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K Audenaert

Publications and source records attributed to K Audenaert.

At least 19 recordsLinked to original sources
PubMed2006

[Information about electroconvulsive therapy on the internet].

This article aims to provide a quantitative and qualitative assessment of the information about electroconvulsive therapy that is currently available on the internet. We carried out a quantitative assessment by entering five search terms into eight (meta)search engines. We achieved our qualitative assessment by visiting the first twenty websites generated by each search on one of the search engines, in particular Google (www.google.com), and by scoring these websites with an adapted Sandvik-score. We conclude that the scored websites are technically sound but are incomplete as far as content is concerned.

Electroconvulsive Therapy↗
PubMed2006

Functional imaging, serotonin and the suicidal brain.

The involvement of the serotonergic system in the pathophysiology of suicidal behaviour has been established through indirect and direct research on serotonin and its metabolites and on serotonin transporters and receptors. Indirect research results include a reduced 5-HIAA in cerebrospinal fluid in violent suicide attempters and a blunted increase in prolactin after a fenfluramine challenge. Direct post-mortem research demonstrated an increase in 5-HT2A receptors. Direct in vivo functional imaging with PET or SPECT demonstrated a reduction in 5-HT2A binding index in suicide attempts in anxious and depressed suicide attempters and an increase in 5-HT2A binding in impulsive suicide attempters. These results are in keeping with 5-HT2A binding studies in depressed patients and impulsive animal research. Interestingly, both an increase and a decrease in 5-HT2A binding index seem to normalize with SSRI treatment.

Brain↗
PubMed2005

The effect of citalopram hydrobromide on 5-HT2A receptors in the impulsive-aggressive dog, as measured with 123I-5-I-R91150 SPECT.

PURPOSE: Involvement of the serotonergic system in impulsive aggression has been demonstrated in both human and animal studies. The purpose of the present study was to investigate the effect of citalopram hydrobromide (a selective serotonin re-uptake inhibitor) on the 5-HT(2A) receptor and brain perfusion in impulsive-aggressive dogs by means of single-photon emission computed tomography. METHODS: The binding index of the radioligand (123)I-5-I-R91150 was measured before and after treatment with citalopram hydrobromide in nine impulsive-aggressive dogs. Regional perfusion was measured with (99m)Tc-ethyl cysteinate dimer (ECD). Behaviour was assessed before treatment and again after 6 weeks of treatment. RESULTS: A correlation was found between decreased binding and behavioural improvement in eight out of nine dogs. The 5-HT(2A) receptor binding index was significantly reduced after citalopram hydrobromide treatment in all cortical regions but not in the subcortical area. None of the dogs displayed alterations in perfusion on the post-treatment scans. CONCLUSION: This study supports previous findings regarding the involvement of the serotonergic system in impulsive aggression in dogs in general. More specifically, the effect of treatment on the 5-HT(2A) receptor binding index could be demonstrated and the decreased binding index correlated with behavioural improvement.

Aggression↗
PubMed2005

Olanzapine in Gilles de la Tourette syndrome: beyond tics.

UNLABELLED: Although there only have been a limited number of double-blind, placebo controlled trials, antipsychotics are considered to be effective drugs for the treatment of tics in Gilles de la Tourette syndrome (GTS). Evidence concerning the efficacy of olanzapine and other atypical antipsychotics in the treatment of tics in GTS is growing, but still limited. Little is known about the use of olanzapine in adult GTS patients and about its effect on comorbid behavioural problems. We report on the use of olanzapine in a 25-year old male GTS patient with comorbid obsessive-compulsive behaviours, who was treated with olanzapine. Tic severity was rated using the Yale Global Tic Severity Scale (Y-GTSS). Comorbid obsessive-compulsive symptoms were assessed with the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Both scales were performed at admission and after 4 weeks of treatment with olanzapine. Treatment with olanzapine (20 mg) resulted not only in a fast reduction of tic severity and frequency, but also in a reduction of obsessive-compulsive behaviours. CONCLUSIONS: This case report further supports the available literature on the use of olanzapine as a therapeutic strategy for tics in GTS and draws attention to its possible use for comorbid behavioural disorders. Further research of antipsychotics in GTS should include measurements of comorbid behavioural symptom clusters.

Adult↗
PubMed2003

Entanglement cost under positive-partial-transpose-preserving operations.

