Radiation dosimetry and biodistribution of 11C-ABP688 measured in healthy volunteers

Introduction: In this study, we assessed the whole-body biodistribution and radiation dosimetry of the new glutamatergic ligand 11C-ABP688. This ligand binds specifically to the metabotropic glutamatergic receptor of subtype 5 (mGluR5). Materials and methods: The study included five healthy male volunteers aged 20-29years. After intravenous injection of 240-260MBq, a series of four to ten whole-body positron emission tomography/computed tomography scans were initiated, yielding 60-80min of data. Residence times were then calculated in the relevant organs, and the software packages Mirdose and Olinda were used to calculate the absorbed radiation dose and the effective dose equivalent. Results: Of the excreted 11C activity at 1hour, approximately 80% were eliminated via the hepato-biliary pathway and 20% through the urinary tract. The absorbed dose (mGy/MBq) was highest in the liver (1.64 E -2 ± 5.08 E -3), gallbladder (8.13 E -3 ± 5.6 E -3), and kidneys (7.27 E -3 ± 2.79 E -3). The effective dose equivalent was 3.68 ± 0.84microSv/MBq. Brain uptake in the areas with high mGluR5 density was 2-3 (SUV). The agreement between the values obtained from Mirdose and the Olinda was excellent. Conclusion: 11C-ABP688 is a very promising ligand for the investigation of mGluR5 receptors in humans. Brain uptake is high and the effective dose equivalent so low that serial examinations in the same subject seem feasibl

Intestinal permeability and gut microbiota interactions of pharmacologically active compounds in valerian and St. John’s wort

Phytomedicines such as valerian and St. John's wort are widely used for the treatment of sleeping disorders, anxiety and mild depression. They are perceived as safe alternatives to synthetic drugs, but limited information is available on the intestinal absorption and interaction with human intestinal microbiota of pharmacologically relevant constituents valerenic acid in valerian, and hyperforin and hypericin in St. John's wort. The intestinal permeability of these compounds and the antidepressant and anxiolytic drugs citalopram and diazepam was investigated in the Caco-2 cell model with bidirectional transport experiments. In addition, interaction of compounds and herbal extracts with intestinal microbiota was evaluated in artificial human gut microbiota. Microbiota-mediated metabolisation of compounds was assessed, and bacterial viability and short-chain fatty acids (SCFA) production were measured in the presence of compounds or herbal extracts. Valerenic acid and hyperforin were highly permeable in Caco-2 cell monolayers. Hypericin showed low-to-moderate permeability. An active transport process was potentially involved in the transfer of valerenic acid. Hyperforin and hypericin were mainly transported through passive transcellular diffusion. All compounds were not metabolized over 24 h in the artificial gut microbiota. Microbial SCFA production and bacterial viability was not substantially impaired nor promoted by exposure to the compounds or herbal extracts

Placental Passage of Protopine in an Ex Vivo Human Perfusion System

The placental passage of protopine was investigated with a human ex vivo placental perfusion model. The model was first validated with diazepam and citalopram, 2 compounds known to cross the placental barrier, and antipyrine as a positive control. All compounds were quantified by partially validated U(H)PLC-MS/MS bioanalytical methods. Protopine was transferred from the maternal to the fetal circuit, with a steady-state reached after 90 min. The study compound did not affect placental viability or functionality, as glucose consumption, lactate production, and beta-human chorionic gonadotropin, and leptin release remained constant. Histopathological evaluation of all placental specimens showed unremarkable, age-appropriate parenchymal maturation with no pathologic findings

Patterns of amyloid accumulation in amyloid-negative cases

Amyloid staging models showed that regional abnormality occurs before global positivity. Several studies assumed that the trajectory of amyloid spread is homogeneous, but clinical evidence suggests that it is highly heterogeneous. We tested whether different amyloid-β (Aβ) patterns exist by applying clustering on negative scans and investigating their demographics, clinical, cognitive, and biomarkers correlates, and cognitive trajectories. 151 individuals from Geneva and Zurich cohorts with T1-MRI, negative Aβ positron emission tomography (PET,centiloid<12) and clinical assessment were included. N=123 underwent tau PET, and N=65 follow-up neuropsychological assessment. We performed k-means clustering using 33 Aβ regional Standardized Uptake Vales ratio. Demographics, clinical, cognitive, and biomarkers differences were investigated. Longitudinal cognitive changes by baseline cluster status were estimated using a linear mixed model. The cluster analysis identified two clusters: temporal predominant (TP) and cingulate predominant (CP). TP tau deposition was higher than CP. A trend for a higher cognitive decline in TP compared to CP was observed. This study suggests the existence of two Aβ deposition patterns in the earliest phases of Aβ accumulation, differently prone to tau pathology and cognitive decline

