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ABSTRACT: This study aimed to compare the QRS duration in a large population of healthy individuals living in Nigeria with a Caucasian population living in Scotland. The Nigerian population consisted of 782 males and 479 females with an age range of 20-87 years. The Caucasian population consisted of 859 males and 637 females with an age range from 18-82 years. For the Nigerian population, the overall QRS duration for males was 87.9 ± 9.4ms and for females, it was 83.4 ± 7.6ms. For the Caucasian population, the overall QRS duration in males was 93.7 ± 9.8ms and in females was 86.1 ± 7.7ms. In both populations, the mean QRS duration was higher in males than in females. There was a significantly longer QRS duration in Caucasian males and females compared to their Nigerian counterparts. However, the upper limits of normal QRS duration differed little between the two races.
Computing in Cardiology, 2010; 10/2010
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ABSTRACT: A security analysis of the recently introduced Quantum Private Query (QPQ) protocol is presented. The latter is a cheat sensitive quantum protocol to perform a private search on a classical database. It allows a user to retrieve an item from the database without revealing which item was retrieved, and at the same time it ensures data privacy of the database (the information that the user retrieves in a query is bounded). The security analysis is based on information-disturbance tradeoffs which show that whenever the provider tries to obtain information on the query, the query (encoded into a quantum system) is disturbed so that the person querying the database can detect the privacy violation. The security bounds are derived under the assumption that a unique answer corresponds to each query. To remove this assumption, some simple variants of the protocol are illustrated, and it is conjectured that analogous security bounds apply to them.
IEEE Transactions on Information Theory 08/2010; · 3.01 Impact Factor
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ABSTRACT: This paper presents an automated method for measuring 3D left ventricular (LV) strain in each imaged time frame from phase unwrapped harmonic phase (HARP) images derived from tagged cardiac magnetic resonance imaging. In previous work, manually-placed branch cuts were used to resolve phase inconsistencies in HARP images before they were unwrapped. This paper presents an automated method for placing branch cuts in short-axis images based on simulated annealing with a new cost function based on temporal phase consistency. This method significantly reduces the amount of user interaction needed to compute 3D strain maps in the entire LV in each imaged time frame. The unwrapped-phase-derived strains were validated on a set of 40 human studies by comparing them to strains estimated by a previously published feature based technique and a previously published unwrapped-phase technique with manual branch cut placement.
Biomedical Imaging: From Nano to Macro, 2009. ISBI '09. IEEE International Symposium on; 08/2009
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ABSTRACT: A consistent image registration formulation with B-spline deformation model is proposed. This formulation avoids the computation of the inverse of a deformation in the iterative optimization and allows the analytical computation of both gradient and Hessian of the cost function. Because of the formulation, the algorithm is computationally efficient and could potentially produce more accurate registration results. Experiments show that the proposed algorithm produces promising results while keeping the estimated deformations consistent.
Biomedical Imaging: From Nano to Macro, 2009. ISBI '09. IEEE International Symposium on; 08/2009
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ABSTRACT: We consider one of the quantum key distribution protocols recently introduced in Ref. [Pirandola et al., Nature Phys. 4, 726 (2008)]. This protocol consists of a two-way quantum communication between Alice and Bob, where Alice encodes secret information via a random phase-space displacement of a coherent state. In particular, we study its security against a specific class of individual attacks which are based on combinations of Gaussian quantum cloning machines.
Quantum, Nano and Micro Technologies, 2009. ICQNM '09. Third International Conference on; 03/2009
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ABSTRACT: This paper presents a method for measuring 3D left ventricular (LV) strain from phase unwrapped harmonic phase (HARP) images derived from tagged cardiac magnetic resonance imaging (MRI). Limited user interaction is needed, but, in contrast to existing techniques, 3D strains can be measured over the entire LV. In addition, unwrapped phase is more robust to interframe motion since it only requires that the average interframe deformation be less than one-half tag spacing. The unwrapped-phase-derived strains were validated on a set of 30 human studies by comparing them to strains estimated by a feature-based technique. The standard deviation of the difference between strains measured by the two methods was less than 5% of the average of the strains from the two methods.
