Formule topologique

Résumé

La formule topologique est une représentation moléculaire simplifiée utilisée en chimie organique et développée par le chimiste organicien Friedrich Kekulé. Une formule topologique fait abstraction de la représentation des atomes de carbone et d'hydrogène pour ne montrer que la structure du squelette. Le squelette Le squelette d'un composé organique est la chaîne d'atomes qui, connectés les uns aux autres, forme l'essentiel de la structure du composé représenté alors que les groupes fonctionnels sont considérés comme des substituants (des « rajouts ») du squelette. Ce squelette peut comporter une ou plusieurs chaînes, branches ou cycles. Les atomes autres que le carbone et l'hydrogène sont appelés hétéroatomes. Un composé organique a des atomes d'hydrogène ou d'autres substituants connectés aux atomes de carbone. L'hydrogène est l'atome le plus couramment lié à un atome carbone et n'est pas explicitement représenté. Les hétéroatomes et les groupements d'atomes sont appelé

Source officielle

https://fr.wikipedia.org/wiki/Formule_topologique

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Detection and Strain Typing of Ancient Mycobacterium leprae from a Medieval Leprosy Hospital

Stewart Cole, Pushpendra Singh

Nine burials excavated from the Magdalen Hill Archaeological Research Project (MHARP) in Winchester, UK, showing skeletal signs of lepromatous leprosy (LL) have been studied using a multidisciplinary approach including osteological, geochemical and biomolecular techniques. DNA from Mycobacterium leprae was amplified from all nine skeletons but not from control skeletons devoid of indicative pathology. In several specimens we corroborated the identification of M. leprae with detection of mycolic acids specific to the cell wall of M. leprae and persistent in the skeletal samples. In five cases, the preservation of the material allowed detailed genotyping using single-nucleotide polymorphism (SNP) and multiple locus variable number tandem repeat analysis (MLVA). Three of the five cases proved to be infected with SNP type 3I-1, ancestral to contemporary M. leprae isolates found in southern states of America and likely carried by European migrants. From the remaining two burials we identified, for the first time in the British Isles, the occurrence of SNP type 2F. Stable isotope analysis conducted on tooth enamel taken from two of the type 3I-1 and one of the type 2F remains revealed that all three individuals had probably spent their formative years in the Winchester area. Previously, type 2F has been implicated as the precursor strain that migrated from the Middle East to India and South-East Asia, subsequently evolving to type 1 strains. Thus we show that type 2F had also spread westwards to Britain by the early medieval period.

Public Library of Science2013

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Synthesis of Adamantane Aminoethers with Antitubercular Potential

Stewart Cole, Anthony Vocat

Background: Intrigued by the fact that aminoadamantane derivatives, bearing the active 1,2-ethylenediamine moiety, are promising antitubercular agents, we report herein the synthesis and the antitubercular evaluation of N,N'-substituded-4,4'-[adamantane-2,2-diyl]bis(phe-noxyalkylamines) 1a-g, N,N'-substituded-4,4'-[adamantane-1,3-diyl]bis(phenoxyalkylamines) 2a-f, N,N'-substituded-[4-(1-adamantyl)phenoxy]alkylamines 3a-d and N,N'-substituded-[4-(2-adamantyl)phenoxy]alkylamines 4a, b. Method: A substituted diarylmethane moiety was introduced on the adamantane skeleton of the new derivatives. The synthesis of the above compounds involved the nucleophilic attack of the corresponding phenoxide, to the appropriate aminoalkylchloride hydrochloride under heating. Results: The double substituted adamantane derivatives with an aminoether side chain exhibit significant activity against Mycobacterium tuberculosis. Conclusion: The length and the nature of the amino end of the side chain influence the antitubercular activity. The double phenolic substitution of the adamantane scaffold and the aminoether side chain with a three-methylene spacer between the phenoxy group and the nitrogen atom present the better results. (analogues 1f, g and 2e, f). These findings merit further investigation aiming at the design of more potent adamantane antituberculars, bearing a number of different substituents on the diarylmethane pharmacophore, which will also be translocated to other posititions on the adamantane ring.

Bentham Science Publ Ltd2017

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Additive and global functions of HoxA cluster genes in mesoderm derivatives

Denis Duboule, Ute Koch, Freddy Radtke

Hox genes encode transcription factors that play a central role in the specification of regional identities along the anterior to posterior body axis. In the developing mouse embryo, Hox genes from all four genomic clusters are involved in range of developmental processes, including the patterning of skeletal structures and the formation of several organs. However, the functional redundancy observed either between paralogous genes, or among neighboring genes from the same cluster, has hampered functional analyses, in particular when synergistic, cluster-specific functions are considered. Here, we report that mutant mice lacking the entire HoxA cluster in mesodermal lineages display the expected spectrum of postnatal respiratory, cardiac and urogenital defects, previously reported for single gene mutations. Likewise, mild phenotypes are observed in both appendicular and axial skeleton. However, a striking effect was uncovered in the hematopoietic system, much stronger than that seen for Hoxa9 inactivation alone, which involves stem cells (HSCs) as well as the erythroid lineage, indicating that several Hoxa genes are necessary for normal hematopoiesis to occur. Finally, the combined deletions of Hoxa and Hoxd genes reveal abnormalities in axial elongation as well as skin morphogenesis that are likely the results of defects in epithelial-mesenchymal interactions.

Elsevier2010

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