Most living cells possess asymmetric membranes in which the concentration of ions in the interior is quite different from that in the extracellular fluid. The unequal distribution of ions plays a major role in the generation of small electric currents that conduct the nerve impulse. This condition appears associated with an exchange of extracellular sodium with intracellular potassium. J. H. Schulman and H. L. Rosanol have used a liquid membrane model for studying the selective flux of various salts through short chain alkyl alcohols. The apparatus consisted essentially of a thermostated polystyrene box with a partition. An aqueous solution was placed in each compartment over which was floated a nonaqueous liquid membrane (FIGURE 1). The advantage of a liquid membrane is twofold: interfacial orientation; interfacial homogeneity versus pore size with a solid membrane. The use of a physicochemical model makes it possible to investigate an initially simple system in which the complexity of the actual membrane can be achieved by adding different physiological components.Schulman and Rosano have studied the diffusion of different salts through different oil layers under varying conditions. This phenomenon was called diffusion transport. In the presence of an amphoteric phospholipid (carrier) in the oil membrane interface, the transport is markedly increased; this phenomenon was called carrier transport. This carrier transport functions also when the diffusion process has been blocked.With regard to the effect of biological components upon the selective flux of salts and ions through nonaqueous membranes, a review of the diffusion transport will be given. B j u s i o n TransportIf V is the volume of oil and A the area of the two identical oil-water interfaces, the cell is equivalent to a membrane of V / A thickness; this is true provided that the thickness of the oil layers is sufficient to allow for a fairly homogeneous system when stirred. The volume of the oil phase is directly related to the partition coefficient of the oil-water system and therefore is related to the diffusion transport. By equating the diffusion transport phenomenon to a diffusion across an homogeneous membrane in the same mathematical form as the general flux equation for electrolytes,2 the results may be represented by assuming the following equation:This article is primarily an extension of this work.

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HIV testing can be included in the routine battery of tests offered at an STD clinic with high patient acceptance. Routine testing can discover those who are unaware of their HIV-positive status, providing an opportunity for early referral for treatment, counseling to avoid disease transmission, and notification of sexual contacts.

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Studies concerned with medication compliance after initial prescription dispensing have been frequently cited in the literature; however, little research has been done on the initial filling of the prescription order. In order to ascertain the degree of compliance at the initial filling level, a study was carried out on a population associated with a neighborhood health center. Overall, the study indicated an initial filling compliance of 94 percent, which was affected by the site of patient encounter, the chronicity of the disease, and the specificity of the medication in relationship to the disease state. It was concluded that: prescriptions for chronic medications are filled at a higher rate than those for acute illnesses; specific medication for a specific illness has a much higher compliance rate than nondisease specific medications; ease of access to a pharmacy is related to a higher compliance level; and frequent patient contact for a specific disease tends to increase compliance.