A route for polonium 210 production from alpha-particle irradiated bismuth-209 target

A method is proposed for production of polonium-210 via the 209Bi(α, 3n)210At nuclear reaction. Bombardment of a bismuth-209 target was performed with a 37 MeV alpha-particle beam that leads to the production of astatine-210 (T1/2 = 8.1 h), which decays to polonium-210. It is purified from the bismuth target matrix by employing liquid-liquid extraction using tributyl phosphate (TBP) in para-xylene from 7 M hydrochloric acid. Back extraction of polonium-210 was performed by 9 M nitric acid. This method allows to purify a tracer amount of Po-210 (2.6 * 10-13 mol) from macroscopic amount of Bi (2.8 * 10-2 mol)

Quilamine HQ1-44, an iron chelator vectorized toward tumor cells by the polyamine transport system, inhibits HCT116 tumor growth without adverse effect

International audienceTumor cell growth requires large iron quantities and the deprivation of this metal induced by synthetic metal chelators is therefore an attractive method for limiting the cancer cell proliferation. The antiproliferative effect of the Quilamine HQ1-44, a new iron chelator vectorized toward tumor cells by a polyamine chain, is related to its high selectivity for the Polyamine Transport System (PTS), allowing its preferential uptake by tumoral cells. The difference in PTS activation between healthy cells and tumor cells enables tumor cells to be targeted, whereas the strong dependence of these cells on iron ensures a secondary targeting. Here, we demonstrated in vitro that HQ1-44 inhibits DNA synthesis and cell proliferation of HCT116 cells by modulating the intracellular metabolism of both iron and polyamines. Moreover, in vivo, in xenografted athymic nude mice, we found that HQ1-44 was as effective as cis-platin in reducing HCT116 tumor growth, without its side effects. Furthermore, as suggested by in vitro data, the depletion in exogenous or endogenous polyamines, known to activate the PTS, dramatically enhanced the antitumor efficiency of HQ1-44. These data support the need for further studies to assess the value of HQ1-44 as an adjuvant treatment in cance

Recent advances in cancer treatment by Iron Chelators

International audienceThe development of new therapeutic alternatives for cancers is a major public health priority. Among the more promising approaches, the iron depletion strategy based on metal chelation in the tumoral environment has been particularly studied in recent decades. After a short description of the importance of iron for cancer cell proliferation, we will review the different iron chelators developed as potential chemotherapeutics. Finally, the recent efforts to vectorize the chelating agents specifically in the microtumoral environment will be discussed in detai

Heterologous Expression of Membrane Proteins: Choosing the Appropriate Host

International audienceBACKGROUND: Membrane proteins are the targets of 50% of drugs, although they only represent 1% of total cellular proteins. The first major bottleneck on the route to their functional and structural characterisation is their overexpression; and simply choosing the right system can involve many months of trial and error. This work is intended as a guide to where to start when faced with heterologous expression of a membrane protein. METHODOLOGY/PRINCIPAL FINDINGS: The expression of 20 membrane proteins, both peripheral and integral, in three prokaryotic (E. coli, L. lactis, R. sphaeroides) and three eukaryotic (A. thaliana, N. benthamiana, Sf9 insect cells) hosts was tested. The proteins tested were of various origins (bacteria, plants and mammals), functions (transporters, receptors, enzymes) and topologies (between 0 and 13 transmembrane segments). The Gateway system was used to clone all 20 genes into appropriate vectors for the hosts to be tested. Culture conditions were optimised for each host, and specific strategies were tested, such as the use of Mistic fusions in E. coli. 17 of the 20 proteins were produced at adequate yields for functional and, in some cases, structural studies. We have formulated general recommendations to assist with choosing an appropriate system based on our observations of protein behaviour in the different hosts. CONCLUSIONS/SIGNIFICANCE: Most of the methods presented here can be quite easily implemented in other laboratories. The results highlight certain factors that should be considered when selecting an expression host. The decision aide provided should help both newcomers and old-hands to select the best system for their favourite membrane protein