Transplacental passage of hyperforin, hypericin, and valerenic acid

Safe medications for mild mental diseases in pregnancy are needed. Phytomedicines from St. John’s wort and valerian are valid candidates, but safety data in pregnancy are lacking. The transplacental transport of hyperforin and hypericin (from St. John’s wort), and valerenic acid (from valerian) was evaluated using the ex vivo cotyledon perfusion model (4 h perfusions, term placentae) and, in part, the in vitro Transwell assay with BeWo b30 cells. Antipyrine was used for comparison in both models. U(H)PLC-MS/MS bioanalytical methods were developed to quantify the compounds. Perfusion data obtained with term placentae showed that only minor amounts of hyperforin passed into the fetal circuit, while hypericin did not cross the placental barrier and valerenic acid equilibrated between the maternal and fetal compartments. None of the investigated compounds affected metabolic, functional, and histopathological parameters of the placenta during the perfusion experiments. Data from the Transwell model suggested that valerenic acid does not cross the placental cell layer. Taken together, our data suggest that throughout the pregnancy the potential fetal exposure to hypericin and hyperforin – but not to valerenic acid – is likely to be minimal

Inhibition of prolyl oligopeptidase : A promising pathway to prevent the progression of age-related macular degeneration

Dry age-related macular degeneration (AMD) is a currently untreatable vision threatening disease. Impaired proteasomal clearance and autophagy in the retinal pigment epithelium (RPE) and subsequent photoreceptor damage are connected with dry AMD, but detailed pathophysiology is still unclear. In this paper, we discover inhibition of cytosolic protease, prolyl oligopeptidase (PREP), as a potential pathway to treat dry AMD. We showed that PREP inhibitor exposure induced autophagy in the RPE cells, shown by increased LC3-II levels and decreased p62 levels. PREP inhibitor treatment increased total levels of autophagic vacuoles in the RPE cells. Global proteomics was used to examine the phenotype of a commonly used cell model displaying AMD characteristics, oxidative stress and altered protein metabolism, in vitro. These RPE cells displayed induced protein aggregation and clear alterations in macromolecule metabolism, confirming the relevance of the cell model. Differences in intracellular target engagement of PREP inhibitors were observed with cellular thermal shift assay (CETSA). These differences were explained by intracellular drug exposure (the unbound cellular partition coefficient, Kpuu). Importantly, our data is in line with previous observations regarding the discrepancy between PREP's cleaving activity and outcomes in autophagy. This highlights the need to further explore PREP's role in autophagy so that more effective compounds can be designed to battle diseases in which autophagy induction is needed. The present work is the first report investigating the PREP pathway in the RPE and we predict that the PREP inhibitors can be further optimized for treatment of dry AMD.Peer reviewe

Transplacental passage of hyperforin, hypericin, and valerenic acid

Safe medications for mild mental diseases in pregnancy are needed. Phytomedicines from St. John’s wort and valerian are valid candidates, but safety data in pregnancy are lacking. The transplacental transport of hyperforin and hypericin (from St. John’s wort), and valerenic acid (from valerian) was evaluated using the ex vivo cotyledon perfusion model (4 h perfusions, term placentae) and, in part, the in vitro Transwell assay with BeWo b30 cells. Antipyrine was used for comparison in both models. U(H)PLC-MS/MS bioanalytical methods were developed to quantify the compounds. Perfusion data obtained with term placentae showed that only minor amounts of hyperforin passed into the fetal circuit, while hypericin did not cross the placental barrier and valerenic acid equilibrated between the maternal and fetal compartments. None of the investigated compounds affected metabolic, functional, and histopathological parameters of the placenta during the perfusion experiments. Data from the Transwell model suggested that valerenic acid does not cross the placental cell layer. Taken together, our data suggest that throughout the pregnancy the potential fetal exposure to hypericin and hyperforin – but not to valerenic acid – is likely to be minimal

Tracing the cosmological assembly of stars and supermassive black holes in galaxies

