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Molecular dynamics simulations of oligonucleotides in solution: visualization of intrinsic curvature.

We have undertaken molecular dynamics simulations on the d(CGCAAAAAAGCG).d(CGCTTTTTTGCG) dodecamer in solution. In this study, we focus on aspects of conformation and dynamics, including the possibility of cross-strand hydrogen bonds. We compare our results with those from crystallography as well as infrared, Raman and NMR spectroscopy and cyclization kinetics. Our method of analysis allows us to visualise the curvature of the helix as a function of time during the simulation. We find that the major distortions of the helix axis path occur at the junctions between the (essentially straight) A-tract and the CG- and GC-tracts, although at one junction this is due to hyperflexibility (i.e., regions of high flexibility with no preferred direction of curvature), while at the other junction a static curvature is found (i.e., a preferred, sustained direction of curvature).

Base Sequence

Regulatory peptides of the gastrointestinal and respiratory tracts.

The gastrointestinal and respiratory tracts contain numerous regulatory peptides produced by and released from specialised epithelial cells and the organ innervation. This complex system of endocrine cells and nerves is generally called "the diffuse neuroendocrine system". Markers are now available which permit the visualisation of the diffuse neuroendocrine system or its individual components. These include antibodies to neuron-specific enolase, chromogranin, neurofilament triplet proteins, the brain protein S100 and antibodies to a variety of regulatory peptides. Peptides present in the gut and lung innervation include: vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), galanin, substance P, calcitonin gene-related peptide (CGRP), neuropeptide tyrosine (NPY), somatostatin and cholecystokinin (the latter two are also localised to endocrine cells of the gut). Bombesin-immunoreactivity is found in nerves in the gut and in endocrine cells of the foetal/neonatal lung. Neuropeptides of the gut and lung originate either from local neurons (e.g. VIP, PHI, galanin) or extrinsic neurons localised in sensory ganglia (e.g. substance P and CGRP) or the sympathetic chain (e.g. NPY). Recent studies point to the involvement of regulatory peptides in diseases of the gut and lung. These, together with detailed distribution studies, provide supportive data on the putative role of the peptides in the control of normal bowel and respiratory functions. The gastrointestinal and respiratory tracts were within the systems investigated by Feyrter during his original observations on the existence of specialised epithelial cells with a putative regulatory function (Feyrter, 1938). These "endocrine/paracrine" cells were found to be scattered in epithelial organs throughout the body. In fact, endocrine cells of the respiratory tract are frequently referred to as "Feyrter's cells". The term "regulatory peptides" was introduced as a generic term (Polak and Bloom, 1983) after the finding that active peptides are produced both by cells of the diffuse endocrine or APUD (amine precursor uptake and decarboxylation) system (Pearse, 1983) and autonomic/sensory nerves. These peptides are released into the circulation from endocrine cells or locally from nerve terminals or paracrine cells. The concept of "gut/brain" peptides was dispelled after the findings that the respiratory tract was provided abundantly with numerous active peptides produced by and released from mucosal endocrine cells and/or the innervation.

Animals

How the horse moves: 1. Significance of graphical representations of equine forelimb kinematics.

The kinematics of 24 two-year-old Dutch Warmblood horses were recorded at the trot (4 m/s) on a high-speed treadmill to study the coordination of joints within the equine forelimb. Joint angle-time, angle-angle, stick, and marker diagrams were used to show forelimb motion graphically. Because the kinematic data referred to the joint angles of the horse standing squarely and were time-standardised to the duration of the stride cycle, mean joint curves could be calculated for the total group. The motion of each segment in the equine forelimb during a complete stride is described and its function in intralimb coordination evaluated. It appeared that the rotation of the scapula and the cranio-caudal movement of the distal forelimb are synchronous and pendular. The carpal joint rapidly snaps into overextension at the beginning of the stance phase to enable the forelimb to work as a propulsive strut. The fetlock joint acts as an elastic spring, thereby conserving energy and, at the same time, absorbs oscillations generated by initial ground contact. Furthermore, the coordination between carpal and fetlock joints in the swing phase appears to be strongly influenced by inertia. Using the graphic tools evaluated in this paper, we were able to visualise the kinematics of the equine forelimb and relate these to specific functions of the forelimb in locomotion. This information can be used to select kinematic variables for clinical studies in which equine forelimb function has to be described and quantified.

Animals

Multiplex PCR for identifying mycobacterial isolates.

