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Role of endoscopic ultrasound in the preoperative assessment of patients with oesophageal cancer.

Despite encouraging results from Europe and America, endoscopic ultrasound (EUS) has yet to become established in the United Kingdom. The aims of this prospective study were to investigate its value in the assessment of patients with benign and malignant oesophageal conditions, and in particular to assess its reliability for local tumour (T) and lymph node (N) staging in patients with oesophageal cancer. EUS was performed in 90 patients: 23 were normal controls, 17 had benign oesophageal diseases and 50 had operable oesophageal cancer. Detailed measurements of the oesophageal wall and regional nodes were made and the accuracy of EUS for locoregional tumour staging was compared with final histology. EUS visualised the normal oesophageal wall as a multilayered structure, thicker distally than proximally. Distal stenotic conditions caused thickening of the proximal wall and loss of this gradient. EUS was highly accurate for both local tumour (92% correct) and lymph node staging (86% correct) and was better than computed tomography, magnetic resonance imaging and open staging performed by the surgeon. Fine needle aspiration biopsy using radial scanning EUS guidance was shown to be feasible. EUS is a valuable technique for investigation of both benign and malignant oesophageal conditions. It provides highly accurate local tumour and regional lymph node staging data in patients with oesophageal cancer.

Endosonography↗

Two-stage model for integration of the lysis protein E of phi X174 into the cell envelope of Escherichia coli.

As a tool for determining the topology of the small, 91-amino acid phi X174 lysis protein E within the envelope complex of Escherichia coli, a lysis active fusion of protein E with streptavidin (E-FXa-StrpA) was used. The E-FXa-StrpA fusion protein was visualised using immune electron microscopy with gold-conjugated anti-streptavidin antibodies within the envelope complex in different orientations. At the distinct areas of lysis characteristic for protein E, the C-terminal end of the fusion protein was detected at the surface of the outer membrane, whereas at other areas the C-terminal portion of the protein was located at the cytoplasmic side of the inner membrane. These results suggest that a conformational change of protein E is necessary to induce the lysis process, an assumption supported by proteinase K protection studies. The immune electron microscopic data and the proteinase K accessibility studies of the E-FXa-StrA fusion protein were used for the working model of the E-mediated lysis divided into three phases: phase 1 is characterised by integration of protein E into the inner membrane without a cytoplasmic status in a conformation with its C-terminal part facing the cytoplasmic side; phase 2 is characterised by a conformational change of the protein transferring the C-terminus across the inner membrane; phase 3 is characterised by a fusion of the inner and outer membranes and is associated with a transfer of the C-terminal domain of protein E towards the surface of the outer membrane of E. coli.

Bacteriolysis↗

Expression of tissue kallikrein and kinin receptors in angiogenic microvascular endothelial cells.

Angiogenesis is the sprouting of new capillary blood vessels from pre-existing ones. The kinin family of vasoactive peptides, formed by the serine protease tissue kallikrein from its endogenous multifunctional protein substrate kininogen, is believed to regulate the angiogenic process. The aim of this study was to determine the expression of tissue kallikrein and kinin receptors in an in vitro model of angiogenesis. Microvascular endothelial cells from the bovine mature and regressing corpus luteum were used only if they reacted with known endothelial cell markers. At first the cultured endothelial cells began sprouting, and within four weeks formed three-dimensional, capillary-like structures. Immunolabelling for tissue prokallikrein and the mature enzyme was intense in the angiogenic endothelial cells derived from mature corpora lutea. Immunoreactivity was lower in non-angiogenic endothelial cells and least in angiogenic endothelial cultures of the regressing corpus luteum. Additionally, using specific antisense DIG-labelled probes, tissue kallikrein mRNA was demonstrated in cells of the angiogenic phenotype. Immunolabelled kinin B2 receptors, but not kinin B1 receptors, were visualised on angiogenic endothelial cells. Our results suggest an important regulatory role for kinins in the multiple steps of the angiogenic cascade that may occur in wound healing and cancer cell growth.

Amino Acid Sequence↗

Use of porcine interspersed repeat sequences in PCR-mediated genotyping.

