Frederick C. Nachod

SOME ASPECTS OF CATION EXCHANGE RESINS AS THERAPEUTIC AGENTS FOR SODIUM REMOVAL

Since Dock’s publication in 1946,’ about fifty papers dealing with the use of cation exchange resins for restricting sodium absorption have appeared.2 Approximately 7.5 per cent of these papers have dealt with studies in human subjects and, as a result, the potentialities, limitations, and hazards4, of the procedure are quite well defined. I t is clear that a valuable therapeutic medicament, although one which requires thorough understanding if it is to be effectively and safely used, has become available. Several typesa of exchange resins can be employed to produce changes in cation metabolism. These resins differ with respect to both matrix and functional groups. Two types of functional groups, the sulfonic and the carboxylic, have been extensively studied in this connection. I t is the object of this paper to discuss critically the inherent differences in behavior of these two materials, specifically: (1) their relative efficiency in the removal of sodium from the alimentary canal; (2) the effect of the sodium and potassium levels in the diet on their cation uptake; and (3) other considerations related to their therapeutic usefulness. If one sets out to evaluate a new therapeutic agent, the chronic toxicity problem must be taken into account. We have carried out in our laboratories an extensive long-term feeding experiment in addition to many short-term studies. FIGURE 1 shows growth curves of some of the animals on the longterm experiment, up to and including its 65th week. This is a length of time which represents approximately one-third the life span of the rats. The results indicated no significant decrease in the rate of growth at resin levels of 10 per cent of the diet. A comparison of in vivo uptake of sodium, potassium, and total alkali metal ions by sulfonic and carboxylic resins is shown in TABLE 1. I t indicates a 25 per cent better average uptake by three sulfonic preparations than with the three carboxylic formulations. It also shows about equal potassium removal, and a better selectivity coefficient of the sulfonic type for sodium. Much has been said about the higher in witro capacity of the carboxylic resins (about 12 meq./g.) in contrast to the sulfonic types (about S meq./g.). It should be remembered, however, that the full capacity of the carboxylic types is realized only at pH values above 10, due to the weak ionization constant of the functional group. Under physiological conditions this high ‘‘ theoretical” capacity is not available. Hence, an efficiency ratio, which we could define as the in vivo capacity for sodium plus potassium divided by the maximum theoretical capacity, yields values of 0.33 and 0.11 for the two types, respectively, i .e. a greater efficiency or saturation of the sulfonic resin. The same conclusion with respect to superiority of sulfonic over carboxylic resins as therapeutic agents was reached by Herken and Wolf,3 who stressed the ad-

Infrared Spectroscopy in H2O, D2O and CH3OH:

As the technique of infrared spectroscopy has developed, more and more problems have arisen where it would be desirable to be able to measure the infrared spectrum of a compound in water or alcoholic solutions.

Use of the tandem-transfer technique in the rapid separation on ion-exchange resin papers of phenyl-alanine and tyrosine from mixtures of amino acids

Abstract Using the tandem-transfer technique ( T -effect), the aromatic amino acids, phenylalanine and tyrosine, have been isolated from casein hydrolyzates and simultaneously separated from each other by one-step chromatography on cation-exchange papers. The total development time is about 80 min, using a 0.2 M , pH-5.2 acetate buffer. Calculations of the optimum conditions for the separation are shown

The T-Effect: A Method for increasing resolution in some systems in which substances traverse a medium at different rates

Abstract By placing two media in tandem ( T -effect), resolution can sometimes be increased without increasing the time required for separation in chromatography, ion-exchange, electrophoresis, distillation, particle classification, production of spectra by refraction of light, etc. Conditions necessary for this increase in resolution are derived mathematically. Optimum conditions for maximum resolution are calculated

Proton Magnetic Resonance of Some Cyclopropane Derivatives

The proton magnetic resonance of fifteen cyclopropane derivatives were studied In each case the substituent groups were on only one of the ring carbons The chemical shifts of the four protons on the remaining two carbons were determined to range from δ values of 0 40 to 1.62 ppm, using as an internal reference tetramethyl silane (with δ = 0 00). Direct evidence on the relative electron withdrawing ability of the substituent groups is presented

Dosimetry of Reference Tetramethylsilane in Nuclear Magnetic Resonance Spectroscopy

Tetramethylsilane (TMS) is a convenient standard (δ = 0 or τ = 10) in nuclear magnetic resonance spectroscopy. However, owing to its high vapor pressure, its specific gravity and low surface tension, pipetting of TMS is difficult. The alternative is the use of TMS in a micro-capillary as an external standard. This again brings about the necessity for correcting for the bulk susceptibility, which differs from solution to solution (1).