In vivo imaging of MMPs is of great (pre)clinical interest and can potentially be realized with modern three-dimensional and noninvasive in vivo molecular imaging techniques such as positron emission ...tomography (PET). Consequently, MMP inhibitors (MMPIs) radiolabeled with positron emitting nuclides (e.g., 18F) represent a suitable tool for the visualization of activated MMPs with PET. On the basis of our previous work and results regarding radiolabeled and unlabeled derivatives of the nonselective MMPIs, we discovered a new class of fluorinated MMPIs with a triazole-substituted hydroxamate substructure. These novel MMPIs are characterized by an increased hydrophilicity compared with the lead structures and excellent MMP inhibition potencies for MMP-2, MMP-8, MMP-9, and MMP-13 (IC50 = 0.006–107 nM). Therefore, one promising fluorinated triazole-substituted hydroxamate (30b) was selected and resynthesised as its 18F-labeled version to yield the potential PET radioligand 18 F30b. The biodistribution behavior of this novel compound was investigated with small animal PET.
Abstract Background Detection of inflamed atherosclerotic plaques is of crucial importance. The carotid artery cuff-model in ApoE−/− mice results in shear-stress induced atherosclerosis with inflamed ...plaques upstream (US) and ‘stable’ plaques downstream (DS) of the cuff. We evaluated the potential of F-18-FDG PET/CT to differentiate these plaque phenotypes. Methods A predefined cuff was implanted round the left ( n = 23) or right ( n = 12) common carotid artery (CCA) of 35 ApoE−/− mice on a cholesterol-rich diet. Small animal F-18-FDG PET/CT was performed after 4, 6 and 8 weeks. F-18-FDG uptake was quantified US and DS of the cuff and on the contralateral CCA. Subsequently, regional F-18-FDG uptake was normalized by the contralateral CCA uptake to obtain plaque-to-background (P/B)-ratios. Thereafter, CCA were explanted and investigated by immunohistology. Results P/B-ratio in the US-plaques increased from 1.22 ± 0.23 at 4 weeks over 1.23 ± 0.32 at 6 weeks to 1.37 ± 0.56 ( p = ns) at 8 weeks after cuff implantation (left and right side of cuff implantation considered together). Uptake in the DS-plaques remained stable (1.14 ± 0.23, 1.10 ± 0.26 and 1.11 ± 0.25; p = ns). Uptake in the US-plaques was significantly higher than in the DS-plaques (all p < 0.05). P/B-ratios correlated with plaque size, degree of stenosis and macrophage density in the plaques. Moreover, there was a correlation between plaque size and macrophage density in the plaque. Conclusions F-18-FDG-PET/CT distinguishes atherosclerotic plaques with an inflamed from those with a ‘stable’ phenotype in a mouse model of shear-stress induced atherosclerosis in vivo.
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The programmed type I cell death, defined as apoptosis, is induced by complex regulated signaling pathways that trigger the intracellular activation of executioner caspases-3, -6 and ...-7. Once activated, these enzymes initiate cellular death through cleavage of proteins which are responsible for DNA repair, signaling and cell maintenance. Several radiofluorinated inhibitors of caspases-3 and -7, comprising a moderate lipophilic 5-(1-pyrrolidinylsulfonyl)isatin lead structure, are currently being investigated for imaging apoptosis in vivo by us and others. The purpose of this study was to increase the intrinsic hydrophilicity of the aforementioned lead structure to alter the pharmacokinetic behavior of the resulting caspase-3 and -7 targeted radiotracer. Therefore, fluorinated and non-fluorinated derivatives of 5-(1-pyrrolidinylsulfonyl)-7-azaisatin were synthesized and tested for their inhibitory properties against recombinant caspases-3 and -7. Fluorine-18 has been introduced by copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) of an alkyne precursor with 2-18Ffluoroethylazide. Using dynamic micro-PET biodistribution studies in vivo the kinetic behavior of one promising PET-compatible 5-pyrrolidinylsulfonyl 7-azaisatin derivative has been compared to a previously described isatin based radiotracer.
The Bindex(®) quantitative ultrasound (QUS) device is currently available and this study analyzed (I) its relative and absolute intra- and inter-session reliability and (II) the relationship between ...the data provided by Bindex(®)-QUS and the bone mineral density (BMD) measured by dual-energy x-ray absorptiometry at corresponding skeletal sites in young and healthy subjects (age: 25.0 ± 3.6 years). Bindex(®)-QUS calculates a density index on the basis of the thickness of cortical bone measured at the distal radius and the distal plus proximal tibia. The data show a very good relative and absolute intra- (ICC = 0.977, CV = 1.5%) and inter-session reliability (ICC = 0.978, CV = 1.4%) for the density index. The highest positive correlations were found between cortical thickness and BMD for the distal radius and distal tibia (r ⩾ 0.71, p < 0.001). The data indicate that the Bindex(®)-QUS parameters are repeatable within and between measurement sessions. Furthermore, the measurements reflect the BMD at specific skeletal sites. Bindex(®)-QUS might be a useful tool for the measurement of skeletal adaptations.
