SEARCH · PubMed Health

Results for “Enhancer mapping”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources

PubMed1994

Modification by caffeine of the sensitization to methamphetamine and cocaine in terms of ambulation in mice.

The repeated administration of caffeine (CAF: 1, 3 and 10 mg/kg s.c.) alone 5 times at 3- to 4-day intervals did not produce any significant change in the sensitivity to the ambulation-increasing effects of CAF itself, methamphetamine (MAP: 1 and 2 mg/kg s.c.) and cocaine (COC: 10 and 20 mg/kg s.c.). Whereas, the repeated administration of MAP (1 and 2 mg/kg) and COC (10 and 20 mg/kg) produced sensitization to the individual drug effects. The combination of MAP or COC with CAF potentiated the effect, and sensitization was produced by the repeated 5-time administrations of the following combinations: MAP (1 mg/kg) with CAF (3 and 10 mg/kg), MAP (2 mg/kg) with CAF (1 and 3 mg/kg), COC (10 mg/kg) with CAF (1 mg/kg) and COC (20 mg/kg) with CAF (1 and 3 mg/kg). Moreover, the mice given COC (10 mg/kg) with CAF (3 and 10 mg/kg) and COC (20 mg/kg) with CAF (1 and 3 mg/kg) exhibited significantly higher sensitivity to challenge COC than those given COC alone. However, the sensitivities to challenge MAP of the mice given MAP with CAF were almost the same with those given MAP alone. These results suggest that, in terms of ambulation in mice, the combination of MAP or COC with CAF elicits potentiation of the acute stimulant effect, and that CAF is responsible in enhancement of COC sensitization, but not MAP sensitization.

Animals↗

PubMed2002

Extraction of functional binding sites from unique regulatory regions: the Drosophila early developmental enhancers.

The early developmental enhancers of Drosophila melanogaster comprise one of the most sophisticated regulatory systems in higher eukaryotes. An elaborate code in their DNA sequence translates both maternal and early embryonic regulatory signals into spatial distribution of transcription factors. One of the most striking features of this code is the redundancy of binding sites for these transcription factors (BSTF). Using this redundancy, we explored the possibility of predicting functional binding sites in a single enhancer region without any prior consensus/matrix description or evolutionary sequence comparisons. We developed a conceptually simple algorithm, Scanseq, that employs an original statistical evaluation for identifying the most redundant motifs and locates the position of potential BSTF in a given regulatory region. To estimate the biological relevance of our predictions, we built thorough literature-based annotations for the best-known Drosophila developmental enhancers and we generated detailed distribution maps for the most robust binding sites. The high statistical correlation between the location of BSTF in these experiment-based maps and the location predicted in silico by Scanseq confirmed the relevance of our approach. We also discuss the definition of true binding sites and the possible biological principles that govern patterning of regulatory regions and the distribution of transcriptional signals.

Algorithms↗

PubMed1994

Enhanced detection of distinguishing features in signal-averaged electrocardiograms from patients with ventricular tachycardia by combined spatial and spectral analyses of entire cardiac cycle.

BACKGROUND: Signals generated by myocardium responsible for ventricular tachycardia (VT) contribute to the entire QRS complex, ST segment, and T wave and are spatially distributed over the entire torso. However, current methods of signal-averaged ECG analysis restrict interrogation to the terminal QRS complex, do not include data on the body surface distributions of the distinguishing features detected, and have a limited clinical value because of a low positive predictive accuracy. Accordingly, we tested the hypothesis that frequency analysis of the entire cardiac cycle of spatially selected ECGs based on isoharmonic maps of the body surface enhance the detection of the unique spectral features in signal-averaged ECGs that differentiate patients with from those without VT. METHODS AND RESULTS: Isoharmonic maps of the body surface were calculated during sinus rhythm with the use of forward problem solutions for 32 patients with sustained VT, 30 without VT, and 10 healthy subjects and analyzed over a bandwidth of 0.05 to 470 Hz. Spectra of ECGs at the maximum and minimum of each patient's isoharmonic map of 1 to 7 Hz demonstrated a broadened bandwidth of significant separation (P < .05) for patients with from those without VT compared with the separation achieved with the use of Frank ECGs alone. Furthermore, the statistical significance within the bands of separation was greater for spatially selected ECGs compared with the Frank leads. Frank leads separated patients over the band from 11 to 84 Hz with a mean value of P = .0094. ECGs at the maximum of 1-to-7-Hz isoharmonic maps separated patients over the 8-to-111-Hz band with a mean value of P = .0062 (range, P < .05 to P < .0000001). ECGs at the minimum of 1-to-7-Hz isoharmonic maps extended the low-frequency end of the band of separation, which covered 0 to 69 Hz with a mean value of P = .0039 (range, P < .05 to P < .0000001). Subgroup analysis verified that results were independent of QRS duration. CONCLUSIONS: Spectral analysis of ECGs that are spatially selected for each patient is superior to orthogonal ECGs and augments detection of distinguishing features in ECGs that identify risk of VT. The new data acquired from analysis of spatially selected ECGs from individual patients provide the information on the specific frequency bands and an improved ECG-lead system required to refine methods of analysis of the signal-averaged ECG.

