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BackgroundAnimal models of inflammatory arthritis such as the collagen-antibody induced arthritis (CAIA) have a variable disease incidence in hind paw arthritis, complicating experimental design.ObjectivesTo investigate the use of 18FDG µPET/CT as a guide for inflammation in joints otherwise inaccessible for clinical scoring, enabling the use of additional joints for histological analysis.MethodsCAIA was induced in 8 male DBA/1 mice using the ArthritoMab Antibody cocktail (4 mg/mouse on day 0), followed by 100 µg LPS at day 3. Body weight, clinical signs of arthritis such as paw swelling and grip strength loss were recorded 3 times per week in both front and hind paws. Whole body 18FDG µPET/CT was performed at day 11, the estimated time of peak inflammation, and inflammation was scored visually on images scaled to the same standardised uptake value. At day 28, animals were euthanized and peripheral joints were collected for histological analysis.ResultsCumulative disease incidence based on paw swelling dropped from 100% to 87.5% when looking only at hind paws, and to 75% when taking into account only the region suitable for histological analysis, namely the ankle and midfoot of the hind paws. Symmetrical, bilateral hind paw arthritis was not observed. While hind paw arthritis showed a tendency to be less severe in comparison to front paw arthritis, grip strength was equally affected, indicating possible involvement of other hind limb joints. µPET/CT images detected inflammation in the hind paws (at least unilateral involvement in 62.5% of the mice, bilateral involvement in 0%), knee joints (at least unilateral in 75%, bilateral in 50%), hip joints (at least unilateral in 50%, bilateral in 0%), elbow joints (at least unilateral in 50%, bilateral in 37.5%) and shoulder joints (at least unilateral in 25%, bilateral in 25%). Histology could confirm this inflammation with the presence of inflammatory infiltrates and bone erosions. Grip strength loss in hind limbs without paw swelling correlated only weakly with knee inflammation detected by µPET/CT.ConclusionIn the CAIA model, inflammatory arthritis can develop in all peripheral joints, in particular with a high incidence in knee joints, which are highly suitable for subsequent histological analysis. Since clinical scoring seems insufficient for detecting these affected joints, implementation of in vivo imaging modalities such as µPET/CT, offers a substantial benefit in disease monitoring and assessment.Disclosure of InterestsNone declared

Consumers' demand and legislation force growers to develop sustainable strategies to control pests and diseases. One of the measures growers can take is the choice to produce species and cultivars with improved pest and disease resistance or tolerance. To support a shift toward growing resistant cultivars, breeding programs should focus more on biotic stress resistance. Yet, resistance breeding in woody ornamentals is difficult due to the high diversity of plant genera and the numerous pests and diseases. In addition, long generation cycles, complex genetics, polyploidy, and the relatively low economic value of individual crops or cultivars make breeding for pest and disease resistance challenging. Breeding programs often aim for selection of improved resistance of one plant genotype towards different pests and/or diseases or towards different pathotypes of one disease. However, some alternative routes to obtain more tolerant cultivars can be explored. In research of edible crops an increased interest is seen in breeding strategies focusing on the loss-of-function of so-called susceptibility genes. Also more fundamental knowledge on inducible plant defense mechanisms might open new horizons for plant breeding in the future. Here we illustrate different approaches using examples from our resistance breeding in ornamentals for two fungal pathogens: box blight in Buxus and powdery mildew in rose, and for one pest organism: broad mite in Rhododendron.

Molecular cytogenetic techniques are valuable tools to study chromosome structure and genome constitution and to perform gene mapping and visualization of chromosomal recombination. In woody ornamental species, which are often characterized by small genomes, small-sized chromosomes and low mitotic index in the tiny-to-handle roots, cytogenetic studies are hardly exploited. We developed the “SteamDrop” protocol, which enabled us to prepare high quality chromosome slides for several woody genera e.g. Buxus, Hydrangea, Buddleja, Hibiscus and Rosa. Study of chromosome number and chromosome morphology, together with knowledge of genetic relationships between species, allowed us to create more straightforward breeding programs for these genera. We also successfully implemented genomic in situ hybridisation (GISH) in different woody ornamental species to prove the hybrid nature of offspring from interspecific crosses within Buddleja and Hibiscus. In addition, knowledge of the physical position of specific genes on chromosomes might promote more efficient breeding and selection. We optimised FISH and Tyramide-FISH on mitotic and pachytene chromosomes of roses. Several single-copy genes (1.1-3 kb) involved in abiotic and biotic stress resistance mechanisms were physically mapped on Rosa wichurana Crep. chromosomes 1, 4 and 7 and genetically mapped on the genetic linkage groups. By this, an anchoring of genetic and physical maps was achieved. In the future, these results will facilitate to pyramid stress related genes in specific genotypes.

AimsAltered alignment and biomechanics are thought to contribute to the progression of osteoarthritis (OA) in the native compartments after medial unicompartmental knee arthroplasty (UKA). The aim of this study was to evaluate the bone activity and remodelling in the lateral tibiofemoral and patellofemoral compartment after medial mobile-bearing UKA.Patients and MethodsIn total, 24 patients (nine female, 15 male) with 25 medial Oxford UKAs (13 left, 12 right) were prospectively followed with sequential 99mTc-hydroxymethane diphosphonate single photon emission CT (SPECT)/CT preoperatively and at one and two years postoperatively, along with standard radiographs and clinical outcome scores. The mean patient age was 62 years (40 to 78) and the mean body mass index (BMI) was 29.7 kg/m2 (23.6 to 42.2). Mean osteoblastic activity was evaluated using a tracer localization scheme with volumes of interest (VOIs). Normalized mean tracer values were calculated as the ratio between the mean tracer activity in a VOI and background activity in the femoral diaphysis.ResultsSignificant reduction of normalized tracer activity was observed one year postoperatively in tibial and femoral VOIs adjacent to the joint line in the lateral compartment. Patellar VOIs and remaining femoral VOIs demonstrated a significant, diminished normalized tracer activity at final follow-up.ConclusionThe osteoblastic bone activity in the native compartments decreased significantly after treatment of medial end-stage OA with a UKA, implying reduced stress to the subchondral bone in the retained compartments after a UKA. Cite this article: Bone Joint J 2019;101-B:915–921.

