Two patients with familial hypercholesterolemia were treated by long-term plasma exchange via an arteriovenous Cimino shunt using unselective membrane separation. Cholesterol was lowered to 40 percent (+/- 3) of peak levels by each procedure. Sieving coefficient was 0.76 (+/- 0.12). With a mean exchange interval of 11 days (+/- 2), the peak cholesterol levels decreased from 406 mg per dl (+/- 28) to 322 mg per dl (+/- 27), the LDL fraction from 338 mg per dl (+/- 9) to 265 mg per dl (+/- 25) whereas the HDL fraction remained unchanged at 28 mg per dl (+/- 4). Electrocardiographic stress testing improved in the first patient after treatment for 12 months.
Heparin and plasmin were co-immobilized on collageno-elastic tubes (CETs) in order to develop a thromboresistant and fibrinolytic vascular prosthesis. The mutual interaction between heparin and plasmin both in the soluble and in the immobilized state was studied. The immobilization condition rendering maximum co-immobilized heparin and plasmin activity was identified to require heparin immobilization followed by plasmin immobilization. Soluble heparin exerts a positive synergistic effect on soluble plasmin. Immobilized heparin enhances plasmin loading on the CET as compared to the heparin-free graft. Heparin, in both the soluble or immobilized state, significantly decreases the Michaelis-Menten (M-M) parameter Km for immobilized plasmin over heparin-free immobilized plasmin. Furthermore, the M-M parameter Vmax for the immobilized plasmin in the presence of heparin decreases over heparin-free immobilized plasmin. These results suggest a decrease in the kinetic constant k3 for heparin-modified immobilized plasmin over the heparin-free form. Co-immobilized heparin-plasmin collagenous grafts represent a unique advance in the development of fibrinolytically active prostheses.
Requirements to be met by an artificial liver support system are the abilities to perform the function of the liver, i.e., to support the functions of protein synthesis, detoxification, and phagocytosis. At present there are no artificial liver support that can satisfy all these conditions other than the detoxification and protein synthesis by removal and supply in plasma exchange. This mode of treatment poses various problems, including the disadvantage of requiring a great amount of plasma (1). Noting the adsorption performance of powdered charcoal, we have developed a new type of adsorbent for clinical application (UPC, BESPORE, Japan Medical Supply Co. Ltd., Hiroshima, Japan) that consists of powdered charcoal immobilized and encapsulated on a blood-biocompatible sheet. UPC is capable of purifying middle to large molecular weight and protein-bound substances, which have been relatively difficult to achieve with conventional blood purification (Fig.1).
It is well-known that acute renal failure is often caused by hemolysis. Its possible causes may be free-hemoglobin (F-Hb), stroma freed from destroyed red blood cell, and their combined action. Especially, a great amount of F-Hb is liable to flow out during extracorporeal circulation. The plasma fractionation using a membrane has so far been applied to remove F-Hb (1). The molecular weight of F-Hb of 68,000 which is nearly equal to that of albumin has made it still difficult to separate F-Hb effectively. Recently, we have developed an adsorbent that is capable of selectively removing F-Hb and succeeded in obtaining its high adsorption performance.
Hemoglobin dissolved in a coacervate system shows the properties of a resuscitation fluid. In the coacervate system used, the equilibrium phase was the colloid rich phase. We propose a new definition of the coacervate phase to be that phase in a coacervate system which is most dissimilar to water in its physical chemical properties.
Since several years matrix-bound biologically active substances are widely used in biosciences, biotechnology and medicine. We are presenting a simple and inexpensive activation procedure for support materials which allows stable binding of C1q and DNA. We could not found a remarkable leakage of the bound ligands. In connection with the good biocompatibility of our procedure, both are important for the application in extracorporeal immunoadsorption. The method is technologically simple and represents an alternative to the activation methods applied so far.
The aim of this study is to prepare PHEMA based polymeric membranes for a transdermal delivery system, which includes a skin permeation enhancer (i.e. ethanol) for nitroglycerin. Membranes were prepared by bulk polymerization of HEMA monomer. Polymerization was achieved in the presence of EGDMA, as the cross-linker, and AIBN as the initiator. MMA was used as a comonomer to improve the mechanical properties and to adjust the permeabilities of the resulting membranes. Water was also included in the polymerization mixture to control the matrix structure. Membranes with different chemical and physical structures were prepared. Swelling behaviour of these matrices in ethanol were observed. Nitroglycerin diffusion through swollen membranes (in ethanol) were investigated. It was obtained that the relative amounts of ingredients (i.e., HEMA, MMA, EGDMA and water) in the casting solutions affect both the equilibrium swelling values and the permeabilities. By increasing the water content and by decreasing the amounts of MMA and EGDMA both parameters can be increased. AIBN does not affect these parameters significantly.