PCR primers derived from porcine short and long interspersed repeat sequences were used to amplify DNA samples isolated from individual members of three-generation pig reference pedigrees. Subsequent high-resolution gel electrophoresis of both SINE and LINE-PCR products allowed direct visualisation of polymorphisms that segregated in a Mendelian manner. Additional polymorphisms were detected by Southern blotting of the gels described above followed by hybridization with simple sequence DNA. Genotyping by interspersed repeat-PCR exploits the natural architecture of the pig genome and allows the typing of polymorphisms by utilizing pre-existing sequence information.

Animals↗

The structure of bacteriorhodopsin at 3.0 A resolution based on electron crystallography: implication of the charge distribution.

Electron crystallography has the potential to visualise the charge status of atoms. This is due to the significantly different scattering factors of neutral and ionised atoms for electrons in the low-resolution range (typically less than 5 A). In previous work, we observed two different types of densities around acidic residues in the experimental (|Fo|) map of bacteriorhodopsin (bR), a light-driven proton pump. We suggested that these might reflect different states of the acidic residues; namely, the protonated (neutral) and the deprotonated (negatively charged) state. To evaluate the observed charge more quantitatively, we refined the atomic model for bR and eight surrounding lipids using our electron crystallographic data set between 8.0 and 3.0 A resolution, where the charge effect is small. The refined model yielded an R-factor of 23.7% and a free R-factor of 33.0%. To evaluate the effect of charges on the density map, we calculated a difference (|Fo|-|Fc|) map including data of a resolution lower than 8.0 A resolution, where the charge effect is significant. We found strong peaks in the difference map mainly in the backbone region of the transmembrane helices. We interpreted these peaks to come from the polarisation of the polar groups in the main chain of the alpha-helices and we examined this by assuming a partial charge of 0.5 for the peptide carbonyl groups. The resulting R and free R-factors dropped from 0.250 and 0.341 to 0.246 and 0.336, respectively. Furthermore, we also observed some strong peaks around some side-chains, which could be assigned to positively charged atoms. Thus, we could show that Asp36 and Asp102 are likely to interact with cations nearby. In addition, peaks found around the acidic residues Glu74, Glu194 and Glu212 have different features and might represent positive charges on polarised water molecules or hydroxonium ions.

Amino Acid Sequence↗

The usefulness of radiographs in diagnosis and management of periodontal diseases: a review.

OBJECTIVES: To review the periodontally significant diagnostic information obtainable from radiographs and the stages during periodontal therapy when the information may influence patient management and treatment outcomes. DATA: Confined to studies involving conventional radiography, as this remains the commonest imaging method in clinical dental practice and primary dental care setting. SOURCES: Literature was reviewed using Medline and manual tracing of references cited in key papers not otherwise elicited. STUDY SELECTION: Studies were selected in order to (i) define the role of radiographs in periodontal diagnosis and management at the initial, corrective and supportive (maintenance) phases of periodontal therapy and (ii) critically review the evidence for the value added by radiographs. CONCLUSIONS: Radiographs provide diagnostic information on alveolar bone levels, plaque retention factors, caries, furcation defects, subgingival calculus and additional pathology. Features visualised are dependent on the radiographic view. A relationship exists between probing attachment loss and radiographic bone height, with a range in level of correlation; clinical attachment may correspond more closely to surgical measurements of bone height. Radiographs can be used in planning initial, corrective and supportive phases of therapy, though some decisions may be made on clinical assessments alone. Evidence in the literature on benefit gained from radiographs taken for periodontal patients is sparse; the extent to which they influence the treatment provided and treatment outcomes is poorly addressed. Further research is indicated to define the role of radiographs when managing the periodontal patient to maximise the potential gain for the patient.

Evidence-Based Medicine↗

Post mortem uterine arteriography and in vivo angiographic diagnosis.

Arteriography of the small pelvis was done to obtain exact data on the extension of uterine tumours. Some findings were useful in differential diagnostics in vivo. The borderline between the uterine corpus and collum cannot be characterized by the elbow of the uterine artery (the end of its parametrian part) but by the most medial loop of the ascending part of the vessel, coinciding with the end of the cervical canal. The cervix gets its blood supply from the uterine artery only in two-thirds of the cases and even if so, the cervico-vaginal branch takes its origin not from the isthmic but from the parametrian part of the uterine artery. Visualisation of small arteries in the parametrium is difficult in vivo mostly because of their modest vascularity.