Aged↗

PubMed1998

The roles of signaling by the p42/p44 mitogen-activated protein (MAP) kinase pathway; a potential route to radio- and chemo-sensitization of tumor cells resulting in the induction of apoptosis and loss of clonogenicity.

During the last 10 years, multiple signal transduction pathways within cells have been discovered. These pathways have been linked to the regulation of many diverse cellular events such as proliferation, senescence, differentiation and apoptosis. This review will focus upon the many roles of signaling by the p42/p44 mitogen-activated protein (MAP) kinase pathway. Recent evidence suggests that signaling by the MAP kinase pathway can both enhance proliferation by increased expression of molecules such as cyclin D1, but also cause growth arrest by increased expression of molecules such as the cyclin kinase inhibitor protein p21(Cip-1/MDA6/WAF1). These differential effects on growth have been correlated to the amplitude and duration of the MAP kinase activity signal. Furthermore several laboratories are reporting data suggesting that inhibition of the MAP kinase pathway, as well as a family of upstream MAP kinase activators, the protein kinase C family, represent an important route to both radio- and chemo-sensitization of tumor cells. Herein, we describe the historical discovery and characterization of the MAP kinase pathway. In addition we describe potential mechanisms by which inhibition of protein kinase C, the MAP kinase pathway, and potentially of p21(Cip-1/MDA6/WAF1) expression, may alter the sensitivities of leukemic and carcinoma cells to cytotoxic insults, leading to increased apoptosis and loss of clonogenicity.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMedDate not supplied

DNA fingerprinting confirms isogenicity of androgenetically derived rainbow trout lines.

Homozygous and hybrid clonal lines of rainbow trout (Oncorhynchus mykiss) were confirmed to be isogenic using multilocus DNA fingerprinting. Homozygous clones were produced by androgenesis and gynogenesis using gametes from androgenetic male and female rainbow trout, respectively. Isogenic F1 hybrid lines were produced by crossing homozygous fish from different strains. One line of hybrid clones showed segregation for maternally inherited DNA fingerprint markers. The female from this cross, the only presumptive homozygous gynogenetic individual used in this study, was thought to have been produced by gynogenesis followed by blockage of the first cleavage division, but based on the DNA fingerprint analysis, apparently was derived by spontaneous polar body retention that maintained heterozygosity at some loci. Mutations at DNA fingerprint loci were not observed, indicating relative stability of fingerprint loci in the clonal lines. DNA fingerprinting appears to be a useful tool for identifying and genetically monitoring clonal lines of rainbow trout. Isogenic lines of rainbow trout will facilitate the production of saturated genetic maps for rainbow trout and enhance such endeavors as quantitative trait locus (QTL) analysis and loss of heterozygosity (LOH) studies in tumors.

Androgens↗

PubMed1995

Enhanced interaction between tubulin and microtubule-associated protein 2 via inhibition of MAP kinase and CDC2 kinase by paclitaxel.