We study the entanglement cost under quantum operations preserving the positivity of the partial transpose (PPT operations). We demonstrate that this cost is directly related to the logarithmic negativity, thereby providing the operational interpretation for this entanglement measure. As examples we discuss general Werner states and arbitrary bipartite Gaussian states. Then we prove that for the antisymmetric Werner state PPT cost and PPT entanglement of distillation coincide. This is the first example of a truly mixed state for which entanglement manipulation is asymptotically reversible, which points towards a unique entanglement measure under PPT operations.

Journal Article↗
PubMed2003

Prefrontal 5-HT2a receptor binding index, hopelessness and personality characteristics in attempted suicide.

BACKGROUND: Depression, hopelessness, impaired problem solving capacities and deficient serotonergic functions have been identified as major causes of suicidal behaviour. In general, the relation between biological markers of attempted suicide and psychological functions has been investigated using indirect peripheral markers of, e.g. the serotonergic system. Recently, functional neuroimaging techniques with radioligands allow direct in vivo assessment of the neurobiological status of the central nervous system. METHODS: We studied the binding index of serotonin-(2a) (5-HT(2a)) receptors in the frontal cortex of attempted suicide patients (n=9) and normal controls (n=13) using [123I]5-I-R91150, a highly selective 5-HT(2a) receptor ligand. Moreover, we measured personality characteristics (using Cloninger's Temperament and Character Inventory) and levels of hopelessness (using Beck's Hopelessness Scale), and studied the association between 5-HT(2a) receptor binding index, hopelessness and these personality dimensions. RESULTS: When compared to normal controls, attempted suicide patients had a significantly lower binding potential of frontal 5-HT(2a) receptors, a higher level of hopelessness, a higher score on the temperament dimension harm avoidance and lower scores on the character dimensions self-directedness and cooperativeness. A significant correlation was found between harm avoidance, hopelessness and binding index in the population of patients that attempted suicide. LIMITATIONS: The limited number of patients and potential ingestion of psychotropic drugs may influence the results of the study. CONCLUSIONS: Lower central serotonergic function, hopelessness and harm avoidance are interrelated phenomena, which may increase the probability of the occurrence of attempted suicide.

Adult↗
PubMed2003

Depression and anxiety during isolation and radionuclide therapy.

The combination of a diagnosis of malignancy and hospitalization, isolation and radioactivity of a radionuclide therapy may have an important effect on the psychological equilibrium of patients and may hamper compliance and acceptability. We performed a psychiatric evaluation in order to study psycho-pathological manifestations and underlying personality related vulnerabilities. During radioisolation, 48 patients (24 male, 24 female; mean age 57.8 years) with a malignant (n=26) or non-malignant (n=22) pathology who needed isolation for radionuclide therapy, completed a series of questionnaires in order to assess anxiety (Spielberger State and Trait Anxiety Inventory; STAI), depression (Beck Depression Inventory; BDI), hopelessness (Beck Hopelessness Scale; BHS), personality characteristics (Temperament and Character Inventory; TCI) and coping strategies (Utrecht's Coping List; UCL). Compared to patients with low state anxiety, patients who experienced a high level of state anxiety showed higher levels of depression (t=-2.10; P=0.04) and hopelessness (t=-4.20; P=<0.001). Their personality was characterized by significantly higher scores on harm avoidance (t=-2.78; P=0.008) and lower scores on self-directedness (t=3.12; P=0.003). Coping strategies were more passive (t=-2.43; P=0.02), avoiding (t=-2.15; P=0.04) and less well aimed (t=2.64; P=0.01). Surprisingly, the nature of disease (malignant versus non-malignant) did not influence these results, nor was there a difference between males and females, age, years of education, having a relationship or not, or the duration of hospitalization. Thus, contrary to what may be expected in isolation with radionuclide therapy, subgroups such as women, elderly, cancer patients or lower educated people do not, a priori, exhibit a higher state anxiety level. Our study shows these levels to be closely related to individual personality traits and coping strategies that are inadequate for the situation. Screening for trait anxiety before admission can be easily done and may guide interventions aimed at increasing patient comfort and acceptability.

Adaptation, Psychological↗
PubMed2002

Biodistribution and displacement studies of the selective 5-HT2A receptor antagonist 123I-5-I-R91150 in the normal dog.

