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1.
Autism Dev Lang Impair ; 9: 23969415241234648, 2024.
Article in English | MEDLINE | ID: mdl-38426035

ABSTRACT

Background and aims: Evidence suggests that autistic children and young people (CAYP) can benefit from age-appropriate psychoeducation. Co-design is a methodology that iteratively involves end users and stakeholders in producing an intervention which may increase engagement and impact. Few age-appropriate co-designed psychoeducation resources for autistic CAYP exist. Therefore, a paper-based resource was co-designed for autistic CAYP who attend mainstream primary education. The resource aims to educate CAYP about their autism and provide strategies to support them to live well with their autism. Methods: This paper describes the evaluation of the prototype resource through online workshops with 12 families and input from four specialist clinicians. The suitability and acceptability of the resource was explored, and sketch notes were taken for respondent validity and engagement purposes. Results: A reflexive thematic analysis identified six themes and two subthemes: (1) content appropriateness (subtheme: strategies and unpredictability); (2) relating to content, (3) feelings and emotions, (4) terminology (subtheme: literal thinking); (5) positivity, and (6) communication aid. Suggested improvements were also identified. Results suggest the resource is suitable and acceptable. Conclusions: Future intervention development research may consider individual differences of autistic CAYP and the co-design of resources for other age groups of neurodiverse populations.

2.
J Atten Disord ; 27(9): 929-938, 2023 07.
Article in English | MEDLINE | ID: mdl-37154203

ABSTRACT

OBJECTIVE: Examine the association between sleep duration, temperament and symptoms of Attention Deficit Hyperactivity Disorder (ADHD) in a biethnic child-population from The Born in Bradford cohort. METHOD: Parent-report sleep duration categorized children as: early short, late short, consistently short or consistently normal sleepers between 6 and 36 months. Temperament was measured using the Infant Characteristics Questionnaire at 6 months. The Strengths and Difficulties Questionnaire assessed symptoms of ADHD at 37, 54, and 61 months. RESULTS: Normal sleepers before 18 months had significantly fewer ADHD symptoms at 37 months compared with consistently short sleepers. Fussiness at 6 months was significantly positively associated with ADHD symptoms at 37 and 54 months; but does not appear to mediate the relationship between sleep duration and ADHD symptoms. CONCLUSION: Awareness of the relationship between short sleep duration and fussiness in infancy and later ADHD symptomatology may support earlier identification of arising difficulties in children.


Subject(s)
Attention Deficit Disorder with Hyperactivity , Sleep Wake Disorders , Infant , Humans , Child, Preschool , Attention Deficit Disorder with Hyperactivity/diagnosis , Attention Deficit Disorder with Hyperactivity/epidemiology , Attention Deficit Disorder with Hyperactivity/complications , Sleep Duration , Temperament , Sleep , Sleep Wake Disorders/epidemiology , Sleep Wake Disorders/complications
3.
Sci Rep ; 11(1): 2535, 2021 01 28.
Article in English | MEDLINE | ID: mdl-33510380

ABSTRACT

To provide a comprehensive analysis of small molecule genotoxic potential we have developed and validated an automated, high-content, high throughput, image-based in vitro Micronucleus (IVM) assay. This assay simultaneously assesses micronuclei and multiple additional cellular markers associated with genotoxicity. Acoustic dosing (≤ 2 mg) of compound is followed by a 24-h treatment and a 24-h recovery period. Confocal images are captured [Cell Voyager CV7000 (Yokogawa, Japan)] and analysed using Columbus software (PerkinElmer). As standard the assay detects micronuclei (MN), cytotoxicity and cell-cycle profiles from Hoechst phenotypes. Mode of action information is primarily determined by kinetochore labelling in MN (aneugencity) and γH2AX foci analysis (a marker of DNA damage). Applying computational approaches and implementing machine learning models alongside Bayesian classifiers allows the identification of, with 95% accuracy, the aneugenic, clastogenic and negative compounds within the data set (Matthews correlation coefficient: 0.9), reducing analysis time by 80% whilst concurrently minimising human bias. Combining high throughput screening, multiparametric image analysis and machine learning approaches has provided the opportunity to revolutionise early Genetic Toxicology assessment within AstraZeneca. By multiplexing assay endpoints and minimising data generation and analysis time this assay enables complex genotoxicity safety assessments to be made sooner aiding the development of safer drug candidates.