AIMS: To develop a multiplex polymerase chain reaction (PCR) method to facilitate identification of mycobacterial isolates. METHODS: Type strains of 14 species of mycobacteria and 56 clinical isolates were lysed by boiling in TE Triton. The lysate (5 microliters) was used directly in a PCR reaction incorporating three pairs of PCR primers expected to amplify fragments from the genome of (a) all mycobacteria, (b) Mycobacterium tuberculosis complex only and (c) M avium only. PCR products were visualised by electrophoresis on agarose gels. RESULTS: Multiplex PCR applied to 14 type strains yielded patterns on electrophoresis which permitted identification of the mycobacterial isolates as M tuberculosis complex, M avium or as mycobacteria other than the former. The identification of 56 clinical isolates by multiplex PCR was consistent with other methods and was accomplished in less than one working day. CONCLUSIONS: This method may facilitate rapid and convenient identification of most clinical isolates of mycobacteria by PCR and gel electrophoresis. Further evaluation is warranted.

Base Sequence

Consideration of time-dose-patterns in 3D treatment planning. An approach towards 4D treatment planning.

PURPOSE: The rendering of the 3D dose distribution together with anatomical information and the volumes of interest (VoI) is essential to get a visual impression of the treatment plan and to find modifications for the optimization of the dose distribution. The integration of biological effects into the 3D treatment planning is of interest for the assessment of different time-dose patterns. MATERIALS AND METHODS: One way of taking into account biological data is to relate the physical dose in critical structures to the corresponding tolerance dose. For that purpose the applied time-dose pattern has to be converted into the standard fractionation scheme being the basis of the tolerance dose. Generally any model can be used for these calculations. Here a modified incomplete repair model is used to calculate the relative biological dose distribution (RBD). The visualization of these biologically isoeffective dose distributions can be performed in the same manner as the physical dose so that the physical and biological dose distributions can by displayed side by side. As this is equivalent to introducing the time as a fourth dimension into 3D treatment planning this is called 4D treatment planning. RESULTS: From 3D dose matrices the biologically isoeffective dose distributions are calculated for the organs at risk. The changes introduced by different time-dose patterns are displayed using the same technique as for rendering 3D treatment plans. The visualisation of the three-dimensional biological dose distributions is shown by means of a patient with an oesophagus carcinoma. The RBD related to the tolerance dose of the organs at risk is displayed for different time-dose fractionations. CONCLUSION: The RBD distribution on a 3D treatment plan can be displayed in the same mode as the physical dose distribution. This offers additionally valuable information in a 3D treatment planning process about the dose to critical organs and the influence of different time-dose patterns.

Color

Immunoperoxidase labelling of albumin at the endothelial cell surface of frog mesenteric microvessels.

Albumin was visualised at the endothelial cell surface of perfused frog mesenteric microvessels using immuno-peroxidase labelling. Vessels in the mesenteries of pithed frogs were washed free of blood and then perfused with frog Ringer solutions containing bovine serum albumin (BSA) at a concentration of 20 mg BSA ml-1, followed by a brief Ringer flush to remove excess albumin from the vessel lumen. The tissues were fixed in 1% glutaraldehyde and a double antibody labelling technique used to identify albumin within the tissue. A dense layer of peroxidase reaction product was seen, which extended 25-50 nm into the vessel lumen. It appeared as a continuous layer lining the luminal openings of interendothelial cell clefts and vesicles open to the luminal cell surface. In some vessels a more irregular layer of peroxidase labelled albumin was seen extending 150 to 200 nm into the vessel lumen, whilst in others clumps of peroxidase labelled albumin were also seen within the vessel lumen. These data offer direct evidence that BSA does interact with the endothelial cell surface of perfused frog mesenteric microvessels but suggest that a proportion is loosley or non-specifically bound to the cell surface and can be removed by a brief Ringer flush. The remainder appears more tightly bound and resistant to Ringer flush.

Animals

[2-dimensional mapping and retinal and papillary microcirculation using scanning laser Doppler flowmetry].

