localizes to the nucleus and the mitotic spindle. Pkl1 null mutants are viable but have increased sensitivity to microtubule-disrupting drugs. Disruption of pkl1+ suppresses mutations in another kinesin-related protein, cut7, which is known to act in the spindle. Overexpression of pkl1 to very high levels causes a similar phenotype to that seen in cut7 mutants: V-shaped and star-shaped microtubule structures are observed, which we interpret to be spindles with unseparated spindle poles. These observations suggest that pkl1 and cut7 provide opposing forces in the spindle. We propose that pkl1 functions as a microtubule-dependent motor that is involved in microtubule organization in the mitotic spindle. Images

Pidoux, A L; LeDizet, M; Cande, W Z

1996-01-01

277

APC/C-Cdh1-dependent anaphase and telophase progression during mitotic slippage  

PubMed Central

Background The spindle assembly checkpoint (SAC) inhibits anaphase progression in the presence of insufficient kinetochore-microtubule attachments, but cells can eventually override mitotic arrest by a process known as mitotic slippage or adaptation. This is a problem for cancer chemotherapy using microtubule poisons. Results Here we describe mitotic slippage in yeast bub2? mutant cells that are defective in the repression of precocious telophase onset (mitotic exit). Precocious activation of anaphase promoting complex/cyclosome (APC/C)-Cdh1 caused mitotic slippage in the presence of nocodazole, while the SAC was still active. APC/C-Cdh1, but not APC/C-Cdc20, triggered anaphase progression (securin degradation, separase-mediated cohesin cleavage, sister-chromatid separation and chromosome missegregation), in addition to telophase onset (mitotic exit), during mitotic slippage. This demonstrates that an inhibitory system not only of APC/C-Cdc20 but also of APC/C-Cdh1 is critical for accurate chromosome segregation in the presence of insufficient kinetochore-microtubule attachments. Conclusions The sequential activation of APC/C-Cdc20 to APC/C-Cdh1 during mitosis is central to accurate mitosis. Precocious activation of APC/C-Cdh1 in metaphase (pre-anaphase) causes mitotic slippage in SAC-activated cells. For the prevention of mitotic slippage, concomitant inhibition of APC/C-Cdh1 may be effective for tumor therapy with mitotic spindle poisons in humans.

2012-01-01

278

PERSONALITY FEATURES AND DISORDER IN THE SUBJECTS IN THE NEW YORK HIGH-RISK PROJECT  

PubMed Central

Summary One hundred and seventy-five offspring of parents in two psychiatrically ill groups and of normal controls in the New York High-Risk Project (NYHRP) were assessed for Axis II personality traits and disorders as defined by the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised (DSM-III-R). These offspring include: subjects at high risk for schizophrenia (HRSz, n = 48), all of whom have a parent with schizophrenic disorder; subjects at high risk for affective disorder (HRAff, n = 40), all of whom have a parent with affective disorder; and subjects at no increased risk for psychiatric illness (NC, n = 87), whose parents are psychiatrically normal. The trained interviewers, who administered a standardized direct interview, were blind to parental clinical status and to previous clinical status of the offspring. The rates for any personality disorder (PD) ranged from 7% to 20%. Comorbidity between Axis I and Axis II disorders was high for all groups.

Squires-Wheeler, Elizabeth; Skodol, Andrew E.; Adamo, Ulla Hilldoff; Bassett, Anne S.; Gewirtz, George R.; Honer, William G.; Cornblatt, Barbara A.; Roberts, Simone A.; Erlenmeyer-Kimling, L.

2011-01-01

279

A single-stage low-frequency electronic ballast for HID lamps featuring high power factor  

Microsoft Academic Search

This paper proposes a high power-factor electronic ballast for metal halide lamps. In the proposed circuit, two buck-boost converters and a buck converter are integrated with a full-bridge inverter of which the four active switches are shared. Two active switches are switched at high frequency, while the others are switched at low frequency. The buck converter is used to step

Hung-Liang Cheng; Yao-Ching Hsieh; Yong-Nong Chang; Kun-Min Tsai

2010-01-01

280

Structural features of powder materials operating under high temperatures, stresses, and wear  

Microsoft Academic Search

It is known that parts of hot zones of metallurgical plants as well as heavily loaded pressing and forging tools operate under\\u000a a high temperature, elevated mechanical stresses, the action of a steam ambient, slag, surface wear due to contact with the\\u000a hot metal, etc. The possibility of providing the requisite properties by using high-temperature alloys has already been exhausted

M. A. Surikova

1998-01-01

281

Moving Magnetic Features Around AR 10930 from High-resolution Data Observed by Hinode/SOT  

NASA Astrophysics Data System (ADS)

We investigate the origin, configuration, and evolution of moving magnetic features (MMFs) in the moat and penumbra regions of NOAA AR 10930 using Hinode/SOT filtergrams and magnetograms. We differentiate MMFs into four types in terms of the location of first appearance and the source of initial flux. The main results are summed up as follows: (1) 50% of the MMFs are produced from or within the penumbra, while 50% are produced within the moat. The MMFs formed in the penumbra normally move outward along radial directions. The MMFs formed in the moat have more dispersed directions of motion. The average speed of most MMFs decreases radially. (2) About 63% of moat fluxes are input by flux emergences. Newly emerged MMFs are normally smaller in size. In their rise phase, they gain flux by adding newly emerging flux or merging other elements, and in the decline phase they lose flux by flux cancellation or fragmentation. The MMFs that are fragments separated from penumbra or other magnetic elements usually have larger flux and longer lifetime. They start their decay process once they are formed. Frequent merging and flux cancellation between MMFs are the dominant factors in MMFs' evolution. (3) Cancellations between opposite-polarity magnetic elements are responsible for most of the low chromospheric bright points. Bipole emergence and MMFs' severance from the penumbra also produce bright points. Elongated or horn-shaped micro-filaments may appear during the separation or cancellation process between magnetic elements.

Li, Xiaobo; Zhang, Hongqi

2013-07-01

282

Essential mitotic functions of DNA topoisomerase IIalpha are not adopted by topoisomerase IIbeta in human H69 cells.  

PubMed

Unique functions of mammalian DNA-topoisomerases IIalpha and -beta are suggested by their distinct cellular distribution and chromatin binding at mitosis. Here, we studied H69-VP cells that, due to a homozygous mutation, express topoisomerase IIalpha mostly outside the nucleus. In these cells topoisomerase IIbeta showed a normal nuclear localization. However, at mitosis it diffused away from the chromatin despite the nuclear lack of the alpha-isoform. 80% of these cells performed chromosome condensation and disjunction with the aid of cytosolic topoisomerase IIalpha, which bound to the mitotic chromatin with low affinity. However, the genotype of these cells was highly polyploid indicating an increased rate of non-disjunction. In 20% of the mutant cells neither topoisomerase II isoform was bound to the mitotic chromatin, which appeared as an unstructured DNA spheroid unable to undergo disjunction and cytokinesis. Parental H69 cells expressing topoisomerase IIalpha inside the nucleus exhibited high affinity binding of the enzyme to the mitotic chromatin. Their genotype was mostly diploid and stable. We conclude (i) that high affinity chromatin binding of topoisomerase IIalpha is essential for chromosome condensation/disjunction and (ii) that topoisomerase IIbeta does not adopt these functions. PMID:9837951

Grue, P; Grässer, A; Sehested, M; Jensen, P B; Uhse, A; Straub, T; Ness, W; Boege, F

1998-12-11

283

A Selective Overview of Variable Selection in High Dimensional Feature Space  

PubMed Central

High dimensional statistical problems arise from diverse fields of scientific research and technological development. Variable selection plays a pivotal role in contemporary statistical learning and scientific discoveries. The traditional idea of best subset selection methods, which can be regarded as a specific form of penalized likelihood, is computationally too expensive for many modern statistical applications. Other forms of penalized likelihood methods have been successfully developed over the last decade to cope with high dimensionality. They have been widely applied for simultaneously selecting important variables and estimating their effects in high dimensional statistical inference. In this article, we present a brief account of the recent developments of theory, methods, and implementations for high dimensional variable selection. What limits of the dimensionality such methods can handle, what the role of penalty functions is, and what the statistical properties are rapidly drive the advances of the field. The properties of non-concave penalized likelihood and its roles in high dimensional statistical modeling are emphasized. We also review some recent advances in ultra-high dimensional variable selection, with emphasis on independence screening and two-scale methods.

Fan, Jianqing

2010-01-01

284

A Characteristic Planetary Feature in Double-Peaked, High-Magnification Microlensing Events  

NASA Astrophysics Data System (ADS)

A significant fraction of microlensing planets have been discovered in high-magnification events, and a significant fraction of these events exhibit a double-peak structure at their peak. However, very wide or very close binaries can also produce double-peaked high-magnification events, with the same gross properties as those produced by planets. Traditionally, distinguishing between these two interpretations has relied on detailed modeling, which is both time-consuming and generally does not provide insight into the observable properties that allow discrimination between these two classes of models. We study the morphologies of these two classes of double-peaked, high-magnification events and identify a simple diagnostic that can be used to immediately distinguish between perturbations caused by planetary and binary companions, without detailed modeling. This diagnostic is based on the difference in the shape of the interpeak region of the light curves. The shape is smooth and concave for binary lensing, while it tends to be either boxy or convex for planetary lensing. In planetary lensing this interpeak morphology is due to the small, weak cusp of the planetary central caustic located between the two stronger cusps. We apply this diagnostic to five observed double-peaked, high-magnification events to infer their underlying nature. A corollary of our study is that good coverage of the interpeak region of double-peaked, high-magnification events is likely to be important for their unique interpretation.

Han, Cheongho; Gaudi, B. Scott

2008-12-01

285

DNAshape: a method for the high-throughput prediction of DNA structural features on a genomic scale.  

PubMed

We present a method and web server for predicting DNA structural features in a high-throughput (HT) manner for massive sequence data. This approach provides the framework for the integration of DNA sequence and shape analyses in genome-wide studies. The HT methodology uses a sliding-window approach to mine DNA structural information obtained from Monte Carlo simulations. It requires only nucleotide sequence as input and instantly predicts multiple structural features of DNA (minor groove width, roll, propeller twist and helix twist). The results of rigorous validations of the HT predictions based on DNA structures solved by X-ray crystallography and NMR spectroscopy, hydroxyl radical cleavage data, statistical analysis and cross-validation, and molecular dynamics simulations provide strong confidence in this approach. The DNAshape web server is freely available at http://rohslab.cmb.usc.edu/DNAshape/. PMID:23703209

Zhou, Tianyin; Yang, Lin; Lu, Yan; Dror, Iris; Dantas Machado, Ana Carolina; Ghane, Tahereh; Di Felice, Rosa; Rohs, Remo

2013-05-22

286

DNAshape: a method for the high-throughput prediction of DNA structural features on a genomic scale  

PubMed Central

We present a method and web server for predicting DNA structural features in a high-throughput (HT) manner for massive sequence data. This approach provides the framework for the integration of DNA sequence and shape analyses in genome-wide studies. The HT methodology uses a sliding-window approach to mine DNA structural information obtained from Monte Carlo simulations. It requires only nucleotide sequence as input and instantly predicts multiple structural features of DNA (minor groove width, roll, propeller twist and helix twist). The results of rigorous validations of the HT predictions based on DNA structures solved by X-ray crystallography and NMR spectroscopy, hydroxyl radical cleavage data, statistical analysis and cross-validation, and molecular dynamics simulations provide strong confidence in this approach. The DNAshape web server is freely available at http://rohslab.cmb.usc.edu/DNAshape/.

Zhou, Tianyin; Yang, Lin; Lu, Yan; Dror, Iris; Dantas Machado, Ana Carolina; Ghane, Tahereh; Di Felice, Rosa; Rohs, Remo

2013-01-01

287

Features of the chemical models of a nonideal atomic plasma at high temperatures  

SciTech Connect

The equation of state for a hydrogen plasma at high temperatures is considered in a physical and a chemical model. A simple expression is obtained that relates the pressure correction in chemical models to the high-temperature limit of the atom partition function. This expression ensures a correct asymptotic behavior of the equation of state in the high-temperature limit. It is explained why the familiar astrophysical model of Hummer, Mihalas, and Daeppen, as applied to helioseismology, yields worse results than a physical model. A modification of the astrophysical model is proposed that makes it possible to use the nearest neighbor approximation to calculate the atom partition function in chemical models in solving astrophysical problems and problems concerning low-temperature plasmas.

Khomkin, A. L.; Shumikhin, A. S. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2008-03-15

288

Features of technology of high-temperature superconductor films for microwave filters  

NASA Astrophysics Data System (ADS)

The characteristics of fourth-order bandpass microwave filters based on high-temperature super-conductor (HTS) films have been numerically simulated and experimentally measured for the devices based on YBCO films purchased from Theva GmbH (Munich) and manufactured at the Institute for Physics of Microstructures (Nizhni Novgorod). Experimental data were used to determine the parameters of the surface impedance model for the HTS films. The results show that HTS-based filters with high performance characteristics can be obtained using HTS films manufactured by different technologies.

Vendik, I. B.; Vendik, O. G.; Zemlyakov, K. N.; Kolmakova, I. V.; Sitnikova, M. F.; Tural'chuk, P. A.; Masterov, D. V.; Pavlov, S. A.; Parafin, A. E.

2011-05-01

289

Dynamics of mitotic activity and expression of viral proteins gp51 and p24 of bovine leukemia virus producing cells.  

PubMed

The dynamics of expression of viral proteins gp51 and p24, virus particle production and mitotic activity of a highly productive bovine leukemia virus clone of the fetal lamb kidney (FLK) cell line were studied. The period of the highest protein production (20-44 h after incubation) was established by the indirect immunofluorescence method using specific monoclonal antibodies. It was followed by a complete formation of the cell monolayer and the most intensive period of the mitotic activity determined by the 3H-thymidine labeling method. After the active synthesis of viral protein, the formation of mature viral particles and their shedding in the intercellular spaces was established electron-microscopically and by the syncytia induction test. A similar comparative study was carried out with a BLV producing short-term lymphocyte culture (STLC). PMID:8157133

Roussev, R; Polianova, M; Portetelle, D; Ivanovna, O

1993-01-01

290

Design features of a seven-cell high-gradient superconducting cavity  

Microsoft Academic Search

A cavity development program is in place at Los Alamos National Laboratory to evaluate structures that could be used to accelerate pions. The work is being guided by the conceptual design of PILAC, a high-gradient superconducting linac for raising the energy of rapidly decaying intense pion beams generated by Los Alamos Meson Physics Facility (LAMPF) to 1 GeV. The specification

D. J. Liska; J. Ledford; S. Black; G. Spalek; J. N. Dimarco

1992-01-01

291

Relationships among Repetitive Behaviors, Sensory Features, and Executive Functions in High Functioning Autism  

ERIC Educational Resources Information Center

|This study examined the relationship between repetitive behaviors and sensory processing issues in school-aged children with high functioning autism (HFA). Children with HFA (N = 61) were compared to healthy, typical controls (N = 64) to determine the relationship between these behavioral classes and to examine whether executive dysfunction…

Boyd, Brian A.; McBee, Matthew; Holtzclaw, Tia; Baranek, Grace T.; Bodfish, James W.

2009-01-01

292

Adiabatic high degree modes of a rotating star. I. General features and real pressure modes  

Microsoft Academic Search

Aims: The influence of the rotation of the Sun on non-radial p-modes with high wave numbers l is studied. To investigate and understand the basic properties of these modes, it is sufficient to consider only the outer layers of the Sun, which can be approximated by a plane layer with constant gravity. Methods: We use a model with a smooth

F. Schmitz; B. Fleck

2010-01-01

293

Distinctive features of fracture processes in screen tubes from nonheated parts of high-pressure boilers  

Microsoft Academic Search

We present the data of metallophysical and metallographic investigations of steam-generating tubes in the lower nonheated parts of high-pressure boilers of heat and electric power plants and study the influence of hydrogen on the corrosion of internal and external surfaces of the tubes.

R. K. Melekhov; O. D. Smiyan; A. V. Vasylyk; V. I. Marchak

1995-01-01

294

A Study of an Alternative High School: Focus, Features and Impact.  

ERIC Educational Resources Information Center

|This paper describes a study of an alternative, innovative high school designed to serve at-risk students and dropouts returning to public school. The PRIDE (Positive Responsible Individuals Desiring Education) Center, located in San Marcos (Texas) Consolidated Independent School District, opened in September 1989. The center's program includes…

Barnes, Susan; Stewart, Jane

295

Precise ego-localization in urban areas using Laserscanner and high accuracy feature maps  

Microsoft Academic Search

Robust ego-localization is an essential technology for future intelligent vehicles and cooperative applications. In this paper a new localization algorithm based on IBEO AS Laserscanners and high accuracy digital maps is proposed. Algorithms to create accurate grid maps with Laserscanners and the extraction of static objects used as landmarks for ego-localization is introduced. The key problem in landmark navigation in

Thorsten Weiss; Nico Kaempchen; K. Dietmayer

2005-01-01

296

p53 regulates a mitotic transcription program and determines ploidy in normal mouse liver.  

PubMed

Functions of p53 during mitosis reportedly include prevention of polyploidy and transmission of aberrant chromosomes. However, whether p53 plays these roles during genomic surveillance in vivo and, if so, whether this is done via direct or indirect means remain unknown. The ability of normal, mature hepatocytes to respond to stimuli, reenter the cell cycle, and regenerate liver mass offers an ideal setting to assess mitosis in vivo. In quiescent liver, normally high ploidy levels in adult mice increased with loss of p53. Following partial hepatectomy, p53(-/-) hepatocytes exhibited early entry into the cell cycle and prolonged proliferation with an increased number of polyploid mitoses. Ploidy levels increased during regeneration of both wild-type (WT) and p53(-/-) hepatocytes, but only WT hepatocytes were able to dynamically resolve ploidy levels and return to normal by the end of regeneration. We identified multiple cell cycle and mitotic regulators, including Foxm1, Aurka, Lats2, Plk2, and Plk4, as directly regulated by chromatin interactions of p53 in vivo. Over a time course of regeneration, direct and indirect regulation of expression by p53 is mediated in a gene-specific manner. Conclusion: Our results show that p53 plays a role in mitotic fidelity and ploidy resolution in hepatocytes of normal and regenerative liver. PMID:23300120

Kurinna, Svitlana; Stratton, Sabrina A; Coban, Zeynep; Schumacher, Jill M; Grompe, Markus; Duncan, Andrew W; Barton, Michelle Craig

2013-02-15

297

MiR-210 disturbs mitotic progression through regulating a group of mitosis-related genes  

PubMed Central

MiR-210 is up-regulated in multiple cancer types but its function is disputable and further investigation is necessary. Using a bioinformatics approach, we identified the putative target genes of miR-210 in hypoxia-induced CNE cells from genome-wide scale. Two functional gene groups related to cell cycle and RNA processing were recognized as the major targets of miR-210. Here, we investigated the molecular mechanism and biological consequence of miR-210 in cell cycle regulation, particularly mitosis. Hypoxia-induced up-regulation of miR-210 was highly correlated with the down-regulation of a group of mitosis-related genes, including Plk1, Cdc25B, Cyclin F, Bub1B and Fam83D. MiR-210 suppressed the expression of these genes by directly targeting their 3?-UTRs. Over-expression of exogenous miR-210 disturbed mitotic progression and caused aberrant mitosis. Furthermore, miR-210 mimic with pharmacological doses reduced tumor formation in a mouse metastatic tumor model. Taken together, these results implicate that miR-210 disturbs mitosis through targeting multi-genes involved in mitotic progression, which may contribute to its inhibitory role on tumor formation.