Biomedical Imaging: From Nano to Macro, 2008. ISBI 2008. 5th IEEE International Symposium on; 06/2008
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ABSTRACT: Interactions between abnormal amyloid precursor protein metabolism and cholinergic dysfunction are increasingly apparent. Both of these major features of Alzheimer's disease occur in restricted loci in normal aging–a potential model for early Alzheimer type pathology. Entorhinal cortex is particularly vulnerable to β-amyloidosis and compared with other cortical areas is remarkable for the relatively high density of nicotinic (3H-nicotine) but not other cholinergic or glutamate receptor binding. With increasing age, post-maturity, there is a persistent decline in nicotinic receptor binding in entorhinal cortex whereas muscarinic Ml and non-Ml, glutamate NMDA and non-NMDA receptors are spared. Normal elderly individuals, distinguished by the absence of βA4 immunoreactive plaques in this area, are differentiated from those with plaques by higher nicotine binding. Amongst individuals with an established history of smoking tobacco, nicotinic receptor binding and hippocampal choline acetyltransferase were elevated compared with non-smokers and preliminary evidence indicates a reduced density of cortical plaques. These findings are consistent with the hypothesis that down regulation of the nicotinic cholinergic receptor—a ligand gated calcium channel known to control the expression of neurotrophins—plays a role in the evolution of Alzheimer-type pathology.
Annals of the New York Academy of Sciences 12/2006; 777(1):388 - 392. · 3.15 Impact Factor
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ABSTRACT: This paper presents a tag point classification algorithm for use in a new technique for tracking tag lines in tagged cardiac magnetic resonance (MR) images. Instead of tracking tag lines from frame to frame in an image sequence with active contours or similar techniques, a set of candidate tag points are detected in each image and then classified as either a false positive or belonging to a particular tag line. The advantage of this approach is that the tag point positions are not pre-smoothed during tracking, allowing smoothness constraint to be applied only in the deformation model fit to the tag points. Results of a preliminary validation experiment on human cardiac MR data are presented that show a classification accuracy of 97.86%
Biomedical Imaging: Nano to Macro, 2006. 3rd IEEE International Symposium on; 05/2006
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ABSTRACT: The capacity C for transmitting classical information is investigated for noisy bosonic channel models. An exact result is obtained for the pure-loss case. Upper and lower bounds are established for channels with active noise sources
Information Theory, 2004. ISIT 2004. Proceedings. International Symposium on; 02/2004
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ABSTRACT: We have used a linear Genetic Programming system with a multitude
of different quotes on financial securities as input in order to evolve
an intraday trading strategy for an individual stock, attempting to
outperform a simple buy and hold strategy over the same period of time
Evolutionary Computation, 2002. CEC '02. Proceedings of the 2002 Congress on; 02/2002
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ABSTRACT: Striatal nicotinic acetylcholine receptors with high affinity for nicotinic agonists are involved with the release of a number of neurotransmitters, including dopamine. Previous findings as to whether these receptors are changed in Parkinson's disease and Alzheimer's disease are inconsistent and no previous investigations have focused on these receptors in dementia with Lewy bodies and schizophrenia, which are also associated with disorders of movement. The present autoradiographic study of striatal [3H]nicotine binding in Alzheimer's and Parkinson's diseases, dementia with Lewy bodies and schizophrenia was conducted with particular reference to the potentially confounding variables of tobacco use and neuroleptic medication. [3H]Nicotine binding in both dorsal and ventral caudate and putamen was significantly reduced in Parkinson's disease (43-67%, n=13), Alzheimer's disease (29-37%, n=13) and dementia with Lewy bodies (50-61%, n=20) compared to age-matched controls (n=42). Although tobacco use in the control group was associated with increased [3H]nicotine binding (21-38%), and neuroleptic treatment in dementia with Lewy bodies and Alzheimer's disease was associated with reduced [3H]nicotine binding (up to 29%), differences between neurodegenerative disease groups and controls persisted in subgroups of Alzheimer's disease cases (26-33%, n=6, in the ventral striatum) and dementia with Lewy body cases (30-49%, n=7, in both dorsal and ventral striatum) who had received no neuroleptic medication compared to controls who had not smoked (n=10). In contrast, striatal [3H]nicotine binding in a group of elderly (56-85 years) chronically medicated individuals with schizophrenia (n=6) was elevated compared with the entire control group (48-78%, n=42) and with a subgroup that had smoked (24-49%, n=8). The changes observed in [3H]nicotine binding are likely to reflect the presence of these receptors on multiple sites within the striatum, which may be differentially modulated in the different diseases. Further study is warranted to explore which nicotinic receptor subunits and which neuronal compartments are involved in the changes in [3H]nicotine binding reported, to aid development of potential nicotinic receptor therapy.
