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Biomedical subjects

J Rozga

Publications and source records attributed to J Rozga.

At least 55 records · Page 3Linked to original sources
PubMed1994

A bioartificial liver to treat severe acute liver failure.

OBJECTIVE: To test the safety and efficacy of a bioartificial liver support system in patients with severe acute liver failure. SUMMARY BACKGROUND DATA: The authors developed a bioartificial liver using porcine hepatocytes. The system was tested in vitro and shown to have differentiated liver functions (cytochrome P450 activity, synthesis of liver-specific proteins, bilirubin synthesis, and conjugation). When tested in vivo in experimental animals with liver failure, it gave substantial metabolic and hemodynamic support. METHODS: Seven patients with severe acute liver failure received a double lumen catheter in the saphenous vein; blood was removed, plasma was separated and perfused through a cartridge containing 4 to 6 x 10(9) porcine hepatocytes, and plasma and blood cells were reconstituted and reinfused. Each treatment lasted 6 to 7 hours. RESULTS: All patients tolerated the procedure(s) well, with neurologic improvement, decreased intracranial pressure (23.0 +/- 2.3 to 7.8 +/- 1.7 mm Hg; p < 0.005) associated with an increase in cerebral perfusion pressure, decreased plasma ammonia (163.3 +/- 21.3 to 112.2 +/- 9.8 microMoles/L; p < 0.01), and increased encephalopathy index (0.60 +/- 0.17 to 1.24 +/- 0.22; p < 0.03). All patients survived, had a liver transplant, and were discharged from the hospital. CONCLUSIONS: This bioartificial liver is safe and serves as an effective "bridge" to liver transplant in some patients.

Adolescent↗
PubMed1993

Control of cerebral oedema by total hepatectomy and extracorporeal liver support in fulminant hepatic failure.

Keeping a patient with fulminant hepatic failure (FHF) alive until a donor liver is available for transplantation can be a problem. We describe an 18-year-old woman with paracetamol-induced FHF, who was treated by total hepatectomy, hypothermia, plasma exchange, and extracorporeal liver support. The patient was anhepatic for 14 h. The liver-support system consisted of plasma separation and perfusion through a charcoal filter and a hollow-fibre module seeded with matrix-attached porcine hepatocytes. With artificial liver treatment there was reversal of severe neurological dysfunction, normalisation of intracranial pressure, and decreased serum ammonia. The patient underwent emergency transplantation with an ABO-incompatible liver, followed by transplantation with a compatible organ eight days later. The patient has fully recovered and is neurologically intact.

Adolescent↗
PubMed1993

Fibroblast transplantation in rats: transduction and function of foreign genes.

The purpose of this study was to develop a method of transduction of normal skin fibroblasts with a retroviral vector expressing the human factor IX (hF-IX) gene and transplantation of the transduced cells into rats. A retroviral vector containing the hF-IX gene, as well as a selectable marker (hygromycin B resistance; HB), was used to transduce cultured normal skin (rat and human) fibroblasts. Transduced fibroblasts were selected with HB; resistant clones were propagated and assessed for expression of active hF-IX in vitro. Transduced cells secreted significant amounts of hF-IX in vitro (327.9 +/- 14.2 ng/10(6) cells) which showed measurable clotting activity, indicating terminal processing of the gene-transcribed hF-IX product by the transduced fibroblasts. Integration of the proviral gene into rat and human fibroblast genomic DNA was confirmed by polymerase chain reaction. Transduced rat fibroblasts were attached to collagen-coated microcarriers and transplanted intraperitoneally into syngeneic recipients. Transplanted microcarrier-attached cells formed aggregates in the peritoneal cavity and exhibited positive immunohistochemical staining for hF-IX up to 8 weeks following transplantation, the time of termination of the experiment. These experimental results may have significant implications in developing strategies for future clinical therapy for hemophilia B.

Animals↗
PubMed1993

Development of a hybrid bioartificial liver.

