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Results for “process mapping”

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PubMed1984

The nucleotide and deduced amino acid sequences of the encephalomyocarditis viral polyprotein coding region.

The nucleotide sequence of 7200 bases of encephalomyocarditis (EMC) viral RNA, including the complete polyprotein-coding region, was determined. The polyprotein is encoded within a unique translational reading frame, 6870 bases in length. Protein synthesis begins with the sequence Met-Ala-Thr, and ends with the sequence Leu-Phe-Trp, 126 bases from the 3' end of the RNA. Viral capsid and noncapsid proteins were aligned with the deduced amino acid sequence of the polyprotein. The proteolytic processing map follows the standard 4-3-4 picornaviral pattern except for a short leader peptide (8 kd), which precedes the capsid proteins. Identification of the proteolytic cleavage sites showed that EMC viral protease, p22, has cleavage specificity for gln-gly or gln-ser sequences with adjacent proline residues. The cleavage specificity of the host-coded protease(s) includes both tyr-pro and gln-gly sequences.

Amino Acid Sequence↗
PubMed1990

Cell surface expression of hybrid murine/human MHC class II beta alpha dimers. Key influence of residues in the amino-terminal portion of the beta 1 domain.

To aid in the identification of key residues responsible for the control of class II MHC beta-alpha dimer assembly and expression, a series of cotransfections of human plus mouse beta- and alpha-genes was performed. The resulting expression data were correlated with the sequences of the relevant proteins to identify residues that played critical roles in these processes. For the I-E/DR homologues good expression was seen for both E beta DR alpha and DR beta E alpha combinations involving several allelically variable beta-chains of each species. These results are consistent with the sequence conservation seen for I-E and DR gene products, and indicate that the species-specific differences that do exist play little role in controlling dimer formation or transport. For A beta chains, a more complex picture was seen. A beta d, but not A beta k or A beta b, was found to coexpress with human alpha-chains. Not only did A beta d show expression with the homologous DQ alpha-chain, but it also was expressed with DR alpha and DP alpha. These data indicate that species-specific residues do not control dimer expression under these conditions and confirm that allelically polymorphic residues have a crucial role in this process. Mapping studies using recombinant A beta genes established the importance of the residues in the amino-terminal half of the beta 1 domain in the differences observed among the A beta alleles. Sequence comparison of DR beta, DP beta, DQ beta, E beta, and A beta chains in this region revealed a single residue (position 12) conserved in most chains and differing in a nonconservative fashion between A beta d vs A beta b or k. A beta d has the conserved lysine at this position, whereas A beta b has methionine and A beta k has glutamine. To test whether this residue actually was important physiologically, a lysine codon was created in a recombinant A beta gene possessing the amino-terminal sequence of the kappa haplotype, and the ability of this mutant chain to be expressed with various mouse A alpha-chains was examined. This mutant chain was shown to gain the ability to be efficiently expressed with A alpha d without losing its ability to be expressed with A alpha k. These data reemphasize the special role played by allelically polymorphic residues in Ia expression and identify one such polymorphic site as position 12.(ABSTRACT TRUNCATED AT 400 WORDS)

Alleles↗
PubMed1985

Uniformity correction for SPECT using a mapped cobalt-57 sheet source.

As little as 1% nonuniformity of the scintillation camera can produce disturbing artifacts in SPECT images. To correct for nonuniformity, acquired images must be divided by the flood-field image of a uniform sheet source. The refillable 99mTc sheet source requires meticulous preparation before each use, and is subject to spillage. We propose the use of a permanent 57Co solid sheet source in conjunction with a map of the radioactivity distribution in the source. The flood-field image of the cobalt source is converted by the map into the equivalent of a flood-field image of an almost perfectly uniform source. An accurate and reproducible method is described for generating a map of the cobalt sheet source from images of it made in multiple positions with the scintillation camera. The mapping process is independent of sensitivity variations across the face of the camera.

Cobalt Radioisotopes↗
PubMed1973

Secondary structure maps of RNA: processing of HeLa ribosomal RNA.