Neuroscience 02/2000; 98(1):79-87. · 3.38 Impact Factor
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ABSTRACT: Neuronal nicotinic receptors have been implicated in schizophrenia on the basis of the high incidence of tobacco smoking in patients, abnormalities in cytisine and alpha-bungarotoxin (alphaBGT) binding in the hippocampus, and linkage between auditory P50 deficits and the region of chromosome 15 coding the alpha7 subunit. In another disease associated with psychosis, dementia with Lewy bodies (DLB), in which visual hallucinations predominate, reductions in nicotine binding have been identified in various cortical and subcortical regions. We investigated both alphaBGT and nicotine binding autoradiographically in different thalamic nuclei in autopsy brain tissue from patients with schizophrenia and DLB. AlphaBGT binding in the reticular nucleus was moderately reduced (25%) in schizophrenia and more extensively reduced (50%) in DLB. There were no significant alterations in nicotine binding in schizophrenia, and in DLB, a trend towards moderate reductions in most nuclei reached significance in the lateral dorsal nucleus. It is concluded that widespread abnormalities of thalamic nicotine are not implicated in schizophrenia or DLB, but that reticular alphaBGT binding may be involved to a lesser and greater extent in the pathophysiology or psychopathology of both disorders.
Journal of Neurochemistry 11/1999; 73(4):1590-7. · 4.06 Impact Factor
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M A Piggott,
E F Marshall,
N Thomas, S Lloyd,
J A Court,
E Jaros,
D Burn,
M Johnson,
R H Perry,
I G McKeith,
C Ballard,
E K Perry
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ABSTRACT: Dementia with Lewy bodies (DLB) is a neuropsychiatric disease associated with extrapyramidal features which differ from those of Parkinson's disease, including reduced effectiveness of L-dopa and severe sensitivity reactions to neuroleptic drugs. Distinguishing Alzheimer's disease from DLB is clinically relevant in terms of prognosis and appropriate treatment. Dopaminergic activities have been investigated at coronal levels along the rostrocaudal striatal axis from a post-mortem series of 25 DLB, 14 Parkinson's disease and 17 Alzheimer's disease patients and 20 elderly controls. [(3)H]Mazindol binding to the dopamine uptake site was significantly reduced in the caudal putamen in DLB compared with controls (57%), but not as extensively as in Parkinson's disease (75%), and was unchanged in Alzheimer's disease. Among three dopamine receptors measured (D1, D2 and D3), the most striking changes were apparent in relation to D2. In DLB, [(3)H]raclopride binding to D2 receptors was significantly reduced in the caudal putamen (17%) compared with controls, and was significantly lower than in Parkinson's disease at all levels. D2 binding was significantly elevated at all coronal levels in Parkinson's disease compared with controls, most extensively in the rostral putamen (71%). There was no change from the normal pattern of D2 binding in Alzheimer's disease. The only significant alteration in D1 binding ([(3)H]SCH23390) in the groups examined was an elevation (30%) in the caudal striatum in Parkinson's disease. There were no differences in D3 binding, measured using [(3)H]7-OH-DPAT, in DLB compared with controls. A slight, significant decrease in D3 binding in the caudal striatum of Parkinson's disease (13%) patients and an increase in Alzheimer's disease (20%) in the dorsal striatum at the level of the nucleus accumbens were found. The concentration and distribution of dopamine were disrupted in both DLB and Parkinson's disease, although in the caudate nucleus the loss of dopamine in DLB was uniform whereas in Parkinson's disease the loss was greater caudally. In the caudal putamen, dopamine was reduced by 72% in DLB and by 90% in Parkinson's disease. The homovanillic acid : dopamine ratio, a metabolic index, indicated compensatory increased turnover in Parkinson's disease, which was absent in DLB despite the loss of substantia nigra neurons (49%), dopamine and uptake sites. These differences between DLB, Parkinson's disease and Alzheimer's disease may explain some characteristics of the extrapyramidal features of DLB and its limited response to L-dopa and severe neuroleptic sensitivity. The distinct changes in the rostrocaudal pattern of expression of dopaminergic parameters are relevant to the interpretation of the in vivo imaging and diagnosis of DLB.
