Evaluation of the Performance and Hematocrit Independence of the HemaPEN as a Volumetric Dried Blood Spot Collection Device

Dried blood spots (DBS) are often used as a less invasive alternative to venous blood sampling. Despite its numerous advantages, the use of conventional DBS suffers from the hematocrit (hct) effect when analyzing a subpunch. This effect could be avoided by using hct-independent sampling devices, of which the hemaPEN is a recent example. This device collects the blood via four integrated 2.74 μL microcapillaries, each depositing the blood on a prepunched paper disc. In this study, we evaluated the technical performance of the hemaPEN devices, using an extensive bioanalytical validation and application on authentic patient samples. An LC-MS/MS method quantifying caffeine and its metabolite paraxanthine in dried whole blood (using the hemaPEN device) was fully validated, meeting all preset acceptance criteria. A comparative analysis of 91 authentic patient samples (hct range: 0.17–0.53) of hemaPEN, 3 mm DBS subpunches, and whole blood revealed a limited hct dependence (≤7% concentration difference over a 0.20–0.50 hct range) for the hemaPEN devices, which we could not attribute to the analytical procedure. Using conventional partial-punch DBS (3 mm punches), concentration differences of ≥25% over this hct range were found. The hemaPEN showed to be robust to the effects of blood sample volume, device lot, analytical operator, and storage stability. The technical performance of the hemaPEN when dealing with patients having a high hct and in cases where a large blood drop is present should be further investigated. Based on the successful validation and application on patient samples, we conclude that the hemaPEN device shows good potential for the volumetric collection of DBS.S.D. would like to thank the Research Foundation-Flanders (FWO) for granting her a PhD fellowship (application number:11F3119N). L.P.-G. would like to thank the Consellería de Cultura, Educacion e Ordenación Universitaria, Xunta de Galicia, for her predoctoral (ED481A-2018/059) contractS

Are the N-demethylated metabolites of U-47700 more active than their parent compound? In vitro μ-opioid receptor activation of N-desmethyl-U-47700 and N,N-bisdesmethyl-U-47700

Studies on the tissue distribution of the new synthetic opioid U-47700 and its main metabolite N-desmethyl-U-47700 revealed about sixfold higher metabolite concentrations in pig brain as compared with the parent compound. To better assess the toxic potential of this drug, the aim of this study was to assess the in vitro μ-opioid receptor (MOR) activation potential of the main metabolites of U-47700, Ndesmethyl-U-47700, and N,N-bisdesmethyl-U-47700, using a live cell-based reporter assay based on NanoLuc Binary Technology®. Cells stably expressing human MOR and β-arrestin 2 (βarr2), each fused via a flexible linker to two complementary inactive subunits of the nanoluciferase, were seeded on poly-D-lysine-coated 96-well plates and treated with N-desmethyl-U-47700, N,N-bisdesmethyl-U-47700, U-47700, or hydromorphone as reference standard. MOR activation results in functional complementation of the nanoluciferase, which can be assessed via luminescence monitoring. The potency of the metabolites is lower than that of U-47700 (EC50 of 186 nM for U-47700, 3770 nM for N-desmethyl-U-47700, and >5 μM for N,N-bisdesmethylU-47700). The maximal efficacy (Emax) observed (relative to hydromorphone, set arbitrarily at 100%) decreased from 183% to 127% and 39.2% for U-47700, N-desmethyl-U-47700, and N,N-bisdesmethyl-U-47700, respectively. Thus, the loss of one or two methyl groups reduced the MOR activation potential, which was more pronounced if both methyl groups were removed. It is thus anticipated that the impact on MOR exerted by the higher metabolite concentration in brain has only little—if any relevance for the strong toxic effects of U-47700

Evaluation of the Capitainer-B microfluidic device as a new hematocrit-independent alternative for dried blood spot collection

The hematocrit-bias still remains one of the most discussed issues when it comes to dried blood spot (DBS) analysis. Therefore, many attempts to cope with this issue have been made, among which the development of novel sampling tools such as the Capitainer-B (further referred to as MF (microfluidic)-DBS) devices. These are designed to allow a straightforward absorption of a fixed volume (13.5 mu L) of blood by a preperforated paper disc, which can be analyzed afterward. The aim of this study was to evaluate the potential of these devices to nullify the hematocrit-based area bias and to investigate whether the amount of blood applied has an influence on the device performance. An LC-MS/MS method for the quantification of caffeine and paraxanthine in MF-DBS was fully validated, meeting all preset acceptance criteria. In a next step, using a set of 133 authentic, venous patient samples with a hematocrit range of 18.8-55.0, concentrations of both compounds in MF-DBS were compared to those in corresponding partial-punch pipetted DBS (PI-DBS) and liquid blood samples. When compared to blood as a reference, the concentrations obtained in MF-DBS were not affected by a bias in function of the evaluated hematocrit, in contrast to those obtained from partial-punch PI-DBS. Furthermore, analysis of samples resulting from spiking different volumes of whole blood at different hematocrit levels, revealed that the amount of blood applied at the device inlet has no influence on the performance of the devices. Therefore, it can be concluded from this study, being the first in which the impact of the hematocrit and the applied volume is evaluated by analyzing authentic, venous patient samples, that MF-DBS devices effectively assist in eliminating the hematocrit-based area bias, independently from the applied blood volume