PURPOSE: To present clinical applications of a new non-invasive method imaging in a high-definition the topography of perfused retinal vessels. METHOD: By a combination of a laser Doppler flowmeter with a scanning laser system the perfusion of the retina and the optic nerve head is visualized and quantified. The principles of measuring blood flow by Laser Doppler Flowmetry are based on the optical Doppler effect: laser light scattered by a moving particle is shifted in frequency by an amount delta f. Our data acquisition and evaluation system is a modified laser scanning tomograph. The technical data are: retinal area of measurement 2.7 mm x 0.7 mm, 10 degree-field with 256 points x 64 lines, measurement accuracy 10 microns, wavelength 670 nm and 790 nm, light power 100 microW, data acquisition time 2,048 s. Every line is scanned 128 times by a line-sampling rate of 4,000 Hz. By performing a discrete Fast Fourier Transformation over 128 intensities of each retinal point the laser Doppler-shift is calculated for each retinal point. With these data a 2-D map with 256 x 64 points of the retinal perfusion is created. The brightness of the picture-point is coded by the value of the Doppler shift. We estimated the reliability and the validity of the method. Perfusion-pictures of the superficial retinal layer and in the optic nerve head were presented. RESULTS: The reliability-coefficients r1 of "Flow", "Volume" and "Velocity" were 0.85, 0.83, and 0.85 respectively. The blood flow measurements by the presented method ("Scanning Laser Doppler Flowmetry") in an artificial capillary gave a linear relationship (r-value 0.973, p < 0.00001) between defined blood velocities and the measured blood flow. By the confocal technique, dependent on the focus, capillaries of the retinal superficial vasculature of the optic nerve head became visible with a high resolution. Off line the blood flow of areas of 110 microns x 110 microns were calculated in terms of laser Doppler flowmetry. CONCLUSION: "Scanning Laser Doppler Flowmetry" facilitates the visualisation of perfused retinal capillaries and vessels in high resolution. The representation of the function of the retinal circulation by SLDF leads to an image similar to the anatomical situation. The 2-dimensional mapping of local blood flow leads to a physiological picture of the retinal perfusion with visible vessels and capillaries.

Adult

Theileria annulata sporozoite antigen fused to hepatitis B core antigen used in a vaccination trial.

A C terminal fragment (SR1) of SPAG-1, a sporozoite surface antigen of Theileria annulata, has been expressed as a fusion protein in the e1 loop of hepatitis B core antigen (HBcAg). This recombinant antigen (HBcAg-SR1) is produced in the form of self-assembling polyhedral particles which have been visualised under the electron microscope. Cattle immunised with HBcAg-SR1 produced high titres of neutralising antibodies. A significant T cell response to both the HBcAg and SR1 determinants was observed but evidence of a T suppressor determinant in SR1 was also revealed. Immunised cattle showed some evidence of protection to sporozoite challenge as assessed by severity of the disease. The significance of these findings for the development of a sub-unit vaccine against T. annulata is discussed.

Animals

Visualisation by electron microscopy of the unique part of the cytoplasmic domain of a desmoglein, a cadherin-like protein of the desmosome type of cell junction.

Part of the cytoplasmic domain of a human desmoglein, Dsg1, a cadherin-like protein found in desmosomes of epithelial cells, has been visualised by electron microscopy. The cloned fragment contains five repeats of a 29 +/- 4 residue sequence unique to desmogleins, followed by a glycine-rich region. In rotary shadowed preparations the molecule consists of a globular head attached to a thin tail, the latter perhaps corresponding to the glycine-rich region. This portion of the molecule is thought to span the width of the inner dense plaque. The structure and dimensions concur well to the configuration deduced from the protein sequence.

Amino Acid Sequence

Chronic sputum production: correlations between clinical features and findings on high resolution computed tomographic scanning of the chest.

BACKGROUND: There are few published data on the correlation between the clinical findings in subjects with chronic sputum production and the appearances on high resolution computed tomographic (HRCT) scans of the chest. METHODS: HRCT scanning of the chest was performed on 40 subjects with chronic sputum production. Three readers independently reported the scans for the presence or absence of bronchiectasis and the extent of bronchiectasis on the basis of the percentage of involved bronchi in each lobe. Relationships were sought between these findings and the clinical history, physical examination, and laboratory investigations. RESULTS: HRCT scanning showed that 27 subjects had bronchiectasis. Of the clinical features only the continual production of purulent sputum and childhood pertussis were associated with bronchiectasis. There was a positive correlation between the extent of bronchiectasis and dyspnoea, and a negative correlation with forced expiratory volume in one second but not with forced vital capacity. CONCLUSIONS: These results indicate that, in subjects with chronic sputum production, only a few clinical features show any correlation with the presence or extent of bronchiectasis as visualised on HRCT scans.

Adult

Breast cancer imaging with radiolabelled peptide from complementarity-determining region of antitumour antibody.