Brain 09/1999; 122 ( Pt 8):1449-68. · 9.46 Impact Factor
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ABSTRACT: A non-weak link joining technique has been developed for YBCO
pseudo-crystals fabricated by seeded peritectic solidification based on
the formation of a liquid phase which segregates from the platelet
boundaries at temperatures above ≈920°C. Electrical and magnetic
measurements on these boundaries suggest that their irreversibility
field can be as high as 7 T at 77 K in fully oxygenated pseudo-crystals
joined along their crystallographic ab-planes which is comparable to the
irreversibility behaviour of the adjacent YBCO grains
IEEE Transactions on Appiled Superconductivity 07/1999; · 1.04 Impact Factor
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ABSTRACT: The human striatum, which receives dopaminergic innervation from the substantia nigra and ventral tegmental area (cell groups A8, A9 and A10), has structural and functional subdivisions both rostrocaudally and dorsoventrally. These relate to motor and non-motor origins of cortical projections and the specific areas of the substantia nigra and ventral tegmental area providing dopaminergic innervation. In the present study, we have evaluated the distribution of a number of dopaminergic parameters in the caudate, putamen and nucleus accumbens at separate coronal levels in a post mortem study in a series of elderly normal individuals aged 55-94 years, with analysis of the effect of post mortem variables. Dopamine D1 receptor density displayed a rostrocaudally declining gradient in the putamen but not in the caudate, such that at levels posterior to the anterior commissure, there was significantly lower D1 binding in the putamen compared to the caudate. The density of dopamine D2 receptors was similar in the putamen and caudate, increasing rostrocaudally. The density of dopamine uptake sites exhibited an increasing rostrocaudal gradient in the caudate, especially ventrally, but not in the putamen, where binding was more constant. The dopamine D3 receptor was concentrated in the ventral striatum, particularly the nucleus accumbens, although there was no evidence of a rostrocaudal gradient. With respect to striosome-matrix compartmentalization, there was no complete segregation, although D1 and D3 receptors were concentrated in striosomes, whereas D2 receptors and uptake sites showed higher density in the matrix. Levels of dopamine were similar in the caudate and putamen, and were significantly elevated at levels including the nucleus accumbens and the anterior commissure. Homovanillic acid and the metabolic index (homovanillic acid/dopamine ratio) were significantly higher in the putamen compared to the caudate, especially at levels from and caudal to the anterior commissure. These distributions of dopamine receptors and metabolic indicators, reflecting the different functional domains of the striatum, are relevant to the interpretation of current in vivo imaging of the dopamine transporter and receptors in neurological and psychiatric disorders. They provide information to assist in the detection of perturbations in expression, in specific diseases, at particular points on rostrocaudal, lateromedial and dorsoventral axes, a level of resolution beyond current neuroimaging capability.
Neuroscience 06/1999; 90(2):433-45. · 3.38 Impact Factor
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ABSTRACT: Changes in the number of high-affinity nicotine binding sites have been widely reported in specific regions of the human brain during aging and in degenerative neurological diseases associated with aging, such as Alzheimer's disease. Nicotinic receptors are highly diverse and a description of the molecular subtypes affected in such conditions has not been achieved to date. To investigate the status of the alpha3 subunit-containing subtypes in such conditions, we assessed by in situ hybridisation the alpha3 mRNA density in the hippocampus, entorhinal cortex and thalamus of Alzheimer's patients and age-matched controls. No significant difference in the expression of the alpha3 mRNA, either qualitative or quantitative, was found between Alzheimer's individuals and controls in any of the analysed areas. This result suggests that the nicotine binding changes occurring in these areas in Alzheimer's patients are not correlated to a variation of the alpha3 mRNA in the same regions. Nevertheless, a negative correlation between the alpha3 mRNA density and the age was observed in the entorhinal cortex of both the Alzheimer's and the normal subjects, suggesting a potentially extensive decay of the alpha3-expressing neurons or loss of alpha3-containing receptors in intact neurons of the entorhinal cortex in the late elderly.