He, Jie; Wu, Jiangbin; Xu, Naihan; Xie, Weidong; Li, Mengnan; Li, Jianna; Jiang, Yuyang; Yang, Burton B.; Zhang, Yaou

2013-01-01

298

Influence of the circadian rhythm in cell division on radiation-induced mitotic delay in vivo  

SciTech Connect

Mitotic delay is described as a classical response to radiation; however, circadian rhythmicity in cell division in vivo has not been considered by many authors. The present study investigated the relation between fluctuations reported as mitotic delay and recovery in vivo and circadian oscillations in mitotic index in mouse corneal epithelium. One aspect involved single doses (approximately 600 rad) given to mice at different circadian stages. The normal circadian rhythm in cell division was never obliterated. Inhibition of mitosis was evident but unpredictable, ranging from 6 to 15 hr after irradiation. Recovery was evident only during the daily increase in mitotic index of controls. The classical interpretation of recovery from mitotic delay may be in an in vitro phenomenon not reflecting in vivo responses, which are apparently strongly circadian stage dependent. The second portion of the study demonstrated a dose-response effect on length of mitotic delay and, to a lesser extent, degree of recovery.

Rubin, N.H.

1982-01-01

299

Special features of high-speed projectile interaction with barriers protected by a water layer  

NASA Astrophysics Data System (ADS)

The stress-strain state (SSS) of projectiles is investigated when a high-speed projectile enters water and interacts with barriers protected by a water layer. Experimental investigations are carried out using a high-speed ballistic setup. Calculations are performed within the framework of mechanics of continuous media for an elastic plastic model of a solid with allowance for fracture and hydrodynamic water model. Depending on the projectile speed, different SSS regimes are observed: from small deformed at a speed of ?1 km/s to fractured at a speed of ?2 km/s. Calculation technique allows distances in water to be determined at which the metal barrier can be punched for the inertial model.

Afanas'eva, S. A.; Belov, N. N.; Burkin, V. V.; D'yachkovskii, A. S.; Evtyushkin, E. V.; Zykov, E. N.; Ishchenko, A. N.; Monakhov, R. Yu.; Rodionov, A. A.; Khabibullin, M. V.; Yugov, N. T.

2013-09-01

300

High Performance Transistors Featured in an Aggressively Scaled 45nm Bulk CMOS Technology  

Microsoft Academic Search

An aggressively scaled high performance 45 nm bulk CMOS technology targeting graphic, gaming, wireless and digital home applications is presented. Through innovative utilization and integration of advanced stressors, thermal processes and other technology elements, at aggressively scaled 45 nm design ground rules, core NFET and PFET realized world leading drive currents of 1150 and 785 uA\\/um at 100 nA\\/um off

Z. Luo; N. Rovedo; S. Ong; B. Phoong; M. Eller; H. Utomo; C. Ryou; H. Wang; R. Stierstorfer; L. Clevenger; S. Kim; J. Toomey; D. Sciacca; J. Li; W. Wille; L. Zhao; L. Teo; T. Dyer; S. Fang; J. Yan; O. Kwon; J. Holt; J. Han; V. Chan; T. K. J. Yuan; H. Lee; S. Lee; A. Vayshenker; Z. Yang; C. Tian; H. Ng; H. Shang; M. Hierlemann; J. Ku; J. Sudijono; M. Ieong

2007-01-01

301

Gas Dynamic Features of Self Ignition of Non Diluted Fuel\\/Air Mixtures at High Pressure  

Microsoft Academic Search

– The self ignition of several non diluted fuel\\/air mixtures at high pressureis studied. Hydrogen,rsc-ocrane and n-heptane have been used as fuels. Experimentshave been performedusing the shock tube technique. Various observation methods, such as recording of pressure and of light band emission and shadow cinematography have been applied. The type of self ignition 35 well as the ignition delay times

R. BLUMENTHAL; K. FIEWEGER; K. H. KOMP; G. ADOMEIT

1997-01-01

302

Gas Dynamic Features of Self Ignition of Non Diluted Fuel\\/Air Mixtures at High Pressure  

Microsoft Academic Search

The self ignition of several non diluted fuel\\/air mixtures at high pressure is studied. Hydrogen, iso-octane and n-heptane have been used as fuels. Experiments have been performed using the shock tube technique. Various observation methods, such as recording of pressure and of light band emission and shadow cinematography have been applied. The type of self ignition as well as the

R. BLUMENTHAL; K. FIEWEGER; K. H. KOMP; G. ADOMEIT

1996-01-01

303

Features of laser heat treatment of high-speed steel tools  

Microsoft Academic Search

1.The life of high-speed steel tools may be increased significantly as the result of laser treatment.2.Positive results are obtained only after treatment of tools with certain pulse power densities, the values of which must be determined in each specific case.3.The optimum values of laser radiation pulse power density must be selected on the basis of the structure of the steel

V. S. D'yachenko; G. N. Tverdokhlebov; A. A. Korosteleva

1984-01-01

304

Features of brittle damages and hydrogen impregnation of high-pressure boiler tube metal  

Microsoft Academic Search

A significant number of failures encountered in high-pressure steam boilers of thermal electric power stations are caused by damage of the tubes of the steam superheaters, which are made of 20, 12Kh1MF, 12Kh2MFSR and 12Kh18N10T steels. A statistical analysis made by the authors determined that a large number of the failures result from the action of hydrogen on the tubes.

A. B. Vainman; O. D. Smiyan; So I. Girnyi; N. P. Kostyuchenko; A. V. Vasilik; R. K. Melekhov

1988-01-01

305

High speed replication of submicron features on large areas by X-ray lithography  

Microsoft Academic Search

To achieve the high throughput necessary for a practical X-ray lithographic system, we have devised a new overall approach to X-ray lithography based on the use of X-rays with wavelengths of 4-6 Å rather than the 8.34-Å wavelength used in previous work. The principal advantage of the shorter wavelengths is that they allow a system to have X-ray windows so

D. Maydan; G. A. Coquin; J. R. Maldonado; S. Somekh; D. Y. Lou; G. N. Taylor

1975-01-01

306

Deltex-1 activates mitotic signaling and proliferation and increases the clonogenic and invasive potential of U373 and LN18 glioblastoma cells and correlates with patient survival.  

PubMed

Glioblastoma (GBM) is a highly malignant primary tumor of the central nervous system originating in glial cells. GBM results in more years of life lost than any other cancer type. Low levels of Notch receptor expression correlates with prolonged survival in various high grade gliomas independent of other markers. Different downstream pathways of Notch receptors have been identified. We tested if the Notch/Deltex pathway, which is distinct from the canonical, CSL-mediated pathway, has a role in GBM. We show that the alternative or non-canonical Notch pathway functioning through Deltex1 (DTX1) mediates key features of glioblastoma cell aggressiveness. For example, DTX1 activates the RTK/PI3K/PKB and the MAPK/ERK mitotic pathways and induces anti-apoptotic Mcl-1. The clonogenic and growth potential of established glioma cells correlated with DTX1 levels. Microarray gene expression analysis further identified a DTX1-specific, MAML1-independent transcriptional program - including microRNA-21- which is functionally linked to the changes in tumor cell aggressiveness. Over-expression of DTX1 increased cell migration and invasion correlating to ERK activation, miR-21 levels and endogenous Notch levels. In contrast to high and intermediate expressors, patients with low DTX1 levels have a more favorable prognosis. The alternative Notch pathway via DTX1 appears to be an oncogenic factor in glioblastoma and these findings offer new potential therapeutic targets. PMID:23451269

Huber, Roland M; Rajski, Michal; Sivasankaran, Balasubramanian; Moncayo, Gerald; Hemmings, Brian A; Merlo, Adrian

2013-02-25

307

High Constitutive Activity Is an Intrinsic Feature of Ghrelin Receptor Protein  

PubMed Central

Despite its central role in signaling and the potential therapeutic applications of inverse agonists, the molecular mechanisms underlying G protein-coupled receptor (GPCR) constitutive activity remain largely to be explored. In this context, ghrelin receptor GHS-R1a is a peculiar receptor in the sense that it displays a strikingly high, physiologically relevant, constitutive activity. To identify the molecular mechanisms responsible for this high constitutive activity, we have reconstituted a purified GHS-R1a monomer in a lipid disc. Using this reconstituted system, we show that the isolated ghrelin receptor per se activates Gq in the absence of agonist, as assessed through guanosine 5?-O-(thiotriphosphate) binding experiments. The measured constitutive activity is similar in its extent to that observed in heterologous systems and in vivo. This is the first direct evidence for the high constitutive activity of the ghrelin receptor being an intrinsic property of the protein rather than the result of influence of its cellular environment. Moreover, we show that the isolated receptor in lipid discs recruits arrestin-2 in an agonist-dependent manner, whereas it interacts with ?-AP2 in the absence of ligand or in the presence of ghrelin. Of importance, these differences are linked to ligand-specific GHS-R1a conformations, as assessed by intrinsic fluorescence measurements. The distinct ligand requirements for the interaction of purified GHS-R1a with arrestin and AP2 provide a new rationale to the differences in basal and agonist-induced internalization observed in cells.

Damian, Marjorie; Marie, Jacky; Leyris, Jean-Philippe; Fehrentz, Jean-Alain; Verdie, Pascal; Martinez, Jean; Baneres, Jean-Louis; Mary, Sophie

2012-01-01

308

The Fisher-Markov Selector: Fast Selecting Maximally Separable Feature Subset for Multiclass Classification with Applications to High-Dimensional Data  

Microsoft Academic Search

Selecting features for multiclass classification is a critically important task for pattern recognition and machine learning applications. Especially challenging is selecting an optimal subset of features from high-dimensional data, which typically have many more variables than observations and contain significant noise, missing components, or outliers. Existing methods either cannot handle high-dimensional data efficiently or scalably, or can only obtain local

Qiang Cheng; Hongbo Zhou; Jie Cheng

2011-01-01

309

A small mission featuring an imaging x-ray polarimeter with high sensitivity  

NASA Astrophysics Data System (ADS)

We show that meaningful, highly sensitive x-ray polarimetry with imaging capability is possible with a small mission tailored to the NASA Explorer program. Such a mission—derived from the Imaging X-ray Polarimetry Explorer (IXPE) proposed to a previous NASA call—takes advantage of progress in light-weight x-ray optics and in gas pixel detectors to achieve sensitive time-resolved, spectrometric, imaging polarimetry. We outline the main characteristics and requirements of this mission and provide a realistic assessment of its scientific utility for modeling point-like and extended x-ray sources and for studying physical processes (including questions of fundamental physics).

Weisskopf, Martin C.; Baldini, Luca; Bellazini, Ronaldo; Brez, Alessandro; Costa, Enrico; Dissly, Richard; Elsner, Ronald F.; Fabiani, Sergio; Matt, Giorgio; Minuti, Massimo; Muleri, Fabio; O'Dell, Steve; Pinchera, Michele; Ramsey, Brian; Rubini, Alda; Sgro', Carmelo; Soffitta, Paolo; Spandre, Gloria

2013-09-01

310

Positron transport and annihilation in expanding flows: A model for the high-latitude annihilation feature  

SciTech Connect

Positron sources in the vicinity of the Galactic Center can account for the recently discovered high-latitude 0.511 MeV annihilation radiation if the positrons are convected away from the disk of the Galaxy and annihilate during transport. Here we describe our treatment for positron energy loss and thermalization, transport, and annihilation. The concept of the Maxwell-Boltzmann length (a generalized stopping distance) is outlined, and a model map of the distribution of annihilation radiation is presented for idealized flows.

Dermer, Charles D.; Skibo, Jeffrey G. [E. O. Hulburt Center for Space Research, Code 7653, Naval Research Laboratory, Washington, District of Columbia 20375 (United States)

1997-05-10

311

Mesenchymal hamartoma of the liver associated with features of Beckwith-Wiedemann syndrome and high serum alpha-fetoprotein levels.  

PubMed

A 5-month-old girl with clinical features of Beckwith-Wiedemann syndrome (BWS), including a repaired omphalocele, an earlobe crease, enlarged adrenal glands, renal size discrepancy, and hyperinsulinemic hyperglycemia, presented with a 1.9-cm liver nodule. Markedly increased serum alpha-fetoprotein (AFP) levels (1,060,000 mg/L), highly suspicious for hepatoblastoma, were detected, and resection of the liver mass was performed. Histologic sections showed features characteristic of a mesenchymal hamartoma of the liver (MHL). No features of embryonal or fetal hepatocellular proliferation or heterologous stromal components were noted. By immunohistochemistry, the hepatocytes expressed AFP, but no nuclear accumulation of beta-catenin was present. Electron microscopy revealed normal, mature hepatocytes. Here we address the diagnostic challenge of the uncommon association of MHL and BWS in the setting of markedly elevated serum AFP levels. In addition, we analyze the unusual pancreatic lesion (focal endocrine adenomatosis) leading to severe hyperinsulinemic hypoglycemia in a patient with possible BWS. We emphasize that MHLs may present with markedly increased serum AFP levels, mimicking hepatoblastomas, and may also be part of the expanding spectrum of findings of BWS. PMID:17535089

Cajaiba, Mariana M; Sarita-Reyes, Carmen; Zambrano, Eduardo; Reyes-Múgica, Miguel

312

A New Mutant Controlling Mitotic Chromosome Disjunction in DROSOPHILA MELANOGASTER  

PubMed Central

A new mutant, mit (mitotic loss inducer), is described. The mutant is recessive and maternal in action, producing gynandromorphs and haplo-4 mosaics among the progeny of homozygous mit females. Mosaic loss of maternal or paternal chromosomes can occur. The probabilities of either maternal or paternal X chromosome loss are equal. mit has been mapped to approximately 57 on the standard X chromosome map.—Using gyandromorphs generated by mit, a morphogenetic fate map, placing the origins of 40 cuticular structures on the blastoderm surface, has been constructed. This fate map is consistent with embryological data and with the two other fate maps generated in different ways.

Gelbart, William M.

1974-01-01

313

Small Compound 6-O-Angeloylplenolin Induces Mitotic Arrest and Exhibits Therapeutic Potentials in Multiple Myeloma  

PubMed Central

Background Multiple myeloma (MM) is a disease of cell cycle dysregulation while cell cycle modulation can be a target for MM therapy. In this study we investigated the effects and mechanisms of action of a sesquiterpene lactone 6-O-angeloylplenolin (6-OAP) on MM cells. Methodology/Principal Findings MM cells were exposed to 6-OAP and cell cycle distribution were analyzed. The role for cyclin B1 to play in 6-OAP-caused mitotic arrest was tested by specific siRNA analyses in U266 cells. MM.1S cells co-incubated with interleukin-6 (IL-6), insulin-like growth factor-I (IGF-I), or bone marrow stromal cells (BMSCs) were treated with 6-OAP. The effects of 6-OAP plus other drugs on MM.1S cells were evaluated. The in vivo therapeutic efficacy and pharmacokinetic features of 6-OAP were tested in nude mice bearing U266 cells and Sprague-Dawley rats, respectively. We found that 6-OAP suppressed the proliferation of dexamethasone-sensitive and dexamethasone-resistant cell lines and primary CD138+ MM cells. 6-OAP caused mitotic arrest, accompanied by activation of spindle assembly checkpoint and blockage of ubiquitiniation and subsequent proteasomal degradation of cyclin B1. Combined use of 6-OAP and bortezomib induced potentiated cytotoxicity with inactivation of ERK1/2 and activation of JNK1/2 and Casp-8/-3. 6-OAP overcame the protective effects of IL-6 and IGF-I on MM cells through inhibition of Jak2/Stat3 and Akt, respectively. 6-OAP inhibited BMSCs-facilitated MM cell expansion and TNF-?-induced NF-?B signal. Moreover, 6-OAP exhibited potent anti-MM activity in nude mice and favorable pharmacokinetics in rats. Conclusions/Significance These results indicate that 6-OAP is a new cell cycle inhibitor which shows therapeutic potentials for MM.

Liu, Ying; Chen, Xiao-Qin; Liang, Heng-Xing; Zhang, Feng-Xiang; Zhang, Bo; Jin, Jie; Chen, Yong-Long; Cheng, Yong-Xian; Zhou, Guang-Biao

2011-01-01

314

Features of brittle damages and hydrogen impregnation of high-pressure boiler tube metal  

SciTech Connect

A significant number of failures encountered in high-pressure steam boilers of thermal electric power stations are caused by damage of the tubes of the steam superheaters, which are made of 20, 12Kh1MF, 12Kh2MFSR and 12Kh18N10T steels. A statistical analysis made by the authors determined that a large number of the failures result from the action of hydrogen on the tubes. In this paper, the mechanisms of hydrogen diffusion, corrosion crack propagation, and brittle failure for steam superheater tubes were analyzed. Hydrogen-related intergranular cracking and thermal fatigue were assessed for the tube steels. It was concluded that hydrogen had a significant effect on processes of crack origin and propagation both in the superheater and in the unheated tubes of the boilers.

Vainman, A.B.; Smiyan, O.D.; Girnyi, S.I.; Kostyuchenko, N.P.; Vasilik, A.V.; Melekhov, R.K.

1988-01-01

315

Microstructure features of high-entropy equiatomic cast AlCrFeCoNiCu alloys  

NASA Astrophysics Data System (ADS)

The structural and phase transformations that take place in the cast high-entropy equiatomic alloy AlCrFeCoNiCu after solidification, homogenizing heat treatment, and cooling have been studied. Analytical transmission microscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, and X-ray diffraction analysis were used to conduct the studies. The elastic modulus, nano-, and microhardness have been measured. The alloy decomposition has been found to occur with the precipitation of no less than six nanoscale phases with different morphologies, structures ( A2, B2, L12), and chemical compositions. All the nanophases are multicomponent solid solutions enriched with several elements, which indicates the pronounced elemental and phase nanomodulation over the alloy volume.

Ivchenko, M. V.; Pushin, V. G.; Uksusnikov, A. N.; Wanderka, N.

2013-06-01

316

Resonant nanocluster technology—from optical coding and high quality security features to biochips  

NASA Astrophysics Data System (ADS)

Metal clusters deposited on a substrate and positioned at a nanometric distance from a wave-reflecting layer act as nanoresonators able to receive, store and transmit energy within the visible and infrared range of the spectrum. Among the unique effects of these metal nanocluster assemblies are high local field enhancement and nanoscale resonant behaviour driving optical absorption in the visible and infrared range of the spectrum. In these types of devices and sensors the precise nanometric assembly coupling the local field surrounding a cluster is critical for allowing resonance with other elements interacting with this field. In particular, the cluster-mirror distance or the cluster-fluorophore distance gives rise to a variety of enhancement phenomena (e.g. resonant-enhanced fluorescence, REF). Depending on the desired application this 'resonance' distance is tuned from 5 up to 500 nm. High-throughput transducers using metal cluster resonance technology are based on surface enhancement of light absorption by metal clusters (surface-enhanced absorption, SEA). These devices can be used for detection of biorecognition binding as well as structural changes in nucleic acids, proteins or any polymer. The optical property made use of in the analytical application of metal cluster films is so-called anomalous absorption. An absorbing film of clusters is positioned 10-400 nm from an electromagnetic wave-reflecting layer. At a well-defined mirror-cluster distance the reflected electromagnetic field has the same phase at the position of the absorbing cluster as the incident field. This feedback mechanism strongly enhances the effective cluster absorption coefficient. These systems are characterized by a narrow reflection minimum whose spectral position shifts sensitively with interlayer thickness, because a given cluster-mirror distance and wavelength defines the optimum phase.

Bauer, G.; Hassmann, J.; Walter, H.; Haglmüller, J.; Mayer, C.; Schalkhammer, T.