We examine possible phenomenological constraints for the joint evolution of supermassive black holes (SMBH) and their host spheroids. We compare all the available observational data on the redshift evolution of the total stellar mass and star formation rate density in the Universe with the mass and accretion rate density evolution of supermassive black holes, estimated from the hard X-ray selected luminosity function of quasars and active galactic nuclei (AGN) for a given radiative efficiency, \epsilon. We assume that the ratio of the stellar mass in spheroids to the black hole mass density evolves as (1+z)^{-\alpha}, while the ratio of the stellar mass in disks+irregulars to that in spheroids evolves as (1+z)^{-\beta}, and we derive constraints on \alpha, \beta and \epsilon. We find that \alpha>0 at the more than 4-sigma level, implying a larger black hole mass at higher redshift for a given spheroid stellar mass. The favored values for \beta are typically negative, suggesting that the fraction of stellar mass in spheroids decreases with increasing redshift. This is consistent with recent determinations that show that the mass density at high redshift is dominated by galaxies with irregular morphology. In agreement with earlier work, we constrain \epsilon to be between 0.04 and 0.11, depending on the exact value of the local SMBH mass density, but almost independently of \alpha and \beta.Comment: 7 pages, 3 figures. Accepted for publication in MNRAS pink page

Predictions for Ultra-Deep Radio Counts of Star-Forming Galaxies

We have worked out predictions for the radio counts of star-forming galaxies down to nJy levels, along with redshift distributions down to the detection limits of the phase 1 Square Kilometer Array MID telescope (SKA1-MID) and of its precursors. Such predictions were obtained by coupling epoch dependent star formation rate (SFR) functions with relations between SFR and radio (synchrotron and free-free) emission. The SFR functions were derived taking into account both the dust obscured and the unobscured star-formation, by combining far-infrared (FIR), ultra-violet (UV) and H_alpha luminosity functions up to high redshifts. We have also revisited the South Pole Telescope (SPT) counts of dusty galaxies at 95,GHz performing a detailed analysis of the Spectral Energy Distributions (SEDs). Our results show that the deepest SKA1-MID surveys will detect high-z galaxies with SFRs two orders of magnitude lower compared to Herschel surveys. The highest redshift tails of the distributions at the detection limits of planned SKA1-MID surveys comprise a substantial fraction of strongly lensed galaxies. We predict that a survey down to 0.25 microJy at 1.4 GHz will detect about 1200 strongly lensed galaxies per square degree, at redshifts of up to 10. For about 30% of them the SKA1-MID will detect at least 2 images. The SKA1-MID will thus provide a comprehensive view of the star formation history throughout the re-ionization epoch, unaffected by dust extinction. We have also provided specific predictions for the EMU/ASKAP and MIGHTEE/MeerKAT survey

Characterization of parameters influencing intracellular bioavailability and prediction of intracellular drug exposure

This thesis work investigates factors influencing intracellular drug disposition. An experimental method for measurement of intracellular bioavailability (Fic), was used throughout. Fic is defined as the ratio between the unbound drug concentration inside the cell and the compound concentration in the cell exterior. First, the impact of transporter proteins—such as the uptake transporter OATP-1B1 and the efflux transporter P-gp—on Fic was assessed in isolation in singly transfected, well-characterized cell models. The net impact of ADME proteins on Fic, including drug transporter proteins and metabolic enzymes, was assessed in primary human hepatocytes. The results indicated that the Fic measurement accurately reflected system-dependent functionality of these proteins. Second, the impact of cellular lipids on Fic was studied, in particular phospholipids (a major constituent of cellular membranes) and neutral lipids (in the form of neutral lipid droplets in adipocytes). Drug partitioning to phospholipids was found to be the major determinant of intracellular fraction of unbound drug (fu,cell), while neutral lipid droplets and cellular proteins played a relatively smaller role. Therefore, the importance of phospholipids, and their major four subspecies—phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS) and phosphatidylinositol (PI)—was investigated in a cell-free approach with purified phospholipids. Finally, Fic was applied in two ways to drug discovery settings. First, Fic successfully harmonized system-dependent CYP450 enzyme inhibition values (IC50) obtained in human hepatocytes and human liver microsomes. Fic measured in suspended human hepatocytes also reflected hepatic enrichment factors of CYP450 inhibitors used in physiologically-based pharmacokinetic modelling. Second, Fic was used as a complementary tool to study the effect of cell-penetrating peptides on intracellular disposition of targeted antisense oligonucleotide conjugates. Overall, the thesis contributes to the mechanistic understanding of Fic and demonstrates its use for drug compound profiling at an early stage in drug discovery settings