Paclitaxel, an anti-mitotic anti-cancer agent, is active against solid tumors. The inhibition of depolymerization and promotion of microtubular assembly are essential for the anti-tumor activity of paclitaxel. Microtubule-associated proteins (MAPs) co-polymerize with tubulin and play some roles in microtubular dynamics. We examined the effect of paclitaxel on the interaction between tubulin and MAPs. Human lung-cancer cells, PC-14, were synchronized to G1/S border by the thymidine-double-block technique. After release from exposure to thymidine, the cells were treated briefly with 2 nM paclitaxel and the levels of alpha and beta tubulins and MAPs were examined after various times. Immunoblot analysis of paclitaxel-treated cells showed no changes in the overall expression of alpha and beta tubulins, microtubule-associated protein 2 (MAP2) or MAPs in comparison with controls. The samples were immunoprecipitated with anti-alpha- and anti-beta-tubulin antibodies and reblotted with an anti-MAP2 antibody, which showed that the amount of co-immuno-precipitated MAP2 in the synchronized cells, were increased by the brief paclitaxel treatment. These results suggest that paclitaxel treatment enhances the interaction between alpha and beta tubulins and MAP2. Since the phosphorylation state of MAP2 regulates the affinity of MAP2 for tubulins, and mitogen-activated protein (MAP) kinase is considered to be one of the kinases responsible for MAP2 phosphorylation, the effect of paclitaxel treatment on the MAP-kinase activity of synchronized PC-14 cells was examined. Two bands with molecular masses of 42 and 44 kDa were detected by an "intra-gel" MAP-kinase assay using myelin basic protein as the substrate. Paclitaxel treatment inhibited the MAP-kinase activity of PC-14 cells and inhibition was maximal at the G2/M phase of the cell cycle. Similar, concentration-dependent inhibition by paclitaxel of cellular MAP kinase of human synchronized small-cell lung carcinoma, H69, was observed. No inhibition of the MAP kinase of the paclitaxel-resistant sub-line H69/Txl by paclitaxel was observed, suggesting that some change of the MAP-kinase cascade had occurred in these cells. No direct inhibition of MAP-kinase activity by paclitaxel was observed in the cell-free assay (in vitro), suggesting that paclitaxel did not inhibit MAP kinase directly. Since it has been speculated that p34cdc2 kinase is also a kinase that phosphorylates MAP2, the effect of paclitaxel treatment on the p34cdc2-kinase activity of synchronized PC-14 and PC-9 cells was examined. Paclitaxel inhibited p34cdc2-kinase activation at the G2/M phase. These results suggest that paclitaxel inhibited MAP kinase and p34cdc2 kinase in vivo indirectly. These actions of paclitaxel may be responsible for the increased affinity between MAP2 and tubulins that it induces.

Amino Acid Sequence↗

PubMed2000

The vagal cardiac accelerator system in the reflex control of heart rate in conscious dogs.

The reactions of the vagal cardioaccelerator (VCA) system to changes in mean arterial pressure (MAP) were studied in five beta-adrenoceptor blocked conscious dogs. An increase in MAP was obtained by administration of vasopressin or methoxamine, a decrease by doxazosin or nitroprusside. In the first series of experiments the MAP changes were induced after muscarinic receptor blockade, in a second series both before and after muscarinic blockade. Prior to these experiments, the maximum VCA activity, defined as the difference between maximum heart rate after muscarinic blockade and the rate after additional nicotinic blockade, was determined. We hypothesized that this quantity, as a measure of VCA activity, depends on the prevailing vagal tone. In the first series of experiments, a rise in MAP evoked an increase in heart rate, a fall in MAP indicated decrease. In the second series, when prior to muscarinic blockade the vagal tone was reflexly raised, the subsequent VCA reflex response to the rise in MAP was attenuated. Prior to the muscarinic blockade the vagal tone was reflexly lowered, the VCA reflex response was enhanced. Direct chronotropic effects of MAP-varying drugs were ruled out by the absence of a heart-rate response in experiments on vagotomized animals. We concluded that the vagal cardioaccelerator system is involved in the reflex control of heart rate. Both the VCA reflex response to changes in systemic blood pressure and the maximum VCA activity however, are determined by the prevailing vagal tone.

Adrenergic beta-Antagonists↗

PubMed2005

MetaCyc and AraCyc. Metabolic pathway databases for plant research.

MetaCyc (http://metacyc.org) contains experimentally determined biochemical pathways to be used as a reference database for metabolism. In conjunction with the Pathway Tools software, MetaCyc can be used to computationally predict the metabolic pathway complement of an annotated genome. To increase the breadth of pathways and enzymes, more than 60 plant-specific pathways have been added or updated in MetaCyc recently. In contrast to MetaCyc, which contains metabolic data for a wide range of organisms, AraCyc is a species-specific database containing only enzymes and pathways found in the model plant Arabidopsis (Arabidopsis thaliana). AraCyc (http://arabidopsis.org/tools/aracyc/) was the first computationally predicted plant metabolism database derived from MetaCyc. Since its initial computational build, AraCyc has been under continued curation to enhance data quality and to increase breadth of pathway coverage. Twenty-eight pathways have been manually curated from the literature recently. Pathway predictions in AraCyc have also been recently updated with the latest functional annotations of Arabidopsis genes that use controlled vocabulary and literature evidence. AraCyc currently features 1,418 unique genes mapped onto 204 pathways with 1,156 literature citations. The Omics Viewer, a user data visualization and analysis tool, allows a list of genes, enzymes, or metabolites with experimental values to be painted on a diagram of the full pathway map of AraCyc. Other recent enhancements to both MetaCyc and AraCyc include implementation of an evidence ontology, which has been used to provide information on data quality, expansion of the secondary metabolism node of the pathway ontology to accommodate curation of secondary metabolic pathways, and enhancement of the cellular component ontology for storing and displaying enzyme and pathway locations within subcellular compartments.