BACKGROUND: Fully integrated PET/MR systems are being used frequently in clinical research and routine. National Electrical Manufacturers Association (NEMA) characterization of these systems is generally done with 18F which is clinically the most relevant PET isotope. However, other PET isotopes, such as 68Ga and 90Y, are gaining clinical importance as they are of specific interest for oncological applications and for follow-up of 90Y-based radionuclide therapy. These isotopes have a complex decay scheme with a variety of prompt gammas in coincidence. 68Ga and 90Y have higher positron energy and, because of the larger positron range, there may be interference with the magnetic field of the MR compared to 18F. Therefore, it is relevant to determine the performance of PET/MR for these clinically relevant and commercially available isotopes. METHODS: NEMA NU 2-2007 performance measurements were performed for characterizing the spatial resolution, sensitivity, image quality, and the accuracy of attenuation and scatter corrections for 18F, 68Ga, and 90Y. Scatter fraction and noise equivalent count rate (NECR) tests were performed using 18F and 68Ga. All phantom data were acquired on the GE Signa integrated PET/MR system, installed in UZ Leuven, Belgium. RESULTS: 18F, 68Ga, and 90Y NEMA performance tests resulted in substantially different system characteristics. In comparison with 18F, the spatial resolution is about 1 mm larger in the axial direction for 68Ga and no significative effect was found for 90Y. The impact of this lower resolution is also visible in the recovery coefficients of the smallest spheres of 68Ga in image quality measurements, where clearly lower values are obtained. For 90Y, the low number of counts leads to a large variability in the image quality measurements. The primary factor for the sensitivity change is the scale factor related to the positron emission fraction. There is also an impact on the peak NECR, which is lower for 68Ga than for 18F and appears at higher activities. CONCLUSIONS: The system performance of GE Signa integrated PET/MR was substantially different, in terms of NEMA spatial resolution, image quality, and NECR for 68Ga and 90Y compared to 18F. But these differences are compensated by the PET/MR scanner technologies and reconstructions methods. ispartof: EJNMMI PHYSICS vol:6 issue:1 ispartof: location:Germany status: published

Although of great public health relevance, the mechanisms underlying disordered eating behavior and body weight regulation remain insufficiently understood. Compelling preclinical evidence corroborates a critical role of the endocannabinoid system (ECS) in the central regulation of appetite and food intake. However, in vivo human evidence on ECS functioning in brain circuits involved in food intake regulation as well as its relationship with body weight is lacking, both in health and disease. Here, we measured cannabinoid 1 receptor (CB1R) availability using positron emission tomography (PET) with [18F]MK-9470 in 54 patients with food intake disorders (FID) covering a wide body mass index (BMI) range (anorexia nervosa, bulimia nervosa, functional dyspepsia with weight loss and obesity; BMI range=12.5–40.6 kg/m2) and 26 age-, gender- and average BMI-matched healthy subjects (BMI range=18.5–26.6 kg/m2). The association between regional CB1R availability and BMI was assessed within predefined homeostatic and reward-related regions of interest using voxel-based linear regression analyses. CB1R availability was inversely associated with BMI in homeostatic brain regions such as the hypothalamus and brainstem areas in both patients with FID and healthy subjects. However, in FID patients, CB1R availability was also negatively correlated with BMI throughout the mesolimbic reward system (midbrain, striatum, insula, amygdala and orbitofrontal cortex), which constitutes the key circuit implicated in processing appetitive motivation and hedonic value of perceived food rewards. Our results indicate that the cerebral homeostatic CB1R system is inextricably linked to BMI, with additional involvement of reward areas under conditions of disordered body weight.

The type 1 neurokinin receptor (NK1R) antagonist aprepitant and its i.v. prodrug fosaprepitant have been approved for prevention of acute and delayed nausea and vomiting associated with chemotherapy. This study evaluated the magnitude and duration of brain NK1R occupancy over a period of 5 days after single-dose i.v. infusion of 150-mg fosaprepitant and single-dose oral administration of 165-mg aprepitant, using serial [(18)F]MK-0999 positron emission tomography (PET) in 16 healthy subjects. Each subject underwent three scans. Brain NK1R occupancy rates after i.v. fosaprepitant at time to peak concentration (T(max); ~30 min), 24, 48, and 120 h after the dose were 100, 100, ≥97, and 41-75%, respectively. After aprepitant, NK1R occupancy rates at these time points (T(max) ~4 h) were ≥99, ≥99, ≥97, and 37-76%, respectively. Aprepitant plasma concentration profiles were comparable for the two dosage forms. The study illustrates the utility of PET imaging in determining central bioequivalence in a limited number of subjects.

To introduce yellow colour in the commercial Buddleja davidii (2n = 4x = 76) assortment, an interspecific breeding programme with B. globosa (2n = 2x = 38) was started. The first step was to perform chromosome doubling in B. globosa. Two of the obtained tetraploid B. globosa plants were subsequently used as male parent in interspecific crosses with the white flowering B. davidii cv. Nanhoensis Alba. In total 182 interspecific crosses were made and 18 F1 hybrids were obtained. Genome size measurements, chromosome counts and genomic in situ hybridisation (GISH) analysis proved the hybrid nature of most of the F1 hybrids. Plant morphology also expressed hybrid characteristics. F1 seedlings inherited the yellowish flower colour from B. globosa. As for many other woody ornamentals, the creation of hybrids through interspecific hybridisation along with polyploidisation offers new opportunities for breeding in Buddleja.