Mise au point d'agents chélatants de radioéléments pour une application en radioimmunothérapie

1-3 Octobre 20

Conception de plates-formes moléculaires hétérocycliques (application à la synthèse d'analogues de nucléosides)

L objet de ce travail est une étude méthodologique en chimie hétérocyclique, qui décrit le développement d une stratégie de synthèse multi-étapes visant l obtention de composés bicycliques azotés. Le chapitre 1 traite de la synthèse d enchaînements hétérodiéniques azotés et soufrés thia(za)diène et (di)azadiène et de leur utilisation dans des réactions de cyclocondensation [4+2] pour la synthèse de plusieurs familles de pyrimidines S-méthylées carbonylées ou thiocarbonylées. Le chapitre 2 décrit les modifications structurales apportées aux pyrimidines en vue de la synthèse d un second cycle. L étape-clé de la synthèse est la substitution nucléophile du groupement méthylsulfanyle présent sur les pyrimidines ; elle conduit à la formation de pyrimido[1,2-a]pyrimidines 1,3,7-trisubstituées. Le chapitre 3 est une application directe de l étude méthodologique décrite aux chapitres précédents, qui présente la synthèse d analogues de nucléosides à base purique à partir de glycosylisothiocyanates.The purpose of this work is a methodological study in heterocyclic chemistry, aiming at the synthesis of nitrogen bicyclic compounds. Chapter 1 deals with the synthesis of sulfur and nitrogen heterodienic chains and their use in [4+2] heterocyclization reactions for the synthesis of carbonylated and thiocarbonylated methylsulfanylpyrimidines. Chapter 2 describes the structural modifications which were brought to pyrimidine rings in order to perform the second ring construction. The key-step of the strategy is the nucleophilic displacement of the methylsulfanyl group on the pyrimidine ring. The synthesis leads to the formation of 1,3,7-trisubstituted pyrimido[1,2-a]pyrimidines. Chapter 3 is an application of the described methodological approach. It outlines the synthesis of puric base nucleoside analogues from glycosylisothiocyanates.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Synthèse de ligands ambidents "N2S2" / "N4" pour des applications en médecine nucléaire

Ce mémoire de thèse décrit la conception et la synthèse de nouveaux agents chélatants pour des applications en médecine nucléaire et plus particulièrement pour la tomographie par émission de positrons (TEP) et la radioimmunothérapie (RIT). Les isotopes du cuivre sont reconnus pour leurs applications en TEP et en RIT, notre attention s est donc plus portée sur la chélation de ce métal. Après avoir déterminé les caractéristiques nécessaires à l obtention de ligands du cuivre, nous présenterons une méthode de synthèse efficace et flexible assistée par irradiations micro-ondes. La particularité de ces ligands est leur ambidence, c'est-à-dire leur capacité potentielle à chélater les métaux soit par quatre atomes d azote (ligands N4 ) soit par deux atomes d azote et deux atomes de soufre (ligands N2S2 ). Cette ambidence est rendue possible par un squelette de type bis(hydrazone) sur lequel sont reliés deux cycles thiazoles pouvant tourner par libre rotation autour d une liaison simple. Une fois établi le fait que ces agents chélatants étaient aisément fonctionnalisables pour être greffés à un vecteur biologique, leurs capacités complexantes ont été évaluées. Les complexes obtenus sont étudiés par différentes techniques analytiques comme l EDX, les spectroscopies UV-visible, IR, de masse, des rayons X, afin de déterminer leur structure. Nous conclurons sur les premiers tests de chélation de 64Cu réalisés dans le but d effectuer de la TEPThis work describes the design and the synthesis of new chelating agents for applications in nuclear medicine and particularly for positron emission tomography (PET) and radioimmunotherapy (RIT). Copper isotopes are known for their use in PET or in RIT, so we focus our attention on the complexation of this metal. After having determined characteristics required to get copper ligands, we present an efficient and versatile microwave-assisted method to synthesize copper ligands. The particularity of these chelating agents is the fact that they are ambident: they are potentially able to chelate metal with four nitrogen atoms (ligands "N4") or with two nitrogen atoms and two sulfur atoms (ligands "N2S2"). This property is given by a bis(hydrazone) skeleton containing two thiazol rings which can spin by free rotation around a single bond. After check that these ligands are easily functionnalisable to be attached to a biological vector, their chelating power was estimated. The complexes obtained were examined by several analytic methods such as EDX, UV, IR, mass, X-ray spectroscopies, to find their structure. We conclude with the first 64Cu complexation tests carried out for PET applicationNANTES-BU Sciences (441092104) / SudocSudocFranceF