Subject(s)
Drug-Related Side Effects and Adverse Reactions , Micronucleus Tests/methods , Mutagenicity Tests , High-Throughput Screening Assays/methods , High-Throughput Screening Assays/standards , Humans , Machine Learning , Micronucleus Tests/standards , Models, Statistical , Mutagenicity Tests/methods , Mutagenicity Tests/standards , Reproducibility of Results
4.
Beilstein J Nanotechnol ; 11: 938-951, 2020.
Article in English | MEDLINE | ID: mdl-32596097

ABSTRACT

Surface functionalization of porous materials allows for the introduction of additional functionality coupled with high mechanical stability of functionalized inner pores. Herein, we investigate the surface-initiated ring-opening polymerization (SI-ROP) of phenylalanine-N-carboxyanhydride (PA-NCA) in porous alumina membranes (ALOX-membranes) with respect to different solvent mixtures (tetrahydrofuran (THF) and dichloromethane (DCM)). It was found that increasing the volume fraction of DCM leads to an increasing amount of fibrillar polymer structures within the porous ALOX-membrane. A three-dimensional fibrillar network with intrinsic porosity was formed in DCM, whereas in THF, a dense and smooth polypeptide film was observed. A post-treatment with a mixture of chloroform and dichloroacetic acid leads to rearrangement of the morphology of the grafted polymer films. The analysis by scanning electron microscopy (SEM), near-infrared spectroscopy (NIR) and contact angle measurements (CA) reveals a change in morphology of the grafted polymer films, which is due to the rearrangement of the secondary structure of the polypeptides. No significant loss of the surface-grafted polypeptides was determined by thermogravimetric (TG) measurements, which indicates that the change in morphology of the polymer films is solely a result of a conformational change of the surface-grafted polypeptides. Furthermore, adsorption of a test analyte (chloroanilic acid) was investigated with respect to different polymer functionalization schemes for reversed-phase solid phase extraction applications. The adsorption capability of the functionalized composite membrane was increased from 16.7% to 38.1% compared to the native ALOX-membrane.

5.
Oncogene ; 39(25): 4869-4883, 2020 06.
Article in English | MEDLINE | ID: mdl-32444694

ABSTRACT

The poly (ADP-ribose) polymerase (PARP) inhibitor olaparib is FDA approved for the treatment of BRCA-mutated breast, ovarian and pancreatic cancers. Olaparib inhibits PARP1/2 enzymatic activity and traps PARP1 on DNA at single-strand breaks, leading to replication-induced DNA damage that requires BRCA1/2-dependent homologous recombination repair. Moreover, DNA damage response pathways mediated by the ataxia-telangiectasia mutated (ATM) and ataxia-telangiectasia mutated and Rad3-related (ATR) kinases are hypothesised to be important survival pathways in response to PARP-inhibitor treatment. Here, we show that olaparib combines synergistically with the ATR-inhibitor AZD6738 (ceralasertib), in vitro, leading to selective cell death in ATM-deficient cells. We observe that 24 h olaparib treatment causes cells to accumulate in G2-M of the cell cycle, however, co-administration with AZD6738 releases the olaparib-treated cells from G2 arrest. Selectively in ATM-knockout cells, we show that combined olaparib/AZD6738 treatment induces more chromosomal aberrations and achieves this at lower concentrations and earlier treatment time-points than either monotherapy. Furthermore, single-agent olaparib efficacy in vitro requires PARP inhibition throughout multiple rounds of replication. Here, we demonstrate in several ATM-deficient cell lines that the olaparib and AZD6738 combination induces cell death within 1-2 cell divisions, suggesting that combined treatment could circumvent the need for prolonged drug exposure. Finally, we demonstrate in vivo combination activity of olaparib and AZD6738 in xenograft and PDX mouse models with complete ATM loss. Collectively, these data provide a mechanistic understanding of combined PARP and ATR inhibition in ATM-deficient models, and support the clinical development of AZD6738 in combination with olaparib.


