Behind the scenes of EQA - characteristics, capabilities, benefits and assets of external quality assessment (EQA).

External quality assessment (EQA) cycles are the smallest complete units within EQA programs that laboratories can use to obtain external assessments of their performance. In each cycle, several samples are distributed to the laboratories registered for participation, and ideally, EQA programs not only cover the examination procedures but also the pre- and post-examination procedures. The properties and concentration range of measurands in individual samples are selected with regard to the intended challenge for the participants so that each sample fulfils its purpose.

Behind the scenes of EQA - characteristics, capabilities, benefits and assets of external quality assessment (EQA).

Providers of external quality assessment (EQA) programs evaluate data or information obtained and reported by participant laboratories using their routine procedures to examine properties or measurands in samples provided for this purpose. EQA samples must offer participants an equal chance to obtain accurate results, while being designed to provide results in clinically relevant ranges. It is the responsibility of the EQA provider to meet the necessary requirements for homogeneity, stability and some other properties of the EQA items in order to offer participants a fair, reliable and technically interesting EQA experience.

The European Organisation of External Quality Assurance Providers in Laboratory Medicine (EQALM) Statement: guidelines for publishing about interlaboratory comparison studies (PubILC).

Data and results from interlaboratory comparison (ILC) studies, external quality assessment (EQA) and proficiency testing (PT) activities are important and valuable contributions both to the further development of all disciplines of medical laboratory diagnostics, and to the evaluation and comparison of diagnostic assays. So far, however, there are no recommendations as to which essential items should be addressed in publications on interlaboratory comparisons. The European Organization of External Quality Assurance Providers in Laboratory Medicine (EQALM) recognized the need for such recommendations, and these were developed by a group of experts.

Optimization of a Nucleophilic Two-Step Radiosynthesis of 6--(2-[F]fluoroethyl)-6--desmethyl-diprenorphine ([F]FE-DPN) for PET Imaging of Brain Opioid Receptors.

We have established a method for nucleophilic one-pot, two-step radiosynthesis of the popular opioid receptor radioligand 6--(2-[F]fluoroethyl)-6--desmethyl-diprenorphine ([F]FE-DPN) from the novel precursor 6--(2-tosyloxyethyl)-6--desmethyl- 3--trityl-diprenorphine (TE-TDDPN), which we designate as the Henriksen precursor. We undertook an optimization of the synthesis conditions, aiming to enhance the accessibility of [F]FE-DPN for positron emission tomography (PET) studies of μ-opioid receptors. Herein, we report an optimized direct nucleophilic F-fluorination and the deprotection conditions for a fully automated radiosynthesis of [F]FE-DPN on a modified GE Tracerlab FX FE synthesis panel.

Treatment outcome at 1 year did not differ between use of cast or walker in the first 3 weeks after an acute Achilles tendon rupture. A registry study of 1304 patients from the Danish Achilles tendon database.

Background: The best choice of orthosis in the treatment of acute Achilles tendon rupture is still under debate.

Objective: To investigate if choice of orthosis in the first 3 weeks of treatment affected patient reported outcome (Achilles tendon Total Rupture Score (ATRS)), tendon elongation (Achilles Tendon Resting Angle (ATRA) and Heel Rise Height (HRH)) and re-rupture.

Methods: Registry study in the Danish Achilles tendon Database.

6-O-(2-[F]Fluoroethyl)-6-O-Desmethyl-Diprenorphine ([F]FE-DPN) Preferentially Binds to Mu Opioid Receptors In Vivo.

Purpose: 6-O-(2-[F]Fluoroethyl)-6-O-desmethyl-diprenorphine ([F]FE-DPN) is regarded as a non-selective opioid receptor radiotracer.

Procedure: Here, we report the first characterization of [F]FE-DPN synthesized from the novel precursor, 6-O-(2-tosyloxyethoxy)-6-O-desmethyl-3-O-trityl-diprenorphine (TE-TDDPN), using a one-pot, two-step nucleophilic radiosynthesis to image opioid receptors in rats and mice using positron emission tomography.

Results: We also show that [F]FE-DPN and [H]DPN exhibit negligible brain uptake in mu opioid receptor (MOR) knockout mice.

Diels-Alder Adducts of Morphinan-6,8-Dienes and Their Transformations.

6,14-ethenomorphinans are semisynthetic opiate derivatives containing an ethylene bridge between positions 6 and 14 in ring-C of the morphine skeleton that imparts a rigid molecular structure. These compounds represent an important family of opioid receptor ligands in which the 6,14-etheno bridged structural motif originates from a [4 + 2] cycloaddition of morphinan-6,8-dienes with dienophiles. Certain 6,14-ethenomorphinans having extremely high affinity for opioid receptors are often non-selective for opioid receptor subtypes, but this view is now undergoing some revision.

Handling of hemolyzed serum samples in clinical chemistry laboratories: the Nordic hemolysis project.