Ribosomal RNA precursors and mature 28S ribosomal RNA from HeLa cells display a highly reproducible secondary structure of hairpin loops after they are spread and examined in an electron microscope. This structure was used to map the linear arrangement of these molecules. Partial digestion with 3'-exonuclease from ascites cell nuclei established that the 28S RNA region is located at the 5'-end of the 45S precursor. A spacer sequence follows the 28S region. This is followed by the 18S RNA region, and by another spacer sequence at the 3'-end. The 41S RNA contains both 18S and 28S regions. The 32S RNA contains only 28S RNA plus spacer, and the 20S RNA contains only 18S RNA plus spacer. Several minor nucleolar RNA components were also mapped with respect to the 45S RNA. These experiments lead to a more detailed processing pathway for HeLa ribosomal RNA which is in good agreement with earlier work.

Exonucleases↗
PubMed1992

Artifact processing in topographic mapping of electroencephalographic activity in neuropsychopharmacology.

Mapping of the electroencephalogram (EEG) has been found to be a valuable method in clinical neuropsychopharmacology. It is evident that careful treatment of artifacts is of utmost importance for EEG data processing, as artifacts that contaminate the EEG data can lead to spurious results. The artifact-processing method described in this article splits signal analysis into a preprocessing step, yielding individual electro-oculographic (EOG) regression factors for EOG minimization, and into a processing step, yielding target variables. The combination of avoiding, minimizing, and identifying artifacts, as well as visual checking of face validity, will help remove artifactual effects from the EEG.

Aged↗
PubMed1983

S1 nuclease mapping analysis of ribosomal RNA processing in wild type and processing deficient Escherichia coli.

S1 nuclease mapping was used to assess rRNA processing in Escherichia coli. Single-stranded DNA probes complementary to the sequences bordering each terminus of 16 S and 23 S rRNA were end-labeled, hybridized to total E. coli RNA, and treated with S1 nuclease. The resultant DNA fragments were then displayed on denaturing polyacrylamide gels. Measurements of steady state levels of precursor rRNA species and measurements of the rates of decay of precursors after transcription arrest by rifampicin gave consistent results. 1) The rRNA precursor species identified in wild type cells corresponded to those previously identified by other means. 2) In RNase III-deficient strains, mature 16 S rRNA termini form at the same rate as in wild type cells; but the normal mature termini of 23 S rRNA are never generated. 3) RNase III cleavage at the 5' end of 23 S rRNA can occur before the 3' end of the same molecule is synthesized. 4) The cleavages that generate the mature termini of 16 S rRNA are interdependent; in the BUMMER strain, slow processing at the 5' end is accompanied by slow processing at the 3' end. Thus, the kinetically observed order of processing reactions is obligate for some cleavages but not for others, and the assumption that complete rRNA processing is required for function fails for 23 S rRNA.

Base Sequence↗
PubMed1990

[Relation between the functional state of cerebral hemispheres and the location and dynamics of the epileptic process].

Computer mapping of spatial synchronism of cortical potentials led away from 48 points was performed in 110 right-handed patients with primary- and secondary-generalized fits. The clinico-electrophysiological analysis was employed to demonstrate a special role played by the left hemisphere in the processes of epileptic activity generalization in different disease patterns and characteristic features of diagnosing the generalized patterns of epilepsy and determination of the focus of localization. The data obtained can be used for disease prediction and estimation of the treatment efficacy.

Action Potentials↗
PubMed1990

Self-organization of associative memory and pattern classification: recurrent signal processing on topological feature maps.

We extend the neural concepts of topological feature maps towards self-organization of auto-associative memory and hierarchical pattern classification. As is well-known, topological maps for statistical data sets store information on the associated probability densities. To extract that information we introduce a recurrent dynamics of signal processing. We show that the dynamics converts a topological map into an auto-associative memory for real-valued feature vectors which is capable to perform a cluster analysis. The neural network scheme thus developed represents a generalization of non-linear matrix-type associative memories. The results naturally lead to the concept of a feature atlas and an associated scheme of self-organized, hierarchical pattern classification.

Algorithms↗
PubMed1988

Probability mapping: power and coherence analyses of cognitive processes.

