Controlled self-assembly of stomatosomes by use of single-component fluorinated dendritic amphiphiles.

A series of novel non-ionic amphiphiles with dendritic oligoglycerol head groups of different generations ([G1]-[G3]) and lipophilic/fluorophilic tail segments, comprising single or double tail alkyl chains, C8F17-perfluoro rod segments as well as flexible spacer groups of different lengths were designed and synthesized. We expected that the differences in the size of the dendritic head groups in combination with perfluorinated segments would have an impact on the supramolecular structures formed in aqueous solution if compared with the hydrogenated analogues. Investigating the self-assembly behavior mainly by cryogenic transmission electron microscopy (cryo-TEM) and cryo-electron tomography (cryo-ET) we found as a new result the formation of perforated bilayer vesicles (stomatosomes) and bicontinuous network structures. Surprisingly, we have observed stomatosome formation by self-assembly of single component fluorinated dendritic amphiphiles. These assembly structures turned out to be extremely robust against harsh conditions, although there are strong indications that they represent non-equilibrium structures, which eventually transform into a bicontinuous cubic network structure of double diamond symmetry. In general, the molecular asymmetry of amphiphiles tuned by chemical design induced the expected trend from spherical micelles through worm-like micelles to perforated bilayers and three-dimensional network structures.

The left ventricular systolic function after digoxin administration in patients with chronic renal failure.

The responses in the left ventricular systolic time intervals following digoxin administration (0.5 mg i.v.) were studied in 11 patients with chronic renal failure and hypertension. The control group comprised 11 patients with mild essential hypertension. There were no clinical signs of congestive heart failure in any of the patients. Before digoxin administration total electromechanical systole (QS2), the pre-ejection period (PEP) and the PEP/LVET ratio were greater, while the left ventricular ejection time (LVET) was shorter than in the control group (P < 0.001). In patients with chronic renal failure digoxin administration induced a reduction in QS2, PEP and PEP/LVET ratio and a prolongation of LVET (P < 0.001). These data suggest latent heart failure in the group of patients studied with chronic renal failure. It seems to be advisable to use digitalis preparations in patients with chronic renal failure despite the absence of clinical signs of heart failure.