Subject(s)
Ataxia Telangiectasia Mutated Proteins/deficiency , Genomic Instability/drug effects , Phthalazines/pharmacology , Piperazines/pharmacology , Poly(ADP-ribose) Polymerase Inhibitors/pharmacology , Pyrimidines/pharmacology , Sulfoxides/pharmacology , A549 Cells , Animals , Ataxia Telangiectasia Mutated Proteins/antagonists & inhibitors , Ataxia Telangiectasia Mutated Proteins/genetics , Ataxia Telangiectasia Mutated Proteins/metabolism , Cell Death/drug effects , Cell Line , Cell Line, Tumor , Chromosome Aberrations/drug effects , Drug Synergism , Humans , Indoles , Mice , Morpholines , Sulfonamides
6.
Mol Cancer Ther ; 19(1): 13-25, 2020 01.
Article in English | MEDLINE | ID: mdl-31534013

ABSTRACT

AZD0156 is a potent and selective, bioavailable inhibitor of ataxia-telangiectasia mutated (ATM) protein, a signaling kinase involved in the DNA damage response. We present preclinical data demonstrating abrogation of irradiation-induced ATM signaling by low doses of AZD0156, as measured by phosphorylation of ATM substrates. AZD0156 is a strong radiosensitizer in vitro, and using a lung xenograft model, we show that systemic delivery of AZD0156 enhances the tumor growth inhibitory effects of radiation treatment in vivo Because ATM deficiency contributes to PARP inhibitor sensitivity, preclinically, we evaluated the effect of combining AZD0156 with the PARP inhibitor olaparib. Using ATM isogenic FaDu cells, we demonstrate that AZD0156 impedes the repair of olaparib-induced DNA damage, resulting in elevated DNA double-strand break signaling, cell-cycle arrest, and apoptosis. Preclinically, AZD0156 potentiated the effects of olaparib across a panel of lung, gastric, and breast cancer cell lines in vitro, and improved the efficacy of olaparib in two patient-derived triple-negative breast cancer xenograft models. AZD0156 is currently being evaluated in phase I studies (NCT02588105).


Subject(s)
Ataxia Telangiectasia Mutated Proteins/therapeutic use , Phthalazines/therapeutic use , Piperazines/therapeutic use , Pyridines/therapeutic use , Quinolines/therapeutic use , Radiation-Sensitizing Agents/therapeutic use , Triple Negative Breast Neoplasms/drug therapy , Triple Negative Breast Neoplasms/radiotherapy , Animals , Ataxia Telangiectasia Mutated Proteins/pharmacology , Cell Line, Tumor , Humans , Male , Mice , Mice, Nude , Phthalazines/pharmacology , Piperazines/pharmacology , Pyridines/pharmacology , Quinolines/pharmacology , Radiation-Sensitizing Agents/pharmacology , Triple Negative Breast Neoplasms/pathology
7.
Sci Adv ; 4(6): eaat1719, 2018 06.
Article in English | MEDLINE | ID: mdl-29938225

ABSTRACT

Poor survival rates of patients with tumors arising from or disseminating into the brain are attributed to an inability to excise all tumor tissue (if operable), a lack of blood-brain barrier (BBB) penetration of chemotherapies/targeted agents, and an intrinsic tumor radio-/chemo-resistance. Ataxia-telangiectasia mutated (ATM) protein orchestrates the cellular DNA damage response (DDR) to cytotoxic DNA double-strand breaks induced by ionizing radiation (IR). ATM genetic ablation or pharmacological inhibition results in tumor cell hypersensitivity to IR. We report the primary pharmacology of the clinical-grade, exquisitely potent (cell IC50, 0.78 nM), highly selective [>10,000-fold over kinases within the same phosphatidylinositol 3-kinase-related kinase (PIKK) family], orally bioavailable ATM inhibitor AZD1390 specifically optimized for BBB penetration confirmed in cynomolgus monkey brain positron emission tomography (PET) imaging of microdosed 11C-labeled AZD1390 (Kp,uu, 0.33). AZD1390 blocks ATM-dependent DDR pathway activity and combines with radiation to induce G2 cell cycle phase accumulation, micronuclei, and apoptosis. AZD1390 radiosensitizes glioma and lung cancer cell lines, with p53 mutant glioma cells generally being more radiosensitized than wild type. In in vivo syngeneic and patient-derived glioma as well as orthotopic lung-brain metastatic models, AZD1390 dosed in combination with daily fractions of IR (whole-brain or stereotactic radiotherapy) significantly induced tumor regressions and increased animal survival compared to IR treatment alone. We established a pharmacokinetic-pharmacodynamic-efficacy relationship by correlating free brain concentrations, tumor phospho-ATM/phospho-Rad50 inhibition, apoptotic biomarker (cleaved caspase-3) induction, tumor regression, and survival. On the basis of the data presented here, AZD1390 is now in early clinical development for use as a radiosensitizer in central nervous system malignancies.


