It is possible to approach further towards an ideal artifical kidney by combination of the hemofiltration with reabsorption system of water and essential solutes from the filtrate. The purpose of this study is to develop filtrate regeneration system in the hemofiltration. The filtrate of the hemofiltration was treated with three different regeneration devices: activated charcoal, standard REDY sorbent system and standard REDY sorbent system plus reverse osmosis process. Extraction of solutes such as waste substances and electrolytes by the regeneration device was measured by means of chemical assays and chromatography analyses. Activated charcoal sufficiently cleared creatinine, uric acid and guanidine derivatives but not urea in the filtrate. Electrolytes unbalance and metabolic acidosis were not improved and compensated by activated charcoal only. Standard REDY sorbent cartridge was capable of removing almost all metabolic wastes and inorganic phosphate as well as calcium and magnesium. NaCl concentration in the regenerated filtrate was increased by REDY system. Supplement of calcium and magnesium was required and sodium chloride should be eliminated by small quantity, when the regenerated filtrate was used as substitution fluid. To prevent bacterial and endotoxin contaminations and elevation of NaCl concentration in the regenerated filtrate with REDY system, combination of R-O process and electrolytes proportion system with REDY system makes better regeneration of the filtrate. Further developments and investigations are necessary to improve performance of the filtrate regeneration system and for clinical application.
Orally diluting hemofiltration (ODHF), where blood was diluted and supplimented with orally administered electrolytes solution and filtered, was applied to two human uremics after preliminary animal experiments. The patients well tolerated for longer than 2 months of the observation period and showed no serious complications. Based upon the same principle, a wearable artificial kidney, which was very simple and compact because of no dialysate delivery system needed, was fabricated and clinically used.
Filtrate treatment system for wearable artificial kidney of filtrationadsorption type was constructed and in vitro experiments were performed. Especially urea treatment was examined in detail. The results are; 1) Urea reduction rate can be raised by using enough urease, but pH rises remarkably. 2) NH4+ exchange capacity of cation exchange resin column can increase by reducing Na+ in advance with electrodialyzer. 3) Utilizing two electrodialyzers, electrolytes can be treated with different reduction rate from that of urea.
Orally diluting hemofiltration, in which blood is diluted and supplemented with orally administered electrolytes solution and filtrated, is feasible to maintain human chronic uremics. Based upon this principle, a compact wearable artificial kidney, which is composed of a hemofiltrator, a new type of blood pump, a filtrate collecting bag, and a control box, but no dialysate delivery system, has been devised. The system functions satisfactorily in an intial clinical application.
In order to design efficient plasma separator with Nuclepore Membrane Filter (0.6μ pore-size), the influence of transmembrane pressure and shear rate on the membrane surface upon filtrating efficiency was examined in vivo using Kiil-type device. Filtrate flow rate increased with pressure and shear rate initially, but soon it became pressure-independent. Based upon this result, we obtained some conditions for miniaturization of plasma separator. 1) High transmembrane pressure is not necessary. 2) Wide, thin and short blood cistern is most efficient.
In hemofiltration therapy, we observed the reduction of filtration rate in the course of therapy. This phenomenon was considered to be the result of “protein cake” formation on the blood side surface of filter membrane, So we made wash-back system to get the “cake” off. Using this system ultrafiltration rate was maintained high. Then we tried another technique named “Transmembrane pressure-free method”. Intermittent ceasing of negative pressure gave equivalent result to wash-back system. We considered that wash away of “protein cake” gave good result in these two methods.
We tried to study whether hemodiafiltration (HDF), a simultaneous application of hemofiltration to hemodialysis, is an effective alternative to the conventional short time dialysis method. Ultrafiltration was demonstrated to accelerate the removal of the solutes in the in-vitro and clinical studies. Three times 3 hr/week HDF with PMMA-HFAK has been carried out in five uremic patients for 2 to 13 months. The chromatographic patterns on Sephadex G-15 of the sera showed that HDF was superior to the conventional hemodialysis in the removal of unknown middle molecule substances, but HDF was equivalent to that in the other points. All patients were treated by this procedure without any side effects.