4-Hydroxyphenylpyruvate Dioxygenase↗

PubMed2000

Enhanced flexibility and aphidicolin-induced DNA breaks near mammalian replication origins: implications for replicon mapping and chromosome fragility.

Common fragile sites are chromosomal loci prone to breakage and rearrangement that can be induced by aphidicolin, an inhibitor of DNA polymerases. Within these loci, sites of preferential DNA breaks were proposed to correlate with peaks of enhanced DNA flexibility, the function of which remains elusive. Here we show that mammalian DNA replication origins are enriched in peaks of enhanced flexibility. This finding suggests that the search for these features may help in the mapping of replication origins, and we present evidence supporting this hypothesis. The association of peaks of flexibility with replication origins also suggests that some origins may associate with minor levels of fragility. As shown here, an increased sensitivity to aphidicolin was found near two mammalian DNA replication origins.

Animals↗

PubMed1992

Mapping of the human gene for the human immunodeficiency virus type 1 enhancer binding protein HIV-EP2 to chromosome 6q23-q24.

The human gene encoding the human immunodeficiency virus type 1 enhancer binding protein HIV-EP2 has been isolated. Using Southern analysis of human-rodent somatic cell hybrid DNA with a human HIV-EP2-specific cDNA probe, the HIV-EP2 gene was assigned to chromosome 6. The gene was further localized to the region 6q23-24 by fluorescence in situ hybridization.

Animals↗

PubMed2002

Electrophysiological mechanism of enhanced susceptibility of hypertrophied heart to acquired torsade de pointes arrhythmias: tridimensional mapping of activation and recovery patterns.

BACKGROUND: Cardiac hypertrophy is associated with increased incidence of sudden death and susceptibility to proarrhythmic effects of antiarrhythmic agents. However, the in vivo electrophysiologic mechanism of the arrhythmias has not been investigated in detail. METHODS AND RESULTS: Dose-dependent susceptibility to Torsade de Pointes (TdP) by class III drug dofetilide, 3, 10, and 30 microg/kg, was compared in 6 control dogs (C) and in 5 dogs 6 to 8 weeks after induction of complete atrioventricular block (AVB) that resulted in ventricular hypertrophy (H). Tridimensional ventricular activation and repolarization (R) patterns were simultaneously analyzed from unipolar extracellular electrograms, and local R was measured from activation recovery intervals. Both R and transmural dispersion of R (TDR) were significantly greater in dogs with H compared with C. Dofetilide resulted in cycle length--dependent and dose-dependent prolongation of R, which was more marked in left ventricular endocardium/midmyocardium compared with epicardium, resulting in significant increase of TDR. These changes were more accentuated in dogs with H compared with C. All 5 dogs with H developed TdP at a dose of 3 to 10 microg/kg, whereas only 1 of 6 C dogs developed TdP at 30 microg/kg. TdP was initiated by subendocardial focal activity that infringed on TDR, resulting in functional conduction block and reentrant excitation. CONCLUSIONS: Enhanced susceptibility of hypertrophied heart to class III drugs is attributable to baseline increased TDR and greater dose-related accentuation of TDR compared with nonhypertrophied heart. This provides the electrophysiologic substrate for drug-induced TdP.

Animals↗

PubMed2006

Implementation and case-study results of potentially better practices for family-centered care: the family-centered care map.

OBJECTIVE: The objective of this study was to enhance the ability to coordinate and deliver care in a holistic manner, through a family-centered care map, so that the developmental, physical, and psychosocial needs of the infant and family are met. METHODS: A Web-based map was based on 7 distinct clinical phases with 3 variations of an infant's course through a NICU. Sixty-three potentially better practices were identified and 7 potentially better practices were implemented through case studies. RESULTS: Measures of family satisfaction revealed improvements in delivery of family-centered care. Increases in discharge growth parameters for extremely low birth weight infants were demonstrated. Length of stay for very low birth weight infants decreased from 73 to 60 days in Vermont. CONCLUSIONS: The collaborative process enhances identification of potentially better practices and results in both qualitative and quantitative improvements in family-centered care.