2003-12-01

317

Features of highly structured equatorial plasma irregularities deduced from CHAMP observations  

NASA Astrophysics Data System (ADS)

In this study five years of CHAMP (Challenging Mini-satellite Payload) fluxgate magnetometer (FGM) data is used to investigate the characteristics of Equatorial Plasma Bubbles (EPBs). We filtered the FGM data by using band-passes with four different cut-off periods to get the EPBs with different maximum spatial scale sizes in the meridional plane ranging from 76-608 km. Associated with the EPB observations at about 400 km, the typical altitude of CHAMP during the year 2000-2005, we also investigate the post-sunset equatorial vertical plasma drift data from ROCSAT-1 (Republic of China Satellite 1). Since the height of the F-layer is highly correlated with the vertical plasma drift and solar flux, we sorted the ROCSAT-1 data into different groups by F10.7. From the integrated vertical drift we have estimated the post-sunset uplift of the ionosphere. By comparing the properties of EPB occurrence for different scale sizes with the global distribution of plasma vertical uplift, we have found that EPBs reaching higher altitudes are more structured than those which are sampled by CHAMP near the top side of the depleted fluxtube. Such a result is in accord with 3-D model simulations (Aveiro and Hysell, 2010). Small-scale EPB structures are observed by CHAMP when the irregularities reach apex heights of 800 km and more. Such events are encountered primarily in the Brazilian sector during the months around November, when the post-sunset vertical plasma drift is high.

Xiong, C.; Lühr, H.; Ma, S. Y.; Stolle, C.; Fejer, B. G.

2012-08-01

318

The Structure, Water Budget, and Radiational Features of a High-Latitude Warm Front.  

NASA Astrophysics Data System (ADS)

On 30 September 1994 an Arctic low pressure system passed over the southern Beaufort Sea area of northern Canada and research aircraft observations were made within and around the warm front of the storm. This study is unique in that the warm front contained subzero centigrade temperatures across the entire frontal region. The overall structure of the warm front and surrounding region was similar to midlatitude storms; however, the precipitation rates, liquid water content magnitudes, horizontal and vertical winds, vertical wind shear, turbulence, and thermal advection were very weak. In addition, a low-level jet and cloud bands were aligned parallel to the warm front, near-neutral stability occurred within and around the front, and conditional symmetric instability was likely occurring. A steep frontal region resulted from strong Coriolis influences that in turn limited the amount of cloud and precipitation ahead of the system. The precipitation efficiency of the storm was high (60%) but is believed to be highly dependent on the stage of development. The mesoscale frontogenetic forcing was primarily controlled by the tilting of isentropic surfaces with confluence/convergence being the secondary influence. Sublimation contributions may have been large in the earlier stages of storm development. Satellite and aircraft radiometers underestimated cloud top heights by as much as 4 km and this was mostly due to the near transparency of the lofted ice layer in the upper portion of the storm. Maximum surface solar radiation deficits ranged between 91 W m2 and 187 W m2 at two surface observing sites. This common type of cloud system must have a major impact on the water and energy cycles of northern Canada in the autumn and therefore must be well accounted for within climate models.

Hanesiak, John M.; Stewart, Ronald E.; Szeto, Kit K.; Hudak, David R.; Leighton, Henry G.

1997-06-01

319

High-Resolution Transcriptome Maps Reveal Strain-Specific Regulatory Features of Multiple Campylobacter jejuni Isolates  

PubMed Central

Campylobacter jejuni is currently the leading cause of bacterial gastroenteritis in humans. Comparison of multiple Campylobacter strains revealed a high genetic and phenotypic diversity. However, little is known about differences in transcriptome organization, gene expression, and small RNA (sRNA) repertoires. Here we present the first comparative primary transcriptome analysis based on the differential RNA–seq (dRNA–seq) of four C. jejuni isolates. Our approach includes a novel, generic method for the automated annotation of transcriptional start sites (TSS), which allowed us to provide genome-wide promoter maps in the analyzed strains. These global TSS maps are refined through the integration of a SuperGenome approach that allows for a comparative TSS annotation by mapping RNA–seq data of multiple strains into a common coordinate system derived from a whole-genome alignment. Considering the steadily increasing amount of RNA–seq studies, our automated TSS annotation will not only facilitate transcriptome annotation for a wider range of pro- and eukaryotes but can also be adapted for the analysis among different growth or stress conditions. Our comparative dRNA–seq analysis revealed conservation of most TSS, but also single-nucleotide-polymorphisms (SNP) in promoter regions, which lead to strain-specific transcriptional output. Furthermore, we identified strain-specific sRNA repertoires that could contribute to differential gene regulation among strains. In addition, we identified a novel minimal CRISPR-system in Campylobacter of the type-II CRISPR subtype, which relies on the host factor RNase III and a trans-encoded sRNA for maturation of crRNAs. This minimal system of Campylobacter, which seems active in only some strains, employs a unique maturation pathway, since the crRNAs are transcribed from individual promoters in the upstream repeats and thereby minimize the requirements for the maturation machinery. Overall, our study provides new insights into strain-specific transcriptome organization and sRNAs, and reveals genes that could modulate phenotypic variation among strains despite high conservation at the DNA level.

Forstner, Konrad U.; Heidrich, Nadja; Reinhardt, Richard; Nieselt, Kay; Sharma, Cynthia M.

2013-01-01

320

Dosimetric features and kinetic analysis of thermoluminescence from ultra-high molecular weight polyethylene  

NASA Astrophysics Data System (ADS)

Thermoluminescence (TL) from beta irradiated ultra-high molecular weight polyethylene has been studied for measurements between 30 and 200 °C. An aliquot studied in this work produced TL glow curves consisting of two peaks, the main peak at 88 °C and a weaker intensity peak at 148 °C for heating at 1 °C s-1 following an excitation dose of 215 Gy. The position of the main peak is poorly reproducible for heating rates of 0.2 and 0.6 °C s-1 investigated with the peak position decreasing when the sample is freshly irradiated and the TL re-measured. The said change in peak position is however less of an effect for measurements made at 1 °C s-1 with the peak position being fairly reproducible in this case. Further measurements of the dosimetric properties of ultra-high molecular weight polyethylene showed that its dose response is linear from 26 Gy to about 161 Gy but exhibits slower growth in intensity with dose from about 860 Gy after regions of sub- and supra-linearity in between. If the TL is not measured immediately after irradiation, the signal fades with the delay approximately exponentially. In addition, a number of tests including phosphorescence analysis showed the possibility that the order of kinetics might not be unique but sensitive to several factors including measurement temperature. Thus for instance, the dependence of the peak position on the stop temperature in the partial heating procedure Tm - Tstop implied first-order kinetics but analysis of the geometrical factor ?g for the same set of data gave ?g = 0.46 ± 0.03 a value corresponding to characteristics somewhat intermediate between first and second order. In comparison, the results of analysis of the phosphorescence recorded at several temperatures on the rising edge of the main peak were only in agreement for measurements at 40 °C with general-order analysis suggesting second-order kinetics apply as did TL-like transformation of the monotonic phosphorescence decay. Both results were also consistent with an additional finding that the time dependence of the isothermal decay at 40 °C was consistent with second-order kinetics. Analysis of the TL for the activation energy using the initial rise method, variable heating rate procedure, TL-like transformation of phosphorescence and the peak shape estimates, produced a self-consistent set of values equal to 0.76 ±0.05 eV, 0.66±0.03 eV, 0.77±0.06 eV and values of the order of 0.8 eV, respectively. The kinetic parameters found in this study compare favourably with literature values.

Chithambo, M. L.

2012-08-01

321

Two Strains of Crocosphaera watsonii with Highly Conserved Genomes are Distinguished by Strain-Specific Features  

PubMed Central

Unicellular nitrogen-fixing cyanobacteria are important components of marine phytoplankton. Although non-nitrogen-fixing marine phytoplankton generally exhibit high gene sequence and genomic diversity, gene sequences of natural populations and isolated strains of Crocosphaera watsonii, one of the two most abundant open ocean unicellular cyanobacteria groups, have been shown to be 98–100% identical. The low sequence diversity in Crocosphaera is a dramatic contrast to sympatric species of Prochlorococcus and Synechococcus, and raises the question of how genome differences can explain observed phenotypic diversity among Crocosphaera strains. Here we show, through whole genome comparisons of two phenotypically different strains, that there are strain-specific sequences in each genome, and numerous genome rearrangements, despite exceptionally low sequence diversity in shared genomic regions. Some of the strain-specific sequences encode functions that explain observed phenotypic differences, such as exopolysaccharide biosynthesis. The pattern of strain-specific sequences distributed throughout the genomes, along with rearrangements in shared sequences is evidence of significant genetic mobility that may be attributed to the hundreds of transposase genes found in both strains. Furthermore, such genetic mobility appears to be the main mechanism of strain divergence in Crocosphaera which do not accumulate DNA microheterogeneity over the vast majority of their genomes. The strain-specific sequences found in this study provide tools for future physiological studies, as well as genetic markers to help determine the relative abundance of phenotypes in natural populations.

Bench, Shellie R.; Ilikchyan, Irina N.; Tripp, H. James; Zehr, Jonathan P.

2011-01-01

322

Feature extraction for cellular shape analysis in high-content screening (HCS) applications  

NASA Astrophysics Data System (ADS)

Detailed information on cellular and sub-cellular interactions can be extracted from large-scale data sets through the application of image processing and analysis techniques from computer vision and pattern recognition. An automated, high-speed method for analysis of cellular systems in 2D includes boundary analysis of the cells and may be extended to texture (content) analysis or further. The overall goal of such analysis is to reach conclusions as to the physiological state and behavior of the cells. In this paper, we focus on shape analysis of cells, as shape is an effective factor for quantification of the many apparent physiological changes. We explore shape analysis techniques, including geometric (regular), Zernike, and Krawtchouk moment invariants. We also report on our investigation of the effects of resolution changes (in imaging systems) on the descriptors of cell shape in terms of stability and consistence of these moment invariants. Our results show that Krawtchouk moment invariants are better cell shape descriptors compared to geometric moment invariants in low resolution images.

Bayraktar, Bulent; Rajwa, Bartek; Robinson, J. Paul

2005-03-01

323

Vibrational features of water at the low-density/high-density liquid structural transformations  

NASA Astrophysics Data System (ADS)

A structural transformation in water upon compression was recently observed at the temperature T=277K in the vicinity of the pressure p?2000atm [R.M. Khusnutdinoff, A.V. Mokshin, J. Non-Cryst. Solids 357 (2011) 1677]. It was found that the transformations are related with the principal structural changes within the first two coordination shells as well as the deformation of the hydrogen-bond network. In this work, we study in detail the influence of these structural transformations on the vibrational molecular dynamics of water by means of molecular dynamics simulations on the basis of the model Amoeba potential (T=290K, p=1.0÷10000atm). The equation of state and the isothermal compressibility are found for the considered (p, T)-range. The vibrational density of states extracted for THz-frequency range manifests two distinct modes, where the high-frequency mode is independent of pressure whereas the low-frequency one has the strong, non-monotonic pressure-dependence and exhibits a step-like behavior at the pressure p?2000atm. The extended analysis of the local structural and vibrational properties discovers that there is a strong correlation between the primary structural and vibrational aspects of the liquid-liquid structural transformation related with the molecular rearrangement within the range of the second coordination shell.

Khusnutdinoff, Ramil M.; Mokshin, Anatolii V.

2012-05-01

324

A Novel Yeast Screen for Mitotic Arrest Mutants Identifies DOC1, a New Gene Involved in Cyclin Proteolysis  

PubMed Central

B-type cyclins are rapidly degraded at the transition between metaphase and anaphase and their ubiquitin-mediated proteolysis is required for cells to exit mitosis. We used a novel enrichment to isolate new budding mutants that arrest the cell cycle in mitosis. Most of these mutants lie in the CDC16, CDC23, and CDC27 genes, which have already been shown to play a role in cyclin proteolysis and encode components of a 20S complex (called the cyclosome or anaphase promoting complex) that ubiquitinates mitotic cyclins. We show that mutations in CDC26 and a novel gene, DOC1, also prevent mitotic cyclin proteolysis. Mutants in either gene arrest as large budded cells with high levels of the major mitotic cyclin (Clb2) protein at 37°C and cannot degrade Clb2 in G1-arrested cells. Cdc26 associates in vivo with Doc1, Cdc16, Cdc23, and Cdc27. In addition, the majority of Doc1 cosediments at 20S with Cdc27 in a sucrose gradient, indicating that Cdc26 and Doc1 are components of the anaphase promoting complex.

Hwang, Lena H.; Murray, Andrew W.

1997-01-01

325

DE/ISIS conjunction comparisons of high-latitude electron density features  

SciTech Connect

Electron number density (N/sub e/) profiles determined remotely by ISIS 1 and 2 topside sounder measurements were compared with in situ ion and electron density measurements by the Dynamics Explorer 2 (DE 2) Langmuir probe during four high-latitude ISIS/DE magnetic field-aligned conjunctions. In all cases, the universal time separations between the two data sets were small (less than 12 min). The horizontal separations away from conjunction were up to several thousand kilometers. The N/sub e/ comparisons near the conjunction times represents the first cross-calibration of in situ probe and remote topside sounding N/sub e/ measurements. The ISIS-derived N/sub e/ values, even at the greatest distance from the sounder (near the F peak), agreed with the DE 2 Langmuir probe measurements to within about 30% over a density range of more than 2 decades on three of the comparisons. The fourth comparison, which only had data on one side of the conjunction in a region with strong N/sub e/ irregularities, showed a difference of about 60%. Away from conjunction the N/sub e/ comparisons were made by displaying N/sub e/ along the orbital tracks on invariant latitude (..lambda..)/magnetic local time (MLT) polar plots, or by displaying N/sub e/ versus time where the two data sets are mapped to one another either along arcs of constant ..lambda.. or along radii of constant MLT. These plots display density structure simultaneously at distinct locations in the convection controlled polar ionosphere.

Hoegy, W.R.; Benson, R.F.

1988-06-01

326

Freeform mirror fabrication and metrology using a high performance test CGH and advanced alignment features  

NASA Astrophysics Data System (ADS)

The metrology of mirrors with an off-axis aspheric or freeform shape can be based on optical testing using a Computer Generated Hologram as wavefront matching element in an interferometric setup. Since the setup can be understood as optical system consisting of multiple elements with six degrees of freedom each, the accuracy strongly depends on the alignment of the surface under test with respect to the transmission element of the interferometer and the micro optics of the CGH. A novel alignment approach for the relative positioning of the mirror and CGH in six degrees of freedom is reported. In the presented work, a proper alignment is achieved by illuminating alignment elements outside the Clear Aperture (CA) of the optical surface with the help of auxiliary holograms next to the test CGH on the substrate. The peripheral holograms on the CGH substrate are used to generate additional phase maps in the interferogram, that indicate positioning errors. Since the reference spheres represent the coordinate system of the mirror and are measured in the same precision as the optical surface, the registration and shape has to be appropriate to embody the mirrors coordinate system. The alignment elements on the mirror body are diamond machined using freeform turning or micro milling processes in the same machine setup used for the mirror manufacturing. The differences between the turning and milling of alignment lenses is discussed. The novel approach is applied to correct the shape error of a freeform mirror using ultra precision machining. The absolute measurement of the quality of freeform mirror shapes including tilt and optical power is possible using the presented alignment concept. For a better understanding, different metrology methods for aspheres and freeforms are reviewed. To verify the novel method of alignment and the measurement results, the freeform surface is also characterized using ultra high accuracy 2½D profilometry. The results of the different techniques for the absolute measurement of freeforms are compared.

Scheiding, Sebastian; Beier, Matthias; Zeitner, Uwe-Detlef; Risse, Stefan; Gebhardt, Andreas

2013-03-01

327

High Susceptibility for Enterovirus Infection and Virus Excretion Features in Tunisian Patients with Primary Immunodeficiencies  

PubMed Central

To estimate the susceptibility to enterovirus infection and the frequency of long-term poliovirus excreters in Tunisian patients with primary immunodeficiencies (PIDs), enteroviruses were assessed in stool specimens of 82 patients with humoral, combined, and other PIDs. Isolated viruses were typed and intratyped by standard molecular techniques, and the whole VP1 region of poliovirus isolates was sequenced. Polioviruses were detected in 6 patients; all isolates were vaccine related. Five patients rapidly stopped excretion; one excreted a poliovirus type 1 isolate for several months, and the isolate accumulated up to 14 mutations in the VP1 region. Nonpolio enteroviruses were identified in 6 patients; 4 of them kept excreting the same strain for more than 6 months. The rate of enterovirus infection was 13.4% of the PID patients and 20.7% of those with an IgG defect; it greatly exceeded the rates generally found in Tunisian supposed-immunocompetent individuals (4.1% during the study period; P = 0.001 and P < 0.0001, respectively). Interestingly, patients with combined immunodeficiencies were at a higher risk for enterovirus infection than those with an exclusively B cell defect. A major histocompatibility complex (MHC) class II antigen expression defect was found in 54% of enterovirus-positive patients and in the unique long-term poliovirus excreter. The study results also suggest that substitutive immunoglobulin therapy may help clearance of a poliovirus infection and that most PID patients have the ability to stop poliovirus excretion within a limited period. However, the high susceptibility of these patients to enterovirus infection reinforces the need for enhanced surveillance of these patients until the use of oral poliovirus vaccine (OPV) is stopped.

Driss, Nadia; Ben-Mustapha, Imen; Mellouli, Fethi; Ben Yahia, Ahlem; Touzi, Henda; Bejaoui, Mohamed; Ben Ghorbel, Mohamed; Barbouche, Mohamed-Ridha

2012-01-01

328

High-risk angina patient. Identification by clinical features, hospital course, electrocardiography and technetium-99m stannous pyrophosphate scintigraphy  

SciTech Connect

We evaluated 193 consecutive unstable angina patients by clinical features, hospital course and electrocardiography. All patients were managed medically. Of the 193 patients, 150 (78%) had a technetium-99m pyrophosphate (Tc-PYP) myocardial scintigram after hospitalization. Of these, 49 (33%) had positive scintigrams. At a follow-up of 24.9 +/- 10.8 months after hospitalization, 16 of 49 patients (33%) with positive scintigrams died from cardiac causes, compared with six of 101 patients (6%) with negative scintigrams (p less than 0.001). Of 49 patients with positive scintigrams, 11 (22%) had had nonfatal myocardial infarction at follow-up, compared with seven of 101 patients (7%) with negative scintigrams (p less than 0.01). Age, duration of clinical coronary artery disease, continuing angina during hospitalization, ischemic ECG, cardiomegaly and a history of heart failure also correlated with cardiac death at follow-up. Ischemic ECG and a history of angina with a crescendo pattern also correlated with nonfatal infarction at follow-up. Patients with continuing angina, an ischemic ECG and a positive scintigram constituted a high-risk unstable angina subgroup with a survival rate of 58% at 6 months, 47% at 12 months and 42% at 24 and 36 months. We conclude that the assessment of clinical features, hospital course, ECG and Tc-PYP scintigraphy may be useful in identifying high-risk unstable angina patients.

Olson, H.G.; Lyons, K.P.; Aronow, W.S.; Stinson, P.J.; Kuperus, J.; Waters, H.J.

1981-10-01

329

High-risk angina patient: identification by clinical features, hospital course, electrocardiography, and technetium-99m stannous pyrophosphate scintigraphy  

SciTech Connect

We evaluated 193 consecutive unstable angina patients by clinical features, hospital course and electrocardiography. All patients were managed medically. Of the 193 patients, 150 (78%) had a technetium-99m pyrophosphate (Tc-PYP) myocardial scintigram after hospitalization. Of these, 49 (33%) had positive scintigrams. At a follow-up of 24.9 +- 10.8 months after hospitalization, 16 of 49 patients (33%) with positive scintigrams died from cardiac causes, compared with six of 101 patients (6%) with negative scintigrams (p < 0.001). Of 49 patients with positive scintigrams, 11 (22%) had had nonfatal myocardial infarction at follow-up, compared with seven of 101 patients (7%) with negative scintigrams (p < 0.01). Age, duration of clinical coronary artery disease, continuing angina during hospitalization, ischemic ECG, cardiomegaly and a history of heart failure also correlated with cardiac death at follow-up. Ischemic ECG and a history of angina with a crescendo pattern also correlated with nonfatal infarction at follow-up. Patients with continuing angina, an ischemic ECG and a positive scintigram constituted a high-risk unstable angina subgroup, with a survival rate of 58% at 6 months, 47% at 12 months and 42% at 24 and 36 months. We conclude that the assessment of clinical features, hospital course, ECG and Tc-PYP scintigraphy may be useful in identifying high-risk unstable angina patients.