In vitro chromosome doubling can be induced by several antimitotic agents. The most commonly used are colchicine, oryzalin and trifluralin. The process of induced chromosome doubling in vitro consists of a typical succession of sub-processes, including an induction phase and a confirmation protocol to measure the rate of success. The induction step depends on a large number of variables: media, antimitotic agents, explant types, exposure times and concentrations. Flow cytometry is the pre-eminent method for evaluation of the induced polyploidization. However, alternative confirmation methods, such as chromosome counts and morphological observations, are also used. Since polyploidization has many consequences for plant growth and development, chromosome doubling has been intensively studied over the years and has found its way to several applications in plant breeding. This review gives an overview of the common methods of chromosome doubling in vitro, the history of the technique, and progress made over the years. The applications of chromosome doubling in a broader context are also discussed.

In the accompanying paper we describe how MRK-409 unexpectedly produced sedation in man at relatively low levels of GABAA receptor occupancy (∼10%). Since it was not clear whether this sedation was mediated via the α2/α3 or α1 GABAA subtype(s), we characterized the properties of TPA023B, a high-affinity imidazotriazine which, like MRK-409, has partial agonist efficacy at the α2 and α3 subtype but is an antagonist at the α1 subtype, at which MRK-409 has weak partial agonism. TPA023B gave dose- and time-dependent occupancy of rat brain GABAA receptors as measured using an in vivo [3H]flumazenil binding assay, with 50% occupancy corresponding to a respective dose and plasma drug concentration of 0.09 mg/kg and 19 ng/mL, the latter of which was similar to that observed in mice (25 ng/mL) and comparable to values obtained in baboon and man using [11C]flumazenil PET (10 and 5.8 ng/mL, respectively). TPA023B was anxiolytic in rodent and primate (squirrel monkey) models of anxiety (elevated plus maze, fear-potentiated startle, conditioned suppression of drinking, conditioned emotional response) yet had no significant effects in rodent or primate assays of ataxia and/or myorelaxation (rotarod, chain-pulling, lever pressing), up to doses (10 mg/kg) corresponding to occupancy of greater than 99%. In man, TPA023B was well tolerated at a dose (1.5 mg) that produced occupancy of >50%, suggesting that the sedation previously seen with MRK-409 is due to the partial agonist efficacy of that compound at the α1 subtype, and highlighting the importance of antagonist efficacy at this particular GABAA receptor population for avoiding sedation in man.

MRK-409 binds to α1-, α2-, α3- and α5-containing human recombinant GABAA receptors with comparable high affinity (0.21–0.40 nM). However, MRK-409 has greater agonist efficacy at the α3 compared with α1 subtypes (respective efficacies relative to the full agonist chlordiazepoxide of 0.45 and 0.18). This compound readily penetrates the brain in rats and occupies the benzodiazepine site of GABAA receptors, measured using an in vivo [3H]flumazenil binding assay, with an Occ50 of 2.2 mg/kg p.o. and a corresponding plasma EC50 of 115 ng/mL. Behaviourally, the α3-preferring agonist efficacy profile of MRK-409 produced anxiolytic-like activity in rodent and primate unconditioned and conditioned models of anxiety with minimum effective doses corresponding to occupancies, depending on the particular model, ranging from ∼35% to 65% yet there were minimal overt signs of sedation at occupancies greater than 90%. In humans, however, safety and tolerability studies showed that there was pronounced sedation at a dose of 2 mg, resulting in a maximal tolerated dose of 1 mg. This 2 mg dose corresponded to a Cmax plasma concentration of 28 ng/mL, which, based on the rodent plasma EC50 for occupancy of 115 ng/mL, suggested that sedation in humans occurs at low levels of occupancy. This was confirmed in human positron emission tomography studies, in which [11C]flumazenil uptake following a single dose of 1 mg MRK-409 was comparable to that of placebo, indicating that occupancy of GABAA receptor benzodiazepine binding sites by MRK-409 was below the limits of detection (i.e.

Fully automated analysis programs have been applied more and more to aid for the reading of regional cerebral blood flow SPECT study. They are increasingly based on the comparison of the patient study with a normal database. In this study, we evaluate the ability of Three-Dimensional Stereotactic Surface Projection (3D-SSP) to isolate effects of age and gender in a previously Studied normal population. The results were also compared with those obtained using Statistical Parametric Mapping (SPM99). Methods. - Eighty-nine Te-99m-ECD-SPFCT studies performed in carefully screened healthy volunteers (46 females, 43 males; age 20-81 years) were analysed using 3D-SSP. A multivariate analysis based on the general linear model was performed with regions as intrasubject factor, gender as intersubject factor and age as covariate. Results. - Both age and gender had a significant interaction effect with regional tracer uptake. An age-related decline (p < 0.001) was found in the anterior cingulate gyrus, left frontal association cortex and left insula. Bilateral occipital association and left primary visual cortical uptake showed a significant relative increase with age (p < 0.001). Concerning the gender effect, women showed higher uptake (p < 0.01) in the parietal and right sensorimotor cortices. An age by gender interaction (p < 0.01) was only found in the left medial frontal cortex. The results were consistent with those obtained with SPM99. Conclusion. - 3D-SSP analysis of normal rCBF variability is consistent with the literature and other automated voxel-based techniques, which highlight the effects of both age and gender. (C) 2009 Elsevier Masson SAS. All rights reserved.

