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PubMed2006

Expression and colocalization of NADPH-diaphorase and Fos in the subnuclei of the parabrachial nucleus in rats following visceral noxious stimulation.

To investigate whether neural nitric oxide synthase (nNOS) in the parabrachial nucleus (PB) is involved in processing visceral noxious stimulation, we mapped the distribution of histochemical staining for nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d), a marker for nNOS, and immunohistochemical staining for Fos, a neuronal activity marker, in the subnuclei of the PB following 2% formalin injection into the stomach of rats. NADPH-d and noxious-stimuli induced Fos staining were also examined in tissue containing PB cells labeled by the retrograde transport of fluogold (FG) injected into the central nucleus of the amygdala (CeA). We found that the number of Fos immunoreactive (Fos-IR) neurons was significantly increased in the dorsal lateral (dl), external lateral (el) and Kölliker-Fuse (KF) subnuclei of the PB. We observed that intensely labeled (type 1) NADPH-d positive neurons were mainly located in the rostral part of the PB; they extended long processes adjacent Fos-IR neurons, but no Fos/type 1 NADPH-d double-labeled neurons were seen. In contrast, lightly labeled (type 2) NADPH-d positive neurons were principally localized in the dl of the PB, in which a few Fos/type 2 NADPH-d double-labeled neurons were detected. Additionally, a large number of FG/Fos double-labeled neurons were observed to be surrounded closely by the intensive NADPH-d staining in the el of the PB. These results suggest that neurons in the el of the PB that project to the CeA are activated by visceral noxious stimulation and could be indirectly influenced by nitric oxide in the PB.

Analysis of Variance↗
PubMed2000

Wavelet analysis of electron-density maps.

The wavelet transform is a powerful technique in signal processing and image analysis and it is shown here that wavelet analysis of low-resolution electron-density maps has the potential to increase their resolution. Like Fourier analysis, wavelet analysis expresses the image (electron density) in terms of a set of orthogonal functions. In the case of the Fourier transform, these functions are sines and cosines and each one contributes to the whole of the image. In contrast, the wavelet functions (simply called wavelets) can be quite localized and may only contribute to a small part of the image. This gives control over the amount of detail added to the map as the resolution increases. The mathematical details are outlined and an algorithm which achieves a resolution increase from 10 to 7 A using a knowledge of the wavelet-coefficient histograms, electron-density histogram and the observed structure amplitudes is described. These histograms are calculated from the electron density of known structures, but it seems likely that the histograms can be predicted, just as electron-density histograms are at high resolution. The results show that the wavelet coefficients contain the information necessary to increase the resolution of electron-density maps.

Algorithms↗
PubMed1992

The synergistic neutralization of Rift Valley fever virus by monoclonal antibodies to the envelope glycoproteins.

A panel of monoclonal antibodies (MAbs) mapping to different antigenic sites on the RVFV G1 and G2 proteins were used to examine the mechanisms involved in neutralization of the virus. Three types of synergistic neutralization of RVFV were observed on mixing various pairs of MAbs. Firstly, enhanced neutralization occurred for two MAb pairs that showed augmented binding for G2. These comprised a combination of a neutralizing MAb with a non-neutralizing antibody, as well as two antibodies which were non-neutralizing individually. In the second category, synergistic neutralization was observed between combinations of MAbs for which increased binding had not been detected. Lastly, mixtures of G1 and G2-specific MAbs were also capable of enhancing neutralization. Post-adsorption neutralization assays revealed that some MAbs neutralized cell-attached virus efficiently, indicating that they can neutralize by inhibiting the infection process after virus attachment. MAbs mapping to G1 IIe, G2I b and G2I c were unable to neutralize adsorbed virus and thus probably neutralize by preventing virus attachment to cells. Several G1-reactive MAbs displayed low level post-adsorption activity, suggesting they may be capable of inhibiting RVFV infectivity at different stages of the replication cycle.