Subject(s)
Ataxia Telangiectasia Mutated Proteins/antagonists & inhibitors , Brain Neoplasms/metabolism , Brain Neoplasms/mortality , Protein Kinase Inhibitors/pharmacology , Radiation-Sensitizing Agents/pharmacology , Animals , Apoptosis/drug effects , Blood-Brain Barrier/drug effects , Blood-Brain Barrier/metabolism , Brain Neoplasms/drug therapy , Brain Neoplasms/pathology , Cell Line, Tumor , Cell Membrane Permeability , Disease Models, Animal , Drug Evaluation, Preclinical , Humans , Mice , Phosphorylation , Protein Kinase Inhibitors/chemistry , Radiation Tolerance/drug effects , Radiation-Sensitizing Agents/chemistry , Signal Transduction/drug effects , Treatment Outcome , Tumor Suppressor Protein p53/genetics , Tumor Suppressor Protein p53/metabolism , X-Rays , Xenograft Model Antitumor Assays
8.
Mol Biosyst ; 11(10): 2738-49, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26135796

ABSTRACT

The HIF-1α/p300 protein-protein interaction plays a key role in tumor metabolism and thus represents a high value target for anticancer drug-development. Although several studies have identified inhibitor candidates using rationale design, more detailed understanding of the interaction and binding interface is necessary to inform development of superior inhibitors. In this work, we report a detailed biophysical analysis of the native interaction with both peptide and Adhiron phage display experiments to identify novel binding motifs and binding regions of the surface of p300 to inform future inhibitor design.


Subject(s)
E1A-Associated p300 Protein/metabolism , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Peptides/chemistry , Peptides/pharmacology , Binding Sites/drug effects , E1A-Associated p300 Protein/chemistry , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/chemistry , Models, Molecular , Peptide Library , Protein Binding/drug effects , Protein Interaction Maps/drug effects , Protein Structure, Secondary
9.
J Biol Chem ; 288(2): 785-92, 2013 Jan 11.
Article in English | MEDLINE | ID: mdl-23152503

ABSTRACT

Amyloid-ß (Aß) is produced by the consecutive cleavage of amyloid precursor protein (APP) first by ß-secretase, generating C99, and then by γ-secretase. APP is also cleaved by α-secretase. It is hypothesized that reducing the production of Aß in the brain may slow the progression of Alzheimer disease. Therefore, different γ-secretase inhibitors have been developed to reduce Aß production. Paradoxically, it has been shown that low to moderate inhibitor concentrations cause a rise in Aß production in different cell lines, in different animal models, and also in humans. A mechanistic understanding of the Aß rise remains elusive. Here, a minimal mathematical model has been developed that quantitatively describes the Aß dynamics in cell lines that exhibit the rise as well as in cell lines that do not. The model includes steps of APP processing through both the so-called amyloidogenic pathway and the so-called non-amyloidogenic pathway. It is shown that the cross-talk between these two pathways accounts for the increase in Aß production in response to inhibitor, i.e. an increase in C99 will inhibit the non-amyloidogenic pathway, redirecting APP to be cleaved by ß-secretase, leading to an additional increase in C99 that overcomes the loss in γ-secretase activity. With a minor extension, the model also describes plasma Aß profiles observed in humans upon dosing with a γ-secretase inhibitor. In conclusion, this mechanistic model rationalizes a series of experimental results that spans from in vitro to in vivo and to humans. This has important implications for the development of drugs targeting Aß production in Alzheimer disease.