2-(4'-[(18)F]fluorophenyl)-1,3-benzothiazole was synthesized as a fluorine-18 labelled derivative of the Pittsburg Compound-B (PIB), which has known affinity for amyloid beta and promising characteristics as tracer for in vivo visualisation of amyloid deposits in patients suffering from Alzheimer's disease (AD). Both the nitro-precursor 2-(4'-nitrophenyl)-1,3-benzothiazole and the non-radioactive reference compound were synthesized using a 1-step synthesis pathway. Labelling was achieved by direct aromatic nucleophilic substitution of the nitro-precursor using [(18)F]fluoride by heating for 20 min at 150 degrees C and with a radiochemical yield of 38%. The reference compound showed high affinity for amyloid in an in vitro competition binding study using human AD brain homogenates (K(i)=9.0 nM) and fluorescence imaging of incubated transgenic APP mouse brain slices confirmed binding to amyloid plaques. A biodistribution study in normal mice showed a high brain uptake at 2 min pi (3.20%ID/g) followed by a fast washout (60 min pi: 0.21%ID/g). A dynamic microPET study was performed in a transgenic APP and normal WT mouse, but, similar to [(11)C]PIB, no difference was seen in tracer retention between both kind of mice. The new (18)F-labelled 2-phenylbenzothiazole showed excellent preclinical characteristics comparable with those of the (11)C-labelled PIB.

SummaryInterspecific crosses within Hibiscus resulted in F1 and F2 (self-pollination of F1) progeny of H. syriacus × H. paramutabilis. Of these populations, seven F1 and five F2 hybrids were analysed for the occurrence of unreduced gametes. Pollen from H. syriacus, H. paramutabilis, and the F1 and F2 hybrids had diameters between 80 – 230 µm. However, two of the F2 hybrids tested also had a few pollen grains (< 1%) with a diameter of 250 µm. Flow cytometry and a study of meiosis in the pollen of these two F2 hybrids revealed that 6 – 10% unreduced pollen was produced. Both the parent plants, H. syriacus ‘Oiseau Bleu’ and H. paramutabilis, and all of the F1 hybrids were tetraploid, with a genome size between 2.32 – 2.48 pg 1C−1. However, all five F2 hybrids were hexaploid, with a genome size between 3.49 – 3.59 pg 1C𢈒1. Since no unreduced pollen could be detected in the F1 H. syriacus × H. paramutabilis hybrids, either by flow cytometry or by a study of meiosis in the pollen, it could be concluded that the...

[(18)F] FDG positron emission tomography (PET) is commonly used to highlight brain regions with abnormal metabolism. Correct interpretation of FDG images is important for investigation of diseases. When the FDG uptake is compared between hemispheres, confusion can arise because it might be difficult to determine whether an observed asymmetry is physiological and due to normal anatomical variation or pathological. In this paper we propose a new method, which calculates an anatomy-corrected asymmetry index (ACAI), to highlight inter-hemispheric metabolic asymmetry in FDG images without the influence of anatomical asymmetry. Using prior anatomical information from MRI, the ACAI method only takes into account voxels that belong to a certain anatomical class. For the evaluation of detection performance, this method is applied on homogeneous brain phantoms and realistic analytical simulated FDG-PET images with known asymmetries. Results from these simulations demonstrated the validity of ACAI and its potential perspective in the future.

Detailed karyotypes of Hydrangea macrophylla, Hydrangea paniculata and Hydrangea quercifolia were constructed on the basis of arm lengths and centromeric index, together with 45S rDNA fluorescence in situ hybridization. Although the chromosomes were small, they were well distinguishable for all species. Chromosome morphology and karyotypes were different for the three species. H. macrophylla had six metacentric (M), eight submetacentric (SM) and four subtelocentric (ST) chromosomes. The karyotype of H. paniculata contained seven M, 10 SM and one ST chromosomes and H. quercifolia had six M, 10 SM and two ST chromosomes. The variability among three species also was expressed by 45S rDNA signals. H. macrophylla had a nucleolar organizing region on chromosome 2, H. paniculata had 45S rDNA signals on chromosomes 2, 5 and 11 and H. quercifolia on chromosomes 3 and 8. Hybridization signal always was distally on the short arm but the strength of the signals was different for the three species. The chromosome portraits made in this study will be used to trace chromosome behaviour in interspecific hybrids resulting from breeding work between the three species.

For diverse reasons, interspecific hybridization was attempted in several woody ornamental genera (Rhododendron, Hydrangea, Hibiscus, Buddleia and Ligustrum), and yielded information on the occurrence and the overcoming of multiple crossing barriers. Prezygotic barriers (inhibition of pollen tube growth) were absent in all genera except Rhododendron. The first signals of postzygotic incongruity were the malformation of endosperm and the inhibition of germination. In order to replace the endosperm and allow maturation of the hybrid embryo and thus solve the lack of endosperm, in vitro media were established for all genera mentioned, mostly resulting in a significant increase of germination rates compared to in vivo germination. After germination, incompatibility between the plastome and nuclear genome may inhibit chloroplast development and chlorophyll formation. As a result, albinism is observed, mainly in interspecific Rhododendron and Hibiscus hybrids. Many hybrids are not viable, and growth aberrations caused by 'hybrid' vigor have been observed in Rhododendron and Hibiscus. Although flowering hybrids have so far only been obtained in the genera Buddleia and Hibiscus, preliminary research efforts with regard to fertility restoring through polyploidization were already performed in all genera. Proof was found for the occurrence of 2n gametes in Rhododendron, that might be a more recommendable tool for allopolyploidization than somatic chromosome doubling.