Adsorption↗
PubMed2002

Ephrin-A5 restricts topographically specific arborization in the chick retinotectal projection in vivo.

The retinotectal map is the best characterized model system to study how axons respond to guidance cues during the formation of the nervous system. Recent studies have shown that the critical event in forming this map is topographic-specific axon branching. To elucidate the in vivo role of the repulsive cue ephrin-A5 in this event, we used chromophore-assisted laser inactivation (CALI) to generate acute loss of ephrin-A5 function in localized areas of the posterior tectum of chick embryos in ovo and analyzed the resulting changes of retinal projections during initial outgrowth (E11) and when retinal axons arborize in the deep layers in the tectum (E12). We confirmed that ephrin-A5 functions to restrict initial axon outgrowth at E11. At E12, CALI of ephrin-A5 did not affect the extent of axon outgrowth on the tectal surface but instead caused ectopic arborization posterior to the topographically correct site in deeper layers of the tectum. This shows that ephrin-A5 restricts arborization during this critical process for developing the retinotopic map. CALI provides an approach to inactivate in vivo function in higher vertebrates with high temporal and spatial specificity that may have wide application.

Animals↗
PubMed2006

Comparative genomic mapping of the bovine Fragile Histidine Triad (FHIT) tumour suppressor gene: characterization of a 2 Mb BAC contig covering the locus, complete annotation of the gene, analysis of cDNA and of physiological expression profiles.

BACKGROUND: The Fragile Histidine Triad gene (FHIT) is an oncosuppressor implicated in many human cancers, including vesical tumors. FHIT is frequently hit by deletions caused by fragility at FRA3B, the most active of human common fragile sites, where FHIT lays. Vesical tumors affect also cattle, including animals grazing in the wild on bracken fern; compounds released by the fern are known to induce chromosome fragility and may trigger cancer with the interplay of latent Papilloma virus. RESULTS: The bovine FHIT was characterized by assembling a contig of 78 BACs. Sequence tags were designed on human exons and introns and used directly to select bovine BACs, or compared with sequence data in the bovine genome database or in the trace archive of the bovine genome sequencing project, and adapted before use. FHIT is split in ten exons like in man, with exons 5 to 9 coding for a 149 amino acids protein. VISTA global alignments between bovine genomic contigs retrieved from the bovine genome database and the human FHIT region were performed. Conservation was extremely high over a 2 Mb region spanning the whole FHIT locus, including the size of introns. Thus, the bovine FHIT covers about 1.6 Mb compared to 1.5 Mb in man. Expression was analyzed by RT-PCR and Northern blot, and was found to be ubiquitous. Four cDNA isoforms were isolated and sequenced, that originate from an alternative usage of three variants of exon 4, revealing a size very close to the major human FHIT cDNAs. CONCLUSION: A comparative genomic approach allowed to assemble a contig of 78 BACs and to completely annotate a 1.6 Mb region spanning the bovine FHIT gene. The findings confirmed the very high level of conservation between human and bovine genomes and the importance of comparative mapping to speed the annotation process of the recently sequenced bovine genome. The detailed knowledge of the genomic FHIT region will allow to study the role of FHIT in bovine cancerogenesis, especially of vesical papillomavirus-associated cancers of the urinary bladder, and will be the basis to define the molecular structure of the bovine homologue of FRA3B, the major common fragile site of the human genome.

Acid Anhydride Hydrolases↗
PubMed1994

Human casein kinase II: structures, genes, expression and requirement in cell growth stimulation.