There is increasing interest in mapping receptors in vivo by using functional imaging modalities such as single photon emission tomography (SPET) and positron emission tomography (PET). Since SPET is a more accessible functional imaging modality than PET and, overall, it is more economical, radioligands suitable for this technique are in greater demand. Recently, 123I-5-I-R91150, a radioligand with high selectivity and affinity for 5-HT(2A) receptors in the brain, was introduced for SPET. This study reports on the whole-body distribution and brain uptake of the selective 123I-5-I-R91150 ligand in four normal dogs. The frontal to cerebellar ratio of uptake in time was determined in three dogs. Time-activity curve of venous blood was determined in one dog. Maximal global brain uptake was found at 10-60 min post-injection. Higher brain uptake was noted in the frontal cortical areas compared to the cerebellum. The frontal-cerebellar ratio reached the highest values at 90-180 min. Reversibility and pharmacological selectivity of ligand binding was demonstrated through displacement and blocking studies with the 5-HT(2A) receptor antagonist ketanserin. This study demonstrates that the specific 5-HT(2A) iodinated ligand can be used for imaging and semi-quantification of the 5-HT(2A) receptors in the canine brain in vivo by using SPET.

Animals↗
PubMed2002

The SA-dependent defense pathway is active against different pathogens in tomato and tobacco.

The importance of salicylic acid (SA) in plant defense against pathogen attack has been elaborately documented. Benzothiadiazole (BTH, BION), a chemical analogue of SA, also induces resistance through the SA-dependent pathway. We investigated the role of SA in both basal defense and induced resistance of tomato (Lycopersicon esculentum) and tobacco (Nicotiana tabacum) against Oidium neolycopersici (a biotrophic pathogen) and Botrytis cinerea (a necrotrophic pathogen). A comparison of NahG transgenic tomato and tobacco (unable to accumulate SA) to their respective wild types revealed that in both crops, SA was not involved in basal defense against O. neolycopersici. SA also played no role in the basal defense of tobacco against B. cinerea but NahG tomato plants were significantly more sensitive to B. cinerea than wild type plants. Activation of the SA-dependent defense pathway via BTH resulted in induced resistance against B. cinerea in tomato but not in tobacco. In contrast, BTH induced resistance against O. neolycopersci in tobacco but not in tomato. Microscopic analysis revealed that BTH treatment could prevent penetration of the odium germ tube through the epidermal cell wall of tobacco leaves whereas penetration was successful on tomato leaves, irrespective of BTH treatment. We conclude that even in two related plant species such as tomato and tobacco, the SA-dependent defense pathway does not trigger the same defense responses. It also means that the outcome of a BTH treatment cannot be predicted and has to be tested for each plant-pathogen combination.

Benzothiazoles↗
PubMed2001

Asymptotic relative entropy of entanglement.

We present an analytical formula for the asymptotic relative entropy of entanglement with respect to positive partial transpose states for Werner states of arbitrary dimension. We then demonstrate its validity using methods from convex optimization. This is the first case in which the asymptotic value of a subadditive entanglement measure has been calculated.

Journal Article↗
PubMed2001

Decreased frontal serotonin 5-HT 2a receptor binding index in deliberate self-harm patients.

Studies of serotonin metabolites in body fluids in attempted suicide patients and of post-mortem brain tissue of suicide victims have demonstrated the involvement of the serotonergic neurotransmission system in the pathogenesis of suicidal behaviour. Recently developed neuroimaging techniques offer the unique possibility of investigating in vivo the functional characteristics of this system. In this study the 5-HT2a receptor population of patients who had recently attempted suicide was studied by means of the highly specific radio-iodinated 5-HT2a receptor antagonist 4-amino-N-[1-[3-(4-fluorophenoxy) propyl]-4-methyl-4-piperidinyl]-5-iodo-2-methoxybenzamide or 123I-5-I-R91150. Nine patients who had recently (1-7 days) attempted suicide and 12 age-matched healthy controls received an intravenous injection of 185 MBq 123I-5-I-R91150 and were scanned with high-resolution brain single-photon emission tomography (SPET). Stereotactic realigned images were analysed semi-quantitatively using predefined volumes of interest. Serotonin binding capacity was expressed as the ratio of specific to non-specific activity. The cerebellum was used as a measure of non-specific activity. An age-dependent 5-HT2a binding index was found, in agreement with previous literature. Deliberate self-harm patients had a significantly reduced mean frontal binding index after correction for age (P=0.002) when compared with controls. The reduction was more pronounced among deliberate self-injury patients (DSI) (P<0.001) than among deliberate self-poisoning patients (DSP). Frontal binding index was significantly lower in DSI patients than in DSP suicide attempters (P<0.001). It is concluded that brain SPET of the 5-HT2a serotonin receptor system in attempted suicide patients who are free of drugs influencing the serotonergic system shows in vivo evidence of a decreased frontal binding index of the 5-HT2a receptor, indicating a decrease in the number and/or in the binding affinity of 5-HT2a receptors.