Molecular Brain Research 01/1999; 63(1):72-8. · 2.00 Impact Factor
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ABSTRACT: Reports of a reduction in the risk of developing Parkinson's disease and Alzheimer's disease in tobacco smokers, together with the loss of high-affinity nicotine binding in these diseases, suggest that consequences of nicotinic cholinergic transmission may be neuroprotective. Changes in brain dopaminergic parameters and nicotinic receptors in response to tobacco smoking have been assessed in this study of autopsy samples from normal elderly individuals with known smoking histories and apolipoprotein E genotype. The ratio of homovanillic acid to dopamine, an index of dopamine turnover, was reduced in elderly smokers compared with age matched non-smokers (P<0.05) in both the caudate and putamen. Dopamine levels were significantly elevated in the caudate of smokers compared with non-smokers (P<0.05). However there was no significant change in the numbers of dopamine (D1, D2 and D3) receptors or the dopamine transporter in the striatum, or for dopamine D1 and D2 receptors in the hippocampus in smokers compared with non-smokers or ex-smokers. The density of high-affinity nicotine binding was higher in smokers than non-smokers in the hippocampus, entorhinal cortex and cerebellum (elevated by 51-221%) and to a lesser extent in the striatum (25-55%). The density of high-affinity nicotine binding in ex-smokers was similar to that of the non-smokers in all the areas investigated. The differences in high-affinity nicotine binding between smokers and the non- and ex-smokers could not be explained by variation in apolipoprotein E genotype. There were no differences in alpha-bungarotoxin binding, measured in hippocampus and cerebellum, between any of the groups. These findings suggest that chronic cigarette smoking is associated with a reduction of the firing of nigrostriatal dopaminergic neurons in the absence of changes in the numbers of dopamine receptors and the dopamine transporter. Reduced dopamine turnover associated with increased numbers of high-affinity nicotine receptors is consistent with attenuated efficacy of these receptors in smokers. A decrease in striatal dopamine turnover may be a mechanism of neuroprotection in tobacco smokers that could delay basal ganglia pathology. The current findings are also important in the interpretation of measurements of nicotinic receptors and dopaminergic parameters in psychiatric conditions such as schizophrenia, in which there is a high prevalence of cigarette smoking.
Neuroscience 12/1998; 87(1):63-78. · 3.38 Impact Factor
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M A Piggott,
E K Perry,
E F Marshall,
I G McKeith,
M Johnson,
H L Melrose,
J A Court, S Lloyd,
A Fairbairn,
A Brown,
P Thompson,
R H Perry
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ABSTRACT: In dementia with Lewy bodies (DLB) mild extrapyramidal symptoms are associated with moderate reductions in substantia nigra neuron density and concentration of striatal dopamine. Many DLB patients treated with typical neuroleptics suffer severe adverse reactions, which result in decreased survival.
In a series of DLB cases, with and without neuroleptic sensitivity, substantia nigra neuron densities, striatal dopamine and homovanillic acid concentrations, and autoradiographic [3H]mazindol and [3H]raclopride binding (to the dopamine transporter and D2 receptor, respectively) were analyzed and compared to control and idiopathic Parkinson's disease cases.
D2 receptors were up-regulated in neuroleptictolerant DLB and Parkinson's disease compared to DLB without neuroleptic exposure and controls. D2 receptors were not up-regulated in DLB cases with severe neuroleptic reactions. Dopamine uptake sites were reduced concomitantly with substantia nigra neuron density in Parkinson's disease compared to controls, but there was no significant correlation between substantia nigra neuron density and [3H]mazindol binding in DLB groups. There was no significant difference in substantia nigra neuron density, [3H]mazindol binding, and dopamine or homovanillic acid concentration between neuroleptic-tolerant and -sensitive groups.
