Radiochemical synthesis of 18F-radiolabelled ProTides for Positron Emission Tomography

Positron Emission Tomography (PET) is a highly sensitive imaging technique used in cancer diagnosis, treatment planning and monitoring of therapy response. [18F] is an optimal PET label considering its half-life (110 min) and imaging resolution. One of the major challenges in [18F]-PET research is the installation of the weakly nucleophilic [18F]fluoride into a precursor molecule to access novel [18F]-tracers. Fluorinated nucleosides represent an important class of diagnostic probes for PET imaging as well as anticancer and antiviral therapeutic agents. However drug resistance still represents a major problem. The ProTide approach is a strategy to synthesize prodrugs of the nucleoside monophosphates which overcome their main resistance mechanisms. The challenge of the project is the [18F]-fluorination (hot fluorination) of ProTides which may be potential new PET imaging agents and could thus represent a model system to visualize pharmaceutical effects and bioactivation of ProTides directly in vivo. The pro-nucleotide multistep synthetic chemistry has been applied for the synthesis of ProTides. The [18F]-radiolabeling of the precursor molecules was performed in an Eckert & Ziegler automated synthetic Modular Lab placed into a shielded hot cell. The radioactive reaction mixtures were analyzed by radio HPLC, and radio TLC. Two different approaches have been followed to access two chemically distinct radiolabelled ProTides. The 3’-[18F]FLT ProTide was synthesised via a late stage [18F]fluorination of ad hoc synthesised precursor molecules (Figure 1). Figure 1: Radiochemical synthesis of 18F- FLT ProTides The 2’-[18F]FIAU ProTide was synthesised via an early stage [18F]fluorination approach (Figure 2). Figure 2: Radiochemical synthesis of 18F-FIAU ProTides These radiolabelled probes could provide evidence for the in vivo behaviour of this class of compounds by answering key questions about their metabolism and uptake directly. In addition, the project focused on the synthesis of two novel classes of non-radiolabelled fluorinated ProTides. A series of uridine based ProTides (FIAU ProTides) and a series of coumarin based FLT ProTides have been synthesised and evaluated for their antiviral activity and fluorescent properties respectively

Intralabyrinthine Schwannoma of the Intravestibular Subtype: A Difficult Diagnosis

Intralabyrinthine schwannoma is a rare, slow-growing, benign tumor that affects the most terminal portions of the vestibular and cochlear nerves. It can be located in the vestibule, cochlea, or semicircular canals. In 2004, Kennedy et al proposed a classification system which recognized 7 subtypes of intralabyrinthine schwannoma; in 2013, Abel et al1 modified the Kennedy classification,2 which included intracochlear, intravestibular (IV), intravestibulocochlear, transmodiolar, transmacular, transotic, and tympanolabyrinthine, to also include translabyrinthine, tumors extending into the CPA, and tumors not otherwise specified. They also proposed to rename intralabyrinthine schwannoma as primary inner ear schwannoma to permit clear subsite categorization. Patients usually have nonspecific symptoms, including hearing loss, tinnitus, and only single episode of vertigo. Among the resulting symptoms, the most frequent is hearing loss, which affects 95% of the patients. Most times, this loss is slow and progressive, but it may be sudden or fluctuating. Less common symptoms include tinnitus (51%), imbalance (35%), vertigo (22%), and ear fullness (2%), which may be present alone or in combination.3-7 We report a rare case of a patient with hearing loss and single episode of vertigo secondary to the intralabyrinthine schwannoma of the IV subtype

Fluorinated nucleosides as an important class of anticancer and antiviral agents

Fluorine-containing nucleoside analogs (NAs) represent a significant class of the US FDA-approved chemotherapeutics widely used in the clinic. The incorporation of fluorine into drug-like agents modulates lipophilic, electronic and steric parameters, thus influencing pharmacodynamic and pharmacokinetic properties of drugs. Fluorine can block oxidative metabolism of drugs and the formation of undesired metabolites by changing H-bonding interactions. In this review, we focus our attention on chemical fluorination reagents and methods used in the NAs field, including positron emission tomography radiochemistry. We briefly discuss both the cellular biology and clinical properties of FDA-approved and fluorine-containing nucleoside/nucleotide analogs in development as well as common resistance mechanisms associated with their use. Finally, we emphasize pronucleotide strategies used to improve therapeutic outcome of NAs in the clinic. </jats:p