Olson, H.G. (Univ. of California, Irvine); Lyons, K.P.; Aronow, W.S.; Stinson, P.J.; Kuperus, J.; Waters, H.J.

1981-10-01

330

Towards a quantitative understanding of mitotic spindle assembly and mechanics  

PubMed Central

The ‘simple’ view of the mitotic spindle is that it self-assembles as a result of microtubules (MTs) randomly searching for chromosomes, after which the spindle length is maintained by a balance of outward tension exerted by molecular motors on the MTs connecting centrosomes and chromosomes, and compression generated by other motors on the MTs connecting the spindle poles. This picture is being challenged now by mounting evidence indicating that spindle assembly and maintenance rely on much more complex interconnected networks of microtubules, molecular motors, chromosomes and regulatory proteins. From an engineering point of view, three design principles of this molecular machine are especially important: the spindle assembles quickly, it assembles accurately, and it is mechanically robust – yet malleable. How is this design achieved with randomly interacting and impermanent molecular parts? Here, we review recent interdisciplinary studies that have started to shed light on this question. We discuss cooperative mechanisms of spindle self-assembly, error correction and maintenance of its mechanical properties, speculate on analogy between spindle and lamellipodial dynamics, and highlight the role of quantitative approaches in understanding the mitotic spindle design.

Mogilner, Alex; Craig, Erin

2010-01-01

331

LEM-4 promotes rapid dephosphorylation of BAF during mitotic exit.  

PubMed

The transitions between the successive cell cycle stages depend on reversible protein phosphorylation events. The phosphorylation state of every protein within a cell is strictly determined by spatiotemporally controlled kinase and phosphatase activities. Nuclear disassembly and reassembly during open mitosis in higher eukaryotic cells is one such process that is tightly regulated by the reversible phosphorylation of key proteins. However, little is known about the regulation of these mitotic events. In particular, although kinase function during entry into mitosis is better studied, very little is known about how proteins are dephosphorylated to allow nuclear reformation at the end of mitosis. We have identified LEM?4, a conserved protein of the nuclear envelope, as an essential coordinator of kinase and phosphatase activities during mitotic exit. Inhibition of VRK?1 kinase and promotion of a PP2A phosphatase complex by LEM?4 tightly regulate the phosphorylation state of BAF, an essential player of nuclear reformation at the end of mitosis. Here I offer extended comments on the contribution of LEM?4 in the regulation of protein phosphorylation and nuclear reformation. PMID:23211644

Gorjánácz, Mátyás

2012-12-04

332

Golgi Partitioning Controls Mitotic Entry through Aurora-A Kinase  

PubMed Central

At the onset of mitosis, the Golgi complex undergoes a multistep fragmentation process that is required for its correct partitioning into the daughter cells. Inhibition of this Golgi fragmentation results in cell cycle arrest at the G2 stage, suggesting that correct inheritance of the Golgi complex is monitored by a “Golgi mitotic checkpoint.” However, the molecular basis of this G2 block is not known. Here, we show that the G2-specific Golgi fragmentation stage is concomitant with centrosome recruitment and activation of the mitotic kinase Aurora-A, an essential regulator for entry into mitosis. We show that a block of Golgi partitioning impairs centrosome recruitment and activation of Aurora-A, which results in the G2 block of cell cycle progression. Overexpression of Aurora-A overrides this cell cycle block, indicating that Aurora-A is a major effector of the Golgi checkpoint. Our findings provide the basis for further understanding of the signaling pathways that coordinate organelle inheritance and cell duplication.

Persico, Angela; Cervigni, Romina Ines; Barretta, Maria Luisa; Corda, Daniela

2010-01-01

333

LEM-4 promotes rapid dephosphorylation of BAF during mitotic exit  

PubMed Central

The transitions between the successive cell cycle stages depend on reversible protein phosphorylation events. The phosphorylation state of every protein within a cell is strictly determined by spatiotemporally controlled kinase and phosphatase activities. Nuclear disassembly and reassembly during open mitosis in higher eukaryotic cells is one such process that is tightly regulated by the reversible phosphorylation of key proteins. However, little is known about the regulation of these mitotic events. In particular, although kinase function during entry into mitosis is better studied, very little is known about how proteins are dephosphorylated to allow nuclear reformation at the end of mitosis. We have identified LEM?4, a conserved protein of the nuclear envelope, as an essential coordinator of kinase and phosphatase activities during mitotic exit. Inhibition of VRK?1 kinase and promotion of a PP2A phosphatase complex by LEM?4 tightly regulate the phosphorylation state of BAF, an essential player of nuclear reformation at the end of mitosis. Here I offer extended comments on the contribution of LEM?4 in the regulation of protein phosphorylation and nuclear reformation.

2013-01-01

334

Bod1 regulates protein phosphatase 2A at mitotic kinetochores.  

PubMed

Mitotic entry and progression require the activation of several mitotic kinases and the proper regulation and localization of several phosphatases. The activity and localization of each of these enzymes is tightly controlled through a series of specific activators, inhibitors and regulatory subunits. Two proteins, Ensa and Arpp-19, were recently identified as specific inhibitors of PP2A-B55 and are critical for allowing full activity of Cdk1/cyclin B and entry into mitosis. Here we show that Bod1, a protein required for proper chromosome alignment at mitosis, shares sequence similarity with Ensa and Arpp-19 and specifically inhibits the kinetochore-associated PP2A-B56 holoenzyme. PP2A-B56 regulates the stability of kinetochore-microtubule attachments by dephosphorylating several kinetochore proteins. Loss of Bod1 changes the balance of phosphorylation at kinetochores, causing defects in kinetochore function. Bod1, Ensa and Arpp-19 define a family of specific PP2A inhibitors that regulate specific PP2A holoenzymes at distinct locations and points in the cell cycle. PMID:24157919

Porter, Iain M; Schleicher, Katharina; Porter, Michael; Swedlow, Jason R

2013-10-25

335

Online feature selection with streaming features.  

PubMed

We propose a new online feature selection framework for applications with streaming features where the knowledge of the full feature space is unknown in advance. We define streaming features as features that flow in one by one over time whereas the number of training examples remains fixed. This is in contrast with traditional online learning methods that only deal with sequentially added observations, with little attention being paid to streaming features. The critical challenges for Online Streaming Feature Selection (OSFS) include 1) the continuous growth of feature volumes over time, 2) a large feature space, possibly of unknown or infinite size, and 3) the unavailability of the entire feature set before learning starts. In the paper, we present a novel Online Streaming Feature Selection method to select strongly relevant and nonredundant features on the fly. An efficient Fast-OSFS algorithm is proposed to improve feature selection performance. The proposed algorithms are evaluated extensively on high-dimensional datasets and also with a real-world case study on impact crater detection. Experimental results demonstrate that the algorithms achieve better compactness and higher prediction accuracy than existing streaming feature selection algorithms. PMID:23520258

Wu, Xindong; Yu, Kui; Ding, Wei; Wang, Hao; Zhu, Xingquan

2013-05-01

336

The essential mitotic peptidyl-prolyl isomerase Pin1 binds and regulates mitosis-specific phosphoproteins  

PubMed Central

Phosphorylation of mitotic proteins on the Ser/Thr-Pro motifs has been shown to play an important role in regulating mitotic progression. Pin1 is a novel essential peptidyl–prolyl isomerase (PPIase) that inhibits entry into mitosis and is also required for proper progression through mitosis, but its substrate(s) and function(s) remain to be determined. Here we report that in both human cells and Xenopus extracts, Pin1 interacts directly with a subset of mitotic phosphoproteins on phosphorylated Ser/Thr-Pro motifs in a phosphorylation-dependent and mitosis-specific manner. Many of these Pin1-binding proteins are also recognized by the monoclonal antibody MPM-2, and they include the important mitotic regulators Cdc25, Myt1, Wee1, Plk1, and Cdc27. The importance of this Pin1 interaction was tested by constructing two Pin1 active site point mutants that fail to bind a phosphorylated Ser/Thr-Pro motif in mitotic phosphoproteins. Wild-type, but not mutant, Pin1 inhibits both mitotic division in Xenopus embryos and entry into mitosis in Xenopus extracts. We have examined the interaction between Pin1 and Cdc25 in detail. Pin1 not only binds the mitotic form of Cdc25 on the phosphorylation sites important for its activity in vitro and in vivo, but it also inhibits its activity, offering one explanation for the ability of Pin1 to inhibit mitotic entry. In a separate paper, we have shown that Pin1 is a phosphorylation-dependent PPIase that can recognize specifically the phosphorylated Ser/Thr-Pro bonds present in mitotic phosphoproteins. Thus, Pin1 likely acts as a general regulator of mitotic proteins that have been phosphorylated by Cdc2 and other mitotic kinases.

Shen, Minhui; Stukenberg, P. Todd; Kirschner, Marc W.; Lu, Kun Ping

1998-01-01

337

Distinctive features of collisionless gradient drift instabilities in a high-{beta} plasma in a highly nonuniform magnetic field  

SciTech Connect

A set of Vlasov-Maxwell equations for collisionless electromagnetic drift instabilities of high-{beta} plasma configurations with a nonuniform magnetic fields is solved. The effect of the transverse static magnetic field variation and magnetic field line curvature, as well as the plasma temperature and density gradients, is considered. It is shown that, in a nonuniform magnetic field, the behavior of the instabilities differs substantially from that in a uniform field. Electromagnetic modes propagating strictly transverse to the lines of the static magnetic field are analyzed in detail, and unstable solutions are obtained for both extraordinary and ordinary waves. Numerical results show that, in the latter case, instability occurs when the magnetic field decreases toward the periphery and the plasma temperature and density gradients are oppositely directed.

Chirkov, A. Yu.; Khvesyuk, V. I. [Bauman Moscow State Technical University (Russian Federation)

2011-05-15

338

High-resolution PFPE-based molding techniques for nanofabrication of high-pattern density, sub-20 nm features: a fundamental materials approach.  

PubMed

Several perfluoropolyether (PFPE)-based elastomers for high-resolution replica molding applications are explored. The modulus of the elastomeric materials was increased through synthetic and additive approaches while maintaining relatively low surface tension values (<25 mN/m). Using large area (>4 in.(2)) master templates, we experimentally show the relationship between mold resolution and material properties such as modulus and surface tension for materials used in this study. A composite mold approach was used to form flexible molds out of stiff, high modulus materials that allow for replication of sub-20 nm post structures. Sub-100 nm line grating master templates, formed using e-beam lithography, were used to determine the experimental stability of the molding materials. It was observed that as the feature spacing decreased, high modulus PFPE tetramethacrylate (TMA) composite molds were able to effectively replicate the nanograting structures without cracking or tear-out defects that typically occur with high modulus elastomers. PMID:20178369

Williams, Stuart S; Retterer, Scott; Lopez, Rene; Ruiz, Ricardo; Samulski, Edward T; DeSimone, Joseph M

2010-04-14

339

A mammalian Partner of inscuteable binds NuMA and regulates mitotic spindle organization  

Microsoft Academic Search

Asymmetric cell division requires the orientation of mitotic spindles along the cell-polarity axis. In Drosophila neuroblasts, this involves the interaction of the proteins Inscuteable (Insc) and Partner of inscuteable (Pins). We report here that a human Pins-related protein, called LGN, is instead essential for the assembly and organization of the mitotic spindle. LGN is cytoplasmic in interphase cells, but associates

P. Todd Stukenberg; Ian G. Macara; Quansheng Du

2001-01-01

340

MIX1: An Essential Component of the C. elegans Mitotic Machinery Executes X Chromosome Dosage Compensation  

Microsoft Academic Search

We show that a functional component of the C. elegans mitotic machinery regulates X chromosome gene expression. This protein, MIX-1, is a member of the dosage compensation complex that associates specifically with hermaphrodite X chromosomes to reduce their gene expression during interphase. MIX-1 also associates with all mitotic chromosomes to ensure their proper segregation. Both dosage compensation and mitosis are

Jason D Lieb; Michael R Albrecht; Pao-Tien Chuang; Barbara J Meyer

1998-01-01

341

The Zebra fish cassiopeia Mutant Reveals that SIL Is Required for Mitotic Spindle Organization  

Microsoft Academic Search

A critical step in cell division is formation of the mitotic spindle, which is a bipolar array of microtubules that mediates chromosome separation. Here, we report that the SCL-interrupting locus (SIL), a vertebrate-specific cytosolic protein, is necessary for proper mitotic spindle organization in zebrafish and human cells. A homozygous lethal zebrafish mutant, cassiopeia (csp), was identified by a genetic screen

Kathleen L. Pfaff; Christian T. Straub; Ken Chiang; Daniel M. Bear; Yi Zhou; Leonard I. Zon

2007-01-01

342

A Genetic Method for Generating Drosophila Eyes Composed Exclusively of Mitotic Clones of a Single Genotype  

Microsoft Academic Search

The genetic analysis of a gene at a late developmental stage can be impeded if the gene is required at an earlier developmental stage. The construction of mosaic animals, particularly in Drosophila, has been a means to overcome this obstacle. However, the phenotypic analysis of mitotic clones is often complicated because standard methods for generating mitotic clones render mosaic tissues

R. Steven Stowers; Thomas L. Schwarz

343

Industrial applications demanding low and high resolution features realized by soft UV-NIL and hot embossing  

NASA Astrophysics Data System (ADS)

There are several applications either currently in production or in late stage R&D, for UV-based Nanoimprint Lithography (UV-NIL) and Hot Embossing (HE) that require a full-field imprint technology in order to make these processes either feasible or costeffective. These applications cover a wide range of features sizes from the millimeter range down to sub-100 nm. Because of the total thickness variation (TTV) associated with the imprinted substrates, full-field imprinting requires fabrication of a "soft" or "working" stamp from a "hard" stamp usually made from materials such as nickel, quartz or silicon. Several materials and processes have previously been identified that allow for full-field imprinting, however, these materials all have drawbacks associated with them that hinder their movement into High Volume Manufacturing (HVM) environments. EV Group Inc (EVG) has, in cooperation with our NILCOMTM partners, identified a novel set of polymeric materials and stamp fabrication processes that allow for full-field imprinting solutions suitable for these HVM environments. These materials have proven effective for imprinting at both millimeter feature sizes all the way down to 50 nm - full field. These materials, and the processes associated with their fabrication into working/soft stamps, should allow for a superior cost-of-ownership benefit and facilitate the movement of imprint lithography into industrial applications.

Miller, R.; Glinsner, T.; Kreindl, G.; Lindner, P.; Wimplinger, M.

2009-03-01

344

High resolution transmission electron microscope Imaging and first-principles simulations of atomic-scale features in graphene membrane  

NASA Astrophysics Data System (ADS)

Ultra-thin membranes such as graphene[1] are of great importance for basic science and technology applications. Graphene sets the ultimate limit of thinness, demonstrating that a free-standing single atomic layer not only exists but can be extremely stable and strong [2--4]. However, both theory [5, 6] and experiments [3, 7] suggest that the existence of graphene relies on intrinsic ripples that suppress the long-wavelength thermal fluctuations which otherwise spontaneously destroy long range order in a two dimensional system. Here we show direct imaging of the atomic features in graphene including the ripples resolved using monochromatic aberration-corrected transmission electron microscopy (TEM). We compare the images observed in TEM with simulated images based on an accurate first-principles total potential. We show that these atomic scale features can be mapped through accurate first-principles simulations into high resolution TEM contrast. [1] Geim, A. K. & Novoselov, K. S. Nat. Mater. 6, 183-191, (2007). [2] Novoselov, K. S.et al. Science 306, 666-669, (2004). [3] Meyer, J. C. et al. Nature 446, 60-63, (2007). [4] Lee, C., Wei, X. D., Kysar, J. W. & Hone, J. Science 321, 385-388, (2008). [5] Nelson, D. R. & Peliti, L. J Phys-Paris 48, 1085-1092, (1987). [6] Fasolino, A., Los, J. H. & Katsnelson, M. I. Nat. Mater. 6, 858-861, (2007). [7] Meyer, J. C. et al. Solid State Commun. 143, 101-109, (2007).

Wang, Wei; Bhandari, Sagar; Yi, Wei; Bell, David; Westervelt, Robert; Kaxiras, Efthimios

2012-02-01

345

The Xenopus TACC homologue, maskin, functions in mitotic spindle assembly.  

PubMed

Maskin is the Xenopus homolog of the transforming acidic coiled coil (TACC)-family of microtubule and centrosome-interacting proteins. Members of this family share a approximately 200 amino acid coiled coil motif at their C-termini, but have only limited homology outside of this domain. In all species examined thus far, perturbations of TACC proteins lead to disruptions of cell cycle progression and/or embryonic lethality. In Drosophila, Caenorhabditis elegans, and humans, these disruptions have been attributed to mitotic spindle assembly defects, and the TACC proteins in these organisms are thought to function as structural components of the spindle. In contrast, cell division failure in early Xenopus embryo blastomeres has been attributed to a role of maskin in regulating the translation of, among others, cyclin B1 mRNA. In this study, we show that maskin, like other TACC proteins, plays a direct role in mitotic spindle assembly in Xenopus egg extracts and that this role is independent of cyclin B. Maskin immunodepletion and add-back experiments demonstrate that maskin, or a maskin-associated activity, is required for two distinct steps during spindle assembly in Xenopus egg extracts that can be distinguished by their response to "rescue" experiments. Defects in the "early" step, manifested by greatly reduced aster size during early time points in maskin-depleted extracts, can be rescued by readdition of purified full-length maskin. Moreover, defects in this step can also be rescued by addition of only the TACC-domain of maskin. In contrast, defects in the "late" step during spindle assembly, manifested by abnormal spindles at later time points, cannot be rescued by readdition of maskin. We show that maskin interacts with a number of proteins in egg extracts, including XMAP215, a known modulator of microtubule dynamics, and CPEB, a protein that is involved in translational regulation of important cell cycle regulators. Maskin depletion from egg extracts results in compromised microtubule asters and spindles and the mislocalization of XMAP215, but CPEB localization is unaffected. Together, these data suggest that in addition to its previously reported role as a translational regulator, maskin is also important for mitotic spindle assembly. PMID:15788567

O'Brien, Lori L; Albee, Alison J; Liu, Lingling; Tao, Wei; Dobrzyn, Pawel; Lizarraga, Sofia B; Wiese, Christiane

2005-03-23

346

Exome Sequencing and High-Density Microarray Testing in Monozygotic Twin Pairs Discordant for Features of VACTERL Association.  