Effect of dilution-substitution on solutes clearance in hemofiltration were investigated, since dilution of the serum is known to reduced protein resistance to hemofiltration and is expected to release the small to middle molecules from the protein-bound condition. Experimental results evidenced: I) Clearance values of middle molecules presented on gel-chromatograms of uremic sera were very similar to those of urea and creatinine, and were not much affected by twice to ten times dilution with electrolytes solution. 2) Sieving coefficient of each solute with molecular weight from 60 to 5000 were unchanged, even when serum protein concentration was reduced to half by dilution. Conclusion is made that the uremic middle molecules will not be bound to protein, and substitution of plasma volume is much more significant compared to dilution of serum in hemofiltration.
Four automatic hereofiltration control systems, DFX-1 (Nikkiso), Balancer (Toray), NY-2 (Nipro), and Hemoprocessor (Saltrius) were clinically evaluated. All four systems appeared accurate in filtrate-substitution fluid balance. Ultrafiltration rate control system of DFX-1 gave poor results, because of the limit of filter efficiency. NY-2 will work as a part of Filtration Reabsorption Artificial Kidney and “Tapped Water” hemofiltration.
Bone atrophy is one of the manifestations of renal osteodystrophy. To measure the grade of atrophy, some methods as X-ray techniques have been applied, that is, 2nd metacarpal index, contour of vertebrae and trabecula. However, it is difficult to detect slight difference of alteration by these methods, moreover, these have disadvantage with subjective measurement. So we have measured BMC of radius by using BMA (Nowland). 1) BMC tend to be lowered with prolongation of dialysis, however, correlation between BMC and duration of dialysis is higher in BMA than in Nordin's Hand Score. 2) As for the alteration of BMC in the short term by the treatment of active D3, BMC is superior in detecting the slight alteration than Hand Score. BMA offer a better reliable aid in the study of BMC.
Recently a remarkable development of membrance and short-term dialysis for dialysis treatment have been evaluated, however, some remain unchanged. The conventional measurement of the blood flow which has measured the velocity of air bubble in a blood circuit or converted r.p.m. of a blood pump has induced a difference among individuals. ME means such as an electromagnetic blood flowmeter and an ultrasonic blood flowmeter which are expensive and largescaled are unable to use for a individual. Our present invention provides a miniature blood flowmeter, placing a venturi tube in the blood circuit for measuring the blood flow by the pressure-difference between the front and rear venturi tubes. The difference at ouput of two pressure gages using OP amp is determined with the blood flowmeter. This method for measuring the rate of flow of blood through the fix-sized venturi tube is possible to measure the blood flow per hour as well as the velocity of a flowing fluid.
A blood pump for hemodialysis automatically regulated by fistulated venous pressure (FVP, the internal pressure of the vein which has an arteriovenous fistula) is newly devised. As FVP has been proven to change correctively with the systemic blood pressure (BP), the pump is to be regulated by BP. A special double lumen needle is used for simultanous leadings of FVP and blood as a blood access. In clinical applications, the system functions satisfactorily while the pump automatically speed down when the patient's BP drops.
Patients with chronic renal failure are required to spend much time for hemodialysis at the hospital, thus making rehabilitation very difficult. If the frequency of hemodialysis decreases, then there will be more possibilities for rehabilitation. In order to obtain the above results, patients need wearable or portable artificial kidneys. We developed a simple wearable artificial kidney system and experimented this system in vitro and invivo with uremic dogs. This system is a sorbent-based about one liter dialysate regeneration system. These experiments obtained satisfactory results, above all the uremic dog survived 12 days using this one particular system.