Chronic heart failure (HF) in adults causes remodeling of the cardiomyocyte transverse tubular system (t-system), which contributes to disease progression by impairing excitation-contraction (EC) ...coupling. However, it is unknown if t-system remodeling occurs in pediatric heart failure. This study investigated the t-system in pediatric viral myocarditis. The t-system and integrity of EC coupling junctions (co-localization of L-type Ca
channels with ryanodine receptors and junctophilin-2) were analyzed by 3D confocal microscopy in left-ventricular (LV) samples from 5 children with myocarditis (age 14 ± 3 months), undergoing ventricular assist device (VAD) implantation, and 5 children with atrioventricular septum defect (AVSD, age 17 ± 3 months), undergoing corrective surgery. LV ejection fraction (EF) was 58.4 ± 2.3% in AVSD and 12.2 ± 2.4% in acute myocarditis. Cardiomyocytes from myocarditis samples showed increased t-tubule distance (1.27 ± 0.05 μm,
= 34 cells) and dilation of t-tubules (volume-length ratio: 0.64 ± 0.02 μm
) when compared with AVSD (0.90 ± 0.02 μm,
< 0.001; 0.52 ± 0.02 μm
,
= 61,
< 0.01). Intriguingly, 4 out of 5 myocarditis samples exhibited sheet-like t-tubules (t-sheets), a characteristic feature of adult chronic heart failure. The fraction of extracellular matrix was slightly higher in myocarditis (26.6 ± 1.4%) than in AVSD samples (24.4 ± 0.8%,
< 0.05). In one case of myocarditis, a second biopsy was taken and analyzed at VAD explantation after extensive cardiac recovery (EF from 7 to 56%) and clinical remission. When compared with pre-VAD, t-tubule distance and density were unchanged, as well as volume-length ratio (0.67 ± 0.04 μm
vs. 0.72 ± 0.05 μm
,
= 0.5), reflecting extant t-sheets. However, junctophilin-2 cluster density was considerably higher (0.12 ± 0.02 μm
vs. 0.05 ± 0.01 μm
,
= 9/10,
< 0.001), approaching values of AVSD (0.13 ± 0.05 μm
,
= 56), and the measure of intact EC coupling junctions showed a distinct increase (20.2 ± 5.0% vs. 6.8 ± 2.2%,
< 0.001). Severe t-system loss and remodeling to t-sheets can occur in acute HF in young children, resembling the structural changes of chronically failing adult hearts. T-system remodeling might contribute to cardiac dysfunction in viral myocarditis. Although t-system recovery remains elusive, recovery of EC coupling junctions may be possible and deserves further investigation.
The balance between proliferation and programmed cell death--apoptosis--is essential for multicellular organisms which use apoptosis to regulate and maintain the number and type of their cells during ...embryogenesis, growth and homeostasis. Increased cell proliferation or enhanced cell loss can be caused by dysregulated apoptosis and are observed in various diseases: in clinical scenarios such as neurodegenerative disorders, myocardial infarction and stroke the rate of apoptosis is upregulated compared to the physiological situation, while in clinical scenarios such as cancer or autoimmune diseases which are connected with pathological proliferation, apoptosis is often downregulated. Therefore, non-invasive imaging of apoptosis is of great clinical interest as patients would clearly benefit from the diagnosis of cell loss post infarction or from monitoring apoptosis triggered by chemotherapy or radiation therapy of tumours. Several biochemical transformations occur in apoptotic cells offering different biological targets for the development of specific molecular biomarkers of apoptosis. Key steps that occur during apoptosis have already been evaluated; among these are the externalisation of phospholipid phosphatidylserine to the outer leaflet of the cell membrane, which can be visualized by labeled annexin A5 and the activation of caspases, especially effector caspase-3, which can be addressed by labeled enzyme substrates or synthetic caspase inhibitors. Here, recent advances in tracer development for the molecular imaging techniques PET, SPECT and optical imaging are presented, the discussion of breakthroughs is involved, drawbacks and methodological issues of apoptosis imaging are highlighted.
