sepharose and Hepatic-Encephalopathy

A system allowing repeated plasma perfusion in the unrestrained conscious rat was developed in order to examine the effects of plasma filtration with on-line sorbent treatment of plasma in various models of disease. In experimental autoimmune glomerulonephritis, perfusion over a column coated with glomerular basement membrane (GBM) antigen lowered circulating levels of anti-GBM antibodies. In experimental endotoxaemia, perfusion over a column coated with polymixin B (PB) lowered circulating endotoxin levels and protected animals from haematological abnormalities and death. In experimental acute hepatic failure, perfusion over a combination of charcoal, resin, and PB columns improved survival in grades II and III hepatic coma. This experimental system has allowed preclinical evaluation of the effectiveness of different sorbents in the treatment of a range of disorders.

Topics: Animals; Anion Exchange Resins; Anti-Glomerular Basement Membrane Disease; Charcoal; Extracorporeal Circulation; Hemoperfusion; Hepatic Encephalopathy; Immunosorbent Techniques; Rats; Rats, Inbred BN; Rats, Inbred Strains; Resins, Synthetic; Sepharose; Shock, Septic; Sorption Detoxification

Topics: Albumins; Anion Exchange Resins; Blood; Cation Exchange Resins; Charcoal; Hepatic Encephalopathy; Humans; Perfusion; Resins, Plant; Sepharose

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.

Topics: Absorption; Acetaminophen; Capsules; Hemoperfusion; Hepatic Encephalopathy; Humans; In Vitro Techniques; Mathematics; Phenols; Polysaccharides; Sepharose; Tyrosine

UDP-glucuronlytransferase, E.C. 2.4.1.17, has been solubilised from the microsomal fraction of liver homogenate from phenobarbital pretreated rabbits by lipase or detergent treatments. A 110-fold purification of the enzyme with respect to the crude homogenate was achieved by precipitation and column separations. The cholate-detergent solubilised enzyme was far more stable than that prepared by the lipase method. The partially purified UDP-glucuronyltransferase has been covalently bound to cyanogen bromide-activated agarose in the form of large haemocompatible beads to the extent of 0.22 mg protein per mg agarose dryweight, equivalent to about 25 mg of swollen gel. The acceptors for glucuronidation employed were the non-physiological phenolic compounds p-nitrophenol and 1-naphthol, and an exogenous and endogenous substance of physiological importance, namely paracetamol and phenol respectively. The immobilised enzyme exhibited at least 80% of the original activity of the solubilised enzyme, and the catalytic function was preserved for a much longer period of time in the carrier-bound form. The system described in this publication could well be applied in an extracorporeal liver assist device for the replacement of glucuronidation function.

Topics: Animals; Artificial Organs; Enzymes, Immobilized; Female; Glucuronates; Glucuronosyltransferase; Hemoperfusion; Hepatic Encephalopathy; Liver; Liver Diseases; Microsomes, Liver; Polysaccharides; Proteins; Rabbits; Sepharose; Uridine Diphosphate Glucuronic Acid

A method is reported by which agarose beads of diameter 1000 to 10000 microns can be prepared from Sepharose (R) 4B (native bead diameter 40 to 190 microns). Haemoperfusion experiments indicate that the enlarged beads are relatively haemocompatible; platelet loss is considerably less than that reported for many other bio-materials employed in haemoperfusion, and haemolysis is slight even after perfusion for several hours at flow-rates in excess of 25 ml/min. The beads can be activated by cyanogen bromide for the immobilisation of proteins. The sites for protein fixation are not restricted to the outside surface of the beads; small water soluble molecules, and serum proteins diffuse quite rapidly through the enlarged beads. A possible medical application of the large beads is in extracorporeal detoxification by chromatographic extraction or enzymatic modification, particularly of lipophilic toxins, using the enlarged beads as a carrier-matrix. The results described in this publication prove the viability of this concept. Such methods should be especially useful as artificial supports in fulminant hepatic failure.

Topics: Acetaminophen; Animals; Bilirubin; Carrier Proteins; Ethanolamines; Hemoperfusion; Hepatic Encephalopathy; Humans; Hyperbilirubinemia; Phenols; Polysaccharides; Rabbits; Sepharose; Serum Albumin