Angiography↗

Lack of CD95/FAS gene somatic mutations in extranodal, nodal and splenic marginal zone B cell lymphomas.

Germline CD95 (also known as FAS, APT1 and APO1) gene mutations have been associated with benign lymphoproliferative diseases and autoimmune processes. Somatic mutations have been reported in human tumours, including lymphomas. Since marginal zone B cell lymphomas usually arise in a background of chronic inflammation, often of autoimmune origin, we searched for CD95 gene mutations in an unselected series of marginal zone B cell lymphomas. The CD95/FAS full coding region, comprising exon-intron junctions, was amplified from genomic DNA by polymerase chain reaction (PCR) in 10 separate reactions. PCR products were analysed by single-strand conformation polymorphism (SSCP) and visualised by silver staining. Bands exhibiting an altered electrophoretic mobility were sequenced. Twenty-seven cases of marginal zone B cell lymphomas of whom fresh or frozen tumour material was available (18 extranodal, five splenic and four nodal) were studied. Previously described silent polymorphisms in exons 7 (C836T) and 3 (T416C) were detected in 42% and in 19% of the cases, respectively. One silent T-to-A substitution at bp 431, within exon 3, was found in one case. Our results did not reveal the presence of CD95 somatic mutations in unselected cases of marginal zone B cell lymphomas. On the basis of our data, we cannot rule out that other genes coding for proteins involved in the CD95-induced apoptotic pathway might be altered. However, this pathway does not seem to play an important role in the pathogenesis of these lymphoma subtypes.

Antigens, Neoplasm↗

Comparison of predicted and observed properties of proteins encoded in the genome of Mycobacterium tuberculosis H37Rv.

Proteome studies complement current molecular approaches through analysis of the actively translated portion of the genome (the "functional proteome"). Two-dimensional gel electrophoresis (2-DGE) utilising immobilized pH gradients of pH 2.3-5.0 and pH 6.0-11.0, developed with predetermined regions of overlap compatible with commercially available pH 4.0-7.0 gradients, permitted the display of a significant portion of the proteome of Mycobacterium tuberculosis H37Rv. A significant portion of the M. tuberculosis proteome, in the molecular mass (M(r)) window 5 kDa to 200 kDa and with isoelectric point (pI) between pH 2.3 and 11.0, was visualised for the first time. A total of 493 protein spots were effectively resolved, including 126 spots that could not be seen using standard pH 4.0-7.0 gradients. These results were used to compare the physical properties of the observed proteins to the theoretical predictions of the recently completed M. tuberculosis H37Rv genome. Most proteins were found in the pI and mass window of pH 4.0-7.0 and 10-100 kDa. Analysis of the predicted proteome revealed a bimodal pI distribution, with substantial numbers of proteins in the pI regions 4.0-7.0 and 9.0-12.0 as has been seen for the majority of completed genomes. Such data may reveal current limitations in experimental extraction and separation of extremely basic, high M(r) and hydrophobic proteins via 2-DGE. Conversely, 13 acidic proteins were observed with pI less than the lowest value predicted by the genome. In addition, a subset of small protein (< 10 kDa) were observed within the pI region of pH 5.0-8.0 that were not predicted by the complete genomic sequence, reflecting the current inability to distinguish small genes from within DNA sequence. This work represents the foundation for comparing the protein expression patterns of different pathogenic and nonpathogenic M. tuberculosis strains. The characterization of M. tuberculosis protein expression, further facilitated by the recent completion of the genome sequence, could aid in developing more effective diagnostic or therapeutic reagents.

Bacterial Proteins↗

Does radiofrequency catheter ablation induce a deterioration in sympathetic innervation? A positron emission tomography study.

