The effect of electrolytes and nonelectrolytes on the micellar behavior of amitriptyline (AMT), an amphiphilic drug, has been investigated using cloud point (CP) and dye solubilization techniques. The critical micelle concentration (cmc) of AMT determined by the Wilhelmy plate method was about 40mM in the presence of 10mM sodium phosphate, and it reduced to about 20mM in the presence of 500mM s...

Permeability characteristics of the membrane lesion generated by the terminal complement proteins are considered in light of recent observations that the measured diffusion of solute across complement-damaged membranes does not conform to the "doughnut hole" model of a discrete transmembrane pore formed by the inserted C5b-9 complex. By using the measured kinetics of steady-state tracer isotope...

obtained here; and (3) the Soret coefficient u* obtained in TGTD experiments on electrolyte solutions differs from the Soret coefficient u obtained in nonelectrolyte mixtures as discussed at the end of section 3. These results agree in form with the results for nonelectrolytes.6 The important new features for electrolytes are (1) the present approach is considerably improved in simplicity and a...

Compacted membrane arrays are formed in the nerve myelin sheath by lowering the water activity (through evaporation or immersion in hypertonic solutions of nonelectrolytes or monovalent salts) or by binding specific cations (Ca(++), La(+++), and tetracaine at concentrations above 5-10 mM). X-ray diffraction observations on intact, hydrated nerves treated to induce compaction provide a control t...

The permeability of lecithin bilayer membranes to nonelectrolytes is in reasonable agreement with Overton's rule. The is, Pd alpha DKhc, where/Pd is the permeability coefficient of a solute through the bilayer, Khc is its hydrocarbon:water partition coefficient, and D is its diffusion coefficient in bulk hydrocarbon. The partition coefficients are by far the major determinants of the relative m...

Dermatological and cosmetic preparations frequently contain active principles which can only act when they penetrate at least the outermost layer of the skin. However, the efficacy of topically applied actives is often suboptimal because the transport into the skin is slow due to the resistance of the outermost layer of the skin, the stratum corneum. Most small water-soluble nonelectrolytes the...

When the water activity (a(w)) of the medium is lowered by the addition of NaCl or nonelectrolytes, an inhibition of germination, growth rate, and total growth is observed in Neurospora crassa. Inhibition of conidial germination is separable from the other effects and is caused, in large measure, by the loss from conidia in media of low water activity of a substance that is essential for their ...