Synthesis and immobilization of a novel acridine derivative on microparticulate silica. A study of its interactions with single-stranded oligonucleotides by high-performance liquid chromatography

A novel approach for immobilizing acridine on 5-microns silica gel is described. The acridine moiety is functionalized with a carboxylic acid group at its reactive 9-position and activated, leading to 9-acridinylpropionic acid N-hydroxysuccinimide ester. This derivative is efficiently bound to the silica matrix through a primary aliphatic amine group at the end of a fifteen-atom spacer arm. The chromatographic properties of the final stationary phases, as evaluated with d(T)10 and d(A)10 at various pH values and organic solvent concentrations, resemble those of hydrophobic weak anion exchangers. When a secondary amine group is placed close to the acridine moiety in one of the packings, enhanced binding of the oligodeoxyribonucleotides is observed that goes beyond a purely additive effec

Introduction of 5'-terminal functional groups into synthetic oligonucleotides for selective immobilization

Oligodeoxyribonucleotides terminating in a 5'-primary amine group are synthesized using solid-phase supported phosphoramidite chemistry. The 5'-terminal amine group in the deprotected oligomers is further derivatized with either succinic anhydride to give 5'-carboxylic acid or with dithiobis(succinimidylpropionate) followed by treatment with dithioerythritol to produce 5'-thiol-terminated oligonucleotides. The 5'-thiol-terminated oligonucleotides are selectively immobilized on solid supports containing either p-chloromercuribenzoate or 2,2'-dithiobis(5-nitropyridine) activated thiol group

Social buffering: relief from stress and anxiety

Communication is essential to members of a society not only for the expression of personal information, but also for the protection from environmental threats. Highly social mammals have a distinct characteristic: when conspecific animals are together, they show a better recovery from experiences of distress. This phenomenon, termed ‘social buffering’, has been found in rodents, birds, non-human primates and also in humans. This paper reviews classical findings on social buffering and focuses, in particular, on social buffering effects in relation to neuroendocrine stress responses. The social cues that transmit social buffering signals, the neural mechanisms of social buffering and a partner's efficacy with respect to social buffering are also detailed. Social contact appears to have a very positive influence on the psychological and the physiological aspects of social animals, including human beings. Research leading towards further understanding of the mechanisms of social buffering could provide alternative medical treatments based on the natural, individual characteristics of social animals, which could improve the quality of life