A double lumen needle has been developed for the access to the bloodstream. Two different size of needles are coaxially assembled, outer needle with lateral perforation near the tip is for inflow and inner needle of for outflow. One sticking of this needle enables to obtain the continuous blood flow through a circuit. In the basic experiment, we found that there was no recirculation of blood due to backmixing at the tip of the needle, if the blood flow rate in the inflow line was not exceed one half of the blood flow rate in the blood vessel and distance between inlet and outlet port was more than 12mm.
A micro-computer is introduced to predict the occurrence of the hypovolemic shock in the artificial dialysis. The prediction is based on the depression and depressing rate of the circulatory system, which are given by the intermittent measurement of the blood pressure with a sphygmomanometer. The micro-computer changes the measuring interval due to the depression index of the circulatory system and dispatches the alarm signal when it detects the critical state of the patient. Three kinds of such systems have been subjected to the clinical tests in the sequence of updated versions to obtain the successful results.
Immunological studies were performed in the dog with the bovine carotid artery treated with ficin and glutaraldehyde. 1) Immunogenicity was not depleted from the artery after ficin treatment only. 2) The ficin and glutaraldehyde treated artery was solublized with ultrasonic method, and then the dog was immunized with the soluble antigen. From this experiment, it was revealed that there was decreased immunogenicity in terms of humoral and cell-mediated immunity. 3) Specific antibody or sensitized lymphocytes were not detected in the dogs implanted with the bovine carotid artery treated with ficin and glutaraldehyde. From these findings, it may be conceibable that ficin and glutaraldehyde treated bovine artery is enough applicable for a clinical use from the immunological point of view.
Freeze-dried umblical cord veins were used for vascular substitute. The umblical cord vessels have been treated with various suspending medium such as 3% and 5% glutamic acid sodium, 5% glutamic acid sodium contained 0.6% pepton and 0.2% ascorbic acid, 10% and 20% DMSO before freezedrying. As the suspending medium, 5% glutamic acid sodium contained 0.6% pepton and 0.2% ascorbic acid was best in view of surface characterization, antithrombogenicity and immunological antigenecity. The freeze-dried human umblical cord vein graft was experimentally replaced to parts of canine abdominal aorta and inferior vena cava. Ten of 20 showed patent more than fourty-five days. The antibody product after transplantation of the graft was not detected by Ouchterlony's method.
An experimental study of modified human umbilical cord veins for venous replacement were made. Histological reaction was markedly observed at the anastomotic site, especially around the Tevdek suture. This reaction was noted contineously enhanced up to one month after implantation, and probably caused obstruction and stenosis of the anastomotic site. This paper presented immunological examinations for the histological reaction. Immunological examinations were made by the immunoelectrophoresis and whole blood microculture technique for the detection of lymphocyte transformation. The immunoglobulin was no significant change up to six months after, but the cellular rejection was markedly observed up to one month after the graft implantation. This fact was histological findings were probably due to the rejective reaction. Using umbilical cord veins was treated with the ficin, glutaraldehyde and ethanol were not enough for venous replacement.
Three kinds of expanded polytetrafluoroethylene (EPTFE) grafts (2μ, 4μ pore size and 30μ fibril length), 5cm. length with a 7 to 10mm. diameter were placed in the infrarenal vena cava in 37 dogs each with and without intravenous drip of a 12, 000 units of urokinase (UK). Early patency rate (less two weeks) in the 2μ pore size group without UK was 85.7%, But, in the 4μ pore size and 30μ fibril length group without UK was 60% and 50% respectively. Long tern patency (2 weeks to 10 months) was poor in all these groups. Early and long term patency in the 2μ pore size group with UK was obteined in five of six grafts. In the 4μ pore size and 30μ fibril length group with UK, however, early and long term patency rate decreased to 60% and 50%. It appears that a 2μ pore size EPTFE graft may be superior to other materials for inferior vana cava replacement with the use of UK.