The use of immobilized enzyme reactors in medicine is briefly reviewed in this presentation. Emphasis is placed on the recent and emerging technology involved in development and clinical applications of such devices.
The observed toxicity of hemoglobin solutions (HbS) might depend, at least in part, on the tendency of Hb to autoxidation with generation of oxygen free-radicals. Aims of this study were: (1) to quantitate plasma elevations of H2O2 and lipid peroxides after replacement of 1/3 of calculated blood volume in various groups of rabbits with different Hb solutions; (2) to correlate these elevations with parameters of brain, heart, lung, liver and kidney injury or dysfunction; and (3) investigate the protective effect of mannitol as a radical scavenger. One Hb solution contaminated with stromal phospholipids raised H2O2 from 31.2 +/- 1.9 to 166 +/- 20 mumol/ml, lipid peroxides from 1.62 +/- 0.5 to 7.29 +/- 0.3 nmol/ml, CK-BB (brain isoenzyme) from 250 +/- 25 to 470 +/- 50 IU/L, CK-MB (myocardial isoenzyme) from 2.98 +/- 0.03 to 10.73 +/- 1.3 IU/L and SGPT from 38.1 +/- 5 to 167 +/- 45 IU/L, and reduced PaO2 from 87 +/- 10 to 57.5 +/- 2.5 mm Hg and creatinine clearance from 1.5 +/- 0.3 to 0.13 +/- 0.03 mg/min/Kg. These changes were progressively less severe with pure unmodified Hb, pure Hb crosslinked with "o-ATP", and pure crosslinked Hb + mannitol (4 mg/ml). These observations indicate a significant role for oxygen-derived radicals in the toxicity of Hb solutions.
The report is based on the results of treatment of 116 patients with severe purulent-destructive abdominal cavity diseases and 320 patients with liver failure due to bile ducts obturation. Along with surgical operations, methods of organism extracorporeal detoxication - haemosorption, exchange plasmapheresis, autoblood ultraviolet irradiation - were used in all patients either in isolation or in combination with each other. Toxical metabolites concentration, blood integral toxicity, peptids with mean molecular weight concentration, liver profile enzimes activity, lipid metabolism indices, general and liver haemodynamics and electroencephalogram were studied. On the basis of correlations between indices obtained by the method of extreme grouping factors-syndromes were formed, and then in accordance with a special program summary evaluation of detoxication was calculated in marks. A drop in lethality by 28, 3% was ensured, as well as a drop in postoperatyonal liver failure by 51, 4%.
In this study a new dynamic measuring chamber for flat biomaterials allowing the estimation of cell adhesion on test surfaces by measuring the cell lost from surface contacting test blood under defined rheological conditions is introduced. This was achieved by constructing a test chamber permitting the contact of small amount of blood with a large geometrical test surface. The construction consists of a spiral-shaped flow channel of 0.3 cm width, 0.02 cm height and 78 cm length. The applicability of the new method was demonstrated by evaluation of platelet adhesion on siliconized glass, fibrinogen coated glass, cuprophane and polyacrylnitrile.
XMO-10, a perfluorocarbon surfactant produced emulsions of a perfluorocarbon (Perfluorotripropylamine, FTPA) in vitro which were stable at a range of temperatures for at least 5 days. Most of the emulsion particles were smaller than 1 micron, and all emulsion particles were of these dimensions when the emulsification mixture included 2% lecithin. XMO-10 produced more stable emulsions with smaller particles than did PF68, a widely-used emulsifying agent. XMO-10 was toxic to cells in culture but this toxicity was reduced or abolished when the XMO-10 was emulsified with perfluorocarbon. XMO-10 and lecithin produced relatively stable emulsions of perflurodecalin. Such emulsions, if non-toxic in vivo, might permit excretion of perfluorocarbon through the lungs and thus would permit infusion of sufficient quantities of the preparations to function in oxygen transport in severely anemic animals and man.