Background Some clinical chemistry measurement methods are vulnerable to interference if hemolyzed serum samples are used. The aims of this study were: (1) to obtain updated information about how hemolysis affects clinical chemistry test results on different instrument platforms used in Nordic laboratories, and (2) to obtain data on how test results from hemolyzed samples are reported in Nordic laboratories. Methods Four identical samples containing different degrees of hemolysis were prepared and distributed to 145 laboratories in the Nordic countries.

Enhancement of Astroglial Aerobic Glycolysis by Extracellular Lactate-Mediated Increase in cAMP.

Besides being a neuronal fuel, L-lactate is also a signal in the brain. Whether extracellular L-lactate affects brain metabolism, in particular astrocytes, abundant neuroglial cells, which produce L-lactate in aerobic glycolysis, is unclear. Recent studies suggested that astrocytes express low levels of the L-lactate GPR81 receptor (EC ≈ 5 mM) that is in fat cells part of an autocrine loop, in which the G-protein mediates reduction of cytosolic cyclic adenosine monophosphate (cAMP).

Metal-Based PSMA Radioligands.

Prostate cancer is one of the most common malignancies for which great progress has been made in identifying appropriate molecular targets that would enable efficient in vivo targeting for imaging and therapy. The type II integral membrane protein, prostate specific membrane antigen (PSMA) is overexpressed on prostate cancer cells in proportion to the stage and grade of the tumor progression, especially in androgen-independent, advanced and metastatic disease, rendering it a promising diagnostic and/or therapeutic target. From the perspective of nuclear medicine, PSMA-based radioligands may significantly impact the management of patients who suffer from prostate cancer.

FIBT versus florbetaben and PiB: a preclinical comparison study with amyloid-PET in transgenic mice.

Background: Over the last decade, an increasing number of studies have been published on the use of amyloid-β (Aβ) PET imaging with different (18)F-radiopharmaceuticals for clinical characterization of Alzheimer's disease (AD) in different stages. However, distinct study cohorts and different quantification techniques allow only for an indirect comparison between the different tracers. Thus, the aim of this study was the direct intra-individual in vivo comparison of different Aβ-targeted radiopharmaceuticals for PET imaging, including the newly developed agent [(18)F]FIBT.

Characterization and first human investigation of FIBT, a novel fluorinated Aβ plaque neuroimaging PET radioligand.

Imidazo[2,1-b]benzothiazoles (IBTs) are a promising novel class of amyloid positron emission tomography (PET) radiopharmaceuticals for diagnosis of neurodegenerative disorders like Alzheimer's disease (AD). Their good in vivo imaging properties have previously been shown in preclinical studies. Among IBTs, fluorinated [(18)F]FIBT was selected for further characterization and advancement toward use in humans.

Comparison of [¹¹C]choline ([¹¹C]CHO) and S(+)-β-methyl-[¹¹C]choline ([¹¹C]SMC) as imaging probes for prostate cancer in a PC-3 prostate cancer xenograft model.

Purpose: Carbon-11- and fluorine-18-labeled choline derivatives have been introduced as promising tracers for prostate cancer imaging. However, due to limited specificity and sensitivity, there is a need for new tracers with higher sensitivity and specificity for diagnosing prostate cancer to improve tracer uptake and enhance imaging contrast. The aim of this study was to compare the properties of [(11)C]choline ([(11)C]CHO) with S(+)-β-methyl-[(11)C]choline ([(11)C]SMC) as tracer for prostate cancer imaging in a human prostate tumor mouse xenograft model by small-animal positron emission tomography/X-ray computed tomography (PET/CT).

Synthesis and evaluation of three structurally related ¹⁸F-labeled orvinols of different intrinsic activities: 6-O-[¹⁸F]fluoroethyl-diprenorphine ([¹⁸F]FDPN), 6-O-[¹⁸F]fluoroethyl-buprenorphine ([¹⁸F]FBPN), and 6-O-[¹⁸F]fluoroethyl-phenethyl-orvinol ([¹⁸F]FPEO).

We report the synthesis and biological evaluation of a triplet of 6-O-(18)F-fluoroethylated derivatives of structurally related orvinols that span across the full range of intrinsic activities, the antagonist diprenorphine, the partial agonist buprenorphine, and the full agonist phenethyl-orvinol. [(18)F]fluoroethyl-diprenorphine, [(18)F]fluoroethyl-buprenorphine, and [(18)F]fluoroethyl-phenethyl-orvinol were prepared in high yields and quality from their 6-O-desmethyl-precursors. The results indicate suitable properties of the three 6-O-(18)F-fluoroethylated derivatives as functional analogues to the native carbon-11 labeled versions with similar pharmacological properties.

A fully automated radiosynthesis of [18F]fluoroethyl-diprenorphine on a single module by use of SPE cartridges for preparation of high quality 2-[18F]fluoroethyl tosylate.

We have developed a new method for automated production of 2-[18F]fluoroethyl tosylate ([18F]FETos) that enables 18F-alkylation to provide PET tracers with high chemical purity. The method is based on the removal of excess ethylene glycol bistosylate precursor by precipitation and subsequent filtration and purification of the filtrate by means of solid phase extraction cartridges (SPE). The method is integrated to a single synthesis module and thereby provides the advantage over previous methods of not requiring HPLC purification, as demonstrated by the full radiosynthesis of the potent opioid receptor PET tracer [18F]fluoroethyldiprenorphine.