ADC Benchmark Range for Correct Diagnosis of Primary and Recurrent Middle Ear Cholesteatoma

Objectives. Magnetic resonance imaging (MRI) and in particular diffusion-weighted imaging (DWI) have been broadly proven to be the reference imaging method to discriminate between cholesteatoma and noncholesteatomatous middle ear lesions, especially when high tissue specificity is required. The aim of this study is to define a range of apparent diffusion coefficient (ADC) values within which the diagnosis of cholesteatoma is almost certain. Methods. The study was retrospectively conducted on a cohort of 124 patients. All patients underwent first- or second-look surgery because primary or secondary acquired cholesteatoma was clinically suspected; they all had preoperative MRI examination 15 days before surgery, including DWI from which the ADC maps were calculated. Results. Average ADC value for cholesteatomas was 859,4 × 10−6 mm2/s (range 1545 × 10−6 mm2/s; IQR = 362 × 10−6 mm2/s; σ = 276,3 × 10−6 mm2/s), while for noncholesteatomatous inflammatory lesions, it was 2216,3 × 10−6 mm2/s (range 1015 × 10−6 mm2/s; IQR = 372,75 × 10−6 mm2/s; σ = 225,6 × 10−6 mm2/s). Interobserver agreement with Fleiss’ Kappa statistics was 0,96. No overlap between two groups’ range of values was found and the difference was statistically significant for p<0.0001. Conclusions. We propose an interval of ADC values that should represent an appropriate benchmark range for a correct differentiation between cholesteatoma and granulation tissue or fibrosis of noncholesteatomatous inflammatory lesions

Radiosynthesis of [18F]-Labelled Pro-Nucleotides (ProTides).

Phosphoramidate pro-nucleotides (ProTides) have revolutionized the field of anti-viral and anti-cancer nucleoside therapy, overcoming the major limitations of nucleoside therapies and achieving clinical and commercial success. Despite the translation of ProTide technology into the clinic, there remain unresolved in vivo pharmacokinetic and pharmacodynamic questions. Positron Emission Tomography (PET) imaging using [18F]-labelled model ProTides could directly address key mechanistic questions and predict response to ProTide therapy. Here we report the first radiochemical synthesis of [18F]ProTides as novel probes for PET imaging. As a proof of concept, two chemically distinct radiolabelled ProTides have been synthesized as models of 3'- and 2'-fluorinated ProTides following different radiosynthetic approaches. The 3'-[18F]FLT ProTide was obtained via a late stage [18F]fluorination in radiochemical yields (RCY) of 15-30% (n = 5, decay-corrected from end of bombardment (EoB)), with high radiochemical purities (97%) and molar activities of 56 GBq/μmol (total synthesis time of 130 min.). The 2'-[18F]FIAU ProTide was obtained via an early stage [18F]fluorination approach with an RCY of 1-5% (n = 7, decay-corrected from EoB), with high radiochemical purities (98%) and molar activities of 53 GBq/μmol (total synthesis time of 240 min)

Reduction of De Novo Lipogenesis Mediates Beneficial Effects of Isoenergetic Diets on Fatty Liver: Mechanistic Insights from the MEDEA Randomized Clinical Trial