Specific tumour imaging with radiolabelled monoclonal antibodies has been extensively investigated. Although some success has been reported, there are many limitations due to the slow kinetics, poor extravasation, catabolism by the reticuloendothelial system, and non-specific uptake of macromolecules such as antibodies. We have tried to overcome some of the problems associated with monoclonal antibodies while retaining their specificity by using an antibody-derived synthetic peptide. A synthetic pentadecapeptide (alpha M2) derived from the third heavy-chain complementarity-determining region (CDR-3H) of a tumour-associated monoclonal antibody was produced and shown to retain its specificity against the pan-carcinoma cell-surface antigen, polymorphic epithelial mucin, detected by the parent antibody. The peptide was radiolabelled with technetium-99m and injected intravenously to image malignant lesions in 26 women with primary, recurrent, or metastatic breast cancer. Visualisation of breast tumours and their metastases was obtained shortly after administration of alpha M2, and was optimum by 3 h. Overall, 57 (77%) of 74 sites were visualised. Successful imaging was achieved in 14 of 15 primary tumour sites and all of eight local recurrences. Five of six metastases in the opposite breast, eight of 15 metastatic axillary lymph nodes, and all of six metastatic supraclavicular lymph nodes were imaged. Metastatic sites in the lungs, mediastinum, chest wall, and liver were poorly visualised because of background cardiac blood pool. alpha M2 detected small lesions ( < 2 cm) as efficiently as larger ones. The peptide was rapidly (3 h) cleared from the circulation. No acute or chronic adverse reactions due to the alpha M2 were observed. Specific tumour targeting with the radiolabelled anticancer peptide alpha M2 offers new opportunities for breast cancer imaging and possibly therapy.

Adult

Visualisation and measurement of the calcium message in guard cells.

We have applied several novel technologies to investigate the role of cytosolic free calcium [Ca2+]i in signal transduction in guard cells of Commelina communis L. Fluorescence ratio imaging and photometry together with the fluorescent Ca2+ indicator Indo-1 were used to directly visualise and measure dynamic spatial and temporal changes in [Ca2+]i in response to various exogenous stimuli. More subtle manipulation of the Ca2+ signal transduction pathway was achieved through the use of photoactivateable, caged Ca2+ and caged inositol-1,4,5-triphosphate (InsP3) released directly into the cytoplasm of the guard cell after microinjection. In these experiments, changes in [Ca2+]i were simultaneously monitored with the fluorescent Ca2+ indicator, Fluo-3. Resting levels of [Ca2+]i (100-200 nM) increased in response to elevated [Ca2+]e, lowering [K+]e, application of the ionophore A-23187 or cytosolic release of either Ca2+ or InsP3 from their caged forms. Stomatal closure was triggered if [Ca2+]i increased above a threshold of about 600 nM. Abscisic acid (ABA) had little effect on [Ca2+]i in the majority of cells studied, being elevated in only a minority of cells investigated. However, stomatal closure occurred in all cases after ABA application. This suggests that ABA acts through both Ca(2+)-independent and Ca(2+)-dependent pathways. The imaging data revealed a substantial heterogeneity in [Ca2+]i within the guard cell. Cytoplasmic regions, particularly near the nucleus, often showed marked elevations and sometimes oscillations. The origin and kinetics of the Ca2+ fluxes leading to the dynamic spatial patterns is discussed along with several new approaches directed towards identification of the source of the Ca2+. These methods include optical sectioning and 3-D reconstruction of both the endomembrane system and [Ca2+]i in living guard cells using confocal microscopy. Overall, our data is consistent with multiple sources for [Ca2+]i, including uptake across the plasma membrane and InsP3- or Ca(2+)-induced Ca2+ release from internal stores.

Calcium

Detection of maternal cell contamination in amniotic fluid cell cultures using fluorescent labelled microsatellites.

A rapid PCR based assay was used to ascertain the presence of maternal cell contamination (MCC) in amniotic fluid cell cultures and to exclude MCC in cases where cytogenetic analysis was possible only from one primary cell culture. Six 6-carboxyfluorescein (FAM) and three 6-carboxyfluorescein hexachloride (HEX) labelled primer sets were used to amplify two tetra- and seven dinucleotide repeat polymorphisms. The PCR amplifications were multiplexed in (three) three primer set reactions and visualised on an Applied Biosystems 373A sequencer running Genescan 672 software. The microsatellite products obtained from 200 amniotic fluid cell cultures where the karyotype was female were compared against corresponding maternal blood PCR products. A single case of MCC was detected indicating the usefulness of such assays. We suggest that screening for MCC should be considered in instances where the amniotic fluid sample is bloodstained or was obtained with difficulty, or where the karyotype is female and chromosome analysis is not possible from more than one primary cell culture.

Amniocentesis

Bilirubin, ferritin, D-dimers and erythrophages in the cerebrospinal fluid of patients with suspected subarachnoid haemorrhage but negative computed tomography scans.