Comparison of cyclic RGD peptides for αvβ3 integrin detection in a rat model of myocardial infarction.

Background: Expression of αvβ3 integrin is increased after myocardial infarction as part of the repair process. Increased expression of αvβ3 has been shown by molecular imaging with 18F-galacto-RGD in a rat model. The 68Ga-labelled RGD compounds 68Ga-NODAGA-RGD and 68Ga-TRAP(RGD)3 have high specificity and affinity, and may therefore serve as alternatives of 18F-galacto-RGD for integrin imaging.

Voxel-based analysis of amyloid-burden measured with [(11)C]PiB PET in a double transgenic mouse model of Alzheimer's disease.

Purpose: The purpose of this study is to validate the feasibility of a voxel-based analysis of in vivo amyloid-β positron emission tomography (PET) imaging studies in transgenic mouse models of Alzheimer's disease.

Procedures: We performed [(11)C]PiB PET imaging in 20 APP/PS1 mice and 16 age-matched controls, and histologically determined the individual amyloid-β plaque load. Using SPM software, we performed a voxel-based group comparison plus a regression analysis between PiB retention and actual plaque load, both thresholded at p FWE < 0.

Synthesis and evaluation of 18F-FE-PEO in rodents: an 18F-labeled full agonist for opioid receptor imaging.

Unlabelled: We have investigated the opioid receptor (OR) agonist (20R)-4,5-α-epoxy-6-(2-(18)F-fluoroethoxy)-3-hydroxy-α,17-dimethyl-α-(2-phenyleth-1-yl)-6,14-ethenomorphinan-7-methanol ((18)F-FE-PEO) as a candidate OR PET ligand. This tracer is attractive because it combines (18)F labeling, is suited to the slow kinetics of high-affinity ligands, and has agonist binding, which has been shown to be more sensitive to changes in OR occupation than is antagonist binding.

Methods: Agonist potency and off-target binding were investigated in vitro, and autoradiographic studies on rat brain sections were used to assess binding patterns.

Design and synthesis of an ¹⁸F-labeled version of phenylethyl orvinol ([¹⁸F]FE-PEO) for PET-imaging of opioid receptors.

The semisynthetic oripavine derivative phenethyl orvinol (PEO), a full agonist at opioid receptors (OR), is an attractive structural motif for developing ¹⁸F-labeled PET tracers with a high degree of sensitivity for competition between endogenous and exogenous OR-ligands. The target cold reference compound 6-O-(2-fluoroethyl)-6-O-desmethylphenylethyl orvinol (FE-PEO) was obtained via two separate reaction routes. A three-step synthesis was developed for the preparation of a tosyloxyethyl precursor (TE-TDPEO), the key precursor for a direct, nucleophilic radiofluorination to yield [¹⁸F]FE-PEO.

Small-animal PET imaging of amyloid-beta plaques with [11C]PiB and its multi-modal validation in an APP/PS1 mouse model of Alzheimer's disease.

In vivo imaging and quantification of amyloid-β plaque (Aβ) burden in small-animal models of Alzheimer's disease (AD) is a valuable tool for translational research such as developing specific imaging markers and monitoring new therapy approaches. Methodological constraints such as image resolution of positron emission tomography (PET) and lack of suitable AD models have limited the feasibility of PET in mice. In this study, we evaluated a feasible protocol for PET imaging of Aβ in mouse brain with [(11)C]PiB and specific activities commonly used in human studies.

White matter hyperintensities predict amyloid increase in Alzheimer's disease.

Impaired amyloid clearance probably contributes to increased amyloid deposition in sporadic Alzheimer's disease (AD). Diminished perivascular drainage due to cerebral small-vessel disease (CSVD) has been proposed as a cause of reduced amyloid clearance. White matter hyperintensities (WMHs) are considered to reflect CSVD and can be measured using fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI).

A convenient route to 4-carboxy-4-anilidopiperidine esters and acids.

The route selection and development of a convenient synthesis of 4-carboxy-4-anilidopiperidines is described. Previous routes were hampered by the low yield of the target esters as well as the inability to convert the esters to the required free acids. Considerations for large-scale production led to a modified synthesis that utilised a tert-butyl ester of 4-carboxy-4-anilidopiperidines which resulted in a dramatic increase in the overall yield of the target N-propionylated- 4-anilidopiperidine-4-carboxylic acids and their corresponding methyl esters.

Cerebrospinal fluid BACE1 activity and brain amyloid load in Alzheimer's disease.

The secretase BACE1 is fundamentally involved in the development of cerebral amyloid pathology in Alzheimer's disease (AD). It has not been studied so far to what extent BACE1 activity in cerebrospinal fluid (CSF) mirrors in vivo amyloid load in AD. We explored associations between CSF BACE1 activity and fibrillar amyloid pathology as measured by carbon-11-labelled Pittsburgh Compound B positron emission tomography ([¹¹C]PIB PET).