Consumer Behavior↗

PubMed1999

Volumetric visualization of head and neck CT data for treatment planning.

PURPOSE: To demonstrate the utility of volume rendering, an alternative visualization technique to surface rendering, in the practice of CT based radiotherapy planning for the head and neck. METHODS AND MATERIALS: Rendo-avs, a volume visualization tool developed at the University of Chicago, was used to volume render head and neck CT scans from two cases. Rendo-avs is a volume rendering tool operating within the graphical user interface environment of AVS (Application Visualization System). Users adjust the opacity of various tissues by defining the opacity transfer function (OTF), a function which preclassifies voxels by opacity prior to rendering. By defining the opacity map (OTF), the user selectively enhances and suppresses structures of various intensity. Additional graphics tools are available within the AVS network, allowing for the manipulation of perspective, field of view, data orientation. Users may draw directly on volume rendered images, create a partial surface, and thereby correlate objects in the 3D scene to points on original axial slices. Information in volume rendered images is mapped into the original CT slices via a Z buffer, which contains the depth information (Z coordinate) for each pixel in the rendered view. Locally developed software was used to project conventionally designed GTV contours onto volume rendered images. RESULTS: The lymph nodes, salivary glands, vessels, and airway are visualized in detail without prior manual segmentation. Volume rendering can be used to explore the finer anatomic structures that appear on consecutive axial slices as "points." Rendo-avs allowed for acceptable interactivity, with a processing time of approximately 5 seconds per 256 x 256 pixel output image. CONCLUSIONS: Volume rendering is a useful alternative to surface rendering, offering high-quality visualization, 3D anatomic delineation, and time savings to the user, due to the elimination of manual segmentation as a preprocessing step. Volume rendered images can be merged with conventional treatment planning images to add anatomic information to the treatment planning process.

Head↗

PubMed1980

Transition series metals and sulfhydryl reagents induce the synthesis of four proteins in eukaryotic cells.

Several transition series metals (copper, cadmium, zinc and mercury) and the sulfhydryl reagent, sodium arsenite, enhance the synthesis of specific proteins in chick embryo cells and in human foreskin cells in culture. The proteins are visible 1--3 h after exposure to concentrations ranging from 10 microM to 100 microM depending upon which reagent is used. These proteins comigrate on acrylamide gel electropherograms with the proteins induced by two copper-chelating drugs, kethoxal bis(thiosemicarbazone) and disulfiram, and by heat shock. However, these proteins migrate in a significantly different manner than do the canavanine-enhanced proteins. The four proteins induced in chick embryo cells are distinct from one another as determined by partial proteolytic mapping. Simlarly, the three proteins induced in human cells are distinct. However, the 100-kilodalton and the 70-kilodalton proteins from chick and from human cells appear to be related as judged by this mapping procedure. The 70 kilodalton protein enhanced by kethoxal bis(thiosemicarbazone), disulfiram, arsenite and heat shock have a high degree of similarity according to this technique. The arsenite and canavanine-enhanced 100-kilodalton proteins are related as are the arsenite-enhanced 70-kilodalton and the canavanine-enhanced 75-kilodalton proteins. The canavanine-enhanced 30 kilodalton protein resembles the arsenite-enhanced 25-kilodalton protein rather than the 35-kilodalton species. In view of these findings, it appears that a variety of treatments, namely, chelating drugs, transition series metals, sulfhydryl reagents, heat shock, and amino acid analogous can induced similar, if not identical, proteins in eukaryotic cells.

Animals↗

PubMed1994

Texture mapping: a new tool for molecular graphics.

The real-time texture mapping capabilities of modern graphics workstations are explored with respect to their applications in a variety of relevant scenarios in interactive molecular modeling techniques. The common usage of texture mapping to reduce geometric complexity while enhancing realism is extended, opening new ways to visualize large amounts of molecular data in a comprehensive fashion. Thus, texture mapping may be employed to (1) display and filter multichannel information of structural properties on molecular surfaces, (2) improve the quality and accuracy of highly complex isodensity contours, (3) increase the rendering speed of space-filling atomic representations by two orders of magnitude and (4) apply volume-rendering techniques to large, three-dimensional density distributions in real time. Implementation of these novel techniques requires only moderate modifications or extensions to existing molecular modeling applications.

Computer Graphics↗

PubMed2000

Chronic blockade of brain "ouabain" prevents sympathetic hyper-reactivity and impairment of acute baroreflex resetting in rats with congestive heart failure.