The experimental replacements of the superior caval vein with expanded polytetrafluoroethylene tubar grafts (fibril length: 4μ, 10μ, 29μ) were performed in 26 dogs. One early occlusion was occurred in seven grafts (4μ) and one in eight grafts (10μ) respectively. A patency rate of total fifteen grafts (4μ, 10μ) was 87%. Two early occlusions and three late occlusions were occurred in eleven grafts (29μ), a patency rate 55%. Clinically, we performed a femoro-femoral grafting for the iliofemoral venous thrombosis (Palma's operation). The pateneywas recognized in venography a month after operation. Expanded Polytetrafluoroethylene. fibril length. Venous prosthesis. porosity.
The conventional synthetic grafts usually show acar contraction by about 10% on the average. The bias cutting permits the graft to be stretched by about 20%, and restore the initial porosity even if scar contraction occurs. Even two years after the implantation in the thoracic aortae of dogs, the grafts were still stretched by 10% on the average; the inner capsule was not more than 200μ in thickness, the space between fiber bundles was as wide as 100μ. It is, hence, capable of keeping the inner capsule thin and maintaining the biological porosity, and is of significance in healing after implantation of grafts.
Investigation has been made on a development, improvement and clinical application of a non-woven vascular prosthesis which has roughened surface, and elasticity with latex rubber layer. This time it's physical property has been strengthened due to the fact that one of the clinical cases developed an aneurysm at the inguinal region which endures frequent bending. The original non-woven vascular prosthesis consisted of two layers. The improved is a four-ply prosthesis that its'each cloth is made thinner in thickness and the rubber layer is made microporous.
1) We evaluated the experimental studies of a new compound graft which consisted of a non-woven polypropylene sheet over which had been placed a tetron mesh layer. 2) In canine aortic replacement using this compound graft (6mm I. D., 6cm length), although the patency rate (100%) were the same of control groups (milli knitt, double veluor dacron), the compound graft was superior in regard of their physical properties and tissue healings. 3) In canine aortoiliac bypass using this graft (4mm I. D., 6cm length), the patency rate was poor (21.3%), so its technical problems and tissue healing process were discussed. 4) Histologic examinations revealed marked connective tissue reaction localized only within the interstices of polypropylene fibers. 5) Since our compound graft is consisted of double layers, we believe that improvement of its blood and tissue compatibility will be much easier than the single layered conventional vascular prostheses.
The gratifying results of fundamental evaluation and clinical use of Gultaraldehyde (GA)-tanned Human Umbilical Cord Vessels (H-UCV) as a vascular substitute were reported in the 15th Congress. Since H-UCV are not applicable for vessels greater than 6mn in diameter, larger sized material has been searched and our interest focused on Equine Umbilical Cord Vessel. The Equine Umbilical Cord has one vein (E-UCV) with diameter of 13-15mm, and two arteries (E-UCA), 6-8mm in diameter. Pressure tolerance test, Tensil-Strain test, Amino Acid Analysis and in vitro Antithrombogenicity were evaluated on these materials. Pressure tolerance test revealed that GA-tanned E-UCV tolerated about 450mnHg as conpared with 300mnHg in GA-tanned H-UCV. Tensil-Strain test revealed that GA-tanned Equine Umbilical Cord Vessels were more increased in elasticity than GA-tanned H-UCV. Amino Acid Analysis indicated that GA-tanned E-UCV lost 78% of Lysine, which is similar to 86% loss in GA-tanned H-UCV. It is assumed that crosslinking by GA takes place mostly among the Lysine residue. E-UCV and H-UCV showed equally high level of anthithrom-bogenicity. Based on these studies, it is expected that Equine Umbilical Cord Vessels are applicable to the blood vessel, especially as the venous, substitute.
As a preparation of human saphenous vein homografts, proteolytis enzymatic digestion using Ficin was mandatory in order to increase the diameter of cadaveric veins. The appropriate digestion time revealed to be 60-90min. However, the strength of the grafts was reduced in accordance with digestion pretreatment. 1.5% Glutar aldehyde was used for a tanning agent Patients with varicose vein will be good donors because of their increased size of veins Hence we conside to use the saphenous vein from varicose patients as well as from cadavers omitting.