Subject(s)
Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Peptides/metabolism , Enzyme Inhibitors/pharmacology , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid beta-Peptides/blood , Cell Line , Humans
10.
J Physiol ; 590(18): 4501-14, 2012 Sep 15.
Article in English | MEDLINE | ID: mdl-22508963

ABSTRACT

Functional analysis has shown that the missense gain-in-function KCNQ1 S140G mutation associated with familial atrial fibrillation produces an increase of the slow delayed rectifier potassium current (I(Ks)). Through computer modelling, this study investigated mechanisms by which the KCNQ1 S140G mutation promotes and perpetuates atrial fibrillation. In simulations, Courtemanche et al.'s model of human atrial cell action potentials (APs) was modified to incorporate experimental data on changes of I(Ks) induced by the KCNQ1 S140G mutation. The cell models for wild type (WT) and mutant type (MT) I(Ks) were incorporated into homogeneous multicellular 2D and 3D tissue models. Effects of the mutation were quantified on AP profile, AP duration (APD) restitution, effective refractory period (ERP) restitution, and conduction velocity (CV) restitution.Temporal and spatial vulnerabilities of atrial tissue to genesis of re-entry were computed. Dynamic behaviours of re-entrant excitation waves (lifespan (LS), tip meandering patterns and dominant frequency) in 2D and 3D models were characterised. It was shown that the KCNQ1 S140G mutation abbreviated atrial APD and ERP and flattened APD and ERP restitution curves. It reduced atrial CV at low excitation rates, but increased it at high excitation rates that facilitated the conduction of high rate atrial excitation waves. Although it increased slightly tissue temporal vulnerability for initiating re-entry, it reduced markedly the minimal substrate size necessary for sustaining re-entry (increasing the tissue spatial vulnerability). In the 2D and 3D models, the mutation also stabilized and accelerated re-entrant excitation waves, leading to rapid and sustained re-entry. In the 3D model, scroll waves under the mutation condition MT conditions also degenerated into persistent and erratic wavelets, leading to fibrillation. In conclusion, increased I(Ks) due to the KCNQ1 S140G mutation increases atrial susceptibility to arrhythmia due to increased tissue vulnerability, shortened ERP and altered atrial conduction velocity, which, in combination, facilitate initiation and maintenance of re-entrant excitation waves.


Subject(s)
Atrial Fibrillation/genetics , Atrial Fibrillation/physiopathology , KCNQ1 Potassium Channel/physiology , Models, Cardiovascular , Action Potentials/physiology , Computer Simulation , Heart Atria/physiopathology , Humans , Mutation
11.
Eur J Pharm Sci ; 46(4): 209-21, 2012 Jul 16.
Article in English | MEDLINE | ID: mdl-21888968

ABSTRACT

Computational models of human atrial cells, tissues and atria have been developed. Cell models, for atrial wall, crista terminalis, appendage, Bachmann's bundle and pectinate myocytes are characterised by action potentials, ionic currents and action potential duration (APD) restitution. The principal effect of the ion channel remodelling of persistent atrial fibrillation (AF), and a mutation producing familial AF, was APD shortening at all rates. Electrical alternans was abolished by the modelled action of Dronedarone. AF induced gap junctional remodelling slows propagation velocity at all rates. Re-entrant spiral waves in 2-D models are characterised by their frequency, wavelength, meander and stability. For homogenous models of normal tissue, spiral waves self-terminate, due to meander to inexcitable boundaries, and by dissipation of excitation. AF electrical remodelling in these homogenous models led to persistence of spiral waves, and AF fibrotic remodelling to their breakdown into fibrillatory activity. An anatomical model of the atria was partially validated by the activation times of normal sinus rhythm. The use of tissue geometry from clinical MRI, and tissue anisotropy from ex vivo diffusion tensor magnetic resonance imaging is outlined. In the homogenous model of normal atria, a single scroll breaks down onto spatio-temporal irregularity (electrical fibrillation) that is self-terminating; while in the AF remodelled atria the fibrillatory activity is persistent. The persistence of electrical AF can be dissected in the model in terms of ion channel and intercellular coupling processes, that can be modified pharmacologically; the effects of anatomy, that can be modified by ablation; and the permanent effects of fibrosis, that need to be prevented.


