To form secondary structure, nucleic acids (NAs) must overcome electrostatic strand-strand repulsion, which is moderated by the surrounding atmosphere of screening ions. The free energy of NA folding therefore depends on the interactions of this ion atmosphere with both the folded and unfolded states. We quantify such interactions using the preferential ion interaction coefficient or ion excess...

We propose a mechanism of an inner medullary concentrating process in which water extraction is accomplished by a colloid osmotic mechanism and hydrostatic pressure. There are 3 essential features of the proposal: 1. the fluid compartmental structure of the inner medullary interstitium: owing to molecular exclusion, negatively charged macromolecules, i.e. hyaluronan and extravasated plasma albu...

The Gibbs energy minimization encompasses active use of the chemical potentials (partial molar Gibbs energies) of the constituents of the system. Usually, these appear at their equilibrium values as a result of the minimization calculation, the mass balance constraints being the necessary subsidiary conditions. Yet, there are several such physico-chemical circumstances where the system is also ...

I N T R O D U C T I O N Gary-Bobo and Solomon (1) have proposed that the anomalous osmotic behavior of the erythrocyte is due to a decrease of the net charge of hemoglobin which occurs when the hemoglobin concentration inside the erythrocyte is raised. Employing Donnan equilibrium studies, they subsequently (2) produced evidence to show that a hemoglobin charge dependence on hemoglobin concentr...

1. Calculations from the Fick diffusion law are shown to predict that membrane equilibria should be established during the course of ultrafiltration. 2. It is shown that the chloride ion is more concentrated and the sodium ion less concentrated in the ultrafiltrate than in the plasma from which the ultrafiltrate was derived. 3. It has been found that by increasing the base bound by protein thro...

Recently the pH of the blood has been exhaustively studied but that of the cerebrospinal fluid has received little attention. Because the composition of spinal fluid is less complex, the determination of pH and interpretation of the results should be simpler than for blood. Cerebrospinal fluid is not only free from hemoglobin but also contains so little protein as to be, for practical purposes,...

The cell-model and its treatment on the Poisson-Boltzmann level are two important concepts in the theoretical description of charged macro-molecules. In this brief contribution to Ref. [1] we provide an introduction to both ideas and summarize a few important results which can be obtained from them. Our article is organized as follows: Section 1 outlines the sequence of approximations which ult...

We present an experimentally guided, multi-phasic, multi-species ionic gel model to compare and make qualitative predictions on the rheology of mucus of healthy individuals (Wild Type) versus those infected with Cystic Fibrosis. The mixture theory consists of the mucus (polymer phase) and water (solvent phase) as well as several different ions: H+, Na+ and Ca2+. The model is linearized to study...

1. Analyses have been made of the electrolytes and proteins of serum and transudates from human subjects. 2. The distribution ratios of HCO(3), Cl, Na, and H(+) deviated from unity as predicted by the Gibbs-Donnan law for similar heterogeneous systems. 3. Analyses of serum, and of artificial salt solutions approximating edema fluid in composition, after equilibration across collodion membranes ...