Casein kinase II (CKII) is an ubiquitous Ser/Thr protein phosphotransferase in control of a variety of crucial cellular functions including metabolism, signal transduction, transcription, translation and replication. CKII levels are consistently higher in neoplastic tissues. The human CKII is composed of subunits alpha, alpha', and beta with molecular masses of 43, 38 and 28 kDa, respectively, that form heterotetrameric holoenzymes (alpha 2 beta 2; alpha alpha' beta 2, alpha'2 beta 2) showing autophosphorylation particularly at subunit beta and hence suspected to play a regulatory role. The amino acid sequences of subunits indicate high evolutionary conservation. Employing the complete set of tissue-derived (placenta) and recombinant (expressed in E. coli) subunits and CKII holoenzymes, the catalytic function of alpha and alpha' and the several-fold stimulation by beta is shown to occur comparably in tissue-derived and recombinant CKII and the autophosphorylation of beta is shown by site-directed mutagenesis to be not decisive for the tuning of CKII activity. The human genome contains two genes encoding CKII alpha. First, there is a processed (pseudo)gene which is 99% homologous to the CKII alpha cDNA and which possesses a promoter-like region adjacently upstream with TATA and CAAT boxes so that transcription cannot be excluded. Second, there is an active gene of which we have characterized so far a 18.9 kb long central fragment which contains 8 exons comprising bases 102-824 of the CKII alpha coding region. The gene fragment contains repetitive elements, most prominently 16 Alu repeats. The genome further contains one as yet uncharacterized CKII alpha' gene and one gene encoding CKII beta. The CKII beta gene has been characterized as a 4.2 kb spanning gene composed of seven exons which possesses three transcription start sites and the translation start site in the second exon. The first intron harbors an Alu repeat also. The promoter region of the CKII beta gene contains elements such as multiple GC boxes, a CpG island, and nonstandard-positioned CAAT boxes but lacks a TATA box thus characterizing the gene as a housekeeping gene. The CKII genes are not clustered at a certain chromosome but rather are distributed over the whole human genome. Using the genomic clones as the probes for in situ hybridization, the active CKII alpha gene was mapped to chromosome 20p13, the processed CKII alpha (pseudo)gene to chromosome 11p15, and the CKII beta gene to chromosome 6p21. (The CKII alpha' gene has been localized on chromosome 16 with a cDNA probe.).(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMedDate not supplied

A review on biomedical image processing and future trends.

The last two decades have witnessed a revolutionary development in the field of biomedical and diagnostic imaging. Imaging procedures and modalities which were only in the experimental research phase in the early part of the last two decades, have now become universally accepted clinical procedures. They include computerized tomography (CT), magnetic resonance imaging, ultrasound imaging, nuclear medicine imaging, computerized hematological cell analysis, etc. In the past, the conventional and relatively simple image processing techniques such as image enhancement, gray-level mapping, spectral analysis, region extraction, etc. have been modified for biomedical images and successfully applied for processing and analysis. The role of image enhancement, gray-level mapping, and image reconstruction from projections algorithms in CT and other radiological imaging modalities is well evident. Recently, many advances in biomedical image processing, analysis, and understanding algorithms have shown a great potential for enhancing and interpreting useful diagnostic information from these images more accurately. This paper presents a review on the current state-of-the-art techniques in biomedical image processing and comments on future trends.

Algorithms↗
PubMed2001

Developmental changes of tau protein and mRNA in cultured rat brain oligodendrocytes.

Oligodendrocytes elaborate an extensive network of multibranched processes and flat membranous sheets. Microtubules (MT) participate in the elaboration and stabilization of myelin-forming processes and are essential for cellular sorting processes. Microtubule-associated proteins (MAPs) are involved in the regulation and stabilization of the dynamic MT network. It has been shown previously that oligodendrocytes express the MAP tau, a phosphoprotein most abundant in neurons of the CNS. In this article, we demonstrate for the first time that oligodendrocytes contain all six tau isoforms, and that tau mRNA and protein expression is developmentally regulated. Immunoblot analysis reveals that tau protein is more abundant, and mature isoforms are more prominent at later stages of development. During the first week of culture maturation, a marked decrease in phosphorylation is observable. Using an RT-PCR approach, we can show that oligodendrocytes express small amounts of exon 3 containing isoforms and that during culture maturation, tau mRNA splice products with 3 MT-binding domains (3R) decrease and mRNA with 4 MT-binding domains (4R) increase. In situ hybridization study demonstrates that tau mRNA is present in precursor cells and in mature oligodendrocytes. Tau mRNA is actively transported into the cellular processes, is specifically present in the primary and some of the secondary processes, enriched at the turning and branching points and the growing tips, and often appears as small patches. Hence, localized tau translation at specific sites in the cellular extensions might contribute to the regulation of MT stability during process formation, early axonal contact establishment, and myelination.