Subject(s)
Anti-Arrhythmia Agents/pharmacology , Arrhythmias, Cardiac/drug therapy , Atrial Function/drug effects , Computer Simulation , Models, Cardiovascular , Systems Biology , Action Potentials , Arrhythmias, Cardiac/genetics , Arrhythmias, Cardiac/pathology , Arrhythmias, Cardiac/physiopathology , Diffusion Tensor Imaging , Fibrosis , Genetic Predisposition to Disease , Heart Atria/drug effects , Heart Atria/pathology , Heart Atria/physiopathology , Humans , Mutation , Phenotype , Time Factors , User-Computer Interface
12.
IEEE Trans Biomed Eng ; 58(10): 2952-5, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21742568

ABSTRACT

Atrial arrhythmias resulting from abnormally rapid focal activity in the atria may be reflected in an altered P-wave morphology (PWM) in the ECG. Although clinically important, detailed relationships between PWM and origins of atrial focal excitations have not been established. To study such relationships, we developed computational models of the human atria and torso. The model simulation results were used to evaluate an extant clinical algorithm for locating the origin of atrial focal points from the ECG. The simulations showed that the algorithm was practical and could predict the atrial focal locations with 85% accuracy. We proposed a further refinement of the algorithm to distinguish between focal locations within the large atrial bundles.


Subject(s)
Body Surface Potential Mapping/methods , Heart Atria/anatomy & histology , Models, Cardiovascular , Tachycardia, Ectopic Atrial/physiopathology , Torso/anatomy & histology , Algorithms , Atrial Function/physiology , Computer Simulation , Female , Heart Atria/physiopathology , Humans , Signal Processing, Computer-Assisted , Torso/physiology
13.
Prog Biophys Mol Biol ; 107(1): 156-68, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21762716

ABSTRACT

Despite a vast amount of experimental and clinical data on the underlying ionic, cellular and tissue substrates, the mechanisms of common atrial arrhythmias (such as atrial fibrillation, AF) arising from the functional interactions at the whole atria level remain unclear. Computational modelling provides a quantitative framework for integrating such multi-scale data and understanding the arrhythmogenic behaviour that emerges from the collective spatio-temporal dynamics in all parts of the heart. In this study, we have developed a multi-scale hierarchy of biophysically detailed computational models for the human atria--the 3D virtual human atria. Primarily, diffusion tensor MRI reconstruction of the tissue geometry and fibre orientation in the human sinoatrial node (SAN) and surrounding atrial muscle was integrated into the 3D model of the whole atria dissected from the Visible Human dataset. The anatomical models were combined with the heterogeneous atrial action potential (AP) models, and used to simulate the AP conduction in the human atria under various conditions: SAN pacemaking and atrial activation in the normal rhythm, break-down of regular AP wave-fronts during rapid atrial pacing, and the genesis of multiple re-entrant wavelets characteristic of AF. Contributions of different properties of the tissue to mechanisms of the normal rhythm and arrhythmogenesis were investigated. Primarily, the simulations showed that tissue heterogeneity caused the break-down of the normal AP wave-fronts at rapid pacing rates, which initiated a pair of re-entrant spiral waves; and tissue anisotropy resulted in a further break-down of the spiral waves into multiple meandering wavelets characteristic of AF. The 3D virtual atria model itself was incorporated into the torso model to simulate the body surface ECG patterns in the normal and arrhythmic conditions. Therefore, a state-of-the-art computational platform has been developed, which can be used for studying multi-scale electrical phenomena during atrial conduction and AF arrhythmogenesis. Results of such simulations can be directly compared with electrophysiological and endocardial mapping data, as well as clinical ECG recordings. The virtual human atria can provide in-depth insights into 3D excitation propagation processes within atrial walls of a whole heart in vivo, which is beyond the current technical capabilities of experimental or clinical set-ups.