Detection and activity profiling of synthetic cannabinoids and their metabolites with a newly developed bioassay

Synthetic cannabinoids (SCs) are the largest group of compounds currently monitored in Europe by the EU Early Warning System on new psychoactive substances. Emerging recreational use of these products has led to multiple cases of adverse health effects and even death. In contrast to marijuana, where Delta(9)-tetrahydrocannabinol (Delta(THC)-T-9) is metabolized to only one major active metabolite, it has been reported that several major phase I metabolites of SCs remain biologically active, exerting cannabinoid (CB) receptor affinity, potency, and efficacy greater than those of Delta(THC)-T-9. It is therefore reasonable that more SCs can also be biotransformed into molecules with various levels of CB activity. Here, we developed and applied a new G-protein coupled receptor (GPCR) activation assay based on NanoLuc binary technology (Promega). More specifically, by demonstrating CB1 and CB2 receptor activation by JWH-018 and a selection of its metabolites, we are the first to show the suitability of the newly developed bioassay for monitoring GPCR-mediated activity. We also successfully applied this reporter system to evaluate the in vitro activity of JWH-122, JWH-210, and PB-22, their S-fluoro analogues (MAM-2201, EAM-2201, and SF-PB-22, respectively), and their main phase I metabolites. By doing so, we demonstrate that several major metabolites of these SCs retain their activity at cannabinoid receptors. All of these active metabolites may prolong the parent compound's psychotropic and physiological effects and may contribute to its toxicity profile. We also demonstrate a proof of concept of the applicability of the newly developed bioassay for screening urine for CB receptor activity exerted by SCs

Visible-Light Photoswitchable Benzimidazole Azo-Arenes as beta-Arrestin2-Biased Selective Cannabinoid 2 Receptor Agonists

Acknowledgements The authors would like to acknowledge Dr. Andrea Holme for excellent technical support and the Iain Fraser Cytometry Centre (University of Aberdeen) for providing access to their equipment. The authors would like to thank Dr. Matthias Scheiner for his contributions towards the development of the calcium mobilization assay and Dr. Valérie Jahns for her efforts towards faster automated analysis of the obtained results. Nick Verhavert is acknowledged for his assistance with the NanoBiT® assay. Diego Rodriguez-Soacha is acknowledged for establishing the rCB1R radioligand binding assay in our laboratory. Special thanks to Dr. Rangan Maitra and RTI International for providing the G16 coupled hCB1 and hCB2 CHO-K1 cell lines. The authors thank Nadine Yurdagül-Hemmrich and Annette Hannawacker for excellent technical support. This project was funded by the German Research Foundation (Deutsche Forschungsgemeinschaft under DFG DE1546/10-1). J. N. Hislop’s financing support was given by NHS Grampian. The research visit of S. A. M. Steinmüller in Dr. Hislop’s laboratory was funded by the Elite Network of Bavaria (grant N° K-BM-2013-247). J. Fender and A. Tutov were supported by the International Doctoral Program “Receptor Dynamics” funded within the framework of the Elite Network of Bavaria (grant N° K-BM-2013- 247). M. H. Deventer was funded by the Research FoundationFlanders (FWO; grant 1S54521N).Peer reviewe

The validation of Short Interspersed Nuclear Elements (SINEs) as a RT-qPCR normalization strategy in a rodent model for temporal lobe epilepsy

Background : In gene expression studies via RT-qPCR many conclusions are inferred by using reference genes. However, it is generally known that also reference genes could be differentially expressed between various tissue types, experimental conditions and animal models. An increasing amount of studies have been performed to validate the stability of reference genes. In this study, two rodent-specific Short Interspersed Nuclear Elements (SINEs), which are located throughout the transcriptome, were validated and assessed against nine reference genes in a model of Temporal Lobe Epilepsy (TLE). Two different brain regions (i.e. hippocampus and cortex) and two different disease stages (i.e. acute phase and chronic phase) of the systemic kainic acid rat model for TLE were analyzed by performing expression analyses with the geNorm and NormFinder algorithms. Finally, we performed a rank aggregation analysis and validated the reference genes and the rodent-specific SINEs (i.e. B elements) individually via Gfap gene expression. Results : GeNorm ranked Hprt1, Pgk1 and Ywhaz as the most stable genes in the acute phase, while Gusb and B2m were ranked as the most unstable, being significantly upregulated. The two B elements were ranked as most stable for both brain regions in the chronic phase by geNorm. In contrast, NormFinder ranked the B1 element only once as second best in cortical tissue for the chronic phase. Interestingly, using only one of the two algorithms would have led to skewed conclusions. Finally, the rank aggregation method indicated the use of the B1 element as the best option to normalize target genes, independent of the disease progression and brain region. This result was supported by the expression profile of Gfap. Conclusion : In this study, we demonstrate the potential of implementing SINEs-notably the B1 element as a stable normalization factor in a rodent model of TLE, independent of brain region or disease progression