We developed a method to determine whole complement hemolytic activity (CH50) in rat plasma using a modification of the method of Mayer(1). Plasma CH50 level in 30 male Sprague Dawley rats was 1000 +/- 200 units. Following infusions with human and rat stroma-free hemoglobin or polyhemoglobin solutions, CH50 did not change significantly in rats when compared to albumin infused rats. On the other hand, CH50 significantly decreased in the group receiving membrane stroma and bacterial endotoxins.
By means of water-soluble carbodiimide coupling technique various bioligands were covalently attached to the surface of uncoated synthetic active carbons and a number of sorbents with certain biological functions were thus designed. Carbonaceous sorbents with immobilized ligands demonstrate increased affinity towards specific sorbates compared to that of starting matrix. As soon as SCN and SCS synthetic carbons are used uncoated they can be highly loaded with protein molecules - up to 80 mg serum albumin, 6-10 mg IgG rabbit etc. per gram of sorbent. Carbonaceous immunosorbents retain biocompatibility and substantial non-specific adsorptive capacity of initial hemosorbents. A conclusion is drawn that uncoated synthetic charcoals can serve a basis for design of selective hemosorbents intended for solving complicated problems of immunocorrection.
Aiming to improve the efficiency of the blood purification convective methods either with spontaneous (CAVH) or with pump-assisted (HF) extracorporeal circulation we inserted after the hemofilter a cartridge containing 70 g of collodion-coated activated charcoal (CAC) microencapsulated, obtaining so hemofiltration and hemoperfusion in series (HF+HP). The obtained results show that in both methods HP addition gives a negligible increase of urea clearance and a practically null increase of phosphate clearance, whereas creatinine and uric acid clearances increase is remarkable especially, in percentage, with low blood flows (CAVH). In the HF+HP system we have also been studying B2-microglobulin (B2-M) clearance aiming at examining the possibility of increasing the removal of substances with higher molecular weight. We have been finding HP addition increases further on B2-M clearance already high in HF. Therefore we think HP addition to convective methods is an interesting step in the attempt to carry out highly efficient blood purification methods.
Hepatocytes isolated from rat liver were immobilized within Ca-alginate. Immobilized hepatocytes could remove ammonia and other toxic substances causing hepatic coma, such as indole, phenol, bilirubin, and short chain fatty acids. Although free hepatocytes lost those activities within 2 days, immobilized hepatocytes maintained those activities for more than 7 days. Immobilized hepatocytes induced tyrosine aminotransferase (TAT) in the presence of dexamethasone and dibutyryl-cAMP and retained the ability to induce TAT for more than 7 days. Biologically active form of coagulation factor II, prothrombin could be synthesized and secreted into medium by immobilized hepatocytes. Moreover, immobilized hepatocytes produced glucose from lactate, alanine, fructose, and galactose. Like adult rat liver, growth-related function and liver-specific function in immobilized hepatocytes were reciprocally controlled by cell density. There are both alpha-, and beta-adrenergic receptors in membrane of liver cells, and the adrenergic action of epinephrine is alpha-predominant in adult rat liver. Monolayer-cultured hepatocytes can not maintain alpha-adrenergic response. However, immobilized hepatocytes maintained alpha-adrenergic response as shown in vivo. Those characteristics of immobilized and three-dimensionally cultured hepatocytes are regarded almost the same as liver cells in vivo. Furthermore, therapeutic effect of immobilized hepatocytes on the hepatic failure were confirmed in the experiment using hepatocytes damaged with D-galactosamine. Therefore, it is suggested that immobilized hepatocytes could be applied to a hybrid artificial liver support.
A comparison was made, for in vitro assessment of toxicity, between six different procedures to extract biomaterials. A new method was developed, with a special insert inside the tissue culture well, that allows relevant contact between cells and material without disturbing physical contact.To predict the toxicity of materials in blood contact, our results suggest that two simple methods ought to be used, one based on water eluates and the other on contact between cells and material.
The advent of high water content, oxygen permeable contact lens materials has made the intracorneal implants more feasible. A major obstacle encountered is the regrowth of a stable epithelium over the implant. Therefore, ammonia gaseous plasma modification technique was used to modify the surface chemical properties of soft contact lens material such as poly(2-hydroxyethyl methacrylate and methacrylic acid), PHEMA-MAA copolymer, in an attempt to enhance the cell attachment and growth of rabbit corneal epithelial cells.