PubMed

Exome sequencing offers an efficient and affordable method to interrogate genetic factors involved in human disease. Performing exome sequencing of monozygotic twins discordant for VACTERL (Vertebral anomalies, Anal atresia, Cardiac malformations, Tracheo-Esophageal fistula, Renal anomalies, and Limb abnormalities) association-type congenital malformations was hypothesized to potentially reveal discordant variants that could demonstrate disease cause(s). After demonstrating monozygosity, we applied high-density microarrays and exome sequencing to 2 twin pairs in which 1 twin had features of VACTERL association while the other was phenotypically normal (demonstrated through comprehensive clinical and radiological evaluation). No obvious discordant genotypic results were found that would explain phenotypic discordance. We conclude that VACTERL association is a complex disease, and while performing microarray analysis and exome sequencing on phenotypically discordant monozygotic twins may hypothetically reveal genetic causes of disorders, challenges remain in applying these methods in this circumstance. PMID:23653574

Solomon, B D; Pineda-Alvarez, D E; Hadley, D W; Hansen, N F; Kamat, A; Donovan, F X; Chandrasekharappa, S C; Hong, S-K; Roessler, E; Mullikin, J C

2013-02-01

347

Exome Sequencing and High-Density Microarray Testing in Monozygotic Twin Pairs Discordant for Features of VACTERL Association  

PubMed Central

Exome sequencing offers an efficient and affordable method to interrogate genetic factors involved in human disease. Performing exome sequencing of monozygotic twins discordant for VACTERL (Vertebral anomalies, Anal atresia, Cardiac malformations, Tracheo-Esophageal fistula, Renal anomalies, and Limb abnormalities) association-type congenital malformations was hypothesized to potentially reveal discordant variants that could demonstrate disease cause(s). After demonstrating monozygosity, we applied high-density microarrays and exome sequencing to 2 twin pairs in which 1 twin had features of VACTERL association while the other was phenotypically normal (demonstrated through comprehensive clinical and radiological evaluation). No obvious discordant genotypic results were found that would explain phenotypic discordance. We conclude that VACTERL association is a complex disease, and while performing microarray analysis and exome sequencing on phenotypically discordant monozygotic twins may hypothetically reveal genetic causes of disorders, challenges remain in applying these methods in this circumstance.

Solomon, B.D.; Pineda-Alvarez, D.E.; Hadley, D.W.; Hansen, N.F.; Kamat, A.; Donovan, F.X.; Chandrasekharappa, S.C.; Hong, S.-K.; Roessler, E.; Mullikin, J.C.

2013-01-01

348

Image-guided spinal injection procedures in open high-field MRI with vertical field orientation: feasibility and technical features  

Microsoft Academic Search

Objective  We prospectively evaluated the feasibility and technical features of MR-guided lumbosacral injection procedures in open high-field\\u000a MRI at 1.0 T.\\u000a \\u000a \\u000a \\u000a Methods  In a CuSO4·5H2O phantom and five human cadaveric spines, fluoroscopy sequences (proton-density-weighted turbo spin-echo (PDw TSE), T1w TSE,\\u000a T2w TSE; balanced steady-state free precession (bSSFP), T1w gradient echo (GE), T2w GE) were evaluated using two MRI-compatible\\u000a 20-G Chiba-type needles. Artefacts were

F. Streitparth; T. Walter; U. Wonneberger; S. Chopra; F. Wichlas; M. Wagner; K. G. Hermann; B. Hamm; U. Teichgräber

2010-01-01

349

Automatic segmentation of brain MRI in high-dimensional local and non-local feature space based on sparse representation.  

PubMed

Automatic extraction of the varying regions of magnetic resonance images is required as a prior step in a diagnostic intelligent system. The sparsest representation and high-dimensional feature are provided based on learned dictionary. The classification is done by employing the technique that computes the reconstruction error locally and non-locally of each pixel. The acquired results from the real and simulated images are superior to the best MRI segmentation method with regard to the stability advantages. In addition, it is segmented exactly through a formula taken from the distance and sparse factors. Also, it is done automatically taking sparse factor in unsupervised clustering methods whose results have been improved. PMID:23260393

Khalilzadeh, Mohammad Mahdi; Fatemizadeh, Emad; Behnam, Hamid

2012-12-21

350

Control of high oceanic features and subduction channel on earthquake ruptures along the Chile-Peru subduction zone  

NASA Astrophysics Data System (ADS)

We discuss the earthquake rupture behavior along the Chile-Peru subduction zone in terms of the buoyancy of the subducting high oceanic features (HOF's), and the effect of the interplay between HOF and subduction channel thickness on the degree of interplate coupling. We show a strong relation between subduction of HOF's and earthquake rupture segments along the Chile-Peru margin, elucidating how these subducting features play a key role in seismic segmentation. Within this context, the extra increase of normal stress at the subduction interface is strongly controlled by the buoyancy of HOF's which is likely caused by crustal thickening and mantle serpentinization beneath hotspot ridges and fracture zones, respectively. Buoyancy of HOF's provide an increase in normal stress estimated to be as high as 10-50 MPa. This significant increase of normal stress will enhance seismic coupling across the subduction interface and hence will affect the seismicity. In particular, several large earthquakes (Mw ? 7.5) have occurred in regions characterized by subduction of HOF's including fracture zones (e.g., Nazca, Challenger and Mocha), hotspot ridges (e.g., Nazca, Iquique, and Juan Fernández) and the active Nazca-Antarctic spreading center. For instance, the giant 1960 earthquake (Mw = 9.5) is coincident with the linear projections of the Mocha Fracture Zone and the buoyant Chile Rise, while the active seismic gap of north Chile spatially correlates with the subduction of the Iquique Ridge. Further comparison of rupture characteristics of large underthrusting earthquakes and the locations of subducting features provide evidence that HOF's control earthquake rupture acting as both asperities and barriers. This dual behavior can be partially controlled by the subduction channel thickness. A thick subduction channel smooths the degree of coupling caused by the subducted HOF which allows lateral earthquake rupture propagation. This may explain why the 1960 rupture propagates through six major fracture zones, and ceased near the Mocha Fracture Zone in the north and at the Chile Rise in the south (regions characterized by a thin subduction channel). In addition, the thin subduction channel (north of the Juan Fernández Ridge) reflects a heterogeneous frictional behavior of the subduction interface which appears to be mainly controlled by the subduction of HOF's.

Contreras-Reyes, Eduardo; Carrizo, Daniel

2011-05-01

351

Resurrecting remnants: the lives of post-mitotic midbodies.  

PubMed

Around a century ago, the midbody (MB) was described as a structural assembly within the intercellular bridge during cytokinesis that served to connect the two future daughter cells. The MB has become the focus of intense investigation through the identification of a growing number of diverse cellular and molecular pathways that localize to the MB and contribute to its cytokinetic functions, ranging from selective vesicle trafficking and regulated microtubule (MT), actin, and endosomal sorting complex required for transport (ESCRT) filament assembly and disassembly to post-translational modification, such as ubiquitination. More recent studies have revealed new and unexpected functions of MBs in post-mitotic cells. In this review, we provide a historical perspective, discuss exciting new roles for MBs beyond their cytokinetic function, and speculate on their potential contributions to pluripotency. PMID:23245592

Chen, Chun-Ting; Ettinger, Andreas W; Huttner, Wieland B; Doxsey, Stephen J

2012-12-11

352

Optimal design of high damping force engine mount featuring MR valve structure with both annular and radial flow paths  

NASA Astrophysics Data System (ADS)

This paper focuses on the optimal design of a compact and high damping force engine mount featuring magnetorheological fluid (MRF). In the mount, a MR valve structure with both annular and radial flows is employed to generate a high damping force. First, the configuration and working principle of the proposed MR mount is introduced. The MRF flows in the mount are then analyzed and the governing equations of the MR mount are derived based on the Bingham plastic behavior of the MRF. An optimal design of the MR mount is then performed to find the optimal structure of the MR valve to generate a maximum damping force with certain design constraints. In addition, the gap size of MRF ducts is empirically chosen considering the ‘lockup’ problem of the mount at high frequency. Performance of the optimized MR mount is then evaluated based on finite element analysis and discussions on performance results of the optimized MR mount are given. The effectiveness of the proposed MR engine mount is demonstrated via computer simulation by presenting damping force and power consumption.

Nguyen, Q. H.; Choi, S. B.; Lee, Y. S.; Han, M. S.

2013-11-01

353

Multiscale analysis of geomorphological and geological features in high resolution digital elevation models using the wavelet transform  

NASA Astrophysics Data System (ADS)

At the end of the 1990s the emergence of high resolution (1 m) digital elevation models (DEMs) settled the context of high precision geomorphological analysis. These new elevation models permitted to reveal structures that remained heretofore undetectable. Earth scientists henceforth benefit from a source of data with a textural detail that was never attained before. Despite its richness, this information must be treated efficiently to extract features helping geomorphologists to analyze the processes occurring at the surface. Such processes are complex, localized and naturally multiscale. Recently, space-frequential descriptors as wavelets have been proposed successfully for the analysis of DEMs. The wavelet transform is widely used in image processing since it allows us to decompose a signal into a weighted sum of atoms with joint space-frequency localization. Such a decomposition facilitates a coherent navigation from scale to scale, but also permits to detect heretofore undiscerned phenomena at different scales. This is appealing in geomorphology, where structural components, related to a given phenomenon, are well determined in these sub-spaces specific to the scale continuum. In this paper, we propose a filtering procedure of the wavelet decomposition as an approach for the analysis of geomorphological multiscale structures. This filtering procedure enhances the high pass information contained at each scale. The proposed bottom-up approach is applied here to a case study to detect geomorphological structural elements in a valley of the Swiss Jura. It demonstrates that the proposed filtering procedure is an efficient tool for geomorphological multiscale generalization.

Kalbermatten, Michael; Van De Ville, Dimitri; Turberg, Pascal; Tuia, Devis; Joost, Stéphane

2012-02-01

354

A THERMODYNAMIC ANALYSIS OF MITOTIC SPINDLE EQUILIBRIUM AT ACTIVE METAPHASE  

PubMed Central

The mitotic apparatus of first-division metaphase eggs of the sea urchin Strongylocentrotus drobachiensis was observed by means of polarization microscopy under controlled temperature conditions. Eggs were fertilized and grown at two temperature extremes in order to produce two different sizes of available spindle pool. Slow division time allowed successive samples of such cells to be observed at the same point in metaphase but at different equilibrium temperatures, yielding curves of metaphase equilibrium birefringence vs. observational temperature. Using the plateau value of birefringence at higher temperatures as a measure of total available spindle pool and the observed birefringence at lower temperatures as a measure of polymerized material at equilibrium, the spindle protein association was evaluated according to the method of Inoué. Both pool conditions produced linear van't Hoff functions. Analysis of these functions yielded enthalpy and entropy changes of +55–65 kcal/mol and +197–233 entropy units (eu), respectively. These values for active mitotic metaphase are quite comparable to those obtained by Inoué and co-workers for arrested meiotic metaphase cells. When other equilibrium treatments were considered, the best fit to the experimental data was still that of Inoué, a treatment which theoretically involves first-order polymerization and dissociation kinetics. Treatment of metaphase cells with D2O by direct immersion drove the equilibrium to completion regardless of temperature, attaining or exceeding a birefringence value equal to the cell's characteristic pool size; perfusion with D2O appeared to erase the original temperature-determined pool size differences for the two growth conditions, attaining a maximum value characteristic of the larger pool condition. These data confirm Inoué's earlier contention that D2O treatment can modify the available spindle pool.

Stephens, R. E.

1973-01-01

355

The mitotic manipulation of cytotrophoblast differentiation in vitro.  

PubMed

The placental syncytiotrophoblast is of paramount importance in optimising feto-maternal interactions. Syncytiotrophoblast is generated by the differentiation and fusion of underlying cytotrophoblasts. This process is aberrant in complicated pregnancies. We hypothesized that cell cycle withdrawal determines the phenotypic decision-making of cytotrophoblasts. We therefore investigated the effects of broad-spectrum mitotic inhibitors on cytotrophoblast differentiation. Villous tissue was dissected from term placentae of normal pregnancies and cultured on Netwell supports. Over 48 h, the original syncytiotrophoblast was detached and underlying cytotrophoblasts exposed. The resulting villi were treated with mitotic blockers (Ara-C, colcemid, cyclohexamide, doxorubicin hydrochloride, hydroxyurea, L-Mimosine, purvalanol A). The media was recovered and analysed for lactacte dehydrogenase (LDH) and human chorionic gondadotrophin (hCG), markers of tissue viability and cytotrophoblast differentiation, respectively. The resulting tissue was processed for proliferative activity thorough Ki-67 immunorecognition. Colcemid, cyclohexamide, hydroxyurea, and purvalanol A showed significant cytotoxicity over 48 h incubation. Villous tissue exposed to 0.01 mM and 0.1mM Ara-C, doxorubicin hydrochloride and L-Mimosine showed no increase in liberated LDH. hCG production increased exponentially with cytotrophoblast differentiation. Higher concentrations of Ara-C and L-Mimosine significantly encouraged hCG production. In addition, total cell and cytotrophoblast proliferation were reduced with Ara-C and L-Mimosine treatment. The inhibition of DNA synthesis and replication with Ara-C and L-Mimosine suppressed active proliferation of villus components and exaggerated the biochemical differentiation of cytotrophoblasts. Cell cycle disruption is therefore a basic trigger for cytotrophoblast differentiation. This approach provides a mechanism for encouraging syncytiotrophoblast formation and may hold benefits for conditions where syncytiotrophoblast cover is attenuated. PMID:16844216

Crocker, I P; Arthur, P; Heazell, A E; Baker, P N

2006-07-17

356

Delocalization of the Microtubule Motor Dynein from Mitotic Spindles by the Human Papillomavirus E7 Oncoprotein is Not Sufficient for Induction of Multipolar Mitoses  

PubMed Central

Dynein is a minus-end directed microtubule motor that transports numerous cargoes throughout the cell. During mitosis, dynein motor activity is necessary for the positioning of spindle microtubules and has also been implicated in inactivating the spindle assembly checkpoint. Mutations in dynein motor and/or accessory proteins are associated with human disease, including cancer, and the delocalization of dynein from mitotic spindles has been correlated with an increased incidence of multipolar spindle formation in some cancer cells that contain supernumerary centrosomes. The high-risk human papillomavirus type 16 (HPV16) E7 oncoprotein induces centrosome overduplication and has been shown to cause multipolar mitotic spindle formation, a diagnostic hallmark of HPV-associated neoplasias. Here we show that HPV16 E7 expression leads to an increased population of mitotic cells with dynein delocalized from the mitotic spindle. This function maps to sequences of HPV16 E7 that are distinct from the region necessary for centrosome overduplication. However, contrary to previous reports, we provide evidence that dynein delocalization by HPV16 E7 is neither necessary nor sufficient to cause the formation of multipolar mitoses.

Nguyen, Christine L.; McLaughlin-Drubin, Margaret E.; Munger, Karl

2008-01-01

357

Delocalization of the microtubule motor Dynein from mitotic spindles by the human papillomavirus E7 oncoprotein is not sufficient for induction of multipolar mitoses.  

PubMed

Dynein is a minus end-directed microtubule motor that transports numerous cargoes throughout the cell. During mitosis, dynein motor activity is necessary for the positioning of spindle microtubules and has also been implicated in inactivating the spindle assembly checkpoint. Mutations in dynein motor and/or accessory proteins are associated with human disease, including cancer, and the delocalization of dynein from mitotic spindles has been correlated with an increased incidence of multipolar spindle formation in some cancer cells that contain supernumerary centrosomes. The high-risk human papillomavirus type 16 (HPV16) E7 oncoprotein induces centrosome overduplication and has been shown to cause multipolar mitotic spindle formation, a diagnostic hallmark of HPV-associated neoplasias. Here, we show that HPV16 E7 expression leads to an increased population of mitotic cells with dynein delocalized from the mitotic spindle. This function maps to sequences of HPV16 E7 that are distinct from the region necessary for centrosome overduplication. However, contrary to previous reports, we provide evidence that dynein delocalization by HPV16 E7 is neither necessary nor sufficient to cause the formation of multipolar mitoses. PMID:18974113

Nguyen, Christine L; McLaughlin-Drubin, Margaret E; Münger, Karl

2008-11-01

358

Overexpression of the dynein light chain km23-1 in human ovarian carcinoma cells inhibits tumor formation in vivo and causes mitotic delay at prometaphase/metaphase.  

PubMed

km23-1 is a dynein light chain that was identified as a TGF? receptor-interacting protein. To investigate whether km23-1 controls human ovarian carcinoma cell (HOCC) growth, we established a tet-off inducible expression system in SKOV-3 cells in which the expression of km23-1 is induced upon doxycycline removal. We found that forced expression of km23-1 inhibited both anchorage-dependent and anchorage-independent growth of SKOV-3 cells. More importantly, induction of km23-1 expression substantially reduced the tumorigenicity of SKOV-3 cells in a xenograft model in vivo. Fluorescence-activated cell sorting analysis of SKOV-3 and IGROV-1 HOCCs demonstrated that the cells were accumulating at G2/M. Phospho-MEK, phospho-ERK and cyclin B1 were elevated, as was the mitotic index, suggesting that km23-1 suppresses HOCCs growth by inducing a mitotic delay. Immunofluorescence analyses demonstrated that the cells were accumulating at prometaphase/metaphase with increases in multipolar and multinucleated cells. Further, although the mitotic spindle assembly checkpoint protein BubR1 was present at the prometaphase kinetochore in Dox+/- cells, it was inappropriately retained at the metaphase kinetochore in Dox- cells. Thus, the mechanism by which high levels of km23-1 suppress ovarian carcinoma growth in vitro and inhibit ovary tumor formation in vivo appears to involve a BubR1-related mitotic delay. PMID:21469138

Pulipati, Nageswara R; Jin, Qunyan; Liu, Xin; Sun, Baodong; Pandey, Manoj K; Huber, Jonathan P; Ding, Wei; Mulder, Kathleen M

2011-04-25

359

The distribution of cytoplasmic microtubules throughout the cell cycle of the centric diatom Stephanopyxis turris: their role in nuclear migration and positioning the mitotic spindle during cytokinesis  

PubMed Central

The cell cycle of the marine centric diatom Stephanopyxis turris consists of a series of spatially and temporally well-ordered events. We have used immunofluorescence microscopy to examine the role of cytoplasmic microtubules in these events. At interphase, microtubules radiate out from the microtubule-organizing center, forming a network around the nucleus and extending much of the length and breadth of the cell. As the cell enters mitosis, this network breaks down and a highly ordered mitotic spindle is formed. Peripheral microtubule bundles radiate out from each spindle pole and swing out and away from the central spindle during anaphase. Treatment of synchronized cells with 2.5 X 10(-8) M Nocodazole reversibly inhibited nuclear migration concurrent with the disappearance of the extensive cytoplasmic microtubule arrays associated with migrating nuclei. Microtubule arrays and mitotic spindles that reformed after the drug was washed out appeared normal. In contrast, cells treated with 5.0 X 10(-8) M Nocodazole were not able to complete nuclear migration after the drug was washed out and the mitotic spindles that formed were multipolar. Normal and multipolar spindles that were displaced toward one end of the cell by the drug treatment had no effect on the plane of division during cytokinesis. The cleavage furrow always bisected the cell regardless of the position of the mitotic spindle, resulting in binucleate/anucleate daughter cells. This suggests that in S. turris, unlike animal cells, the location of the plane of division is cortically determined before mitosis.

1986-01-01

360

Design and operating features of the high-level waste vitrification system for the West Valley demonstration project  

SciTech Connect

A liquid-fed joule-heated ceramic melter system is the reference process for immobilization of the high-level liquid waste in the US and several foreign countries. This system has been under development for over ten years at Pacific Northwest Laboratory and other national laboratories operated for the US Department of Energy. Pacific Northwest Laboratory contributed to this research through its Nuclear Waste Treatment Program and used applicable data to design and test melters and related systems using remote handling of simulated radioactive wastes. This report describes the equipment designed in support of the high-level waste vitrification program at West Valley, New York. Pacific Northwest Laboratory worked closely with West Valley Nuclear Services Company to design a liquid-fed ceramic melter, a liquid waste preparation and feed tank and pump, an off-gas treatment scrubber, and an enclosed turntable for positioning the waste canisters. Details of these designs are presented including the rationale for the design features and the alternatives considered.