Aging↗
PubMed1981

Redundancy reduction for improved display and analysis of body surface potential maps. I. Spatial compression.

The Karhunen-Loeve technique of random process representation was investigated as a method of quantitatively characterizing body surface potential maps. One hundred ninety-two lead body surface potential maps from 124 normal subjects and 97 patients with independently documented heart disease were used in the study. Each map frame in QRS and ST-T of 34 maps in a test set was represented as a linear sum of orthonormal distributions derived from the covariance matrix estimated from all QRS frames in the 221 training maps. A 16:1 reduction in spatial data of the test set was achieved with rms errors of 45 and 21 microV in QRS and ST-T, respectively. Results suggest that 12 independent waveforms, derived from the 192 measured ECGs, may be used in place of those 192 ECGs. In addition to providing a convenient and familiar method of display for map data, the technique puts the data in an appropriate form for quantitative statistical analysis.

Cardiomegaly↗
PubMed1988

Optimization of MR protocols: a statistical decision analysis approach.

A new method of optimizing MRI data acquisition protocols is presented. Tissues are modeled with probability density functions (PDFs) of tissue parameter values (such as T1, T2). The imaging data acquisition process is modeled as a mapping from a tissue parameter space to a signal strength space. Tissue parameter PDFs are mapped to signal strength PDFs for each tissue in a clinical problem. The efficacy of an MRI protocol is evaluated using the methods of statistical decision analysis applied to the signal strength PDFs, including the propagation of noise. This procedure evaluates the ability to discriminate different tissues based on the signal strengths produced with the protocol. The model can incorporate an arbitrary number of tissues, parameters, and pulse sequences in the protocol. The multivariate nature of MRI and the observed broad distribution of tissue parameter values makes this model more appropriate for optimizing data acquisition protocols than methods which maximize the signal-difference-to-noise ratio between discrete values of the tissue parameters. It is shown that these two methods may calculate different optimal protocols. The method can be used to optimize data acquisition for quantitative computer-based tissue classification, as well as imaging. Data acquisition and image processing philosophies are discussed in light of the method.

Computer Simulation↗
PubMed2005

Localization of a disease-associated mutation site in the three-dimensional structure of the cardiac muscle ryanodine receptor.

The cardiac muscle ryanodine receptor (RyR2) functions as a calcium release channel in the heart. Up to 40 mutations in RyR2 have been linked to genetic forms of sudden cardiac death. These mutations are largely clustered in three regions of the sequence of the polypeptide: one near the N terminus, one in the central region, and the third in the C-terminal region. The central region includes 11 mutations, and an isoleucine-proline motif (positions 2427 and 2428) in the same region is predicted to contribute to the binding of FKBP12.6 protein. We have mapped the central mutation site in the three-dimensional structure of RyR2 by green fluorescent protein insertion, cryoelectron microscopy, and single-particle image processing. The central mutation site was mapped to a "bridge" of density that connects cytoplasmic domains 5 and 6, which have been suggested to undergo conformational changes during channel gating. Moreover, the location of this central mutation site is not close to that of the FKBP12.6-binding site mapped previously by cryoelectron microscopy.

Animals↗
PubMed1998

Role of mitogen-activated protein kinase in the angiotensin II-induced DNA synthesis in vascular smooth muscle cells.