In an attempt to introgress an increased growth vigour and improved flowering into H. syriacus two different breeding strategies were followed. A first approach focused on creating hexaploid H. syriacus plants. This was done by crossing tetraploid H. syriacus cultivars with colchicine doubled (octoploid) H. syriacus `Oiseau Bleu' seedlings. The generated hexaploid progeny had an increased growth vigour compared to tetraploid cultivars. The F1 seedlings were also sterile. Out of the hexaploid F1 population an improved blue flowered plant was selected and multiplied. The second strategy emphasized on the interspecific hybridization between H. syriacus and H. paramutabilis. When used as a seed parent, H. paramutabilis failed to set fruits. However, in reciprocal crosses flowers reacted by fruit setting. Also in these crosses a high number of fruits aborted in an early stage of development. Germination of the surviving seeds occurred within 2-3 weeks. The generated seedlings grew vigorously. Leaves of all seedlings had an intermediate morphology compared to those of H. paramutabilis and H. syriacus, indicating that the obtained progenies were true interspecific hybrids.

BACKGROUND: The pathophysiological role of the extensive interictal cerebral hypometabolism in complex partial seizures (CPS) in refractory mesial temporal lobe epilepsy with hippocampal sclerosis (mTLE-HS) is poorly understood. Our aim was to study ictal-interictal SPECT perfusion versus interictal fluorodeoxyglucose (FDG)-PET metabolic patterns. METHODS: Eleven adults with refractory unilateral mTLE-HS, who were rendered seizure free after epilepsy surgery, were included. All had an interictal FDG-PET and an interictal and ictal perfusion SPECT scan. FDG-PET data were reconstructed using an anatomy-based reconstruction algorithm, which corrected for partial volume effects, and analyzed semi-quantitatively after normalization to white matter activity. Using Statistical Parametric Mapping (SPM), we compared interictal metabolism of the patient group with a control group. We correlated metabolic with ictal perfusion changes in the patient group. RESULTS: Global cerebral grey matter glucose metabolism in patients was decreased 10-25% compared with control subjects. Interictal PET hypometabolism and ictal SPECT hypoperfusion were maximal in the ipsilateral frontal lobe. Ictal frontal lobe hypoperfusion was associated with crossed cerebellar diaschisis. The ipsilateral temporal lobe showed maximal ictal hyperperfusion and interictal hypometabolism, which was relatively mild compared with the degree of hypometabolism affecting the frontal lobes. CONCLUSION: Interictal hypometabolism in mTLE-HS was greatest in the ipsilateral frontal lobe and represented a seizure-related dynamic process in view of further ictal decreases. Crossed cerebellar diaschisis suggested that there is a strong ipsilateral frontal lobe inhibition during CPS. We speculate that surround inhibition in the frontal lobe is a dynamic defense mechanism against seizure propagation, and may be responsible for functional deficits observed in mTLE. ispartof: NeuroImage vol:32 issue:2 pages:684-695 ispartof: location:United States status: published

Objective: The objectives of the present study were to assess brain atrophy in multiple sclerosis (MS) patients during different disease stages and to investigate by PET and [11C]PK11195, a marker of microglial activation, the relationship between inflammation, atrophy and clinically relevant measures. Methods: Eight healthy subjects and 22 MS patients were included. Semiquantitative [11C]PK11195 uptake values, with normalization on cortical grey matter, were measured for magnetic resonance imaging T2- and T1-lesions and normal appearing white matter (NAWM). As atrophy index we used the ratio of the amount of white and grey matter divided by the ventricular size, using an optimized a priori based segmentation algorithm (SPM99). Results: Atrophy was significantly greater in MS patients compared to age-matched controls. A significant correlation was found between brain atrophy and both disease duration and disability, as measured with the Expanded Disability Status Scale. For NAWM, [11C]PK11195 uptake increased with the amount of atrophy, while T2-lesional [11C]PK11195 uptake values decreased according to increasing brain atrophy. Conclusions: The present study suggests that brain atrophy, correlating with disease duration and disability, is directly related to NAWM and T2-lesional inflammation as measured by microglial activation.

Interspecific crosses within the genera Ligustrum and Hydrangea were made to introduce new genetic variation. Ploidy determinations and pollen tube staining revealed no prezygotic barriers within the gene pool used. Green and vigorous Hydrangea seedlings could only be obtained from crosses in which H. paniculata was used as seed parent. The reciprocal crosses did not yield germinating ovules. H. paniculata × H. quercifolia seedlings showed an introgression of paternal AFLPmarkers. In Ligustrum, abortion rates were very high except for crosses within the evergreen section. Germination of ovules was only achieved after fruits had developed on the seed parent for 11 weeks. Introgression rates of paternal DNAsequences are divergent; only crosses between L. japonicum and L. lucidum were found to be true hybrids.

A comparative study was carried out on two promising presynaptic dopamine transporter single-photon emission tomography (SPECT) radioligands with a fast pharmacokinetic profile, 123I-FP-beta-CIT (FP) and 99mTc-TRODAT-1 (TR), in order to assess their differential diagnostic power in early parkinsonism and their sensitivity for detection of disease progression. This cross-sectional study was conducted on 96 patients with early-stage parkinsonism referred in a tertiary clinical setting. Mean disease duration was 2.0+/-1.3 years, and patients had a modified Hoehn and Yahr (HY) stage of 1-2 (average 1.2). Forty-seven patients received TR, and 49 received FP. In both groups, ten patients with normal presynaptic function were included as a control population; all other patients were clinically diagnosed as having idiopathic Parkinson's disease. Groups were matched for gender, age, disease duration and modified HY stage. Triple-head gamma camera SPECT was analysed using a semiquantitative index of transporter binding (BI). Discriminant analysis with cross-validation resulted in a maximal classification accuracy for FP of 93% (sensitivity 95% and specificity 86%) for the contralateral putamen BI. For TR, the corresponding values were 87% accuracy, 92% sensitivity and 70% specificity. For FP, disease duration was correlated with both the putamen BI (-8.8%/year, rho=-0.41, P=0.025) and the putamen/caudate ratio (-7.4%/year, rho=-0.51, P=0.004), but for TR no significant correlation was found (all P values0.5). In conclusion, both FP and TR show high sensitivity in a clinically relevant setting, but FP has superior accuracy for early differential diagnosis of idiopathic parkinsonism and non-degenerative extrapyramidal disorders, as well as better sensitivity for disease follow-up.