Siemens, D.H.; Beary, M.M.; Barnes, S.M.; Berger, D.N.; Brouns, R.A.; Chapman, C.C.; Jones, R.M.; Peters, R.D.; Peterson, M.E.

1986-03-01

361

Prevalence and clinical features of Thought-Perception-Sensitivity Symptoms: results from a community survey of Korean high school students.  

PubMed

Epidemiologic research indicates that psychosis and depression most frequently develop during adolescence. Hence, an efficient strategy for improving youth mental health would be to focus on detection of early-stage psychosis and depression in adolescence. In this study, 1461 high school students were surveyed using self-report scales. Students who scored equal to or above the cut-off value on any of the scales and who agreed to a further examination proceeded to a second assessment, using the Kiddie Schedule for Affective Disorders and Schizophrenia and Comprehensive Assessment of At-Risk Mental States along with self-reporting scales. The estimated prevalence of adolescents at ultra-high risk (UHR) for psychosis and of depression-spectrum disorders was 1.26 and 3.69% respectively. Compared with the normal group, experiences of bullying, suicidal ideation, and suicide attempts were significantly higher in these two groups; the subjects at UHR for psychosis were found to have significantly lower academic performance and lower ratings on SCRS; and submissive behavior was more prevalent in the depression-spectrum group. Our results reveal several clinical features of adolescents at UHR for psychosis and with depression-spectrum disorder and underscore the importance of accurate assessment of and early appropriate care for these adolescents. PMID:22475525

Kang, Nam-In; Park, Tae-Won; Yang, Jong-Chul; Oh, Keun-Young; Shim, Shi-Ha; Chung, Young-Chul

2012-04-03

362

Closed MAD2 (C-MAD2) is selectively incorporated into the mitotic checkpoint complex (MCC)  

PubMed Central

The mitotic checkpoint is a specialized signal transduction pathway that monitors kinetochore-microtubule attachment to achieve faithful chromosome segregation. MAD2 is an evolutionarily conserved mitotic checkpoint protein that exists in open (O) and closed (C) conformations. The increase of intracellular C-MAD2 level during mitosis, through O?C-MAD2 conversion as catalyzed by unattached kinetochores, is a critical signaling event for the mitotic checkpoint. However, it remains controversial whether MAD2 is an integral component of the effector of the mitotic checkpoint—the mitotic checkpoint complex (MCC). We show here that endogenous human MCC is assembled by first forming a BUBR1:BUB3:CDC20 complex in G2 and then selectively incorporating C-MAD2 during mitosis. Nevertheless, MCC can be induced to form in G1/S cells by expressing a C-conformation locked MAD2 mutant, indicating intracellular level of C-MAD2 as a major limiting factor for MCC assembly. In addition, a recombinant MCC containing C-MAD2 exhibits effective inhibitory activity toward APC/C isolated from mitotic HeLa cells, while a recombinant BUBR1:BUB3:CDC20 ternary complex is ineffective at comparable concentrations despite association with APC/C. These results help establish a direct connection between a major signal transducer (C-MAD2) and the potent effector (MCC) of the mitotic checkpoint, and provide novel insights into protein-protein interactions during assembly of a functional MCC.

Tipton, Aaron R; Tipton, Michael; Yen, Tim

2011-01-01

363

Mitotic catastrophe triggered in human cancer cells by the viral protein apoptin  

PubMed Central

Mitotic catastrophe is an oncosuppressive mechanism that senses mitotic failure leading to cell death or senescence. As such, it protects against aneuploidy and genetic instability, and its induction in cancer cells by exogenous agents is currently seen as a promising therapeutic end point. Apoptin, a small protein from Chicken Anemia Virus (CAV), is known for its ability to selectively induce cell death in human tumor cells. Here, we show that apoptin triggers p53-independent abnormal spindle formation in osteosarcoma cells. Approximately 50% of apoptin-positive cells displayed non-bipolar spindles, a 10-fold increase as compared to control cells. Besides, tumor cells expressing apoptin are greatly limited in their progress through anaphase and telophase, and a significant drop in mitotic cells past the meta-to-anaphase transition is observed. Time-lapse microscopy showed that mitotic osteosarcoma cells expressing apoptin displayed aberrant mitotic figures and/or had a prolonged cycling time during mitosis. Importantly, all dividing cells expressing apoptin eventually underwent cell death either during mitosis or during the following interphase. We infer that apoptin can efficiently trigger cell death in dividing human tumor cells through induction of mitotic catastrophe. However, the killing activity of apoptin is not only confined to dividing cells, as the CAV-derived protein is also able to trigger caspase-3 activation and apoptosis in non-mitotic cancer cells.

Lanz, H L; Zimmerman, R M E; Brouwer, J; Noteborn, M H M; Backendorf, C

2013-01-01

364

Prognostic factors in gastric cancer: the value of vascular invasion, mitotic rate and lymphoplasmacytic infiltration.  

PubMed Central

A retrospective analysis of 321 gastric cancer patients was made to assess the prognostic value of TNM classification, tumour differentiation, Laurén classification, proliferative rate, inflammatory reaction and tumour invasion in vascular or neural structures of the gastric wall. The TNM classification showed the strongest correlation with survival in univariate and multivariate analyses (P < 0.0001). The invasion in lymphatic or vascular system and Laurén classification were also independent prognosticators in multivariate analysis (P < 0.05). In univariate analysis, the WHO-grade, the size and the location of the tumour and perinueral invasion were significant prognostic factors (P < 0.01), as were the infiltration of lymphocytes and plasma cells in the tumour (P < 0.05). On the other hand, the mitotic indices reflecting the proliferative activity of the tumour cells showed no significant correlation with the prognosis. The results indicate that the prognostic power of the TNM classification can be further increased by assessment of the above special histological features in gastric cancer.

Setala, L. P.; Kosma, V. M.; Marin, S.; Lipponen, P. K.; Eskelinen, M. J.; Syrjanen, K. J.; Alhava, E. M.

1996-01-01

365

Synergic reprogramming of mammalian cells by combined exposure to mitotic Xenopus egg extracts and transcription factors  

PubMed Central

Transfer of somatic cell nuclei to enucleated eggs and ectopic expression of specific transcription factors are two different reprogramming strategies used to generate pluripotent cells from differentiated cells. However, these methods are poorly efficient, and other unknown factors might be required to increase their success rate. Here we show that Xenopus egg extracts at the metaphase stage (M phase) have a strong reprogramming activity on mouse embryonic fibroblasts (MEFs). First, they reset replication properties of MEF nuclei toward a replication profile characteristic of early development, and they erase several epigenetic marks, such as trimethylation of H3K9, H3K4, and H4K20. Second, when MEFs are reversibly permeabilized in the presence of M-phase Xenopus egg extracts, they show a transient increase in cell proliferation, form colonies, and start to express specific pluripotency markers. Finally, transient exposure of MEF nuclei to M-phase Xenopus egg extracts increases the success of nuclear transfer to enucleated mouse oocytes and strongly synergizes with the production of pluripotent stem cells by ectopic expression of transcription factors. The mitotic stage of the egg extract is crucial, because none of these effects is detected when using interphasic Xenopus egg extracts. Our data demonstrate that mitosis is essential to make mammalian somatic nuclei prone to reprogramming and that, surprisingly, the heterologous Xenopus system has features that are conserved enough to remodel mammalian nuclei.

Ganier, Olivier; Bocquet, Stephane; Peiffer, Isabelle; Brochard, Vincent; Arnaud, Philippe; Puy, Aurore; Jouneau, Alice; Feil, Robert; Renard, Jean-Paul; Mechali, Marcel

2011-01-01

366

Relative cataractogenic effects of X rays, fission-spectrum neutrons, and 56Fe particles: A comparison with mitotic effects  

SciTech Connect

The eyes of Sprague-Dawley rats were irradiated with doses of 2.5-10 Gy 250-kVp X rays, 1.25-2.25 Gy fission-spectrum neutrons (approximately 0.85 MeV), or 0.1-2.0 Gy 600-MeV/A 56Fe particles. Lens opacifications were evaluated for 51-61 weeks following X and neutron irradiations and for 87 weeks following X and 56Fe-particle irradiations. Average stage of opacification was determined relative to time after irradiation, and the time required for 50% of the irradiated lenses to achieve various stages (T50) was determined as a function of radiation dose. Data from two experiments were combined in dose-effect curves as T50 experimental values taken as percentages of the respective T50 control values (T50-% control). Simple exponential curves best describe dose responsiveness for both high-LET radiations. For X rays, a shallow dose-effect relationship (shoulder) up to 4.5 Gy was followed at higher doses by a steeper exponential dose-effect relationship. As a consequence, RBE values for the high-LET radiations are dose dependent. Dose-effect curves for cataracts were compared to those for mitotic abnormalities observed when quiescent lens epithelial cells were stimulated mechanically to proliferate at various intervals after irradiation. Neutrons were about 1.6-1.8 times more effective than 56Fe particles for inducing both cataracts and mitotic abnormalities. For stage 1 and 2 cataracts, the X-ray Dq was 10-fold greater and the D0 was similar to those for mitotic abnormalities initially expressed after irradiation.

Riley, E.F.; Lindgren, A.L.; Andersen, A.L.; Miller, R.C.; Ainsworth, E.J. (Univ. of Iowa, Iowa City (USA))

1991-03-01

367

Conventional and high resolution scanning electron microscopy of outer and inner surface features of cerebellar nerve cells.  

PubMed

This paper provides an exploration into the inner and outer surfaces of vertebrate cerebellar neurons utilizing secondary electron (SE-I and SE-II) topographic contrasts. SE-I enriched chromium coated, cryofractured Rhesus monkey cerebellum staged within the condenser/objective stage of SEMs equipped with high brightness LaB6 and field emission emitters generated quality images of intact and fractured nerve cells studied at intermediate and high magnifications. These images were compared with conventional SE-III images of gold-palladium teleost fish cerebellar neurons and transmission electron micrographs of mouse cerebellar nerve cells obtained either by thin-sections or freeze-etch replicas. Chromium coated Rhesus monkey granule and Golgi cell surfaces revealed smooth, accurately delineated profiles of true cell surface features, which lacked the SE-III dominated brilliance of conventional teleost fish gold or gold-palladium, decorated neurons. Chromium coated fractured nerve processes showed the outer smooth surface of interconnected anastomotic networks or ER tubules, vesicles and cisterns. Cross fractured presynaptic endings of parallel fibers in the molecular layer exhibited spheroidal synaptic vesicles and SE-I edge brightness contrast delineated their limiting plasma membranes. Fractured synaptic endings showed a homogeneous extravesicular material surrounding the synaptic vesicles. The presynaptic dense projections appeared as columnar shaped structures. The postsynaptic membrane and associated postsynaptic density showed a discontinuous surface formed by round subunits 25-35 nm in diameter. The neuroglial cytoplasm ensheathing nerve process exhibited a smooth discontinuous surface. The surface of the myelin sheath showed a mixed population of globular structures 10-30 nm in diameter, apparently corresponding, according to freeze-etch images, to protein and phospholipid microdomains. PMID:1458441

Castejón, O J; Apkarian, R P

1992-10-01

368

Serum high mobility group box-1 (HMGB1) is closely associated with the clinical and pathologic features of gastric cancer  

PubMed Central

Background High mobility group box-1 (HMGB1) is a newly recognized factor regulating cancer cell tumorigenesis, expansion and invasion. We investigated the correlation between the serum HMGB1 levels and the clinical and pathologic features of gastric cancer and evaluated the validity of HMGB1 as a potential biomarker for the early diagnosis of gastric cancer. Methods A total of 227 subjects were classified into 5 disease groups according to the 'gastritis-dysplasia-carcinoma' sequence of gastric carcinogenesis and their serum levels of HMGB1 were analyzed by an enzyme-linked immunosorbent assay (ELISA) method. Clinical parameters, International Union Against Cancer (UICC) TNM stage, cancer size, differentiation or lymphatic invasion, vascular or perineural invasion and prognosis were used as analysis variables. Results The serum HMGB1 levels were significantly different among disease groups (ANOVA, p < 0.05) and HMGB1 levels tended to increase according to the progression of gastric carcinogenesis. Serum HMGB1 levels were significantly associated with depth of invasion, lymph node metastasis, tumor size, and poor prognosis (p < 0.05). However, HMGB1 levels were not associated with patient gender or age, differentiation of tumor cells, or lymphatic, vascular and perineural invasion, or the existence of distant metastasis in advanced cancer (p > 0.05). The sensitivity and specificity of serum HMGB1 was 71% and 67% (cut-off value of 5 ng/ml) for the diagnosis of early gastric cancer, and 70% and 64% (cut-off value of 4 ng/ml) for the diagnosis of high-risk lesions, respectively. These values were greater than those for carcinoembryonic antigen (CEA) (30–40% of sensitivity). Conclusion HMGB1 appears to be a useful serological biomarker for early diagnosis as well as evaluating the tumorigenesis, stage, and prognosis of gastric cancer.

Chung, Hye Won; Lee, Sang-Guk; Kim, Heejung; Hong, Duck Jin; Chung, Jae Bock; Stroncek, David; Lim, Jong-Baeck

2009-01-01

369

Visual search for high-level configural differences as well as low-level critical features is highly efficient early in childhood.  

PubMed

Visual search, or the ability to locate a single target from a field of distractors, is used as a means of assessing the capacity of the visual system with regard to the detection of low-level stimulus dimensions such as color, line orientation, and other specific perceptual features and higher level characteristics such as three-dimensional (3-D) orientation implied by pictorial cues to depth or occlusion. Target-distractor differences of importance to the visual system result in rapid (and possibly preattentive) target location while differences of lesser importance (or differences that are less salient) tend to elicit slower, less efficient search performance (search in this latter case may require attentional resources.) Adult abilities in this type of task have been tested extensively, but comparatively little is known about the development of these abilities. The present investigation was conducted to test, across a range of ages in childhood, the ability to detect visual search targets defined by a low-level critical feature (a texton; B. Julesz, 1981) and by static (pictorial) cues to depth. Children 2 to 9 years of age and adults were tested with each type of target. Previous data from infant studies predicted that the texton-defined differences would elicit highly efficient search performance, and this proved to be the case. When no texton difference was present, however, children's search was highly inefficient. Children between 4 to 9 years of age also proved to be quite efficient at locating a target, differing only by a pictorially rendered 3-D orientation from the distractors, but were much less efficient when the static cues to 3-D orientation were removed. These findings confirm previous reports that the basic processes underlying visual search are functional early in development, but suggest that children's search is less efficient than adult search when attention is required for object localization. PMID:12325139

Gerhardstein, Peter; Kraebel, Kimberly S; Gillis, Jennifer; Lassiter, Shana

2002-11-01

370

A dynamic, mitotic-like mechanism for bacterial chromosome segregation  

PubMed Central

The mechanisms that mediate chromosome segregation in bacteria are poorly understood. Despite evidence of dynamic movement of chromosome regions, to date, mitotic-like mechanisms that act on the bacterial chromosome have not been demonstrated. Here we provide evidence that the Vibrio cholerae ParAI and ParBI proteins are components of an apparatus that pulls the origin region of the large V. cholerae chromosome to the cell pole and anchors it there. ParBI interacts with a conserved origin-proximal, centromere-like site (parSI) that, following chromosome replication, segregates asymmetrically from one pole to the other. While segregating, parSI stretches far away from neighboring chromosomal loci. ParAI forms a dynamic band that extends from the pole to the segregating ParBI/parSI complex. Movement of ParBI/parSI across the cell occurs in concert with ParAI retraction. Deletion of parAI disrupts proper origin localization and segregation dynamics, and parSI no longer separates from nearby regions. These data suggest that ParAI forms a dynamic structure that pulls the ParBI-bound chromosome to the pole in a process analogous to anaphase of eukaryotic mitosis.

Fogel, Michael A.; Waldor, Matthew K.

2006-01-01

371

The Prp19 Complex Directly Functions in Mitotic Spindle Assembly  

PubMed Central

The conserved Prp19 (pre-RNA processing 19) complex is required for pre-mRNA splicing in eukaryotic nuclei. Recent RNAi screens indicated that knockdown of Prp19 complex subunits strongly delays cell proliferation. Here we show that knockdown of the smallest subunit, BCAS2/Spf27, destabilizes the entire complex and leads to specific mitotic defects in human cells. These could result from splicing failures in interphase or reflect a direct function of the complex in open mitosis. Using Xenopus extracts, in which cell cycle progression and spindle formation can be reconstituted in vitro, we tested Prp19 complex functions during a complete cell cycle and directly in open mitosis. Strikingly, immunodepletion of the complex either before or after interphase significantly reduces the number of intact spindles, and increases the percentage of spindles with lower microtubule density and impaired metaphase alignment of chromosomes. Our data identify the Prp19 complex as the first spliceosome subcomplex that directly contributes to mitosis in vertebrates independently of its function in interphase.

Hofmann, Jennifer C.; Tegha-Dunghu, Justus; Drager, Stefanie; Will, Cindy L.; Luhrmann, Reinhard; Gruss, Oliver J.

2013-01-01

372

The prp19 complex directly functions in mitotic spindle assembly.  

PubMed

The conserved Prp19 (pre-RNA processing 19) complex is required for pre-mRNA splicing in eukaryotic nuclei. Recent RNAi screens indicated that knockdown of Prp19 complex subunits strongly delays cell proliferation. Here we show that knockdown of the smallest subunit, BCAS2/Spf27, destabilizes the entire complex and leads to specific mitotic defects in human cells. These could result from splicing failures in interphase or reflect a direct function of the complex in open mitosis. Using Xenopus extracts, in which cell cycle progression and spindle formation can be reconstituted in vitro, we tested Prp19 complex functions during a complete cell cycle and directly in open mitosis. Strikingly, immunodepletion of the complex either before or after interphase significantly reduces the number of intact spindles, and increases the percentage of spindles with lower microtubule density and impaired metaphase alignment of chromosomes. Our data identify the Prp19 complex as the first spliceosome subcomplex that directly contributes to mitosis in vertebrates independently of its function in interphase. PMID:24069358

Hofmann, Jennifer C; Tegha-Dunghu, Justus; Dräger, Stefanie; Will, Cindy L; Lührmann, Reinhard; Gruss, Oliver J

2013-09-19

373

Poleward microtubule flux mitotic spindles assembled in vitro  

PubMed Central

In the preceding paper we described pathways of mitotic spindle assembly in cell-free extracts prepared from eggs of Xenopus laevis. Here we demonstrate the poleward flux of microtubules in spindles assembled in vitro, using a photoactivatable fluorescein covalently coupled to tubulin and multi-channel fluorescence videomicroscopy. After local photoactivation of fluorescence by UV microbeam, we observed poleward movement of fluorescein-marked microtubules at a rate of 3 microns/min, similar to rates of chromosome movement and spindle elongation during prometaphase and anaphase. This movement could be blocked by the addition of millimolar AMP-PNP but was not affected by concentrations of vanadate up to 150 microM, suggesting that poleward flux may be driven by a microtubule motor similar to kinesin. In contrast to previous results obtained in vivo (Mitchison, T. J. 1989. J. Cell Biol. 109:637-652), poleward flux in vitro appears to occur independently of kinetochores or kinetochore microtubules, and therefore may be a general property of relatively stable microtubules within the spindle. We find that microtubules moving towards poles are dynamic structures, and we have estimated the average half-life of fluxing microtubules in vitro to be between approximately 75 and 100 s. We discuss these results with regard to the function of poleward flux in spindle movements in anaphase and prometaphase.

1991-01-01

374

Anthrax toxin receptor 2a controls mitotic spindle positioning.  