Background: Non‐alcoholic liver steatosis (NAS) results from an imbalance between hepatic lipid storage, disposal, and partitioning. A multifactorial diet high in fiber, monounsaturated fatty acids (MUFAs), n‐6 and n‐3 polyunsaturated fatty acids (PUFAs), polyphenols, and vitamins D, E, and C reduces NAS in people with type 2 diabetes (T2D) by 40% compared to a MUFA‐rich diet. We evaluated whether dietary effects on NAS are mediated by changes in hepatic de novo lipogenesis (DNL), stearoyl‐CoA desaturase (SCD1) activity, and/or β‐ oxidation.; Methods: According to a randomized parallel group study design, 37 individuals with T2D completed an 8‐week isocaloric intervention with a MUFA diet (n = 20) or multifactorial diet (n = 17). Before and after the intervention, liver fat content was evaluated by proton magnetic resonance spectroscopy, serum triglyceride fatty acid concentrations measured by gas chromatography, plasma β‐hydroxybutyrate by enzymatic method, and DNL and SCD‐1 activity assessed by calculating the palmitic acid/linoleic acid (C16:0/C18:2 n6) and palmitoleic acid/palmitic acid (C16:1/C16:0) ratios, respectively; Results: Compared to baseline, mean ± SD DNL significantly decreased after the multifactorial diet (2.2 ± 0.8 vs.1.5 ± 0.5, p = 0.0001) but did not change after the MUFA diet (1.9 ± 1.1 vs. 1.9 ± 0.9, p = 0.949), with a significant difference between the two interventions (p = 0.004). The mean SCD‐1 activity also decreased after the multifactorial diet (0.13 ± 0.05 vs. 0.10 ± 0.03; p = 0.001), but with no significant difference between interventions (p = 0.205). Fasting plasma β‐hydroxybutyrate concentrations did not change significantly after the MUFA or multifactorial diet. Changes in the DNL index significantly and positively correlated with changes in liver fat (r = 0.426; p = 0.009). Conclusions: A diet rich in multiple beneficial dietary components (fiber, polyphenols, MUFAs, PUFAs, and other antioxidants) compared to a diet rich only in MUFAs further reduces liver fat accumulation through the inhibition of DNL. Registered under ClinicalTrials.gov no. NCT03380416

Virtual screening, SAR and discovery of 5-(indole-3-yl)-2-[(2-nitrophenyl)amino] [1,3,4]-oxadiazole as a novel Bcl-2 inhibitor

A new series of oxadiazoles were designed to act as inhibitors of the anti-apoptotic Bcl-2 protein. Virtual screening led to the discovery of new hits that interact with Bcl-2 at the BH3 binding pocket. Further study of the structure-activity relationship of the most active compound of the first series, compound 1, led to the discovery of a novel oxadiazole analogue, compound 16j, that was a more potent small molecule inhibitor of Bcl-2. 16j had good in vitro inhibitory activity with sub-micromolar IC50 values in a metastatic human breast cancer cell line (MDA-MB-231) and a human cervical cancer cell line (HeLa). The antitumour effect of 16j is concomitant with its ability to bind to Bcl-2 protein as shown by an enzyme linked immunosorbent assay (IC50 = 4.27 μM). Compound 16j has a great potential to develop into highly active anticancer agent

Thyroid papillary carcinoma arising in ectopic thyroid tissue within a neck branchial cyst

BACKGROUND: Thyroid gland derives from one median anlage at the base of the tongue, and from the two fourth branchial pouches. A number of anomalies may occur during their migration. These can be in form of ectopic tissues, which are frequently found along the course of thyroglossal duct and rarely in other sites, many of these may develop same diseases as the thyroid gland. CASE PRESENTATION: A 36-years-old female presented with a 3 month history of left side neck mass. The mass disappeared following aspiration of brown colored fluid, which on cytological examination showed cells with nuclear irregularities that warranted the resection of the lesion. The histology demonstrated a thyroid papillary carcinoma arising within the branchial cyst. Thereafter, the patient underwent a total thyroidectomy with central lymph nodes dissection. Histology showed a multifocal papillary carcinoma with central lymph nodes metastases. Only four cases of primary thyroid carcinomas in neck branchial cyst have been described so far. CONCLUSION: In a lateral cystic neck mass, although rare, occurrence of ectopic thyroid tissue and presence of a papillary thyroid carcinoma should be kept in mind