Activated microglia are involved in the immune response of multiple sclerosis (MS). The peripheral benzodiazepine receptor (PBR) is expressed on microglia and up-regulated after neuronal injury. [11C]PK11195 is a positron emission tomography (PET) radioligand for the PBR. The objective of the present study was to investigate [11C]PK11195 imaging in MS patients and its additional value over magnetic resonance imaging (MRI) concerning the immuno-pathophysiological process. Seven healthy and 22 MS subjects were included. Semiquantitative [11C]PK11195 uptake values were assessed with normalization on cortical grey matter. Uptake in Gadolinium-lesions was significantly increased compared with normal white matter. Uptake in T2-lesions was generally decreased, suggesting a PBR down-regulation. However, uptake values increased whenever a clinical or MR-relapse was present, suggestive for a dynamic process with a transient PBR up-regulation. During disease progression, an increase of normal-appearing white matter (NAWM) uptake was found, propagating NAWM as the possible real burden of disease. In conclusion, [11C]PK11195 and PET are able to demonstrate inflammatory processes with microglial involvement in MS.

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-HT2a) 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-HT2a 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-HT2a 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-HT2a 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.

Performance on the Verbal Fluency Test, as a measure of the ability of initiating processes, is reduced in depressed suicidal patients. The hampered results in this prefrontal executive task parallel the reduction in prefrontal blood perfusion and metabolism in depressed subjects. A neuropsychological activation study with the verbal fluency paradigm could evaluate a possible blunted increase in perfusion in the prefrontal cortex in depressed suicidal patients. Twenty clinically depressed patients who had recently attempted suicide and 20 healthy volunteers were included in a single photon emission computed tomography (SPECT) split-dose activation study following a verbal fluency paradigm. Statistical parametric mapping was used to determine voxelwise significant changes. Differences in regional cortical activation between the letter fluency and category fluency tasks in attempted suicide patients were found. These patients showed a blunted increase in perfusion in the prefrontal cortex. Methodological restrictions concerning group uniformity, medication bias and subjective effort of the participants are discussed. Our findings indicate a blunted increase in prefrontal blood perfusion as a possible biological reason for reduced drive and loss of initiative in attempted suicide patients.

A prospective pilot trial was performed in 20 patients randomised to receive either (131)I-Lipiodol therapy alone (n=10) or (131)I-Lipiodol combined with a short low-dose cisplatin infusion (n=10), the aim being to evaluate the possible positive influence of a radiosensitiser on toxicity and tumour response. An activity of 1,354-2,128 MBq (mean 1,824 MBq) [36.6-57.5 mCi (mean 49.3 mCi)] (131)I-labelled Lipiodol was administered by selective instillation in the hepatic artery. Cisplatin was given in a dose of 30 mg/m(2) at day -1 and day +6 (day 0: (131)I-Lipiodol). The primary endpoint of this trial was toxicity of therapy; points of secondary interest were tumour response and survival at 6 months. With the use of cisplatin we found a higher percentage of stable or diminished tumour size (90%, vs 40% without). A benefit in group survival at 6 months was not evident. Low-grade stomatitis in one patient and minor changes in peripheral blood count were probably directly related to cisplatin, but its administration is unlikely to be associated with an excess of serious side-effects. The use of low-dose cisplatin infusion as a radiosensitising agent in (131)I-Lipiodol therapy for hepatocellular carcinoma seems safe and may be beneficial for tumour control. Larger patient groups are necessary for confirmation and to establish the future role of (131)I-Lipiodol in hepatocellular carcinoma.

Accurate quantification of emission computed tomography data (PET-SPECT) is limited by partial volume effects. This paper compares two approaches, described in the literature, to measure accurately the true tissue tracer activity within a tissue compartment, defined by anatomical side information. The first approach is based on the selection of an appropriate number of regions. The second method is based on a minimum norm least square solution, taking into account the whole image. These methods assume a constant activity within one tissue compartment and have similar performance when this assumption is correct. We demonstrate the equivalence of both methodologies in the case of an appropriate region selection for the first technique. We also propose two new methods allowing activity fluctuations within the same anatomical tissue compartment. The first technique uses the minimum norm least square solution to estimate a higher number of activities within one tissue compartment while taking into account the whole reconstructed emission computed tomography image. The second method estimates the activity of a tissue compartment locally by linear regression analysis within a sliding window. A simple simulation study shows that these techniques yield a more accurate quantification in the case of a nonhomogeneous activity distribution within one tissue compartment.