Failure to up-regulate D2 receptors in response to neuroleptic blockade or reduced dopaminergic innervation may be the critical factor responsible for neuroleptic sensitivity.
Biological Psychiatry 11/1998; 44(8):765-74. · 8.28 Impact Factor
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ABSTRACT: The dopamine D2 receptor gene contains a TaqI repeat fragment length polymorphism creating two alleles DRD2*A1 and DRD2*A2. It has been previously suggested that the lesser allele, DRD2*A1, is more prevalent in individuals who are susceptible to impulsive/addictive/compulsive behaviour, for example, alcoholics, polysubstance abusers and tobacco smokers. We genotyped a series of 104 smokers and 117 non smokers and compared the allele frequencies between the groups. A subset (n = 87) of the smoking population also completed the Classification of Smoking by Motives questionnaire and were given scores for five criteria that drive smoking: automatic, dependence, sedative, stimulant and indulgence. Another subset (n = 52) completed the Fagerstrom Tolerance Questionnaire and were given scores for nicotine dependence. We did not find any increase in allele A1 frequency when comparing smokers to non smokers. Furthermore, neither measure of dependence was affected by possession of the A1 allele; the only difference between DRD2*A1 bearing and DRD2*A2 homozygous individuals in terms of smoking motives was found in the scores for indulgence; the former having a moderately reduced score (by 17%, p < 0.05). We conclude that, in the individuals studied, the dopamine D2 receptor TaqI locus does not affect the drive to smoke. This may be caused by the locus being unrelated to impulsive/addictive/compulsive behaviour, the polymorphism being in linkage disequilibrium with another distinct locus or, alternatively, smoking may represent a behaviour that is not directly comparable to impulsive/addictive/compulsive behaviours previously associated with the DRD2*A1 allele.
Pharmacogenetics 05/1998; 8(2):125-8.
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E Perry,
J Court,
R Goodchild,
M Griffiths,
E Jaros,
M Johnson, S Lloyd,
M Piggott,
D Spurden,
C Ballard,
I McKeith,
R Perry
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ABSTRACT: Brain tissue obtained at autopsy continues to provide unique opportunities in current dementia research. Not only is tissue analysis still essential for diagnosis, but investigation of neurochemical pathology, at a level of resolution beyond current in vivo imaging, continues to provide new insights into the involvement of neurotransmitter signalling systems. These are relevant to therapy which, with respect to symptoms such as cognitive impairment, psychosis and depression, is currently targeted to specific transmitter (cholinergic, dopaminergic and serotonergic) systems. This paper focuses on dopaminergic, cholinergic and histaminergic parameters in Alzheimer's disease (AD), Dementia with Lewy bodies (DLB) and Parkinson's disease (PD). In the normal striatum the dopamine transporter and D2 receptor exhibit distinct rostral-caudal distributions and D2 binding is affected by genetic polymorphism at the Taq 1A locus. The transporter is reduced in both DLB and PD but not AD, correlating with severity of extrapyramidal dysfunction, and receptor abnormalities are apparent in DLB patients responding adversely to neuroleptics. Striatal nicotine receptors are lost in all 3 disorders, further reduced as a result of neuroleptic medication, and elevated as a result of tobacco use. In the thalamus there are selective reductions in presynaptic cholinergic activity in DLB in the reticular nucleus which relate to symptoms of hallucinations and fluctuating consciousness prevalent in this disorder. In the hippocampus coupling of muscarinic M1 receptors, relevant to response to cholinergic therapy, is impaired in areas most affected by beta-amyloid plaques and intact in less affected areas. Analysis of histamine H2 receptors indicates that, despite presynaptic histamine abnormalities in AD, receptor numbers are normal. Such clinically and therapeutically relevant observations on human brain neurochemistry provide a basis for improving therapeutic strategies and prospects of diagnostic in vivo chemical imaging.
Acta Neurovegetativa 02/1998; 105(8-9):915-33. · 2.73 Impact Factor