The purpose of this paper is to describe the applicability of the Tracheal Biograft to venous implantation. Glutaraldehyde (G. A) preserved Tracheal Biograft has the following features; 1) antithrombogenicity, 2) rigid, flexible, pliable, 3) smooth inner surface, 4) tapered graft, 5) possibility of Y bifurcation graft with use of carina. Glutaraldehyde-preserved Tracheal Biografts with a diameter of 12mm to 15mm were implanted to superior vena cavae of 20 mongrel dogs. At the operation each azygos vein was ligated. The implanted grafts were observed angiographically, microscopically, including scanning electron microscopic inspections. All of these grafts were found to be patent when examined during the period ranging from two hours to twelve months after implantation. Microscopically, the Biografts revealed smooth and thin inner capsule. Inflammatory reaction was not marked at the site of anastomosis, though small round cells were scarcely observed.
The treated homologous canine aorta or heteologous bovine carotid artery was implanted in the inferior vena cava below the renal vein. 1) Ficin and glutaraldehyde treated canine aorta resulted in the degradation in the early stage following implantation. On the other hand, 100% patency was obtained in the homograft treated with 1.5% glutaraldehyde but with out ficin. 2) Early graft closure occur due to circumferential compression in the bovine heterograft which was treated with ficin for 2.5 hours and subsequently with glutaraldehyde. The graft treated with ficin for 1.5 hours became harder, and better patency rate was obtained with this graft. There was no marked difference in terms of patency and histological healing between these homo and heterograft. However, the heterograft is more favorable because of the easy access of the material.
1. Bovine hareiograft treated with Neochrome tanning showed luminal dilaration about one year after implantation. However, its severity remaind uuchanged for the followiug four years. Anastomotic sites healed well and gragt lumen was covered with thinn fibrin membrane also suggesting good healing being in progress. Despite of this later obsavation, clinical application seems unfavorable because of the early tendency of dilatation. 2 Glutar aldehyde tanned graft, on the other hand, remained well open until three years without dilatation or visible stenosis of anastomotic sites. But at five years period, the graft became slightly dilated and moreover the distal anasto motic area became markedly stenotic. This stenosis was conceivably resalted from the pannus tissue which became dissected disfally and then protruded into the lumen. Without solution of this later problem, long term patency of the graft appears to be difficult.
The histologic finding of auto-alloplastic graft transplantation for vessels, capsulated with peritoneum, was stadied in the long period. Poor vascular plex us of nutrition and no muscular cell were found in the adventia and media layers, which were different to the normal abdominal aorta Interestirgly, no fibrotic hyperplasia or cellular infiltration was presented, meanwhile the thickness of the wall resembled to normal vessel in the structure. In the central part of the graft, endothelial cells were exfoliated scatteredly but no thrombotic formation overthere. On the centrary, endothelial regimentation repeated and fibrin mat of the course of endothelial formation was presented. Multiple holes or depresion was found in these parts, which may be related with nutrition of tissue. 1) The auto-alloplastic graft is mesodermal, same as vessels. Therefore the structure was presented stabely. 2) Though the long stable of this graft was presented, exfoliation of endotheluim and regimentation occurred. 3) Nutrition was important in the course of endothelial cell formation from fibrin mat. 4) Hyperplasia of collagen fiber in the anastomasis got less if getting stable.
Several prostheses were compared in anastomotic intimal hyperplasia. Composite grafts (inner diameter 4-6mm) with two different prostheses longitudinally were transplanted to a cervical and bilateral femoral arteries in dogs. Anastomotic rings (Tantalum) were fitted up on some of the anastomoses. Variable degree stenosis were observed on the anastomotis of all grafts. Anastomotic intinal hyperplasia was more slight in low porous prosthesis than in high porous prosthesis and in large diameter than in small diameter. The hyperplasia in EPTFE and Double Velour Graft were less marked. Anastomotic ring was effective for blood flow volume and long term patency.