Adolescent↗
PubMed2001

99mTc-ECD brain perfusion SPET: variability, asymmetry and effects of age and gender in healthy adults.

Reliable and high-resolution reference data for regional cerebral blood flow measured with single-photon emission tomography (SPET) are necessary for optimal clinical and research use. Therefore, a large dataset of normal technetium-99m labelled ethylene cysteine dimer (ECD) perfusion SPET in carefully screened healthy volunteers with an age range spanning six decades was created, with correction for non-uniform attenuation and scatter and based on an anatomically standardised analysis. Eighty-nine healthy volunteers, stratified for gender (46 females, 43 males; age 20-81 years), were included. Twelve volunteers underwent repeated 99mTc-ECD SPET after 2.5+/-2.3 weeks. An automated whole-brain volume of interest analysis with MANOVA as well as voxelwise analysis using SPM99 was conducted. Average intersubject variability was 4.8% while intrasubject reproducibility was 3.0%. An age-related decline in tracer uptake was found in the anterior cingulate gyrus, bilateral basal ganglia, left prefrontal, left lateral frontal and left superior temporal and insular cortex (all P=0.001-0.02). There was an overall increase in right/left asymmetry with age, which was most pronounced in the frontal and temporal neocortex. The most significant correlations between AI and age decade were found in the prefrontal (R=0.35, P=0.001) and superior temporal neocortex (R=0.43, P<0.001). Women had significantly higher uptake in the right parietal cortex (P<0.001), while men showed higher uptake in the cerebellum and the left anterior temporal and orbitofrontal cortex (all P<0.01). This normative dataset allows age- and gender-specific patient and group assessment of 99mTc-ECD perfusion SPET under a wide variety of clinical circumstances in relation to normal variations and highlights the importance of both age- and gender-specific normal datasets for optimal analysis sensitivity.

Adult↗
PubMed2001

In vivo evaluation of 4-[123I]iodo-N-[2[4-(6-trifluoromethyl-2-pyridinyl)-1-piperazinyl]ethyl]benzamide, a potential SPECT radioligand for the 5-HT1A receptor.

4-[123I]Iodo-N-[2-[4-(6-trifluoromethyl-2-pyridinyl)-1-piperazinyl]ethyl]benzamide (1.123I), a potential SPECT 5-HT(1A) radioligand, was evaluated in vivo in rats. Biodistribution studies were performed leading to a % ID in the brain of 0.22 at 5 min p.i. No significant differences in % ID/g tissue of the different isolated brain regions (hippocampus, hypothalamus, striatum, cortex and cerebellum) could be demonstrated. Blocking experiments with 8-OH-DPAT, WAY100635 and ketanserin could not show any significant change in tracer uptake in the isolated brain regions. These data suggest that uptake in the brain does not represent binding of 1.123I to the 5-HT(1A) receptor.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2001

The classical stroop interference task as a prefrontal activation probe: a validation study using 99Tcm-ECD brain SPECT.

This study investigated the feasibility of brain single photon emission computed tomography (SPECT) functional imaging in a neuropsychological test setting, following a single-day protocol with a split-dose paradigm. The Stroop Color Word Test (SCWT) is an example of a well-documented prefrontal activation task. In a split-dose protocol, ten right-handed healthy volunteers were injected twice with 370 MBq 99Tcm-ethyl cysteinate dimer while performing consecutively both series of card-reading of the SCWT. Images were reconstructed using filtered back-projection and normalized to a standard template in Talairach coordinates. Statistical Parametric Mapping (SPM96) was used to determine voxelwise significant changes. A first activation cluster was found in the left medial prefrontal cortex, consisting of the gyrus cinguli anterior and the gyrus frontalis medius and superior. A second activation cluster included the right gyrus frontalis dorsalis and medius. These findings confirm to a large extent the results of previous functional magnetic resonance imaging, positron emission tomography studies of Stroop-like tasks. The choice and validity of various methodological characteristics of the experimental design leading to these results is critically discussed. It is concluded that brain SPECT activation with the Stroop Color Word Test under standard neuropsychological conditions in healthy volunteers, is both technically and practically feasible.