Subject(s)
Atrial Fibrillation/pathology , Atrial Fibrillation/physiopathology , Computer Simulation , Models, Anatomic , User-Computer Interface , Anisotropy , Electrocardiography , Female , Heart Atria/anatomy & histology , Heart Atria/pathology , Heart Atria/physiopathology , Humans , Magnetic Resonance Imaging , Sinoatrial Node/pathology , Sinoatrial Node/physiopathology , Torso/anatomy & histology
14.
IEEE Trans Vis Comput Graph ; 17(1): 101-14, 2011 Jan.
Article in English | MEDLINE | ID: mdl-21071790

ABSTRACT

This paper describes an automatic mechanism for drawing metro maps. We apply multicriteria optimization to find effective placement of stations with a good line layout and to label the map unambiguously. A number of metrics are defined, which are used in a weighted sum to find a fitness value for a layout of the map. A hill climbing optimizer is used to reduce the fitness value, and find improved map layouts. To avoid local minima, we apply clustering techniques to the map-the hill climber moves both stations and clusters when finding improved layouts. We show the method applied to a number of metro maps, and describe an empirical study that provides some quantitative evidence that automatically-drawn metro maps can help users to find routes more efficiently than either published maps or undistorted maps. Moreover, we have found that, in these cases, study subjects indicate a preference for automatically-drawn maps over the alternatives.


Subject(s)
Algorithms , Computer Graphics , Computer-Aided Design , Information Storage and Retrieval/methods , Maps as Topic , User-Computer Interface , Computer Simulation , Humans , Pattern Recognition, Automated/methods , Software
15.
Article in English | MEDLINE | ID: mdl-19964086

ABSTRACT

Atrial fibrillation (AF) accounts for a large proportion of healthcare expenditure world wide. Mechanisms underlying the genesis and maintenance of AF are still poorly understood. Though AF is largely thought to be caused and perpetuated by dysfunctions of cellular ion channels, disrupted intercellular gap junctional electrical coupling, and/or structural changes in the atria, it is also associated with abnormal secretion of hormones, such as a high level of Homocysteine (Hcy). It was found that a high concentration Hcy induces electrical remodeling of ion channels in human atrial cells that include the ultra rapid potassium, inward rectifier potassium and transient outward potassium currents. Such Hcy-induced ion channel remodeling in repolarising potassium currents has been hypothesized to be pro-arrhythmic. In this study, we carried out multi-scale simulations to evaluate the effects of Hcy-induced changes in potassium currents on the electrical activity of human atrium at single cell, 1D strand of tissue, and 3D anatomical models. We found that high Hcy concentration produced marked changes in atrial action potentials, including a more hyperpolarized resting potential, elevated plateau potential during early stages of repolarization and abbreviated action potential duration (APD). Losses in rate dependent accommodation of APD and effective refractory period were observed. In the tissue models, high Hcy concentration slowed down atrial excitation conduction at low rates, but facilitated it at high rates. Simulated re-entrant scroll waves in the 3D model self-terminated under Control condition, but sustained under high Hcy condition. These results collectively demonstrate the pro-arrhythmic effects of a high level Hcy in promoting and sustaining AF.


Subject(s)
Arrhythmias, Cardiac/pathology , Biophysics/methods , Electrophysiology/methods , Heart Atria/pathology , Homocysteine/blood , Action Potentials/physiology , Algorithms , Arrhythmias, Cardiac/blood , Atrial Fibrillation/physiopathology , Computer Simulation , Electric Conductivity , Gap Junctions , Humans , Models, Anatomic , Potassium Channels/metabolism , Time Factors
16.
J Biomed Opt ; 10(2): 024033, 2005.
Article in English | MEDLINE | ID: mdl-15910106

ABSTRACT

We describe what is, to the best of our knowledge, the first pilot study of coregistered tomographic x-ray and optical breast imaging. The purpose of this pilot study is to develop both hardware and data processing algorithms for a multimodality imaging method that provides information that neither x-ray nor diffuse optical tomography (DOT) can provide alone. We present in detail the instrumentation and algorithms developed for this multimodality imaging. We also present results from our initial pilot clinical tests. These results demonstrate that strictly coregistered x-ray and optical images enable a detailed comparison of the two images. This comparison will ultimately lead to a better understanding of the relationship between the functional contrast afforded by optical imaging and the structural contrast provided by x-ray imaging.