Radiofrequency catheter ablation (RFCA) is an effective treatment for the interruption of accessory bypass tracts in WPW syndrome or the modification of the AV-nodal conduction system in patients with AV-nodal tachycardias. However RFCA may also damage cardiac innervation. The purpose of this pilot study was to assess possible changes in sympathetic innervation after RFCA as evaluated by the cathecholamine analog carbon-11-hydoxyephedrine (HED) positron emission tomography (PET) which allows the visualisation of sympathetic nerve terminals. We investigated nine patients with supraventricular tachycardias before and two to six weeks after RFCA. Myocardial perfusion was depicted by n-13-ammonia-PET. In addition to visual analysis, HED retention was quantified in the myocardial quadrant distal to the location of intervention; these results were compared with values in remote areas. Before RFCA, myocardial perfusion showed homogenous distribution in 8 of 9 patients. One patient showed a perfusion defect in the posterior wall. HED retention matched perfusion distribution in all patients. After RFCA there was no significant change observed either in ammonia or in HED distribution. Quantitative HED retention data showed no significant change before versus after RFCA. Thus, HED-PET does not demonstrate any abnormalities of tracer uptake indicating integrity of sympathetic nerve terminals after radiofrequency ablation therapy.

Adult↗

A simple and rapid method for detecting human immunodeficiency virus by PCR.

A simple, sensitive and specific method using the polymerase chain reaction (PCR) for amplification of human immunodeficiency virus type 1 (HIV-1) is described. The method involves minimal manipulations. Peripheral blood mononuclear cells (PBMC) were prepared by a rapid Ficoll-Paque gradient method. Lymphocytes were lysed in PCR buffer containing Proteinase K and detergents, and subjected to amplification under stringent conditions, using two primer pairs. Amplified DNA sequences were hybridized with a 3'-end labelled probe, electrophoresed on agarose gels and visualised by ethidium bromide staining. Identification of amplified HIV-1 proviral DNA sequences was confirmed by autoradiography. HIV-1 sequences were amplified in all samples from 103 HIV-1 seropositive individuals, but not in 40 HIV-1 seronegative controls. The absence of contamination may be attributable in part to minimisation of manipulations before amplification.

Base Sequence↗

RT97: a marker for capsaicin-insensitive sensory endings in the rat skin.

The mouse monoclonal antibody RT97, which recognises the 200-kDa neurofilament subunit in its phosphorylated form, selectively labels the somata of sensory A-fibres (large light cells) in the dorsal root ganglion of the rat. We have tested the hypothesis that this antibody also visualises large diameter sensory fibres and their end structures in peripheral tissue, in particular in the skin. RT97 immunoreactivity is found in endings that are known to be served by myelinated afferent fibres, including Meissner-like endings, Merkel discs, hair follicle receptors, Pacinian corpuscles and free nerve endings. RT97 immunoreactivity has not, however, been observed in endings of presumably unmyelinated sensory fibres (intraepidermal fibres immunoreactive for substance P and calcitonin gene-related peptide) or in sympathetic fibres innervating sweat glands and blood vessels. In addition, neither systemic (100-150 mg/kg as adults) nor perineural capsaicin pre-treatment affects RT97 immunoreactivity in the skin. The data indicate that RT97 is a useful marker in the study of the capsaicin-insensitive sensory innervation of the skin and possibly other peripheral organs.

Animals↗

DIPLOMO: the tool for a new type of evolutionary analysis.

A package of computer programs called DIPLOMO (DIstance PLOt MOnitor) has been developed for making pairwise comparisons of different estimates of the distances between a set of taxa by plotting them against each other in a simple scatter plot. Taxa with similar relative distance characteristics are thereby grouped graphically. Groupings of different taxa may be directly identified, and the distance characteristics of chosen groups visualised and compared using devices to give them different colours or symbols. The program is particularly useful for detecting and analysing subtle trends in gene sequence evolution. This is done by comparing different components of change, for example synonymous versus non-synonymous nucleotide changes, transversions versus transitions and changes in different genes of the same set of taxa, etc. The program has a wide range of other uses, for example comparing different methods of sequence analysis, assessing which components of genetic change correlate best with phenotypic change or with geographical separation. This paper describes the DIPLOMO package, and illustrates typical DIPLOMO analyses using lentivirus gene sequence data.

Biological Evolution↗

Discriminant functions.

Discriminant Functions (DFs), first described by Fisher in 1936, have been applied to the classification of microcytic disorders such as iron deficiency and heterozygous thalassemia. Mathematically DFs are weighted linear combinations of variables. If the underlying assumption of multivariate normality is valid DFs provide the best possible classification. Variables may need to be transformed before the DF is derived. When two groups have to be classified it is easy to visualise the DF. With one variable the DF is represented by the point which provides the best separation. In the bivariate situation the two groups form ellipses and the DF is the best line of separation whilst in the trivariate case the two groups are ellipsoids and a plane forms the best separation. Ratios and power functions are equivalent to DFs but they are less efficient and less rigorously derived. To apply DFs in hematological practice it is necessary to carefully select the measurements to be included and to define the case selection criteria. Once the DF has been derived it should be tested on a new data set and its transferability assessed. Like any single test the DF will have sensitivity and specificity which may need to be adjusted by changing the "cut-off" if the DF is used for screening rather than for differential diagnosis.

