GMP Production of [18 F]SynVesT-1, a Radioligand for in vivo PET Imaging of Synaptic Vesicle Glycoprotein 2A

[¹⁸ F]SynVesT-1 (also known as [¹⁸ F]SDM-8 or [¹⁸ F]MNI-1126) is a potent and selective synaptic vesicle glycoprotein 2 (SV2A) positron emission tomography (PET) imaging agent. I order to fulfill the increasing clinical demand of an ¹⁸ F-labelled SV2A PET ligand, we have developed a fully automated procedure to provide a sterile and pyrogen-free GMP-compliant product of [¹⁸ F]SynVesT-1 suitable for clinical studies in humans. [¹⁸ F]SynVesT-1 is synthesized via a rapid copper-mediated radiofluorination protocol. The procedure was developed and established on a commercially available module, TracerMaker (ScanSys Laboratorieteknik ApS, Copenhagen, Denmark), a synthesis platform originally developed to conduct carbon-11 radiochemistry. From ~130 GBq (end-of-bombardment), our newly developed procedure enabled us to prepare [¹⁸ F]SynVesT-1 in an isolated radioactivity yield of 14220 ± 800 MBq (n = 3), which corresponds to a radiochemical yield (RCY) of 19.5 ± 0.5%. The radiochemical purity (RCP) and enantiomeric purity of each of the final formulated batches exceeded 98%. The overall synthesis time was 90 min and the molar activity 330 ± 60 GBq/μmol (8.9 ± 1.6 Ci/μmol). The produced [¹⁸ F]SynVesT-1 was stable over 8 hours at room temperature and is suitable for in vivo PET imaging studies in human subjects.

Dietary green-plant thylakoids decrease gastric emptying and gut transit, promote changes in the gut microbial flora, but does not cause steatorrhea

Green-plant thylakoids increase satiety by affecting appetite hormones such as ghrelin, cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1). The objective of this study was to investigate if thylakoids also affect gastrointestinal (GI) passage and microbial composition. To analyse the effects on GI passage, 16 rats were gavage-fed a control or thylakoid-supplemented high-fat diet (HFD) 30 min before receiving Evans blue. Another 16 rats were fed a control HFD or thylakoid HFD for two weeks prior to the intragastric challenge with Evans blue. The amount of Evans blue in the stomach and the distance of migration in the intestines after 30 min were used as a measurement of gastric emptying and intestinal transit. These were reduced by thylakoid supplementation in the acute study, and however not significantly also after the two-week diet study.

The second aim of the study was to investigate if thylakoid-supplementation affects the gut microbiota and amount of faecal fat in healthy human volunteers (n = 34) receiving thylakoid or placebo treatments for three months. Microbiota was analysed using 16S rRNA gene sequencing and qPCR, and faecal fat was extracted by dichloromethane. The total bacteria, and specifically the Bacteriodes fragilis group, were increased by thylakoid treatment versus placebo, while thylakoids did not cause steatorrhea. Dietary supplementation with thylakoids thus affects satiety both via appetite hormones and GI fullness, and affects the microbial composition without causing GI adverse effects such as steatorrhea. This suggests thylakoids as a novel agent in prevention and treatment of obesity.

Structural and functional consequences of buserelin-induced enteric neuropathy in rat

BACKGROUND

Women treated with gonadotropin-releasing hormone (GnRH) analogs may develop enteric neuropathy and dysmotility. Administration of a GnRH analog to rats leads to similar degenerative neuropathy and ganglioneuritis. The aim of this study on rat was to evaluate the early GnRH-induced enteric neuropathy in terms of distribution of neuronal subpopulations and gastrointestinal (GI) function.

METHODS

Forty rats were given the GnRH analog buserelin (20 μg, 1 mg/ml) or saline subcutaneously, once daily for 5 days, followed by 3 weeks of recovery, representing one treatment session. Two weeks after the fourth treatment session, the animals were tested for GI transit time and galactose absorption, and fecal weight and fat content was analyzed. After sacrifice, enteric neuronal subpopulations were analyzed. Blood samples were analyzed for zonulin and antibodies against GnRH and luteinizing hormone, and their receptors.

RESULTS

Buserelin treatment transiently increased the body weight after 5 and 9 weeks (p < 0.001). Increased estradiol in plasma and thickened uterine muscle layers indicate high estrogen activity. The numbers of both submucous and myenteric neurons were reduced by 27%-61% in ileum and colon. The relative numbers of neurons containing calcitonin gene-related peptide (CGRP), cocaine- and amphetamine-related transcript (CART), galanin, gastrin-releasing peptide (GRP), neuropeptide Y (NPY), nitric oxide synthase (NOS), serotonin, substance P (SP), vasoactive intestinal peptide (VIP) or vesicular acetylcholine transporter (VAchT), and their nerve fiber density, were unchanged after buserelin treatment, but the relative number of submucous neurons containing somatostatin tended to be increased (p = 0.062). The feces weight decreased in buserelin-treated rats (p < 0.01), whereas feces fat content increased (p < 0.05), compared to control rats. Total GI transit time, galactose absorption, zonulin levels in plasma, and antibody titers in serum were unaffected by buserelin treatment.

CONCLUSIONS

A marked enteric neuronal loss with modest effects on GI function is found after buserelin treatment. Increased feces fat content is suggested an early sign of dysfunction.