The activation of mitogen-activated protein (MAP) kinase and increase in intracellular free calcium concentration ([Ca2+]i) are discussed in reference to activation of different protein kinases and growth of vascular smooth muscle cells (VSMCs). The aim of the present study was to investigate the role of angiotensin (Ang) II-induced increase in [Ca2+]i for activation of 44-kD/42-kD MAP kinase (p44mapk/p42mapk) and DNA synthesis in VSMCs. Experiments were performed by chelation of [Ca2+]i by the intracellular chelator 1,2-bis-(o-amino-5-methylphenoxy)ethane-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester (MAPTAM). Ca2+ was measured by the fura 2 method. MAP kinase activation was determined by the Western blotting method. DNA synthesis was determined by measurement of [3H]thymidine incorporation into the cell DNA. Treatment of VSMCs with 20 micromol/L MAPTAM for 30 minutes resulted in a complete abolishment of the maximal Ang II-induced increase at 10 seconds. Ang II phosphorylated the p44mapk/p42mapk in a time-dependent manner, showing a maximum at 3 minutes. In MAPTAM-treated cells, the maximal phosphorylation of MAP kinase isoforms was shifted to 5 minutes, and dephosphorylation was delayed compared with untreated cells. In concordance with this finding, the induction of the MAP kinase phosphatase-1 was markedly impaired in MAPTAM-treated cells. Ang II induced a 2.3-fold increase in [3H]thymidine incorporation into DNA synthesis in untreated cells. This effect was not reduced in MAPTAM-treated cells. Treatment of the cells with PD 98059 (10 micromol/L), a MAP kinase kinase inhibitor, caused 85% inhibition of the Ang II-induced activation of MAP kinases but did not inhibit the Ang II-induced DNA synthesis. In conclusion, the Ang II-induced stimulation of the MAP kinase is a Ca2+-dependent process. Furthermore, blockade of the Ang II-induced stimulation of the early intracellular events, such as increase in [Ca2+]i or phosphorylation of the MAP kinase, is not accompanied by an inhibition of the Ang II-induced DNA synthesis.

Angiotensin II↗
PubMed1994

Structural and functional organization of herpes simplex virus DNA polymerase investigated by limited proteolysis.

The 1235 residue herpes simplex virus DNA polymerase is a prototype alpha-like DNA polymerase and also an antiviral drug target. To investigate its organization, we mapped favored cleavage sites for seven proteases and identified three major classes of stable proteolytic fragments: 70-85-kDa N-terminal fragments, 50-70-kDa fragments that start near residues 600-700, and 12-kDa C-terminal fragments. In coimmunoprecipitation experiments, the first two classes of fragments remained associated; thus, cleavage in the center of the protein did not resolve structurally separate domains. In contrast, the 12-kDa C-terminal fragments did not remain associated with other fragments, suggesting a small separable C-terminal domain. The 70-85-kDa N-terminal fragments contained 3'-5' exonuclease and ribonuclease H activities; however, cleavage at the center of the molecule or near the C terminus appeared to destroy DNA polymerase activity. All three major classes of fragments bound DNA in DNA-cellulose chromatography and Southwestern blot analyses. The C-terminal fragments bound the viral polymerase processivity factor, UL42. The results map activities to regions of herpes simplex virus polymerase and suggest a model for its organization that may be pertinent to other DNA polymerases.

Animals↗
PubMed2006

Rapid and automatic calculation of the midsagittal plane in magnetic resonance diffusion and perfusion images.