Diagnosis↗

In situ hybridisation and in situ polymerase chain reaction detection of parvovirus B19 DNA within cells.

Modification of an in situ polymerase chain reaction (ISPCR) technique is described for the detection of B19 parvovirus infection. Specific amplification of B19 DNA inside fixed cells was followed by hybridisation with a digoxigenin-labelled probe and then visualised by immunochemical reaction. The assay had higher sensitivity compared to direct in situ hybridisation and still allowed cellular localisation and characterisation of infected cells. This assay can be used as a confirmatory method for PCR in tissues and will allow further identification of tissues permissive for B19 parvovirus infection.

Base Sequence↗

Linkage studies of X-linked mental retardation: high frequency of recombination in the telomeric region of the human X chromosome (fragile site/linkage/recombination/X chromosome).

One of the commonest forms of X-linked mental retardation is associated with a fragile site at Xq27 on the human X chromosome which can be visualised structurally after culturing cells in folate-deficient media. Unusually, the mutation can be transmitted through a phenotypically normal male. There is already some evidence that the gene loci for G6PD and factor IX are linked to this mental retardation locus. We have followed the inheritance of a DNA sequence 52A, in fragile site families that are also informative for factor IX. We demonstrate that these probes are localised at Xq27/Xq28-Xqter, close physically to the fragile site. We did not find close linkage between 52A, factor IX, and the fragile site in the families studied despite 52A and factor IX showing linkage in normal families. We discuss the importance of these data for the genetic mapping of this region of the human X chromosome and the implication for the use of these DNA probes for clinical diagnosis.

Animals↗

Visualisation by low-angle shadowing of the leucocyte-common antigen. A major cell surface glycoprotein of lymphocytes.

The leucocyte-common antigen (L-CA) from rat thymocytes is a cell surface glycoprotein of 180 000 apparent mol. wt. with an 80-kd cytoplasmic domain. This paper reports the molecular dimensions of the molecule visualised by electron microscopy after low-angle shadowing. The L-CA monomer consists of a globular head region of approximately 12 nm diameter and a short tail approximately 18 nm long. In deoxycholate both monomers and multimers are seen with aggregation occurring at the head groups. When the detergent is removed, larger clusters are formed with tails extending from a central aggregate. A 100-kd tryptic fragment of L-CA that is known to include the extracellular parts of the molecule also exists in monomer and multimer forms and is seen to have a rod-like structure of length 28 nm without evidence of the head group. Altogether the data indicate that the rod-like structure is found outside the cell and that the extra sequence that forms the head is inside. The tryptic fragment is likely to be derived by cleavage after the transmembrane sequence.

Animals↗

Effect of pyrolysis temperature on composition, surface properties and thermal degradation rates of Brazil Nut shells.

Changes in chemical and surface characteristics of Brazil Nut shells (Bertholletia excelsa) due to pyrolysis at different temperatures (350 degrees C, 600 degrees C, 850 degrees C) were examined. For this purpose, proximate and ultimate analyses, physical adsorption measurements of N2 (-196 degrees C) and CO, (25 degrees C) as well as samples visualisation by scanning electronic microscopy (SEM) were performed. Appreciable differences in the residue characteristics, depending markedly on the pyrolysis temperature, were observed. Release of volatile matter led to the development of pores of different sizes. Progressive increases in micropore development with increasing pyrolysis temperature took place, whereas a maximum development of larger pores occurred at 600 degrees C. Furthermore, kinetics measurements of Brazil Nut shells pyrolysis from ambient temperature up to 900 degrees C were performed by non-isothermal thermogravimetric analysis. A model taking into account the significant changes in the residue during pyrolysis, through an increase in the activation energy with temperature and solid conversion, were found to properly fit the kinetics data over the wide range of degradation investigated.

Kinetics↗