The resolution of a PET scanner (2.5–4.5 mm for brain imaging) is similar to the thickness of the cortex in the (human) brain (2.5 mm on average), hampering accurate activity distribution reconstruction. Many techniques to compensate for the limited resolution during or post-reconstruction have been proposed in the past and have been shown to improve the quantitative accuracy. In this study, state-of-the-art reconstruction techniques are compared on a voxel-basis for quantification accuracy and group analysis using both simulated and measured data of healthy volunteers and patients with epilepsy. Methods Maximum a posteriori (MAP) reconstructions using either a segmentation-based or a segmentation-less anatomical prior were compared to maximum likelihood expectation maximization (MLEM) reconstruction with resolution recovery. As anatomical information, a spatially aligned 3D T1-weighted magnetic resonance image was used. Firstly, the algorithms were compared using normal brain images to detect systematic bias with respect to the true activity distribution, as well as systematic differences between two methods. Secondly, it was verified whether the algorithms yielded similar results in a group comparison study. Results Significant differences were observed between the reconstructed and the true activity, with the largest errors when using (post-smoothed) MLEM. Only 5–10% underestimation in cortical gray matter voxel activity was found for both MAP reconstructions. Higher errors were observed at GM edges. MAP with the segmentation-based prior also resulted in a significant bias in the subcortical regions due to segmentation inaccuracies, while MAP with the anatomical prior which does not need segmentation did not. Significant differences in reconstructed activity were also found between the algorithms at similar locations (mainly in gray matter edge voxels and in cerebrospinal fluid voxels) in the simulated as well as in the clinical data sets. Nevertheless, when comparing two groups, very similar regions of significant hypometabolism were detected by all algorithms. Conclusion Including anatomical a priori information during reconstruction in combination with resolution modeling yielded accurate gray matter activity estimates, and a significant improvement in quantification accuracy was found when compared to post-smoothed MLEM reconstruction with resolution modeling. AsymBowsher provided the most accurate subcortical GM activity estimates. It is also reassuring that the differences found between the algorithms did not hamper the detection of hypometabolic regions in the gray matter when performing a voxel-based group comparison. Nevertheless, the size of the detected clusters differed. More elaborated and application-specific studies are required to decide which algorithm is best for a group analysis.

Several simulations of SPECT neuroactivation studies have been performed in order to determine the influence of both study size and activation focus characteristics on the detection of brain activation foci following a pixel-based statistical analysis. This was achieved by developing a methodology based on the Hoffman software brain phantom, SPECT acquisition simulation software, standard reconstruction software, and the Statistical Parametric Mapping (SPM96) package. We present results on the minimal activation levels required for focus detection. Furthermore, the improved sensitivity of the analysis resulting from the use of an iterative reconstruction technique (OSEM) with regard to the classical filtered backprojection (FBP) is assessed quantitatively, and the various physical, processing, and physiological parameters that potentially influence the detection of foci are discussed. Finally, the influence is investigated of the height threshold as implemented in SPM96 upon the size of the detected foci. Practical guidelines are proposed with regard to the number of subjects per group for SPECT activation studies following the split-dose design.

A PACS (Picture Archiving and Communication System) is a system that is able to store, exchange, display and manipulate images and associated diagnoses from any modality within a hospital in a timely and cost-effective way. Several developments, such as the DICOM standard, fast and convenient networking, and new storage solutions for large amounts of data, make the setup of such a PACS system possible. As the information acquired with various imaging modalities is then available and often complementary, it is desirable for the clinician to have a point-by-point spatial co-registration of images from different modalities in order to enable a synergistic use of the multimodality imaging of a patient for increased diagnostic accuracy. Various types of algorithms are available for the matching of medical images from the same or from different modalities. Co-registration algorithms based on voxel properties consist of a similarity or dissimilarity measure and an iterative or non-iterative method minimizing the dissimilarity or maximizing the similarity between the two images by a transformation of one image relative to the other.

We evaluated the methodological issues underlying the assessment of normal confidence intervals, as used in clinically based region-of-interest (ROI) semi-quantification of 99 Tc m -HMPAO brain SPET. At two different centres equipped with high-resolution, triple-headed gamma cameras, HMPAO SPET scans were performed on two groups of 24 and 15 healthy volunteers respectively. Together with an operator-defined analysis (ODA), a semi-automated analysis (SAA) was conducted on the normal datasets in one centre. Tests of intra- and inter-observer variability were performed. Repeat scans were performed within 72 h after the first to analyse short-term regional inter-study variations. The overall regional uptake showed significant differences in most regions between both normal datasets. Intra-observer and inter-observer reproducibility were on average within 4% for the ODA, while for the SAA it was less than 1%. Inter-study variations were excellent for both centres, ranging from -4% to +3% for most regions studied. The variability in clinical brain perfusion studies largely depends on the reproducibility of the data analysis technique. A semi-automated approach shows clear advantages over an entirely operator-defined approach. Intra-subject repeat studies show enough stability for use as reliable baseline measurements in the construction of a normal database or to allow activation studies with high sensitivity.

The aim of this study was to assess the accuracy and computing time needed for MRI-SPET and SPET-SPET brain co-registration using eight different algorithms (Hermes software from Nuclear Diagnostics Ltd run on a SUN Ultra Sparc 2) to determine the clinically most suitable algorithm. MRI-SPET co-registration was evaluated using phantom studies. To approximate clinical dual-headed SPET studies, a Hoffman brain phantom was filled with 99 Tc m . For MRI imaging (1.5 Tesla), the phantom was filled with water and doped with Gd-DTPA for contrast enhancement. For both modalities, phantom images were acquired and reconstructed using a routine clinical protocol. MRI and SPET images were matched by Downhill Simplex minimization of the sum of absolute Count Differences (CD), the sum of the Square Root of absolute count differences (SR), the Difference in Shape between the binary masks (SD), the number of Sign Changes in the subtracted image (SC), the Variance of intensities between corresponding pixels (VAR), the sum of absolute count differences between the 2D- and 3D-Gradient images (2DG-3DG) and, finally, the standard deviation of the Uniformity Index (UI), that is the intensity ratio between spatially corresponding voxels. Six degrees of freedom were allowed (three translation and three rotation parameters, three scaling parameters were constrained). The accuracy of the matching process with these different similarity measures was evaluated via the residual mismatch between external markers. We found that CD, SR, VAR and UI give the most accurate registration compared with the other similarity measures. For the evaluation of SPET-SPET co-registration, five 99 Tc m -ECD brain perfusion SPET scans were performed with a dual-headed gamma camera. These studies were then manually misaligned, and subsequently re-aligned using the methods outlined above. For this application, CD, SR and VAR were also found to give the most accurate registration. For all of these algorithms, the computing time required was clinically acceptable (i.e. less than 10 min).

