Effect of moisture on and kinetic features of the ultrafiltration rate of dialysis membrane.
The kinetic features of ultrafiltration of cellulose dialysis membrane stored under various humidity and temperature conditions were studied to obtain basic information of shelf-life characteristics of dialyzers. The ultrafiltration rate (UFR) decreased with time and the UFR-time curve suggested that the UFR would approach a certain equilibrium value. This phenomenon could be simulated well by the following equation: UFR = a.b.t/(1 + a.t) + c, where a, b, and c are constants and t is time. The effect of moisture adsorption onto the membrane on the UFR is discussed. A hypothesis is that in the amorphous region of cellulose, adsorbed water molecules would serve as molecular crosslinks through hydrogen bonding, and as this would reduce size of fine pores in the amorphous region, the UFR decreases.
Properties of hydrated cellulose membranes for hemodialysis after storage and radiation sterilization
The problem of the influence of long-term storage of hydrated cellulose membranes for hemodialysis on their functional properties and also on the changes of their properties on radiation sterilization has arisen in connection with the need to establish guarantees for the storage life of membranes before using them in single-use dialyzers. There is also the need to determine guarantees for the storage lives of the dialyzers themselves which are sterilized by the radiation method. In the latter case the membrane is subjected to y-ster ~, ilization and subsequent storage directly in hermetically sealed single-use dialyzers.
Thrombogenicity of some biomedical materials: platelet-interface reactions.
Fifty-eight polymers and other materials were evaluated for compatibility with human blood in an in vitro test system. Assays for platelet factor 3 activation, activation of the coagulation sequences, and release of hemoglobin and adenine nucleotides were performed on blood exposed to each of the 58 test materials. Of the materials tested, collagen, heparinized hydrin rubber, poly (methyl methacrylate), graphite-benzalkonium-heparin, poly (methyl acrylate), isotactic poly(methyl methacrylate), grafted poly (ethylene oxide) on poly (acrylic acid), balata rubber, L-1624 from 3M Co., and chlorinated poly (vinyl chloride) appeared most compatible with blood. Chemical affinities appeared to have little to do with blood compatibility of the materials tested. Electron microscopic examination of blood components adherent to selected test materials following exposure to blood was carried out. Each of the three polymers with “good” and the two polymers with “poor” blood compatibility characteristics which were examined by electron microscopy was coated with a thin unilaminar adsorbate from blood. Platelets and fibrin were focally deposited on this adsorbate. Of the test surfaces examined, only glass was covered by a trilaminar adsorbate. Mechanisms of formation of the adsorbates are discussed.