RATIONALE AND OBJECTIVES: A near real-time and fully automatic method for calculation of the midsagittal plane (MSP) for magnetic resonance (MR) diffusion and perfusion images is introduced. MATERIALS AND METHODS: The method is based on the Kullback-Leibler's (KL) measure quantifying the difference between two intensity distributions. The MSP is a sagittal plane with the highest KL measure. The method was validated quantitatively for 61 diffusion-weighted imaging (DWI), cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), peak height (PKHT), and time to peak (TPP) data sets of 11 stroke patients based on the ground truth provided by two raters. RESULTS: Average angular errors are less than 1 degrees for DWI and less than 2 degrees for CBF and CBV. Average distance errors measured in the worst case (on the brain's bounding box) are less than 2.5 mm for DWI and less than 5 mm for CBF and CBV. This algorithmic accuracy is at the level of interrater variability. Results obtained for the other perfusions maps (MTT, PKHT, TTP) were inferior; therefore, processing of CBF or CBV is preferred for accurate and robust calculation of the MSP from perfusion maps. Calculation of the MSP takes about half a second on a standard computer. CONCLUSIONS: The proposed method is near real-time and fully automatic, and neither user interaction nor parameter setting is needed. It does not require preprocessing of data. The method potentially is useful in rapid and automated processing of MR stroke diffusion and perfusion images.

Algorithms↗
PubMed1997

PET imaging of maze processing.

Covered maze traversal models nonverbal planning, involving sequential execution of moves using learned spatial maps. To determine the neural substrate involved in maze processing, eleven adults underwent [H(2)15O]-PET while performing motor control, following the computer; visual control, choosing the wall with more dead-ends; uncovered maze, traversing fully visible mazes; covered maze, traversing mazes only locally visible. Maze processing lateralizes to the right hemisphere: uncovered maze versus controls revealed area 23 and 29 activation; covered maze versus controls activated areas 8, 10 and 19. The extrastriate region may store path information, evoked by prefrontal areas for spatial planning and navigation.

Adolescent↗
PubMed1989

Antifolate drug selection results in duplication and rearrangement of chromosome 7 in Plasmodium chabaudi.

We selected lines of Plasmodium chabaudi that are resistant to high levels of the antifolate drug pyrimethamine and have shown that rearrangement and duplication of a portion of chromosome 7 has occurred in the resistant lines. This chromosomal duplication results in an increase in the chromosome number from 14 to 15: two derived chromosomes (450 kilobases and 1.1 megabases) were smaller than the original chromosome 7 (1.3 megabases), so that essentially only a 200-kilobase region was duplicated. This region contained the DHFR-TS gene and the closely linked Hsp70 gene. We have macrorestriction mapped chromosome 7 from the pyrimethamine-susceptible line (DS) and also the duplicated chromosome 7s in the resistant line. From these maps, we have proposed a process for the karyotype changes. Sequencing of the DHFR gene from the parent and derived chromosomes showed that there were no mutations in the coding sequence. As a result of the duplication of the DHFR-TS gene, there is at least a twofold increase in expression of the DHFR-TS gene, and this may explain the ability of the pyrimethamine-resistant lines to grow in increased amounts of the drug.

Amino Acid Sequence↗
PubMed2005

Map plasticity in somatosensory cortex.

Sensory maps in neocortex are adaptively altered to reflect recent experience and learning. In somatosensory cortex, distinct patterns of sensory use or disuse elicit multiple, functionally distinct forms of map plasticity. Diverse approaches-genetics, synaptic and in vivo physiology, optical imaging, and ultrastructural analysis-suggest a distributed model in which plasticity occurs at multiple sites in the cortical circuit with multiple cellular/synaptic mechanisms and multiple likely learning rules for plasticity. This view contrasts with the classical model in which the map plasticity reflects a single Hebbian process acting at a small set of cortical synapses.

Animals↗
PubMed1994

Mouse thioredoxin gene maps on chromosome 4, whereas its pseudogene maps on chromosome 1.

Thioredoxins are involved in various biochemical systems and mediate both redox and nonredox functions. In mammalian cells, thioredoxin functions as an endogenous glucocorticoid receptor activating factor and as an adult T-cell leukemia-derived factor (ADF) that stimulates expression of interleukin-2 receptor in human T-cell leukemia virus (HTLV)-I transformed T cells. We have mapped the thioredoxin gene (Txn) and its processed pseudogene (Txn-ps1) in the mouse using a panel of interspecific backcross mice. Txn maps to Chr 4, whereas Txn-ps1 maps to the proximal region of Chr 1.

Animals↗