Behenamidopropyl Dimethylamine: unique behaviour in solution and in hair care formulations.

SYNOPSIS: The rise of ecological awareness among consumers and industry has impacted the cationic surfactants market. The most used cationic surfactants present some drawbacks in this sense. Therefore, new molecules are being studied and developed which fulfil eco-toxicological requirements without losing performance. One of these surfactants is Behenamidopropyl Dimethylamine (BAPDMA). This biodegradable amidoamine, which converts into a cationic surfactant at acidic pH, shows outstanding water solubility, despite its very long alkyl chain. Its behaviour in solution has been exhaustively studied. The conditioning performance of this product is superior to that of commonly used cationic surfactants, providing a superior sensorial profile and improved combing force reductions on hair. Moreover, other applications for this product in the non-ionic form have been studied, such as conditioning agent in 2 in 1 shampoos, where it also shows colour protection effects, and as gelling agent in hair colouration creams. This multifunctional and high performance profile, together with an improved biodegradation and aquatic toxicity compared with currently used cationic surfactants, make this product a very interesting eco-friendly alternative for the hair care market.

Stereochemistry of phenyl alpha-nitronyl nitroxide radicals

An extensive investigation of the conformations adopted by the family of phenyl alpha-nitronyl nitroxides has been carried out. A database containing 110 crystal structures was used in a statistical study of the solid-state geometries and conformations of these radicals. This study revealed that the favoured conformations involve a twisted distortion in the imidazolyl rings and a twist between the aromatic and heterocyclic rings in the molecules. As a consequence, these radicals show two types of preferred conformations in the solid state: the pseudo-anti enantiomeric pair and the pseudo-eclipsed pair, the latter type being the most statistically probable. A new chiral member of this group of radicals that bears a lactate moiety, (R)-1, and its corresponding racemic compound, (R,S)-1, have been prepared in order to study the influence of chiral induction from the stereogenic centre on the torsion angle between the aromatic and heterocyclic rings of the alpha-nitronyl nitroxides. The X-ray crystal structures of the enantiopure and racemic compounds, which both reveal chains of molecules sustained by strong O-H...O hydrogen bonds between the carboxylic acid group and the ON group of the radical in the solid, as well as their magnetic properties have been determined. Remarkably, the molecules with a given stereogenic centre have a single helical sense between their component rings, even in the racemic crystal. Chiral induction from the stereogenic centre to the radical unit has also been proved by CD spectroscopy in the solid state. The results of these experiments have been rationalised by ab initio calculations of the spectra.

Changes in cervicocephalic kinesthesia after a proprioceptive rehabilitation program in patients with neck pain: a randomized controlled study.

Head repositioning accuracy (HRA) after full range active motion was evaluated in 60 cervicalgic patients. The mean angular error was 7.7 degrees +/- 3.3 (mean +/- SD) and 82% were outside a threshold value of 4.5 degrees. After randomization 30 patients followed a rehabilitation program based on eye-head coupling (RG) and 30 served as a control group (CG). At 10 week follow-up, a greater gain in HRA was observed in the RG (2 degrees +/- 2.7, mean +/- SD) than in the CG (0 +/- 2.6, mean +/- SD) (p = 0.005). Clinical parameters (pain, drug intake, range of motion, and self assessed functional improvement) were also more improved in the RG than in the CG. These data emphasize the role of a neck proprioception alteration in chronic neck pain and suggest that a rehabilitation program based on eye-head coupling should be included in most medical management of cervicalgic patients.

Cervicocephalic kinesthetic sensibility in patients with cervical pain.

Head orientation in space makes use of multiple sensory afferents, among which the cervical proprioceptive cues could play a predominant role. To quantify the alteration of neck proprioception in patients with cervical pathology, we proposed a test for the clinical evaluation of the ability to relocate the head on the trunk after an active head movement, for 30 healthy subjects and 30 patients with cervical pain. The data demonstrated that this ability was significantly poorer in the patient group, indicating an alteration in neck proprioception. This test permits a discriminant classification of healthy and sick subjects, justifies proprioceptive rehabilitation programs, and allows a quantitative evaluation of their results.