The positivity effect in older adults : the role of affective interference and inhibition

Objectives: Research shows that aging often involves a decrease in the experience of negative affect and might even be associated with a stabilization or an increase in experience concerning positive affect. As it has been suggested that these changes could be related to the processing of emotional information, the aim of this study was to investigate interference and inhibition toward sad and happy faces in healthy elderly people compared to a younger population. Method: We used an affective modification of the negative priming task. If interference is related to enhanced inhibition, reduced interference from negative stimuli and a related weakened inhibition toward negative stimuli in the elderly group would be in line with the positivity hypothesis. Results: As expected, the results indicated that interference from negative stimuli was significantly lower in older adults as compared to younger adults, whereas this was not the case for positive stimuli. Moreover, at inhibitory level a significantly reduced processing of negative stimuli was observed only in the older adult group, whereas there was no such effect in the case of positive material. Conclusion: These observations are indicative for a decreased negative bias in older adults at information processing level. This provides new insights with regard to age-related differences in emotion processing

The hospital organization of the future

The future of hospital Nuclear Medicine is triggered by the hospital organisation itself. In general, the hospital organisation of the present requires substantial changes in order to be competitive, economical, and abreast of the rapid progresses in medical developments and patient management. It also must be flexible to changes in health politics. In this special report an organisational hospital structure is outlined which may help encounter the challenging hospital future. Some hospitals have already implemented convincing changes, whereas others are far behind

Reliability of intrasubject absolute quantification of kidney function measured with 99mTc DMSA in piglets

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Reduction of artefacts caused by hip implants in CT-based attenuation-corrected PET images using 2-D interpolation of a virtual sinogram on an irregular grid

Purpose: Metallic prosthetic replacements, such as hip or knee implants, are known to cause strong streaking artefacts in CT images. These artefacts likely induce over- or underestimation of the activity concentration near the metallic implants when applying CT-based attenuation correction of positron emission tomography (PET) images. Since this degrades the diagnostic quality of the images, metal artefact reduction (MAR) prior to attenuation correction is required. Methods: The proposed MAR method, referred to as virtual sinogram-based technique, replaces the projection bins of the sinogram that are influenced by metallic implants by a 2-D Clough-Tocher cubic interpolation scheme performed in an irregular grid, called Delaunay triangulated grid. To assess the performance of the proposed method, a physical phantom and 30 clinical PET/CT studies including hip prostheses were used. The results were compared to the method implemented on the Siemens Biograph mCT PET/CT scanner. Results: Both phantom and clinical studies revealed that the proposed method performs equally well as the Siemens MAR method in the regions corresponding to bright streaking artefacts and the artefact-free regions. However, in regions corresponding to dark streaking artefacts, the Siemens method does not seem to appropriately correct the tracer uptake while the proposed method consistently increased the uptake in the underestimated regions, thus bringing it to the expected level. This observation is corroborated by the experimental phantom study which demonstrates that the proposed method approaches the true activity concentration more closely. Conclusion: The proposed MAR method allows more accurate CT-based attenuation correction of PET images and prevents misinterpretation of tracer uptake, which might be biased owing to the propagation of bright and dark streaking artefacts from CT images to the PET data following the attenuation correction procedur