Adult↗
PubMed2001

57Co SPECT, 99mTc-ECD SPECT, MRI and neuropsychological testing in senile dementia of the Alzheimer type.

Inflammatory mechanisms contribute to the pathophysiology of senile dementia of the Alzheimer type (sDAT). Previous studies have shown that 57Co single photon emission computed tomography (SPECT) is able to visualize inflammatory lesions, probably by means of the final common pathway of Ca2+ homeostasis disturbance in both neuronal degeneration and inflammation. The aims of this study were: (1) to detect 57Co SPECT changes in sDAT patients; (2) to correlate these findings with those of conventional neuroimaging techniques and neuropsychological testing (NPT); and (3) to compare 57Co SPECT findings in sDAT patients with those in other types of dementia. Six patients suffering from probable sDAT were included and compared with four patients suffering from other types of dementia. All patients had a magnetic resonance imaging (MRI) scan, NPT, 57Co and 99mTc-ethyl cysteinate dimer (ECD) SPECT scan. Perfusion SPECT images were semiquantitatively evaluated by comparison with an age-matched normal database, while 57Co SPECT scans were assessed qualitatively. MRI and 99mTc-ECD SPECT scans yielded conclusive results with regard to the exclusion of other pathologies and the confirmation of the diagnosis. Using visual analysis, 57Co SPECT scans were unable to show any regional raised uptake, irrespective of the disorder, depth or extent of the perfusion defects, presence of atrophy on MRI or the results of NPT.

Aged↗
PubMed2001

Automated stereotactic standardization of brain SPECT receptor data using single-photon transmission images.

UNLABELLED: Intra- or intersubject registration of anatomically poorly defined SPECT data, such as in neuroreceptor imaging, is important for longitudinal or group analysis. However, accurate registration is difficult with only emission CT (ECT) data. We investigated fully automated registration using transmission CT (TCT) data as an intermediary image set. METHODS: The accuracy of TCT registration was compared to that of ECT registration for four types of data: gray-matter distribution (with [99mTc]ethylcysteinate dimer (ECD)), neocortical distribution (with [123I]R91150, a highly specific 5-HT2a receptor ligand), and striatal distribution of the D2-receptor ligand (with [123I]iodobenzamide (IBZM)) and the dopamine transporter ligand (with [123I]2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane (CIT)). In total, 10 datasets of the various study types were used, all collected on a Toshiba GCA9300 gamma camera with super-high-resolution fanbeam collimators and 3 x 370 MBq of 153Gd transmission sources (4-min sequential TCT scanning for receptor studies and 20-min simultaneous scanning for [99mTc]ECD studies). Per dataset, 15 random misalignments of 9 rigid-body parameters (translation, rotation, and anisotropic scaling) were conducted. All coregistrations were done twice, both to the subject's original scan and to a study-specific template. This was done manually by two independent experienced observers and with three automated voxel similarity algorithms: mutual information (M.I.), count difference (C.D.), and uniformity index (U.I.). As an outcome measure, the impact of misregistration on semiquantification for the various study types was established. RESULTS: TCT matching allowed registration within 3.3 mm, 2.4 degrees, and 1.2% scaling (mean squared values for all directions) with an overall accuracy decrease in the following order: C.D. > M.I. > manual > U.I. For [99mTc]ECD and [123I]IBZM, TCT registration was as accurate as ECT registration, while it was far superior for the other receptor data types, especially for abnormal studies. The automated TCT registration accuracy corresponded to average quantification errors of 2.9% ([99mTc]ECD), 4.2% ([123I]BZM), 5.7% ([123I]R91150), and 6.1% ([123I]beta-CIT). CONCLUSION: Fully automated registration through intermediary TCT images is clinically feasible, fast, and accurate. In addition to nonuniform attenuation correction, TCT scanning therefore allows coregistration for group comparisons of SPECT receptor data on a standardized or pixel-by-pixel basis.

Adolescent↗