PubMed

Oriented mitosis is essential during tissue morphogenesis. The Wnt/planar cell polarity (Wnt/PCP) pathway orients mitosis in a number of developmental systems, including dorsal epiblast cell divisions along the animal-vegetal (A-V) axis during zebrafish gastrulation. How Wnt signalling orients the mitotic plane is, however, unknown. Here we show that, in dorsal epiblast cells, anthrax toxin receptor 2a (Antxr2a) accumulates in a polarized cortical cap, which is aligned with the embryonic A-V axis and forecasts the division plane. Filamentous actin (F-actin) also forms an A-V polarized cap, which depends on Wnt/PCP and its effectors RhoA and Rock2. Antxr2a is recruited to the cap by interacting with actin. Antxr2a also interacts with RhoA and together they activate the diaphanous-related formin zDia2. Mechanistically, Antxr2a functions as a Wnt-dependent polarized determinant, which, through the action of RhoA and zDia2, exerts torque on the spindle to align it with the A-V axis. PMID:23201782

Castanon, I; Abrami, L; Holtzer, L; Heisenberg, C P; van der Goot, F G; González-Gaitán, M

2012-12-02

375

Human mitotic chromosomes consist predominantly of irregularly folded nucleosome fibres without a 30-nm chromatin structure  

PubMed Central

How a long strand of genomic DNA is compacted into a mitotic chromosome remains one of the basic questions in biology. The nucleosome fibre, in which DNA is wrapped around core histones, has long been assumed to be folded into a 30-nm chromatin fibre and further hierarchical regular structures to form mitotic chromosomes, although the actual existence of these regular structures is controversial. Here, we show that human mitotic HeLa chromosomes are mainly composed of irregularly folded nucleosome fibres rather than 30-nm chromatin fibres. Our comprehensive and quantitative study using cryo-electron microscopy and synchrotron X-ray scattering resolved the long-standing contradictions regarding the existence of 30-nm chromatin structures and detected no regular structure >11 nm. Our finding suggests that the mitotic chromosome consists of irregularly arranged nucleosome fibres, with a fractal nature, which permits a more dynamic and flexible genome organization than would be allowed by static regular structures.

Nishino, Yoshinori; Eltsov, Mikhail; Joti, Yasumasa; Ito, Kazuki; Takata, Hideaki; Takahashi, Yukio; Hihara, Saera; Frangakis, Achilleas S; Imamoto, Naoko; Ishikawa, Tetsuya; Maeshima, Kazuhiro

2012-01-01

376

Evidence of Activity-Specific, Radial Organization of Mitotic Chromosomes in Drosophila  

Microsoft Academic Search

A fluorescently labeled protein specifically binding to genes was reproducibly found at the periphery of condensed mitotic fruit fly chromosomes, illustrating preservation of a radial structure between consecutive divisions.

Yuri G. Strukov; Tûba H. Sural; Mitzi I. Kuroda; John W. Sedat

2011-01-01

377

Mitotic Recombination and Genetic Changes in Saccharomyces cerevisiae during Wine Fermentation  

PubMed Central

Natural strains of Saccharomyces cerevisiae are prototrophic homothallic yeasts that sporulate poorly, are often heterozygous, and may be aneuploid. This genomic constitution may confer selective advantages in some environments. Different mechanisms of recombination, such as meiosis or mitotic rearrangement of chromosomes, have been proposed for wine strains. We studied the stability of the URA3 locus of a URA3/ura3 wine yeast in consecutive grape must fermentations. ura3/ura3 homozygotes were detected at a rate of 1 × 10?5 to 3 × 10?5 per generation, and mitotic rearrangements for chromosomes VIII and XII appeared after 30 mitotic divisions. We used the karyotype as a meiotic marker and determined that sporulation was not involved in this process. Thus, we propose a hypothesis for the genome changes in wine yeasts during vinification. This putative mechanism involves mitotic recombination between homologous sequences and does not necessarily imply meiosis.

Puig, Sergi; Querol, Amparo; Barrio, Eladio; Perez-Ortin, Jose E.

2000-01-01

378

Immunocytochemical identification of mitotic Hofbauer cells in cultures of first trimester human placental villi  

Microsoft Academic Search

In cultures of first trimester human placental villi, mitotic Hofbauer cells have been identified using a combined autoradiographic and immunostaining technique for the demonstration of HCG, a marker for Hofbauer cells.

M. Frauli; H. Ludwig

1987-01-01

379

Phenothiazine and carbazole-related compounds inhibit mitotic kinesin Eg5 and trigger apoptosis in transformed culture cells.  

PubMed

The effects of phenothiazine and carbazole derivatives on the cell-cycle progression of human transformed culture cells were analyzed. After 2 days incubation, 5 microM 1-phenethylamino-3-phenothiazin-10-yl-propan-2-ol (1) induced strong mitotic arrest followed by cell death, and 20 microM 1-(3,6-dichloro-9H-carbazol-9-yl)-3-phenethylamino-2-propanol (5) and 1-(3,6-dibromo-9H-carbazol-9-yl)-3-phenethylamino-2-propanol (6) also induced cell death. The TUNEL-positive nuclei characteristic of apoptotic cell death were detected in cells treated with the compounds. We observed beta- and gamma-tubulins in the arrested cells after the addition of compound 1, and found that more than 90% of the mitotic cells exhibited the monoastral spindle instead of the normal bipolar spindle. The inhibitory effects of compounds 1, 5, and 6 on the microtubule-activated ATPase activity of mitotic kinesin Eg5, which is essential for bipolar spindle formation, were obtained. The most effective inhibitor, compound 1, had an IC(50) of 1.52 microM. We also examined their toxicities on various cell lines. Compound 1 had less toxicity with the non-transformed cell line WI-38, whereas it exhibited strong toxicity with the transformed cell lines WI38VA13, HL-60 and HeLa. On the other hand, a high dose of compound 6 caused cell death in both types of culture cells. These results suggest that compound 1, an Eg5 inhibitor, selectively kills transformed culture cells. PMID:16814965

Okumura, Hiromi; Nakazawa, Junko; Tsuganezawa, Keiko; Usui, Takeo; Osada, Hiroyuki; Matsumoto, Takehisa; Tanaka, Akiko; Yokoyama, Shigeyuki

2006-05-24

380

The high incidence of acute hemolysis due to favism in Ahvaz, Iran—clinical features and laboratory findings  

Microsoft Academic Search

ObjectiveTo collect comprehensive information about the features of favic patients in Ahvaz (Capital of Khouzestan, Iran) and analyze the extent of the differences with their corresponding in other regions.

Seyyed Mohammad Hasan Aletayeb; Bashir Chomeili; Mehri Taheri; Tahereh Ziaei Kajbaf; Mehran Hakimzadeh; Majid Aminzadeh; Morteza Shojaei Moghadam; Susan Maleki

2010-01-01

381

Opposing motor activities are required for the organization of the mammalian mitotic spindle pole  

Microsoft Academic Search

We use both in vitro and in vivo approaches to examine the roles of Eg5 (kinesin-related protein), cytoplasmic dynein, and dynactin in the organization of the microtubules and the localization of NuMA (Nu- clear protein that associates with the Mitotic A__ppara- tus) at the polar ends of the mammalian mitotic spindle. Perturbation of the function of Eg5 through either im-

Tirso Gaglio; Alejandro Saredi; James B. Bingham; M. Josh Hasbani; Steven R. Gill; Trina A. Schroer; Duane A. Compton

1996-01-01

382

Synaptonemal complex protein SYCP3 impairs mitotic recombination by interfering with BRCA2  

Microsoft Academic Search

The meiosis-specific synaptonemal complex protein SYCP3 has been reported to be aberrantly expressed in tumours. However, in contrast to its well-defined function in meiosis, its possible role in mitotic cells is entirely unknown. Here, we show that SYCP3 is expressed in a range of primary tumours and that it impairs chromosomal integrity in mitotic cells. Expression of SYCP3 inhibits the

Miyuki Okajima; Aiko Kinomura; Yoshihiro Fujii; Takashi Hiyama; Jiying Sun; Satoshi Tashiro; Noriko Hosoya; Kiyoshi Miyagawa

2011-01-01

383

Mitotic Activity of Thymocytes in a Synthetic Tissue Culture Medium. Effect of L-AIanine  

Microsoft Academic Search

DNA synthesis in guinea pig thymocytes suspended in RPMI 1640 medium increased to a peak after 4–5 h in culture and was followed by increased mitotic activity, indicating that many thymocytes in S phase proceeded through G2 into mitosis. Addition of L-alanine to the medium markedly increased the DNA synthesis within 1 h and the mitotic frequency from 6 h.

G. Sandberg; U. Ernström

1979-01-01

384

Merotelic Kinetochore Orientation Is a Major Mechanism of Aneuploidy in Mitotic Mammalian Tissue Cells  

Microsoft Academic Search

In mitotic cells, an error in chromosome seg- regation occurs when a chromosome is left near the spindle equator after anaphase onset (lagging chromo- some). In PtK1 cells, we found 1.16% of untreated ana- phase cells exhibiting lagging chromosomes at the spin- dle equator, and this percentage was enhanced to 17.55% after a mitotic block with 2 m M nocodazole.

Daniela Cimini; Bonnie Howell; Paul Maddox; Alexey Khodjakov; Francesca Degrassi; E. D. Salmon

2001-01-01

385

XKCM1: A Xenopus Kinesin-Related Protein That Regulates Microtubule Dynamics during Mitotic Spindle Assembly  

Microsoft Academic Search

We isolated a cDNA clone encoding a kinesin-related protein, which we named XKCM1. Antibodies to XKCM1 stain mitotic centromeres and spindle poles. Immunodepletion and antibody addition experiments in an in vitro spindle assembly assay show that XKCM1 is required for both establishment and maintenance of mitotic spindles. The structures that form in the absence of XKCM1 contain abnormally long microtubules.

Claire E Walczak; Timothy J Mitchison; Arshad Desai

1996-01-01

386

[Comparison of the changes in mitotic activity and in serotonin concentration in regenerating liver].  

PubMed

Mobilization of serotonin in intestine and its accumulation in liver and spleen tissues were observed at the initial periods after partial hepatectomy. Later on, content of serotonin was gradually decreased in liver tissue, however, its dynamics exhibited a phasic pattern--the minimal level of the amine coincided in time with the maximal mitotic activity. A negative correlation was found between the content of endogenous serotonin and mitotic activity. Possible role of endogenous serotonin in proliferating processes is discussed. PMID:6858025

Kulinski?, V I; Udovitsina (Cherkasova), T I; Vstavskaia, Iu A; Rykov, S A

387

Expression of the Mitotic Motor Protein Eg5 in Postmitotic Neurons: Implications for Neuronal Development  

Microsoft Academic Search

It is well established that the microtubules of the mitotic spindle are organized by a variety of motor proteins, and it appears that the same motors or closely related variants organize microtu- bules in the postmitotic neuron. Specifically, cytoplasmic dy- nein and the kinesin-related motor known as CHO1\\/MKLP1 are used within the mitotic spindle, and recent studies suggest that they

Lotfi Ferhat; Crist Cook; Muriel Chauviere; Maryannick Harper; Michel Kress; Gary E. Lyons; Peter W. Baas

1998-01-01

388

Myosin-10 and actin filaments are essential for mitotic spindle function.  

PubMed

Mitotic spindles are microtubule-based structures responsible for chromosome partitioning during cell division. Although the roles of microtubules and microtubule-based motors in mitotic spindles are well established, whether or not actin filaments (F-actin) and F-actin-based motors (myosins) are required components of mitotic spindles has long been controversial. Based on the demonstration that myosin-10 (Myo10) is important for assembly of meiotic spindles, we assessed the role of this unconventional myosin, as well as F-actin, in mitotic spindles. We find that Myo10 localizes to mitotic spindle poles and is essential for proper spindle anchoring, normal spindle length, spindle pole integrity, and progression through metaphase. Furthermore, we show that F-actin localizes to mitotic spindles in dynamic cables that surround the spindle and extend between the spindle and the cortex. Remarkably, although proper anchoring depends on both F-actin and Myo10, the requirement for Myo10 in spindle pole integrity is F-actin independent, whereas F-actin and Myo10 actually play antagonistic roles in maintenance of spindle length. PMID:18606852

Woolner, Sarah; O'Brien, Lori L; Wiese, Christiane; Bement, William M

2008-07-07

389

AMPK Regulates Mitotic Spindle Orientation through Phosphorylation of Myosin Regulatory Light Chain  

PubMed Central

The proper orientation of the mitotic spindle is essential for mitosis; however, how these events unfold at the molecular level is not well understood. AMP-activated protein kinase (AMPK) regulates energy homeostasis in eukaryotes, and AMPK-null Drosophila mutants have spindle defects. We show that threonine172 phosphorylated AMPK localizes to the mitotic spindle poles and increases when cells enter mitosis. AMPK depletion causes a mitotic delay with misoriented spindles relative to the normal division plane and a reduced number and length of astral microtubules. AMPK-depleted cells contain mitotic actin bundles, which prevent astral microtubule-actin cortex attachments. Since myosin regulatory light chain (MRLC) is an AMPK downstream target and mediates actin function, we investigated whether AMPK signals through MRLC to control spindle orientation. Mitotic levels of serine19 phosphorylated MRLC (pMRLCser19) and spindle pole-associated pMRLCser19 are abolished when AMPK function is compromised, indicating that AMPK is essential for pMRLCser19 spindle pole activity. Phosphorylation of AMPK and MRLC in the mitotic spindle is dependent upon calcium/calmodulin-dependent protein kinase kinase (CamKK) activity in LKB1-deficient cells, suggesting that CamKK regulates this pathway when LKB1 function is compromised. Taken together, these data indicate that AMPK mediates spindle pole-associated pMRLCser19 to control spindle orientation via regulation of actin cortex-astral microtubule attachments.

Thaiparambil, Jose T.; Eggers, Carrie M.

2012-01-01

390

Repeated furrow formation from a single mitotic apparatus in cylindrical sand dollar eggs.  

PubMed

The methods used previously to demonstrate the ability of a single mitotic apparatus to elicit multiple furrows involved considerable cell distortion and did not permit the investigator to control the positioning of the parts or to observe satisfactorily the early stages of furrow development. In this investigation, Echinarachnius parma eggs were confined in 82 microns i.d. transparent, silicone rubber-walled capillaries, and the mitotic apparatus was moved by pushing the poles inward with 55-microns-diameter glass balls. When the mitotic apparatus was shifted immediately after the furrow first appeared, a new furrow appeared in the normal relation to the new position in 1-2 minutes. The same mitotic apparatus could elicit up to 13 furrows as it was shifted back and forth by alternately pushing in the poles. The previous furrow regressed as the new furrow developed. The operations protracted the furrow establishment period to as long as 24.5 minutes after establishment of the first furrow. The characteristics of furrow regression were related to the distance the mitotic apparatus was moved. It is unlikely that regression was caused either by stress imposed on the surface or the removal of the mitotic apparatus from the vicinity of the furrow. PMID:3989496

Rappaport, R

1985-04-01

391

Four important features in the Ward Hunt Ice Shelf revealed from the high-temporal- and high-spatial-resolution images taken by Formosat-2 in Summer 2008  

NASA Astrophysics Data System (ADS)

Massive ice shelf collapsing in Polar Regions is indisputably a clear warning of global warming. To investigate such a rapid change of a breaking up event at a remote site requires an innovative approach that is able to make both high-temporal- and high-spatial-resolution observations. Deploying a high-spatial-resolution sensor in a daily revisit orbit, Formosat-2 successfully captured the details of Wilkins Ice Shelf disintegration event in March 2008, using its 2-m multi-spectral remote sensing imagery. Right after a few extensive fractures were found in the largest ice shelf in the Arctic (Ward Hunt Ice Shelf, WHIS) and reported in May 2008, Formosat-2 was employed to make an intensive observation in this region. A total of eleven scenes of WHIS were acquired from 5 June to 30 August 2008, and ten of them were taken in a preferable low-cloud- cover condition. After the basic processing of level-2 georeferencing, band-to-band coregistration, spectral summation intensity modulation pan-sharpening, and multi-temporal images coregistration, we are able to summarize four important features in WHIS from the time series of Formosat-2 images. First, the sea ice velocity field in the vicinity of WHIS can be inferred by using ice floes as tracers and manually identifying identical floes in consecutive images. There is an eastward flow along the coast of Ellesmere Island. This flow is one of the main forces that gradually tears apart the outermost WHIS in summer. Second, a considerable number of melt ponds with scales of a few to tens of meters is found across the lower part of WHIS. As the temperature rises in summer, the total area of melt ponds increases as a result. In some cases, the melting water soon drains away and a large scale of disintegration occurs afterwards. Third, the extent of organic sedimentary material, namely microbial mat, can be clearly identified from these multispectral images. Fourth, the recent break-up event poses a threat to Disraeli Fiord, the largest remaining epishelf lake in the Northern Hemisphere. A new channel has formed recently, which may accelerate the drainage of the epishelf lake. This research demonstrates that high-spatial- and high- temporal-resolution optical imagery taken from Formosat-2 is a useful data source for studying the collapse of ice shelf in Polar Regions.

Liu, C.; Chang, Y.; Yan, S.; Wu, A.

2008-12-01

392

A Signature Inferred from Drosophila Mitotic Genes Predicts Survival of Breast Cancer Patients  

PubMed Central

Introduction The classification of breast cancer patients into risk groups provides a powerful tool for the identification of patients who will benefit from aggressive systemic therapy. The analysis of microarray data has generated several gene expression signatures that improve diagnosis and allow risk assessment. There is also evidence that cell proliferation-related genes have a high predictive power within these signatures. Methods We thus constructed a gene expression signature (the DM signature) using the human orthologues of 108 Drosophila melanogaster genes required for either the maintenance of chromosome integrity (36 genes) or mitotic division (72 genes). Results The DM signature has minimal overlap with the extant signatures and is highly predictive of survival in 5 large breast cancer datasets. In addition, we show that the DM signature outperforms many widely used breast cancer signatures in predictive power, and performs comparably to other proliferation-based signatures. For most genes of the DM signature, an increased expression is negatively correlated with patient survival. The genes that provide the highest contribution to the predictive power of the DM signature are those involved in cytokinesis. Conclusion This finding highlights cytokinesis as an important marker in breast cancer prognosis and as a possible target for antimitotic therapies.

Damasco, Christian; Lembo, Antonio; Somma, Maria Patrizia; Gatti, Maurizio; Di Cunto, Ferdinando; Provero, Paolo

2011-01-01

393

Transcript levels of the Saccharomyces cerevisiae DNA repair gene RAD18 increase in UV irradiated cells and during meiosis but not during the mitotic cell cycle.  

PubMed Central

We have examined the transcript levels of the Saccharomyces cerevisiae DNA repair gene RAD18 in UV irradiated cells, in the mitotic cell cycle, and during meiosis. Levels of RAD18 mRNA increased upon UV irradiation, but remained constant during the mitotic cell cycle. During meiosis, RAD18 mRNA levels rose about 4 fold at a stage coincident with the period when high levels of genetic recombination occur. RAD18 resembles the other DNA repair genes, RAD2, RAD6, RAD7, RAD23, and RAD54, all of which also exhibit increased transcription in response to DNA damage and during meiosis. Comparisons of sequences in 5' flanking regions of RAD genes suggest that different upstream sequences are involved in regulating the expression of DNA repair genes belonging to different epistasis groups. Images

Jones, J S; Prakash, L

1991-01-01

394

High-speed, full 3D feature metrology for litho monitoring, matching, and model calibration with scatterometry  

NASA Astrophysics Data System (ADS)

We studied the potential of optical scatterometry to measure the full 3D profile of features representative to real circuit design topology. The features were selected and printed under conditions to improve the measurability of the features by scatterometry without any loss of information content for litho monitoring and control applications. The impact of the scatterometry recipe and settings was evaluated and optimal settings were determined. We have applied this strategy on a variety of structures and gathered results using the YieldStar angular reflection based scatterometer. The reported results show that we obtained effective decoupling of the measurement of the 3 dimensions of the features. The results match with predictions by calibrated lithographic simulations. As a verification we have successfully performed a scanner matching experiment using computational Pattern Matcher (cPM) in combination with YieldStar as a metrology tool to characterize the difference between the scanners and verify the matching. The results thus obtained were better than using CD-SEM for matching and verification.