Striatal dopamine D2-muscarinic acetylcholine M1 receptor-receptor interaction in a model of movement disorders

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor control deficits, which is associated with the loss of striatal dopaminergic neurons from the substantia nigra. In parallel to dopaminergic denervation, there is an increase of acetylcholine within the striatum, resulting in a striatal dopaminergic-cholinergic neurotransmission imbalance. Currently, available PD pharmacotherapy (e.g., prodopaminergic drugs) does not reinstate the altered dopaminergic-cholinergic balance. In addition, it can eventually elicit cholinergic-related adverse effects. Here, we investigated the interplay between dopaminergic and cholinergic systems by assessing the physical and functional interaction of dopamine D2 and muscarinic acetylcholine M1 receptors (D2R and M1R, respectively), both expressed at striatopallidal medium spiny neurons. First, we provided evidence for the existence of D2R-M1R complexes via biochemical (i.e., co-immunoprecipitation) and biophysical (i.e., BRET1 and NanoBiT®) assays, performed in transiently transfected HEK293T cells. Subsequently, a D2R-M1R co-distribution in the mouse striatum was observed through double-immunofluorescence staining and AlphaLISA® immunoassay. Finally, we evaluated the functional interplay between both receptors via behavioral studies, by implementing the classical acute reserpine pharmacological animal model of experimental parkinsonism. Reserpinized mice were administered with a D2R-selective agonist (sumanirole) and/or an M1R-selective antagonist (VU0255035), and alterations in PD-related behavioral tasks (i.e., locomotor activity) were evaluated. Importantly, VU0255035 (10 mg/kg) potentiated the antiparkinsonian-like effects (i.e., increased locomotor activity and decreased catalepsy) of an ineffective sumanirole dose (3 mg/kg). Altogether, our data suggest the existence of putative striatal D2R/M1R heteromers, which might be a relevant target to manage PD motor impairments with fewer adverse effects

Understanding the pharmacokinetics of synthetic cathinones: Evaluation of the blood–brain barrier permeability of 13 related compounds in rats

This is the pre-peer reviewed version of the following article:Understanding the pharmacokinetics of synthetic cathinones: Evaluation of the blood–brain barrier permeability of 13 related compounds in rats, which has been published in final form at https://doi.org/10.1111/adb.12979. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Synthetic cathinones are the second most commonly seized new psychoactive substance family in Europe. These compounds have been related to several intoxication cases, including fatalities. Although the pharmacological effects, metabolism, and pharmacokinetics of cathinones have been studied, there is little information about the permeability of these compounds through the blood–brain barrier (BBB). This is an important parameter to understand the behavior and potency of cathinones. In this work, 13 selected cathinones have been analyzed in telencephalon tissue from Sprague–Dawley rats intraperitoneally dosed at 3 mg/kg. Our results revealed a direct relationship between compound polarity and BBB permeability, with higher permeability for the more polar cathinones. The chemical moieties present in the cathinone had an important impact on the BBB permeability, with lengthening of the α‐alkyl chain or functionalization of the aromatic ring with alkyl moieties resulting in lower concentration in telencephalon tissue. Our data suggest that transport of cathinones is a carrier‐mediated process, similar to cocaine transport across the BBB

Dual-Acting Small Molecules: Subtype-Selective Cannabinoid Receptor 2 Agonist/Butyrylcholinesterase Inhibitor Hybrids Show Neuroprotection in an Alzheimer's Disease Mouse Model.

We present the synthesis and characterization of merged human butyrylcholinesterase (hBChE) inhibitor/cannabinoid receptor 2 (hCB2R) ligands for the treatment of neurodegeneration. In total, 15 benzimidazole carbamates were synthesized and tested for their inhibition of human cholinesterases, also with regard to their pseudoirreversible binding mode and affinity toward both cannabinoid receptors in radioligand binding studies. After evaluation in a calcium mobilization assay as well as a β-arrestin 2 (βarr2) recruitment assay, two compounds with balanced activities on both targets were tested for their immunomodulatory effect on microglia activation and regarding their pharmacokinetic properties and blood-brain barrier penetration. Compound 15d, containing a dimethyl carbamate motif, was further evaluated in vivo, showing prevention of Aβ25-35-induced learning impairments in a pharmacological mouse model of Alzheimer's disease for both short- and long-term memory responses. Additional combination studies proved a synergic effect of BChE inhibition and CB2R activation in vivo