Matrix metalloproteinases (MMPs) are zinc- and calcium-dependent endopeptidases. Representing a subfamily of the metzincin superfamily, MMPs are involved in the proteolytic degradation of components ...of the extracellular matrix. Unregulated MMP expression, MMP dysregulation and locally increased MMP activity are common features of various diseases, such as cancer, atherosclerosis, stroke, arthritis, and others. Therefore, activated MMPs are suitable biological targets for the specific visualization of such pathologies, in particular by using radiolabeled MMP inhibitors (MMPIs). The aim of this work was to develop a radiofluorinated molecular probe for noninvasive in vivo imaging for the detection of up-regulated levels of activated MMPs in the living organism. Fluorinated MMPIs (26, 31 and 38) based on the pyrimidine-2,4,6-trione lead structure RO 28-2653 (1) were synthesized, and their MMP inhibition potency was evaluated in vitro. The radiosynthesis and the in vivo biodistribution of the first (18)F-labeled prototype, MMP-targeted tracer (18)F26, suitable for molecular imaging by means of positron emission tomography (PET) were realized.
Background: Severe traumatic brain injury (TBI) is associated with a high mortality rate and those that survive commonly have permanent disability. While there is a broad consensus that appropriate ...prehospital treatment is crucial for a favorable neurological outcome, evidence to support currently applied treatment strategies is scarce. In particular, the relationship between prehospital treatments and patient outcomes is unclear. The BRAIN-PROTECT study therefore aims to identify prehospital treatment strategies associated with beneficial or detrimental outcomes. Here, we present the study protocol. Study Protocol: BRAIN-PROTECT is the acronym for BRAin INjury: Prehospital Registry of Outcome, Treatments and Epidemiology of Cerebral Trauma. It is a prospective observational study on the prehospital treatment of patients with suspected severe TBI in the Netherlands. Prehospital epidemiology, interventions, medication strategies, and nonmedical factors that may affect outcome are studied. Multivariable regression based modeling will be used to identify confounder-adjusted relationships between these factors and patient outcomes, including mortality at 30 days (primary outcome) or mortality and functional neurological outcome at 1 year (secondary outcomes). Patients in whom severe TBI is suspected during prehospital treatment (Glasgow Coma Scale score ≤ 8 in combination with a trauma mechanism or clinical findings suggestive of head injury) are identified by all four helicopter emergency medical services (HEMS) in the Netherlands. Patients are prospectively followed up in 9 participating trauma centers for up to one year. The manuscript reports in detail the objectives, setting, study design, patient inclusion, and data collection process. Ethical and juridical aspects, statistical considerations, as well as limitations of the study design are discussed. Discussion: Current prehospital treatment of patients with suspected severe TBI is based on marginal evidence, and optimal treatment is basically unknown. The BRAIN-PROTECT study provides an opportunity to evaluate and compare different treatment strategies with respect to patient outcomes. To our knowledge, this study project is the first large-scale prospective prehospital registry of patients with severe TBI that also collects long-term follow-up data and may provide the best available evidence at this time to give useful insights on how prehospital care can be improved.
Abstract
OBJECTIVES
This study evaluated the various risk factors for chylothorax and persistent serous effusions (>7 days) after congenital heart surgery and developed equations to calculate the ...probability of their occurrence.
METHODS
We performed a retrospective review of different medical databases at the University Hospital of Erlangen between January 2014 and December 2016. Full model regression analysis was used to identify risk factors, and prediction algorithms were set up to calculate probabilities. Discriminative power of the models was checked with the help of C-statistics.
RESULTS
Of 745 operations on 667 patients, 68 chylothoraxes (9.1%) and 125 persistent pleural effusions (16.8%) were diagnosed. Lowest temperature P = 0.043; odds ratio (OR) 0.899, trisomy 21 (P = 0.001; OR 5.548), a higher vasoactive inotropic score on the day of surgery (P = 0.001; OR 1.070) and use of an assist device (P = 0.001; OR 5.779) were significantly associated with chylothorax. Risk factors for persistent serous effusions were a given or possible involvement of the aortic arch during the operation (P = 0.000; OR 3.982 and 2.905), univentricular hearts (P = 0.019; OR 2.644), a higher number of previous heart operations (P = 0.014; OR 1.436), a higher vasoactive inotropic score 72 h after surgery (P = 0.019; OR 1.091), a higher central venous pressure directly after surgery (P = 0.046; OR 1.076) and an aortic cross-clamp time >86 min (P = 0.023; OR 2.223), as well as use of an assist device (P = 0.002; OR 10.281). The prediction models for both types of effusions proved to have excellent discriminative power.
CONCLUSIONS
Persistent serous effusion is associated with a higher vasoactive inotropic score 72 h after surgery, an aortic cross-clamp time >86 min and elevated central venous pressure directly after surgery, which, in combination, potentially indicate cardiac stress. The developed logistic algorithm helps to estimate future likelihood.
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