PET Agents in Dementia:An Overview

This article presents an overview of imaging agents for PET that have been applied for research and diagnostic purposes in patients affected by dementia. Classified by the target which the agents visualize, seven groups of tracers can be distinguished, namely radiopharmaceuticals for: (1) Misfolded proteins (beta-amyloid, tau, alpha-synuclein), (2) Neuroinflammation (overexpression of translocator protein), (3) Elements of the cholinergic system, (4) Elements of monoamine neurotransmitter systems, (5) Synaptic density, (6) Cerebral energy metabolism (glucose transport/ hexokinase), and (7) Various other proteins. This last category contains proteins involved in mechanisms underlying neuroinflammation or cognitive impairment, which may also be potential therapeutic targets. Many receptors belong to this category: AMPA, cannabinoid, colony stimulating factor 1, metabotropic glutamate receptor 1 and 5 (mGluR1, mGluR5), opioid (kappa, mu), purinergic (P2X7, P2Y12), sigma-1, sigma-2, receptor for advanced glycation endproducts, and triggering receptor expressed on myeloid cells-1, besides several enzymes: cyclooxygenase-1 and 2 (COX-1, COX-2), phosphodiesterase-5 and 10 (PDE5, PDE10), and tropomyosin receptor kinase. Significant advances in neuroimaging have been made in the last 15 years. The use of 2-[F-18]-fluoro-2-deoxy-D-glucose (FDG) for quantification of regional cerebral glucose metabolism is well-established. Three tracers for beta-amyloid plaques have been approved by the Food and Drug Administration and European Medicines Agency. Several tracers for tau neurofibrillary tangles are already applied in clinical research. Since many novel agents are in the preclinical or experimental stage of development, further advances in nuclear medicine imaging can be expected in the near future. PET studies with established tracers and tracers for novel targets may result in early diagnosis and better classification of neurodegenerative disorders and in accurate monitoring of therapy trials which involve these targets. PET data have prognostic value and may be used to assess the response of the human brain to interventions, or to select the appropriate treatment strategy for an individual patient. (C) 2021 The Authors. Published by Elsevier Inc

The 10-word learning task in the differential diagnosis of early Alzheimer's disease and elderly depression: a cross-sectional pilot study

Objectives: Identification of early Alzheimer's disease (AD) has become very important. Episodic memory tasks appear to have predictive power for indicating early AD. Deficits in encoding and storage processes that are characteristic of AD, however, must be distinguished from non-AD deficits that can also affect memory, including difficulties that may be present in depression. This pilot study was set up to ascertain whether a 10-word-list-learning task (delayed recognition and rate of forgetting) may be useful in making the differentiation between mild AD and depression. Method: A Dutch version of Rey's auditory verbal learning test was administered to 36 mild AD patients, 41 depressed patients, and 47 healthy controls. Data were analyzed in a cross-sectional manner. Results: Receiver operating characteristic analyses showed that for differentiating mild AD and depression, both delayed recognition and percentage of forgetting have sufficient diagnostic accuracy. Conclusion: Percentage of forgetting had the highest diagnostic accuracy for differentiating mild AD and depressed patients and may be useful in the early detection of AD

The new integrated nuclear medicine and radiology residency program in the Netherlands:Why do residents choose to subspecialize in nuclear medicine and why not?

Purpose: To explore reasons that influence a resident's choice for the nuclear medicine subspecialty in the integrated nuclear medicine and radiology residency program in the Netherlands. Methods: A web questionnaire was developed and distributed among residents in the Dutch integrated nuclear medicine and radiology training. Results: A total of 114 residents were included. The survey results revealed four categories of incentives to choose the nuclear medicine subspecialty: 1) Expertise of nuclear medicine physicians and their quality of supervision in the training hospital, 2) Opportunities to do scientific research during and after residency, 3) Diversity of pathology, radiotracers, examinations and therapies in the training hospital, and 4) The expectation that the role of hybrid imaging will increase in the future. They also revealed four groups of disincentives to choose the nuclear medicine subspecialty: 1) Lack of collaboration and integration between nuclear medicine and radiology in some training hospitals, 2) Imbalance between nuclear medicine and radiology during the first 2.5 years of basic training during residency at the expense of nuclear medicine, 3) Uncertainty regarding the international recognition of the nuclear medicine subspecialty training, and 4) Uncertain future of nuclear medicine regarding the chances of employment and the ratio of work activities of nuclear medicine to radiology. Conclusion: This study provided insight into residents' motives to pursue or refrain from nuclear medicine subspecialization in an integrated nuclear medicine and radiology residency program. Medical imaging specialists in training hospitals and developers of curricula for nuclear medicine and radiology training should take these motives into account to ensure a sufficient outflow of newly graduated nuclear medicine specialists

One pot ‘click’ reactions: tandem enantioselective biocatalytic epoxide ring opening and [3+2] azide alkyne cycloaddition

Halohydrin dehalogenase (HheC) can perform enantioselective azidolysis of aromatic epoxides to 1,2-azido alcohols which are subsequently ligated to alkynes producing chiral hydroxy triazoles in a one-pot procedure with excellent enantiomeric excess.