In rats with congestive heart failure (CHF) post myocardial infarction (MI) acute blockade of brain "ouabain" reverses sympathetic hyperactivity and chronic blockade prevents the desensitization of baroreflex function. This study was conducted to determine: i) if chronic blockade of brain "ouabain" maintains normal sympathetic reactivity; and ii) if acute baroreflex resetting (another parameter of baroreflex function) also becomes impaired, and if so, does brain "ouabain" contribute to impairment in acute baroreflex resetting. CHF post MI was induced by acute coronary artery ligation in Wistar rats. Animals were treated with 200 microg x day(-1) i.c.v. or i.v. Fab fragments (which bind brain "ouabain" with high affinity), or treated with 200 microg x day(-1) i.c.v. gamma-globulins (control group). The length of treatment was 0.5-8 weeks or 4-8 weeks post MI. At 8 weeks mean arterial pressure (MAP), central venous pressure (CVP), heart rate (HR), and renal sympathetic nerve activity (RSNA) were recorded in concious rats at rest and in response to: i) air-jet stress, ii) i.c.v. guanabenz (an alpha2-adrenoceptor agonist), and iii) a 30 min i.v. infusion of nitroprusside (NP). Excitatory responses to air stress and inhibitory responses to guanabenz of MAP, HR, and RSNA were significantly enhanced in rats with CHF versus the sham-operated treated group. This enhancement was prevented in the CHF group treated with i.c.v., but not i.v., Fab. Nitroprusside induced a sustained decrease in MAP (approximately 25 mmHg) and a transient decrease in CVP. Heart rate and RSNA increased significantly within 1 min of beginning the infusion. The peak increases as well as the product of changes in MAP-HR and RSNA-HR were significantly smaller in rats with CHF treated with gamma-globulins versus sham rats and versus CHF rats treated with i.c.v. Fab. In sham-operated rats and CHF rats treated with i.c.v. Fab, RSNA and HR began to decrease within 3-4 min of beginning the NP infusion and had returned to baseline by 20 min. In contrast, RSNA and HR remained increased throughout the infusion in the CHF rats treated with gamma-globulins. These data indicate that in rats with CHF acute resetting of the arterial baroreflex in response to a lower BP becomes impaired, and chronic blockade of brain "ouabain" prevents both this change in baroreflex resetting as well as sympathetic hyperactivity.

Animals↗

PubMed2006

Site-specific mutation of the interferon sensitivity-determining region (ISDR) modulates hepatitis C virus replication.

The number of amino acid substitutions in the interferon sensitivity-determining region (ISDR) in the nonstructural 5A (NS5A) gene of hepatitis C virus (HCV) is closely associated with the interferon (IFN) response and viral load. Several HCV replicon-based studies have reported that ISDR sequences had an influence on viral replication in vitro. However, it is unclear as to how different ISDR sequences affect HCV replication. Various clinically observed ISDR sequences were introduced into HCV replicons and their contribution to viral replication was investigated using a colony formation assay and/or a transient replication assay. A mapping study of the ISDR was performed to identify the amino acid positions that critically affect replication. While no colonies were formed in the colony formation assay using HCV replicons with few mutations (0, 1 and 3) in the ISDR, numerous colonies (>200) appeared when using constructs with six mutations. Introduction of various distinct ISDR sequences with multiple mutations resulted in replication enhancement in transient assays. A mapping study identified several specific sites in the ISDR that critically affected replication, including codon 2209 which, in patients, was closely associated with a strong response to IFN. ISDR sequences associated with a clinical IFN response and viral load modulated the replication of HCV replicons, suggesting the importance of the ISDR sequence in HCV infection.

Amino Acid Sequence↗

PubMed2000

Dual resonant birdcage coils for 1H detected 13C microscopic imaging at 11.7 T.

Liquid state, rotating frame cross polarisation experiments are very sensitive to RF field inhomogeneity. In this work, we present an easily fabricated, co-resident high- and low-pass linear birdcage resonator, optimised to perform liquid state rotating frame polarisation transfer at 1H and 13C frequencies. Both the RF fields have been experimentally mapped, and used to validate the spatial signal dependence of a proton detected, 13C image. The predicted performance was then confirmed using PRAWN-based, cyclic J-cross polarisation (CYCLCROP) imaging. A novel variant of a B(1)-field mapping approach is also presented, using the signal enhancement of the CYCLCROP sequence to generate proton detected, 13C field maps.

Biophysical Phenomena↗