Biomedical subjects

K Harstick

Publications and source records attributed to K Harstick.

4 recordsLinked to original sources

PubMed1981

Properties of agarose-encapsulated adsorbents. II. Elimination of endogenous and exogenous phenolic compounds from human serum.

Phenolic compounds derived from the amino acid tyrosine are endogenous toxins, which are believed to be involved in the pathogenesis of hepatic coma. There are also xenobiotic phenolic substances, such as p-hydroxy-acetanilide (paracetamol or acetaminophen), which can lead to serious complications if taken in an overdose. In both cases, a drastic therapeutic measure such as haemoperfusion may be indicated to eliminate the toxin from the blood. In the present work, human serum has been dosed with the phenolic compounds of immediate relevance in exogenous and endogenous intoxication, and the effectiveness of various adsorbent materials for the elimination of the toxins from the serum has been investigated. Resins and charcoal in the native state have been compared with those encapsulated into large agarose beads, a process which improves the haemocompatibility and thus the practicability of the adsorbents. A certain degree of specificity has been observed. Whereas phenolic acids are adsorbed quite effectively onto the strongly basic ion exchange resins of the Dowex 1X type, particularly 1X8 or 2X8, phenol or paracetamol are less effectively eliminated. In contrast to many other classes of toxin, the Amberlite XAD-type resins are ineffective for all the phenolic substances investigated. Charcoal is the most effective adsorber in most cases, particularly when encapsulated in powder form into agarose beads.

Absorption↗

PubMed1981

Properties of agarose-encapsulated adsorbents. I. Adsorption of digoxin from human serum.

The elimination of the cardioactive steroid, digoxin, from human serum by a range of adsorbent phases has been investigated. In the native state, the uncharged resins of the Amberlite XAD-type proved more effective than the ion-exchange resins, Dowex 1X, or active charcoal. Of the materials tested, Amberlite XAD-8 is by far the best suited resin for haemoperfusion in cases of digoxin overdose, whereby the less efficient XAD-4 is more commonly employed at present in clinics. In order to improve the haemocompatibility of the adsorbent materials, the technique of encapsulation into large agarose beads has been employed. In contrast to the effects observed with many other classes of xenobiotics, encapsulation into agarose beads results in a considerable loss of adsorptive capacity of digoxin by Amberlite XAD-8. The poor performance of active charcoal in form of granules can be improved by an order-of-magnitude using charcoal powder encapsulated in agarose. Thus, the latter material, or uncoated XAD-8 resin should be considered as a better alternative to materials in current use for extracorporeal detoxification in cases of digoxin overdose.

Anion Exchange Resins↗

PubMed1979

The removal of hypnotic drugs from human serum. A comparative investigation of the adsorptive properties of native and agarose-encapsulated resins and charcoal.

The adsorptive capacities of some ion-exchange resins and activated charcoal towards the hypnotic drugs, phenobarbital, glutethimide, carbromal, and methaqualone, have been investigated. Furthermore, the properties of some of these resins and charcoal, encapsulated in an agarose matrix in the form of beads, have been compared with those of the adsorbent phases in their native states. In general, the adsorptive capacities of charcoal were at least as good as, and frequently better than those of the resins. Amberlite XAD-type resins had a higher affinity than Dowex-type resins for all the drugs tested, except for phenobarbital, which was not adsorbed to a satisfactory extent onto Amberlite XAD-4. The encapsulation of adsorbent phases into agarose beads of diameter 5-10 mm results in a reduction of the adsorbtion of the drugs. Nonetheless, the remaining adsorptive capacity is sufficient for application in an extracorporeal detoxification system. Moreover, the overwhelming advantage of good haemocompatibility is provided by the agarose-encapsulated adsorbents.

Adsorption↗

PubMed1979

Agarose-encapsulated adsorbents.

A method is described for the encapsulation of ion-exchange and adsorbent resins of native particle diameter 0.2-1.0 mm into agarose spheres of diameter 5-10 mm. Plasma components diffuse rapidly through the agarose coating, but blood corpuscles have no direct access to the resins. At least 0.3 g of resin can be incorporated into 1 g of the agarose beads, so that the effective surface area with regard to erythrocytes, thrombocytes, and leucocytes is reduced by a factor of at least 5, and up to 20, depending on the native resin particle size. Pulverised active charcoal, or resins in powder form can also be encapsulated in this manner. The haemocompatibility of the agarose coating seems to be considerably more acceptable than that of the adsorbents in their native state.

Adsorption↗