In recent years different mapping techniques have proved to be an efficient means in studying cognitive processes. Our approach is based on recordings with 19 EEG channels and the computation of spectral parameters. Power and coherence values are obtained from the EEG of control recordings and recordings during the performance of cognitive tasks and are compared for significant differences. The statistical procedures used yield descriptive error probabilities for the rejection of the null hypothesis which are mapped either colour coded or by black and white squares. The usefulness of this method is demonstrated on a mental cube rotation study involving 31 students, 13 males and 18 females. One essential result during the performance of this test is an increase of theta power only in females. As far as local coherence and the theta band are concerned, males show increased values right parietally and right temporo-occipitally; opposed to this, in females the left hemisphere is more affected. In the beta bands, local coherence increases in males right parietally and left temporo-occipitally. Contrary to this, in females the parietal increase of local coherence is more accentuated in the left hemisphere but temporo- occipital coherence is increased in the right hemisphere. In both sexes interhemispheric parietal coherence increases during cube rotation suggesting increased functional couplings between the hemispheres. This study demonstrates that the inclusion of the coherence parameter in brain mapping furthers the detection of sex and hemispheric differences during the performance of cognitive tasks.

Adult↗
PubMedDate not supplied

Data representation for subsequent image interpretation.

Radiological scans acquired using either the X-ray CT or the NMR imaging techniques provide a wealth of information about tissue behaviour under that imaging modality and contrast agent. To reason about the image in an interpretation stage the scans have to be converted from a pixel by pixel representation to a symbolic form. The technique used by us to generate such a description is region-based segmentation. Each region refers to a pixel or group of pixels having a common attribute. This work has provided a quantitative measure for the partial evaluation of the segmentation which can be applied independent of attribute or combination of attributes. From our initial studies of the behaviour of CT scans a precept for segmentation was developed. The segmentation employs a one-to-one map as an adaptive mechanism. The segmentation criterion at each point in the image therefore depends on the value at the corresponding point in the map. Any process can be used to generate this map, and so easily utilizes new operators as they are developed.

Artificial Intelligence↗
PubMed1988

Mapping techniques for document processing.

An information retrieval system should provide references to the set of documents the user must evaluate in order to satisfy his/her information requirements. A major concern in this evaluation process is whether or not a document meets the user's needs. In many document retrieval systems there is no relevant information regarding the content of the documents. This makes it very difficult to evaluate if a document is relevant to the user's initial query. This suggests the need for a method to compare the documents on a word by word basis. Fully automated methods are too complex and difficult to generalize upon. A semiautomated user driven method for document mapping is described in this paper. It should decrease the amount of time required to validate the information content of a query.

Documentation↗
PubMed1990

Crystalluria, medullary matrix crystal deposits and bladder calculi associated with an acutely induced renal papillary necrosis.

A single (100 mg/kg) intraperitoneal dose of 2-bromoethanamine hydrobromide induced renal papillary necrosis (RPN) acutely in rodents and caused a transient crystalluria between 4 and 8 h after dosing. These crystals comprised struvite or magnesium ammonium phosphate (MAP) as assessed by shape, solubility, infra-red spectrum and X-ray microprobe analysis. Acid-soluble, bi-refringent crystals were also present within the renal medullary matrix during the same time period as the crystalluria. The presence of the MAP was associated with loss of the anionic renal medullary mucopolysaccharides staining. A total of 5/64 rats with a 2-bromoethanamine-induced renal papillary necrosis and monitored for up to 160 days had bladder calculi that were predominantly MAP. These data suggest that medullary mucopolysaccharide matrix disruption associated with RPN leads to a release of previously bound cations, super-saturation and the nucleation of crystalline MAP. These processes could also be implicated in the formation of MAP bladder calculi.

Animals↗
PubMed1988

Spectral processing for parallel recording of elemental maps.

Seven different one-, two-, or three-parameter analytic expressions were tested for their applicability to electron energy-loss spectral processing for mapping of atomic distributions in images of magnesium oxide crystals. Two-point two-parameter fits all provided indistinguishable results. Fine structure in the spectrum produced major quantitative inconsistencies for any given expression. This effect was exacerbated with the use of three-parameter expressions. Mass-thickness effects on the oxygen map of Mg0 were inconsequential up to a crystal thickness of 30 nm, but became dominant and unacceptable at a 50% increase in thickness above this. This observation can be explained by a specific single inelastic scatter coupled with any number of elastic scattering events.

Crystallization↗