OBJECTIVE: The authors developed an extracorporeal liver support system and tested its efficacy in experimental animals with liver failure. The first clinical use of this system to treat a patient with liver failure is reported. SUMMARY BACKGROUND DATA: Multiple attempts have been made, ranging from plasma exchange to use of charcoal columns, to develop liver support systems for treating patients with acute severe liver failure. None of these systems has achieved wide clinical use. There is a need for providing liver support as a "bridge" to transplantation and for treating patients with potentially reversible liver dysfunction. METHODS: A hybrid liver support system has been developed consisting of plasma perfusion through a charcoal column and a porous hollow fiber module inoculated with 5 x 10(9) matrix-attached hepatocytes. The system was tested in dogs with ischemic liver failure (n = 7) who underwent plasmapheresis; a control group (n = 6) underwent charcoal perfusion alone. A patient with liver failure was treated with this hybrid system. RESULTS: After 6 hours of hybrid liver support treatment, animals had significantly decreased serum ammonia and lactate levels, increased glucose level, normal prothrombin time, and increased systolic blood pressure compared with controls treated with charcoal perfusion alone. Use of the system to treat a patient was well tolerated with evidence of clinical improvement. CONCLUSIONS: Plasma perfusion through a system consisting of a charcoal column and matrix-attached porcine hepatocytes had significant beneficial effects in animals with liver failure and was well tolerated by a patient with liver failure.

Animals↗
PubMed1993

Selective intraportal hepatocyte transplantation in analbuminemic and Gunn rats.

Although significant progress has been achieved in isolated hepatocyte transplantation, the optimal site of cell implantation has not yet been determined. We have developed a novel experimental method of intraportal hepatocyte transplantation that allows easy assessment of the morphology and function of transplanted hepatocytes. Donor hepatocytes were harvested from Sprague-Dawley rats by in situ EDTA/collagenase perfusion. Fifteen recipient Nagase analbuminemic rats (NAR) underwent cannulation of the gastroduodenal vein under ether anesthesia. Either the posterior or anterior liver lobes were selectively infused with cells by occluding the portal venous supply of the nontransplanted liver lobes. Normal donor hepatocytes (2 x 10(7)) suspended in normal saline were infused over 1 min (4 ml). Recipients were treated with cyclosporine for the duration of the experiment. Plasma albumin levels were determined by ELISA, before and at various intervals after transplantation. In NAR rats transplanted with normal hepatocytes, there was a significant (P < 0.003) and sustained (12 weeks) increase in plasma albumin levels. Control NAR rats transplanted with NAR hepatocytes (n = 8) showed no significant changes in plasma albumin levels. Similarly, normal Wistar hepatocytes were infused intraportally into the posterior lobes of Gunn rats (n = 4), which lack the ability to conjugate bilirubin. Pre- and posttransplantation bile was collected following bile duct cannulation. Bile analysis by HPLC, demonstrated a significant (P = 0.04) increase in the level of bilirubin conjugates following transplantation and a corresponding decrease in total serum bilirubin (P = 0.04). Our experimental data demonstrate that direct selective intraportal infusion of hepatocytes is an effective technique of hepatocyte transplantation in the rat.

Animals↗
PubMed1993

In vivo regional delivery of retrovirally mediated foreign genes to rat liver cells: need for partial hepatectomy for successful foreign gene expression.

A novel surgical technique was developed to deliver retroviral gene vectors directly to a rat liver lobe in vivo. It was observed that viral infection efficiency was enhanced by inducing hepatocyte DNA synthesis by prior partial hepatectomy. Two retroviral vectors were used to integrate specific bacterial genes: an amphotropic virus expressing the hph gene for hygromycin B phosphotransferase and an ecotropic virus expressing the lac-Z gene for beta-galactosidase. The vectors were directed to the liver by in situ selective perfusion of the posterior liver lobes with a viral suspension with inflow and outflow catheters. Male Sprague-Dawley rats were divided into three groups. Animals in the first group underwent 70% partial hepatectomy and the remnant liver lobes were allowed to regenerate for 20 hours before perfusion with the viral supernatant. Group 2 rats were perfused with viral supernatant and 2 hours later underwent 70% partial hepatectomy. Animals in the third group were perfused with the viral supernatant without partial hepatectomy. Viral transduction of hepatocytes was assessed 4 or 6 days after treatment. Hygromycin B-resistant hepatocytes were isolated from the liver remnants of rats in group 1 (21.6%) and group 2 (26.9%). No resistant hepatocytes could be detected in hepatocytes from either control rats perfused with medium alone or those from rats that did not undergo hepatectomy (group 3). In animals that received the ecotropic virus, only those that underwent hepatectomy before virus exposure (group 1) showed a small number of hepatocytes expressing beta-galactosidase in liver sections.

Animals↗
PubMed1993

Development of a bioartificial liver: properties and function of a hollow-fiber module inoculated with liver cells.