RAAV WITH CHEMICALLY MODIFIED CAPSID

The invention is directed to the field of gene therapy, i.e. gene delivery into target cells, tissue, organ and organism, and more particularly to gene delivery via viral vectors. The inventors showed that it is possible by chemical coupling to modulate the coupling of a ligand in the surface of the capsid of AAV, for example AAV2 and AAV3b. In particular, the present invention relates to a recombinant Adeno-Associated Virus (rAAV) vector particle having at least one primary amino group contained in the capsid proteins, chemically coupled with at least one ligand L, wherein coupling of said ligand L is implemented through a bond comprising a -CSNH- bond and an optionally substituted aromatic moiety. Particularly, the inventors tested the chemical coupling of mannose ligand on AAV2 for subretinally injection to rats. The present invention further relates to a method for chemically coupling an Adeno-Associated Virus (AAV) vector particle with at least one ligand L and to a Recombinant Adeno-Associated Virus (rAAV) vector particle obtained by said method as well as a pharmaceutical composition comprising it and their corresponding medical use

Développement de nouveaux ligands polyaminés du fer pour la vectorisation anticancéreuse (synthèse, caractérisation et évaluation biologique)

The aim of this work is the development of new and selective iron (III) chelators bearing polyamine moieties to target the PTS and to induce specifically an iron depletion into tumor cells. These hybrid molecules, named Quilamines, are based on the association of 8-hydroxyquinoline with different polyamine chains. Synthesis and biological studies of different polyamine moieties, analogues of spermidine and spermine, showed that the homospermidine chain was the best choice for an efficient vectorization. Biological analysis highlighted a great PTS selectivity and a promising antiproliferative activity for some Quilamines. Structural modifications of the ligands allowed to modulate the iron complexation properties and to increase the selectivity and efficiency. Finally, for one compound, potentiometric titrations showed a high iron affinity constant and a good selectivity toward other biological metals such as cooper and zinc.L'objectif de ce travail de thèse est de développer de nouveaux ligands, spécifiques du fer (III), comportant une partie polyaminée pour la vectorisation par le STP afin d'induire spécifiquement une déplétion en fer dans les cellules tumorales et inhiber leur prolifération. Ces molécules chimères, appelées Quilamines, sont basées sur l'association de la 8-hydroxyquinoléine avec différentes chaînes polyaminées. La synthèse et l'étude biologique de différents motifs polyaminés dérivant de la sperdimine et de la spermidine ont montré que la chaîne homospermidine apparaît comme un vecteur de choix. De plus, des tests cellulaires de cytotoxicité ont mis en avant une forte sélectivité pour le STP ainsi qu'une activité antiproliférative prometteuse de certaines Quilamines. Des modifications structurales des ligands ont permis de changer le mode de coordination du fer et moduler leur efficacité ainsi que leur sélectivité pour le STP. Enfin, pour un des composés, l'analyse potentiométrique a mis en évidence une forte constante d'affinité pour le fer ainsi qu'une sélectivité vis-à-vis des autres métaux d'intérêt biologique comme le cuivre et le zinc.NANTES-BU Sciences (441092104) / SudocSudocFranceF