Cramer, Hugo; Chen, Alek; Li, Fahong; Leray, Philippe; Charley, Anne-Laure; van Look, Lieve; Bekaert, Joost; Cheng, Shaunee

2012-03-01

395

High Prevalence of Polycystic Ovaries and Associated Clinical, Endocrine, and Metabolic Features in Women with Previous Gestational Diabetes Mellitus  

Microsoft Academic Search

The prevalence of polycystic ovaries, according to ultrasonography, and associated clinical, endocrine, and metabolic features were in- vestigated in women with previous gestational diabetes mellitus (GDM). Thirty-four women with GDM 3-5 yr before the investigation and 36 controls with uncomplicated pregnancies, selected for similar age, parity, and date of delivery, were investigated. The women with previous GDM showed a higher

JAN HOLTE; GIANLUCA GENNARELLI; LEIF WIDE; HANS LITHELL; CHRISTIAN BERNE

2010-01-01

396

Plumes anchored by a high viscosity lower mantle in a 3D mantle convection model featuring dynamically evolving plates  

Microsoft Academic Search

Previous studies have shown that 3D vigorously convecting systems featuring plate-like surface motion and lower mantle viscosities much greater than the upper mantle viscosity can yield long lived intraplate plumes if plate boundaries remain fixed. We investigate whether plumes originating in a lower mantle 90 times more viscous than the upper mantle will maintain relatively fixed positions when dynamic plate

J. P. Lowman; A. D. Gait; C. W. Gable; H. Kukreja

2008-01-01

397

The Auto-ubiquitylation of E3 Ubiquitin-protein Ligase Chfr at G2 Phase Is Required for Accumulation of Polo-like Kinase 1 and Mitotic Entry in Mammalian Cells*  

PubMed Central

The E3 ubiquitin-protein ligase Chfr is a mitotic stress checkpoint protein that delays mitotic entry in response to microtubule damage; however, the molecular mechanism by which Chfr accomplishes this remains elusive. Here, we show that Chfr levels are elevated in response to microtubule-damaging stress. Moreover, G2/M transition is associated with cell cycle-dependent turnover of Chfr accompanied by high autoubiquitylation activity, suggesting that regulation of Chfr levels and auto-ubiquitylation activity are functionally significant. To test this, we generated Chfr mutants Chfr-K2A and Chfr-K5A in which putative lysine target sites of auto-ubiquitylation were replaced with alanine. Chfr-K2A did not undergo cell cycle-dependent degradation, and its levels remained high during G2/M phase. The elevated levels of Chfr-K2A caused a significant reduction in phosphohistone H3 levels and cyclinB1/Cdk1 kinase activities, leading to mitotic entry delay. Notably, polo-like kinase 1 levels at G2 phase, but not at S phase, were ?2–3-fold lower in cells expressing Chfr-K2A than in wild-type Chfr-expressing cells. Consistent with this, ubiquitylation of Plk1 at G2 phase was accelerated in Chfr-K2A-expressing cells. In contrast, Aurora A levels remained constant, indicating that Plk1 is a major target of Chfr in controlling the timing of mitotic entry. Indeed, overexpression of Plk1 in Chfr-K2A-expressing cells restored cyclin B1/Cdk1 kinase activity and promoted mitotic entry. Collectively, these data indicate that Chfr auto-ubiquitylation is required to allow Plk1 to accumulate to levels necessary for activation of cyclin B1/Cdk1 kinase and mitotic entry. Our results provide the first evidence that Chfr auto-ubiquitylation and degradation are important for the G2/M transition.

Kim, Jo-Sun; Park, Yong-Yea; Park, Sun-Yi; Cho, Hyeseon; Kang, Dongmin; Cho, Hyeseong

2011-01-01

398

Critical role of anti-apoptotic Bcl-2 protein phosphorylation in mitotic death.  

PubMed

Microtubule inhibiting agents (MIAs) characteristically induce phosphorylation of the major anti-apoptotic Bcl-2 family members Mcl-1, Bcl-2 and Bcl-xL, and although this leads to Mcl-1 degradation, the role of Bcl-2/Bcl-xL phosphorylation in mitotic death has remained controversial. This is in part due to variation in MIA sensitivity among cancer cell lines, the dependency of cell fate on drug concentration and uncertainty about the modes of cell death occurring, thus making comparisons of published reports difficult. To circumvent problems associated with MIAs, we used siRNA knockdown of the anaphase-promoting complex activator, Cdc20, as a defined molecular system to investigate the role, specifically in mitotic death, of individual anti-apoptotic Bcl-2 proteins and their phosphorylated forms. We show that Cdc20 knockdown in HeLa cells induces mitotic arrest and subsequent mitotic death. Knockdown of Cdc20 in HeLa cells stably overexpressing untagged wild-type Bcl-2, Bcl-xL or Mcl-1 promoted phosphorylation of the overexpressed proteins in parallel with their endogenous counterparts. Overexpression of Bcl-2 or Bcl-xL blocked mitotic death induced by Cdc20 knockdown; phospho-defective mutants were more protective than wild-type proteins, and phospho-mimic Bcl-xL was unable to block mitotic death. Overexpressed Mcl-1 failed to protect from Cdc20 siRNA-mediated death, as the overexpressed protein was susceptible to degradation similar to endogenous Mcl-1. These results provide compelling evidence that phosphorylation of anti-apoptotic Bcl-2 proteins has a critical role in regulation of mitotic death. These findings make an important contribution toward our understanding of the molecular mechanisms of action of MIAs, which is critical for their rational use clinically. PMID:24091677

Eichhorn, J M; Sakurikar, N; Alford, S E; Chu, R; Chambers, T C

2013-10-03

399

Evidence for the presence of inhibitors of mitotic factors during G1 period in mammalian cells  

PubMed Central

Our earlier studies indicated that the mitotic factors, which induce germinal vesicle breakdown and chromosome condensation when injected into fully grown Xenopus oocytes, are preferentially associated with metaphase chromosomes and that they bind to chromatin as soon as they are synthesized during the G2 phase. In this study, we attempted to determine the fate of these factors as the cell completes mitosis and enters G1. Extracts from HeLa cells at different points during G1, S, and G2 periods were mixed with mitotic extracts in various proportions, incubated, and then injected into Xenopus oocytes to determine their maturation-promoting activity. The maturation-promoting activity of the mitotic extracts was neutralized by extracts of G1 cells during all stages of G1 but not by those of late S and G2 phase cells. Extracts of quiescent (G0) human diploid fibroblasts exhibited very little inhibitory activity. However, UV irradiation of G0 cells, which is known to cause decondensation of chromatin, significantly enhanced the inhibitory activity of extracts of these cells. These factors are termed inhibitors of mitotic factors (IMF). They seem to be activated, rather than newly synthesized, as the cell enters telophase when chromosomes begin to decondense. The IMF are nondialyzable, nonhistone proteins with a molecular weight of greater than 12,000. Since mitotic factors are known to induce chromosome condensation, it is possible that IMF, which are antagonistic to mitotic factors, may serve the reverse function of the mitotic factors, i.e., regulation of chromosome decondensation.

1983-01-01

400

DeadEasy Mito-Glia: Automatic Counting of Mitotic Cells and Glial Cells in Drosophila  

PubMed Central

Cell number changes during normal development, and in disease (e.g., neurodegeneration, cancer). Many genes affect cell number, thus functional genetic analysis frequently requires analysis of cell number alterations upon loss of function mutations or in gain of function experiments. Drosophila is a most powerful model organism to investigate the function of genes involved in development or disease in vivo. Image processing and pattern recognition techniques can be used to extract information from microscopy images to quantify automatically distinct cellular features, but these methods are still not very extended in this model organism. Thus cellular quantification is often carried out manually, which is laborious, tedious, error prone or humanly unfeasible. Here, we present DeadEasy Mito-Glia, an image processing method to count automatically the number of mitotic cells labelled with anti-phospho-histone H3 and of glial cells labelled with anti-Repo in Drosophila embryos. This programme belongs to the DeadEasy suite of which we have previously developed versions to count apoptotic cells and neuronal nuclei. Having separate programmes is paramount for accuracy. DeadEasy Mito-Glia is very easy to use, fast, objective and very accurate when counting dividing cells and glial cells labelled with a nuclear marker. Although this method has been validated for Drosophila embryos, we provide an interactive window for biologists to easily extend its application to other nuclear markers and other sample types. DeadEasy MitoGlia is freely available as an ImageJ plug-in, it increases the repertoire of tools for in vivo genetic analysis, and it will be of interest to a broad community of developmental, cancer and neuro-biologists.

Forero, Manuel Guillermo; Learte, Anabel R.; Cartwright, Stephanie; Hidalgo, Alicia

2010-01-01

401

SIRT2, a tubulin deacetylase, acts to block the entry to chromosome condensation in response to mitotic stress  

Microsoft Academic Search

We previously identified SIRT2, an nicotinamide adenine dinucleotide (NAD)-dependent tubulin deacetylase, as a protein downregulated in gliomas and glioma cell lines, which are characterized by aneuploidy. Other studies reported SIRT2 to be involved in mitotic progression in the normal cell cycle. We herein investigated whether SIRT2 functions in the mitotic checkpoint in response to mitotic stress caused by microtubule poisons.

T Inoue; M Hiratsuka; M Osaki; H Yamada; I Kishimoto; S Yamaguchi; S Nakano; M Katoh; H Ito; M Oshimura

2007-01-01

402

Dust Extinction in High-z Galaxies with GRB Afterglow Spectroscopy - The 2175{\\\\AA} Feature at z=2.45  

Microsoft Academic Search

We report the clear detection of the 2175A dust absorption feature in the\\u000aoptical afterglow spectrum of the gamma-ray burst (GRB) GRB070802 at a redshift\\u000aof z=2.45. This is the highest redshift for a detected 2175A dust bump to date,\\u000aand it is the first clear detection of the 2175A bump in a GRB host galaxy,\\u000awhile several tens of

A. El ´ õasdottir; J. P. U. Fynbo; J. Hjorth; C. Ledoux; D. J. Watson; A. C. Andersen; D. Malesani; P. M. Vreeswijk; J. X. Prochaska; J. Sollerman; A. O. Jaunsen

2008-01-01

403

A 90nm high volume manufacturing logic technology featuring novel 45nm gate length strained silicon CMOS transistors  

Microsoft Academic Search

This paper describes the details of a novel strained transistor architecture which is incorporated into a 90nm logic technology on 300mm wafers. The unique strained PMOS transistor structure features an epitaxially grown strained SiGe film embedded in the source drain regions. Dramatic performance enhancement relative to unstrained devices are reported. These transistors have gate length of 45nm and 50nm for

T. Ghani; M. Armstrong; C. Auth; M. Bost; P. Charvat; G. Glass; T. Hoffmann; K. Johnson; C. Kenyon; J. Klaus; B. McIntyre; K. Mistry; A. Murthy; J. Sandford; M. Silberstein; S. Sivakumar; P. Smith; K. Zawadzki; S. Thompson; M. Bohr

2003-01-01

404

The Utilization during Mitotic Cell Division of Loci Controlling Meiotic Recombination and Disjunction in DROSOPHILA MELANOGASTER  

PubMed Central

To inquire whether the loci identified by recombination-defective and disjunction-defective meiotic mutants in Drosophila are also utilized during mitotic cell division, the effects of 18 meiotic mutants (representing 13 loci) on mitotic chromosome stability have been examined genetically. To do this, meiotic-mutant-bearing flies heterozygous for recessive somatic cell markers were examined for the frequencies and types of spontaneous clones expressing the cell markers. In such flies, marked clones can arise via mitotic recombination, mutation, chromosome breakage, nondisjunction or chromosome loss, and clones from these different origins can be distinguished. In addition, meiotic mutants at nine loci have been examined for their effects on sensitivity to killing by UV and X rays.—Mutants at six of the seven recombination-defective loci examined (mei-9, mei-41, c(3)G, mei-W68, mei-S282, mei-352, mei-218) cause mitotic chromosome instability in both sexes, whereas mutants at one locus (mei-218) do not affect mitotic chromosome stability. Thus many of the loci utilized during meiotic recombination also function in the chromosomal economy of mitotic cells.—The chromosome instability produced by mei-41 alleles is the consequence of chromosome breakage, that of mei-9 alleles is primarily due to chromosome breakage and, to a lesser extent, to an elevated frequency of mitotic recombination, whereas no predominant mechanism responsible for the instability caused by c(3)G alleles is discernible. Since these three loci are defective in their responses to mutagen damage, their effects on chromosome stability in nonmutagenized cells are interpreted as resulting from an inability to repair spontaneous lesions. Both mei-W68 and mei-S282 increase mitotic recombination (and in mei-W68, to a lesser extent, chromosome loss) in the abdomen but not the wing. In the abdomen, the primary effect on chromosome stability occurs during the larval period when the abdominal histoblasts are in a nondividing (G2) state.—Mitotic recombination is at or above control levels in the presence of each of the recombination-defective meiotic mutants examined, suggesting that meiotic and mitotic recombination are under separate genetic control in Drosophila.—Of the six mutants examined that are defective in processes required for regular meiotic chromosome segregation, four (l(1)TW-6cs, cand, mei-S332, ord) affect mitotic chromosome behavior. At semi-restrictive temperatures, the cold sensitive lethal l(1)TW-6cs causes very frequent somatic spots, a substantial proportion of which are attributable to nondisjunction or loss. Thus, this locus specifies a function essential for chromosome segregation at mitosis as well as at the first meiotic division in females. The patterns of mitotic effects caused by cand, mei-S332, and ord suggest that they may be leaky alleles at essential loci that specify functions common to meiosis and mitosis. Mutants at the two remaining loci (nod, pal) do not affect mitotic chromosome stability.

Baker, Bruce S.; Carpenter, Adelaide T. C.; Ripoll, P.

1978-01-01

405

Computer simulations predict that chromosome movements and rotations accelerate mitotic spindle assembly without compromising accuracy.  

PubMed

The mitotic spindle self-assembles in prometaphase by a combination of centrosomal pathway, in which dynamically unstable microtubules search in space until chromosomes are captured, and a chromosomal pathway, in which microtubules grow from chromosomes and focus to the spindle poles. Quantitative mechanistic understanding of how spindle assembly can be both fast and accurate is lacking. Specifically, it is unclear how, if at all, chromosome movements and combining the centrosomal and chromosomal pathways affect the assembly speed and accuracy. We used computer simulations and high-resolution microscopy to test plausible pathways of spindle assembly in realistic geometry. Our results suggest that an optimal combination of centrosomal and chromosomal pathways, spatially biased microtubule growth, and chromosome movements and rotations is needed to complete prometaphase in 10-20 min while keeping erroneous merotelic attachments down to a few percent. The simulations also provide kinetic constraints for alternative error correction mechanisms, shed light on the dual role of chromosome arm volume, and compare well with experimental data for bipolar and multipolar HT-29 colorectal cancer cells. PMID:19717443

Paul, Raja; Wollman, Roy; Silkworth, William T; Nardi, Isaac K; Cimini, Daniela; Mogilner, Alex

2009-08-26

406

Non-anti-mitotic concentrations of taxol reduce breast cancer cell invasiveness.  

PubMed

Taxol is widely used in breast cancer chemotherapy. Its effects are primarily attributed to its anti-mitotic activity. Microtubule perturbators also exert antimetastatic activities which cannot be explained solely by the inhibition of proliferation. Voltage-dependent sodium channels (Na(V)) are abnormally expressed in the highly metastatic breast cancer cell line MDA-MB-231 and not in MDA-MB-468 cell line. Inhibiting Na(V) activity with tetrodotoxin is responsible for an approximately 0.4-fold reduction of MDA-MB-231 cell invasiveness. In this study, we focused on the effect of a single, 2-h application of 10 nM taxol on the two cell lines MDA-MB-231 and MDA-MB-468. At this concentration, taxol had no effect on proliferation after 7 days and on migration in any cell line. However it led to a 40% reduction of transwell invasion of MDA-MB-231 cells. There was no additive effect when taxol and tetrodotoxin were simultaneously applied. Na(V) activity, as assessed by patch-clamp, indicates that it was changed by taxol pre-treatment. We conclude that taxol can exert anti-tumoral activities, in cells expressing Na(V), at low doses that have no effect on cell proliferation. This effect might be due to a modulation of signalling pathways involving sodium channels. PMID:19111674

Tran, Truong-An; Gillet, Ludovic; Roger, Sébastien; Besson, Pierre; White, Edward; Le Guennec, Jean-Yves

2008-12-26

407

Active ADP-ribosylation Factor-1 (ARF1) Is Required for Mitotic Golgi Fragmentation*S  

PubMed Central

In mammalian cells the Golgi apparatus undergoes an extensive disassembly process at the onset of mitosis that is believed to facilitate equal partitioning of this organelle into the two daughter cells. However, the underlying mechanisms for this fragmentation process are so far unclear. Here we have investigated the role of the ADP-ribosylation factor-1 (ARF1) in this process to determine whether Golgi fragmentation in mitosis is mediated by vesicle budding. ARF1 is a small GTPase that is required for COPI vesicle formation from the Golgi membranes. Treatment of Golgi membranes with mitotic cytosol or with purified coatomer together with wild type ARF1 or its constitutive active form, but not the inactive mutant, converted the Golgi membranes into COPI vesicles. ARF1-depleted mitotic cytosol failed to fragment Golgi membranes. ARF1 is associated with Golgi vesicles generated in vitro and with vesicles in mitotic cells. In addition, microinjection of constitutive active ARF1 did not affect mitotic Golgi fragmentation or cell progression through mitosis. Our results show that ARF1 is active during mitosis and that this activity is required for mitotic Golgi fragmentation.

Xiang, Yi; Seemann, Joachim; Bisel, Blaine; Punthambaker, Sukanya; Wang, Yanzhuang

2012-01-01

408

Condensed Mitotic Chromosome Structure at Nanometer Resolution Using PALM and EGFP- Histones  

PubMed Central

Photoactivated localization microscopy (PALM) and related fluorescent biological imaging methods are capable of providing very high spatial resolutions (up to 20 nm). Two major demands limit its widespread use on biological samples: requirements for photoactivatable/photoconvertible fluorescent molecules, which are sometimes difficult to incorporate, and high background signals from autofluorescence or fluorophores in adjacent focal planes in three-dimensional imaging which reduces PALM resolution significantly. We present here a high-resolution PALM method utilizing conventional EGFP as the photoconvertible fluorophore, improved algorithms to deal with high levels of biological background noise, and apply this to imaging higher order chromatin structure. We found that the emission wavelength of EGFP is efficiently converted from green to red when exposed to blue light in the presence of reduced riboflavin. The photon yield of red-converted EGFP using riboflavin is comparable to other bright photoconvertible fluorescent proteins that allow <20 nm resolution. We further found that image pre-processing using a combination of denoising and deconvolution of the raw PALM images substantially improved the spatial resolution of the reconstruction from noisy images. Performing PALM on Drosophila mitotic chromosomes labeled with H2AvD-EGFP, a histone H2A variant, revealed filamentous components of ?70 nm. This is the first observation of fine chromatin filaments specific for one histone variant at a resolution approximating that of conventional electron microscope images (10–30 nm). As demonstrated by modeling and experiments on a challenging specimen, the techniques described here facilitate super-resolution fluorescent imaging with common biological samples.

Matsuda, Atsushi; Shao, Lin; Boulanger, Jerome; Kervrann, Charles; Carlton, Peter M.; Kner, Peter; Agard, David; Sedat, John W.

2010-01-01

409