A compound prosthesis which was woven with alternate yarns of nonabsobable (Collagen) and absorbable (Tetron) fibers was made and had been implanted with a Woven Teflon graft or a Double Velour graft for 118-221 days. The healing of grafts was compaired macro-and microscopically and adherence of surrounding tissue on grafts was measured. Result: (1) Collagen fibers was disappeared during 120 days and was absorbed during 221 days. (2) The healing of the Compound graft was better than of Woven Teflon graft and Double Velour graft. (3) The adherence of surrounding tissue on the Compound graft was stronger than of Woven Teflon graft but was lesser than of Double Velour graft.
We had developed the direct ultrafiltrate perfusion (DUP) system as a new assisted artificial liver and reported previously. In this study, we manufactured the new small hemodialyser, “Mini Rhodial”, which can perform not only DUP but also the hemodialysis. As we can easily change the volume of the dialysate tank in this dialyser, it has great advantage for the light weight's animal experiments in the research of the hepatic failure treatment. Using this equipment we carried out the 8 hours DUP treatment against the hepatic failure dogs (caused by Eck-fistula, ligation of portal vein, common bile duct and hepatic artery), and examined the effects of this DUP treatment by obtaining the temporal change of the concentration of the various substances in blood and plasma. Futhermore, we investigated about the new adsorbers which can adsorb the ammonia, billirubin and non estelified fatty acid from the serum and confirmed the high adsorption ratio.
1. We made artificial CSF. 2. We confirmed a safety of artificial CSF perfusion in consciousness clear dogs. 3. We observed the influence of methionine or ammonia into CSF and the effects of artificial CSF perfusion. 4. Injection of methionine or ammonia into CSF induced encephalopathy and artifical CSF perfusion improved the symptoms. 5. We observed the effects of artificial CSF perfusion in dogs with DMNA-induced acute liver ischemia. 6. Reductionn of CSF amino acids and improvement of EEG findings by artificial CSF perfusion method were observed.
The cause of hepatic failure is unknown and supposed to be multifactorial. In the experiments of present series, selective elimination of fatsoluble substance (s) which was one of the causative agents in hepatic failure was attempted. In the preceding paper, indole-a marker of fat-soluble substances-was efficiently cleared from the blood line into silicone oil line. In this report, glutethimide-one of fat-soluble hypnotics-was selected as a marker of fat-soluble substances. Glutethimide was also efficiently eliminated from the blood line into silicone oil line. Clinical use of lipid hemodialysis was possibly suggested.
Ionex is a new cationic resin specially designed to adsorb bilirubin in the blood. It ionically binds conjugated and unconjugated bilirubin and removes bilirubin fran the blood but the addsoption of albumin and other fraction of plasma proteins is minimum. Experiments using the in vitro model-circuit revealed that the adsorption of bilirubin from the blood to Ionex was 2 to 3 times more than that to the conventional activated charcoal beads used for the treatment of hepatic cans. Sixty-six percent of conjugated bilirubin and 47% of unconjugated bilirubin was removed from the blood after in vitro 2-hour perfusion with the heparinized whole blood obtained from the jaundiced dogs. Extracorporeal circulation with Ionex oolumn was performed using 9 dogs which were previously jaundiced by ligation of the choledochus. Removal rage of direct an indirect bilirubin after 2-hour direct heroperfusion using Ionex column (30gm) ranged fran 60 and 56% maximun to 8 and 0%m ninum respectively. These wide ranges of difference in bilirubin removal rates among the in vivo experiments were related to the severity of blood clot formation within the Ionex column. Methods to prevent platelet adhesion to the surface of Ionex is being investigated.