The absolute measurement of regional cerebral blood flow can be made non-invasively if dynamic scanning is performed immediately following the intravenous injection of 99 Tc m -labelled HMPAO or ECD. By application of an elementary one-step kinetic model in which the arterial input curve is estimated from a region of interest over the anterior aortic arch projection, a brain perfusion index (BPI) can be calculated which is correlated to the total hemispheric blood flow. The aim of this study was to assess the variability of the BPI approach as applied to the calculation of cerebral blood flow. For 46 patients (30 men, 16 women) aged 23.7-74.4 years (mean 60.3), we calculated hemispheric BPI factors. For two subgroups of 10 patients chosen at random, several data-processing parameters, including the number of noise suppression steps and the linear slope interval for the Patlak fit, were assessed. To determine the influence of region-of-interest selection and to estimate intra- and inter-observer differences, three independent observers conducted a repeat analysis of all 46 patients. From five patients who underwent the same injection procedure twice, an estimate of intra-subject reproducibility was calculated. Temporal noise reduction of the input data significantly decreased the intra-observer variability. Visual estimation of the linear interval in the Patlak curve is mucl less reproducible than automatic interval selection; very high interval borders in particular signiticantly decrease the calculated BPI, The intra-observer coefficients of variation for the BPI wer 5.3, 5.6 and 7.9% respectively, corresponding to 2.8, 3.0 and 4.1% when converted to hemispheric CBE The slight inter-observer differences found could be attributed to differing processing parameters. For the five patients in whom the procedure was repeated, the hemispheric BPI reproducibility index was on average 2.6%. Determination of absolute hemispheric blood flow can be performed in a precise manner by means of a dynamic scan during the first 2 min after tracer injection after careful optimization of the processing parameters.

To compensate for off-axis dose reduction, biconical-shaped Pb field flattening filters were constructed for a specific high-power static TaC bremsstrahlung target configuration, at end-point energies 5 and 10 MeV. The filter design was optimized by full Monte Carlo simulation. The absolute dose calculation was compared to experimental ionization and Fricke measurements. Spectral data were analysed and the influence of incident electron beam parameters (diameter, oblique incidence) was simulated. With the constructed filtered set-up we are able to produce any required γ-dose rate up to a maximum value of 35 kGy/h in a water phantom at SSD 25 cm. The accomplished homogeneity at this distance is better than a few per cent over a surface of 25 cm diameter perpendicular to the beam axis, for both energies.

Based on the design of an existing conical-shaped, high-power electron beam stop, an optimized TaC bremsstrahlung converter was constructed through detailed Monte Carlo simulation of static beams with end-point energy in the range 4–15 MeV. For an optimized Ta foil thickness, absolute three-dimensional water phantom dose computations were compared to Fricke and ionization dosimetry data, corrected with calculated off-axis stopping power ratios, Dose rates of 45 Gy/s are achieved at 10 MeV for SSD 25 cm.

Both L and DL-alanine ESR powder spectra have been studied in the dose range of 1–10 6 Gy. By using Maximum Likelihood Common Factor Analysis (MLCFA), it has been demonstrated that the ESR spectrum of L-alanine is at least 3-fold composite over the whole dose range considered. For DL-alanine, in certain dose ranges only two ESR components could be detected. Possible consequences for the application and optimization of alanine dosimetry are discussed.

The Gent University 15 MeV 20kW linear electron accelerator facility was initially designed for fundamental nuclear physics research. During the last years a large effort has been devoted to the expansion of the range of machine applications in view of a new extensive experimental programme in the fields of atomic and solid-state physics, biomaterials research, polymer chemistry, space research, food technology, high-dose dosimetry and radiation therapy. The accelerator facility in its present configuration, the peripheral equipment and the experimental programme are described with emphasis on the original features.

Calcitonin gene-related peptide (CGRP) is a potent vasodilator and sensory neuropeptide implicated in the pathophysiology of migraine headache. CGRP receptor (CGRP-R) antagonists, including telcagepant, have shown clinical efficacy in treating migraine. CGRP-Rs are expressed in the CNS, particularly in the brainstem and cerebellum as well as in the periphery on vascular smooth muscle cells. To investigate whether central CGRP-Rs were likely to be involved in the anti-migraine effects of CGRP-R antagonists we examined central CGRP-R occupancy (CGRP RO) at an efficacious dose of telcagepant in healthy volunteers and in migraineurs during ictal and interictal periods using the novel PET tracer [11C]MK-4232. CGRP RO was evaluated in healthy subjects (n=3) at the lowest clinically efficacious dose (140 mg, PO) of telcagepant ~2h after dosing, coinciding with the time point of efficacy evaluation in clinical migraine studies. PET imaging showed only low CGRP RO (4% - 10%) which is within test-retest variability, suggesting that central activity is not a pre-requisite for anti-migraine efficacy of CGRP-R antagonists. A supratherapeutic telcagepant dose (1120 mg, PO) produced only moderate (43-58%, n=4) CGRP RO at ~Tmax (3h after administration). Subsequently, the possibility that brain penetration of telcagepant, a P-gp brain efflux pump substrate, may be increased in migraine patients or during migraine by blood brain barrier opening, was investigated by PET studies in the ictal and interictal periods in migraineurs (n=3) ~2 h after telcagepant dosing (140 mg, PO). Comparison of [11C]MK-4232 PET study results from ictal and interictal periods in migraineurs to healthy volunteers, suggests similar low RO and no significant differences between states. In conclusion, PET studies with the CGRP-R PET tracer [11C]MK-4232 after therapeutic doses of telcagepant in healthy volunteers and migraineurs suggest that central antagonism of CGRP-R is not necessary for therapeutic efficacy in migraine pain relief and that migraine pain is therefore at least in part peripheral in origin.