Subject(s)
Breast Diseases/diagnosis , Diagnosis, Computer-Assisted , Mammography , Optics and Photonics , Aged , Equipment Design , Female , Humans , Mammography/instrumentation , Middle Aged , Optics and Photonics/instrumentation , Pilot Projects
17.
J Biomed Opt ; 10(1): 11013, 2005.
Article in English | MEDLINE | ID: mdl-15847579

ABSTRACT

Time domain (TD) diffuse optical measurement systems are being applied to neuroimaging, where they can detect hemodynamics changes associated with cerebral activity. We show that TD systems can provide better depth sensitivity than the more traditional continuous wave (CW) systems by gating late photons, which carry information about deep layers of the brain, and rejecting early light, which is sensitive to the superficial physiological signal clutter. We use an analytical model to estimate the contrast due to an activated region of the brain, the instrumental noise of the systems, and the background signal resulting from superficial physiological signal clutter. We study the contrast-to-noise ratio and the contrast-to-background ratio as a function of the activation depth and of the source-detector separation. We then present experimental results obtained with a time-gated instrument on the motor cortex during finger-tapping exercises. Both the model and the experimental results show a similar contrast-to-noise ratio for CW and TD, but that estimation of the contrast is experimentally limited by background fluctuations and that a better contrast-to-background ratio is obtained in the TD case. Finally, we use the time-gated measurements to resolve in depth the brain activation during the motor stimulus.


Subject(s)
Brain/physiology , Cerebrovascular Circulation , Optics and Photonics , Artifacts , Hemodynamics , Humans , Models, Neurological , Motor Activity/physiology , Motor Cortex/physiology , Time Factors
18.
J Opt Soc Am A Opt Image Sci Vis ; 21(6): 1035-49, 2004 Jun.
Article in English | MEDLINE | ID: mdl-15191186

ABSTRACT

A method is presented for fluorescence optical diffusion tomography in turbid media using multiple-frequency data. The method uses a frequency-domain diffusion equation model to reconstruct the fluorescent yield and lifetime by means of a Bayesian framework and an efficient, nonlinear optimizer. The method is demonstrated by using simulations and laboratory experiments to show that reconstruction quality can be improved in certain problems through the use of more than one frequency. A broadly applicable mutual information performance metric is also presented and used to investigate the advantages of using multiple modulation frequencies compared with using only one.


Subject(s)
Algorithms , Connective Tissue/metabolism , Connective Tissue/ultrastructure , Image Interpretation, Computer-Assisted/methods , Microscopy, Fluorescence/methods , Models, Biological , Spectrometry, Fluorescence/methods , Tomography, Optical/methods , Computer Simulation , Diffusion , Image Enhancement/methods , Phantoms, Imaging
19.
Opt Lett ; 28(21): 2061-3, 2003 Nov 01.
Article in English | MEDLINE | ID: mdl-14587815

ABSTRACT

We present three-dimensional diffuse optical tomography of the hemodynamic response to somatosensory stimulation in a rat. These images show the feasibility of volumetrically imaging the functional response to brain activity with diffuse light. A combination of positional optode calibration and contrast-to-noise ratio weighting was found to improve imaging performance.


Subject(s)
Brain/physiology , Tomography, Optical Coherence , Algorithms , Animals , Computer Simulation , Feasibility Studies , Forelimb/physiology , Image Processing, Computer-Assisted , Light , Models, Theoretical , Rats , Scattering, Radiation
20.
Appl Opt ; 42(25): 5181-90, 2003 Sep 01.
Article in English | MEDLINE | ID: mdl-12962399

ABSTRACT

We introduce a modified Tikhonov regularization method to include three-dimensional x-ray mammography as a prior in the diffuse optical tomography reconstruction. With simulations we show that the optical image reconstruction resolution and contrast are improved by implementing this x-ray-guided spatial constraint. We suggest an approach to find the optimal regularization parameters. The presented preliminary clinical result indicates the utility of the method.


Subject(s)
Breast , Image Processing, Computer-Assisted , Imaging, Three-Dimensional , Mammography , Optics and Photonics , Tomography , Computer Simulation , Female , Humans , Models, Theoretical
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