High-resolution anion-exchange chromatographic systems for the analysis of physiological fluids have newly developed. This study aims to clarify the characteristics of chromatographic patterns in the subjects with hepatic failure. Experimental models of hepatic failure in dogs were performed by side-to-side portacaval shunt, ligation of common bile duct and ligation of hepatic artery. Chromatograms of the serum show the sevral significant abnormal peaks which are persumed to be Xanthin (retention time, at 15min. ), Urocanic acid and Uroerythrin(27min.), Kynurenic acid(140-60min.) and, Indoleacetic acid andIndolacrylic acid(75min.) by analogy with identification of the peaks in human urine. In cace of urine, significant fifferences (after 50min.) have been observed between normal and hepatic failure subjects.
Many kinds of activated charcoal have been used as a treatment of hepatic failure and uremia. Therefore we developed a new activated charcoal (Felt charcoal) and compared it with coconut broken charcoal, bead-shaped activated charcoal in vitro and in vivo. This Felt charcoal is made from pure cellulosic fibers and coated with poly HEMA in order to minimize thrombogenicity and risk of particle release. The result of this study suggest that the Felt charcoal has wide adsorption spectrum and very high affinity of many toxins, so rapidly adsorbs the toxic substances from blood. It will be available especially for the artificial kidney.
Some products of activated clay were coated with cellulose or dextrin and named CACy-0, 1, 2 and DACy-1, 2, 3 and 4 respectively. Ammonia was adsorped successfully by CACy-2 in vitro. Five dogs with hepatic failure were recieved plasma separationg-adsorption with CACy-2 and three animals were accompanied by slight improvement in biochemical liver function. High performance liquid chromatogram indicated that some peaks were disappeared by CACy-2, injecting serum of a dog with hepatic failure. It is suggested as results of this study that plasma separating-adsorption with CACy will be available to treat for the hepatic failure.
A group of polyion complexes(PICs) is one of candidates for non-thrombogenic materials. In this paper, we report our recent results on the interaction between various types of PIC and blood components (plasma proteins, platelets), which play an influential role in the course of thrombus formation, with the use of our newly developed methods2, 3, 5. The behavior of proteins and platelets on PIC coated surface was significantly influenced by molecular structure of PIC. The degree of aggregation and metamorphosis of adhered platelets was observed to relate with the degree of conformational change of adsorbed albumin. Among the PICs examined, our newly synthesized PIC, P(p-QEAS)-PSSS, showed most promising properties for biomedical use.
This report describs our current attempts to design and test liver cell perfusion. Seven adult dogs were used in our experiment, they were divided in two groups at two and five respectively. One was control group, another was supported with hepatocyte group. Hepatic support system chamber was made of acryl board (10×10×1cm), and it was separated in three spaces with Neucljeopore Membrane Filter (NMF). Middle space was filled with hepatocyte (50-70g) of rabbit. This hepatocyte was isolated with #24 metal mesh from the liver which was wash out Lactete-Ringer's solution. The chamber was connected with hepatic failure canine external shunt. The longest survival of the dog was 18 hours. This results were suggested that chamber was effective to the theraphy of hepatic failure. But the chamber membrane area was not enough to big dogs.
The objective of this research program is to develop a liver tissue to be employed in a hepatic assist device for metabolic activity of the liver. Two forms of the liver tissue, slice and cube, were first compared. As for incubation medium, perfluorocheaical emulsion was employed with ar without tissue culture media. Urea production rate was a major indicator to assess metabolic activity of the tissue. The result indicated that i) the liver tissue in slice form yields higher activity than that in cubic form, ii) the liver slice actively utilize loaded aarmonia, and iii) although the perfluorochaical enulsion alone can maintain the viability of the liver tissue, its combination with tissue culture media further enhance the metabolic activity. Viability of the tissue was maintained up to 20 hours or more and over 24 hours' maintenance appeared possible. It is believed that the liver tissue thus prepared could be incorporated in “An artificial liver” in terms of metabolic replac anent.