AIM: To assess the diagnostic value of cerebrospinal fluid (CSF) spectrophotometry, cytology, ferritin, and D-dimer measurements in the investigation of suspected subarachnoid haemorrhage in patients with negative or equivocal computed tomography (CT) scans. METHODS: CSF specimens submitted for assessment of xanthochromia were examined for erythrophages using a cytospin preparation stained with Wright's stain, for ferritin using the Ciba-Corning Magic IRMA assay, D-dimers using the Dimertest 2 latex agglutination slide test, and for bilirubin by scanning spectrophotometry. The patients were divided into three groups for data analysis and the results compared with the existing methods, CT, and angiogram results. Final diagnoses were reviewed by a consultant neurologist. RESULTS: Thirty six patients were recruited. In those patients with confirmed subarachnoid haemorrhage CSF cytology had a low sensitivity and there were false negative results with both the D-dimer and ferritin assays. Eleven patients with a negative or equivocal CT scan underwent angiography, but only one aneurysm and no arterio-venous malformations or bleeding points were identified. In the patient with the aneurysm there was no laboratory evidence of subarachnoid haemorrhage. Six patients had CSF abnormalities detected by the special tests only and in none of these cases was subarachnoid haemorrhage confirmed. All results were normal in four out of five cases of traumatic tap. CONCLUSIONS: This is a small study, but it shows that, depending on the timing of the lumbar puncture, false negative results can occur with both ferritin and D-dimer measurements. It suggests that neither of these tests adds significantly to the information provided by CT, visualisation of CSF, and spectrophotometry and confirms that, despite the use of spectrophotometry, D-dimer and ferritin assays in selecting patients for angiography, the proportion of patients with negative CT scans and colourless CSF with demonstrable vascular lesions remains low.

Bilirubin

Multi-dimensional visualisation of laboratory findings and functional test results for analysing the clinical course of disease in medicine.

The illustration of a patient's history by a graphical primitive is discussed. Illustration technology is presented which simultaneously represents quantitative examination findings (e.g., laboratory values) and qualitative findings (e.g., from function diagnostics) by a single geometrical figure. Depending on the medical results, this figure takes on characteristic forms which can be identified as patterns typical for a specific disease. The procedure developed is integrated in a user interface which is implemented in the form of a computerized medical record for use on a pentop computer. This portable computer assists the physician during ward rounds, supplies additional, intelligence-based information, serves quality control, and streamlines working procedures making them more efficient.

Clinical Laboratory Information Systems

GENOLYTE: a PC-based computer program for visualisation of genomic DNA sequences.

This paper describes the program "GENOLYTE" which has been developed for the visualisation and identification of the global and local patterns of long genomic DNA sequences quickly in a few minutes, with the aid of a microcomputer. Apart from global and local identification, GENOLYTE comparatively depicts the similarity of two or more than two genomic DNA sequences. The utility of the program has been demonstrated by analysing the complete mitochondrial DNA sequences (taken from EMBL databank) as an example and the results are discussed from therein. The program written in TURBO C++ has the following minimum requirements: (i) PC 386 AT, (ii) SVGA colour monitor, (iii) the [BGI] directory of TURBO C++ version 3.0.

Animals

Baculovirus-mediated high level expression of a human thiopurine methyl transferase.

We have expressed the human thiopurine methyltransferase cDNA in a baculovirus vector in Sf21 (Spodoptera frugiperda) cells. This system expresses the enzyme at levels such that the thiopurine methyltransferase enzyme may be readily visualised by Coomassie blue stained sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The expressed enzyme catalysed the methylation of 6-mercaptopurine with an apparent Km of 892 microM, similar to that observed in human liver cytosol ie. 657 microM however, the Vmax was 13,500 pmole/mg/min, which is approximately 400 times higher than the Vmax observed in human liver cytosol ie. 33 pmole/mg/min. The thiopurine methyltransferase inhibitors 6-thioxanthine, p-methoxybenzoic acid and 3,5-dimethoxy benzoic acid were found to be potent inhibitors of the expressed enzyme.

Animals

Visualising the dissociation of sequence selective ligands from individual binding sites on DNA.

We have used a modification of the footprinting technique to measure the dissociation of mithramycin, echinomycin and nogalamycin from their binding sites in a natural DNA fragment. Complexes with radiolabelled DNA were dissociated by addition of unlabelled DNA. Samples were removed at various times and subjected to DNase I digestion, and the rate of dissociation from each site was estimated from the time-dependent disappearance of the footprints. For echinomycin the slowest rate of dissociation is from ACGT, while the slowest site for mithramycin contains four contiguous guanines. The dissociation of nogalamycin is extremely slow, even from its weaker sites; the slowest rate was from ACGTA, which took longer than 4 h, even at 37 degrees C.

Base Sequence