We have developed a bioartificial liver support system utilizing hollow-fiber bioreactor, plasmapheresis and microcarrier cell culture technologies. Liver cells were obtained through portal vein perfusion with ethylenediaminetetraacetate or ethylenediaminetetraacetate/collagenase. A mathematical model of mass transport in a hollow-fiber module, at various plasma flow velocities and system configurations, was developed. The bioartificial liver's ability to carry out specific differentiated metabolic liver functions was tested in vitro and in vivo. A reproducible large-animal model of acute ischemic liver failure was developed. Most major first-generation cyclosporine and 19-norterstosterone metabolites were isolated after substrate addition to the bioartificial liver in vitro. After bioartificial liver treatment for 6 hr (with dog or pig liver cells), dogs with acute liver failure had significantly lower serum ammonia and lactate levels and significantly higher serum glucose levels than did control animals treated with a bioartificial liver system inoculated with microcarriers alone. In addition, bioartificial liver-treated animals had significantly higher mean systolic blood pressures than did controls. Liver cell viability at the end of the 6-hr in vivo experiment was greater than 90%.

Animals↗
PubMed1993

Use of a novel bioartificial liver in a patient with acute liver insufficiency.

We have developed a bioartificial liver support system (BAL) using porcine hepatocytes attached to microcarriers and placed on the outer surface of hollow fibers. The BAL system was attached to a plasmapheresis device that was then used to treat the plasma of a patient with acute liver failure. Our aim was to test the efficacy and safety of this system after a single short treatment period. A patient with alcohol-induced, severe, acute liver failure manifested by coagulopathy, rising plasma ammonia level, and deteriorating mental status was studied. The procedure was well tolerated by the patient, who remained hemodynamically stable throughout the treatment period. A marked increase in coagulation factor V, VII, VIII, and IX activities, a decrease in serum ammonia level (120 to 32 mumol/L), a twofold increase in all serum amino acids except for aminobutyric acid, and an improvement in mental status were noted after a 6-hour treatment period. This preliminary report of the first use of this novel BAL system in conjunction with plasmapheresis appears promising. A clinical study is now in progress to prove its efficacy.

Adult↗
PubMed1992

A model for directed foreign gene delivery to rat liver cells in vivo.

A novel technique for directed delivery of retroviral genes to rat liver cells in vivo is described. Vascular isolation of the liver was achieved in situ and perfusate containing retrovirus expressing the bacterial gene conferring resistance to Hygromycin-B was delivered selectively to the posterior liver lobes. After 15 min, normal blood flow to the liver was restored. The portal venous branch supplying the two anterior liver lobes was ligated either at the same time (Group I, n = 4) or 20 hr prior to perfusion (Group II, n = 4) to stimulate DNA synthesis in the posterior lobes. Controls (Group III, n = 4) were perfused with retrovirus without portal branch ligation. Hepatocyte transduction was assessed 7 days later by isolating the cells and assessing their viability in a selection medium. In Group I and II rats, 9.2 +/- 0.5 and 16.0 +/- 1.0%, respectively, of harvested hepatocytes, expressed the Hygromycin-B gene. In contrast, a significantly smaller number of hepatocytes (2.8 +/- 0.9%, P less than 0.003) expressed the gene in the absence of stimulation of DNA synthesis.

Animals↗
PubMed1992

A simple two-stage technique of total hepatectomy in the rat.

We describe a novel, two-stage technique of total hepatectomy in the rat. In the first stage, acute and progressive atrophy of the posterior liver lobes attached to the inferior vena cava is induced by selective portal venous branch ligations. Two weeks later, when these lobes comprise approximately only 3% of the total liver mass, the hepatic artery is ligated and the enlarged anterior liver lobes are resected. An end-to-side porto-caval shunt is then carried out to ensure vascular integrity of the splanchnic area. This procedure was associated with no operative mortality and glucose-supplemented animals had a mean survival time of 20 +/- 5 hr. The anhepatic state was associated with significant metabolic and biochemical changes associated with necrosis of a small residual liver parenchyma. This animal preparation is a reproducible model of the anhepatic phase of experimental fulminant hepatic failure.

Animals↗
PubMed1992

Evidence for intestinal release of absorbed selenium in a form with high hepatic extraction.

Selenium is readily absorbed from the gastrointestinal tract and utilized for synthesis of selenoproteins. Roles of intestine, liver, and selenoprotein P in this process were evaluated. Rats were given 75Se-selenite by stomach tube, and distribution of 75Se was followed for 3 h. A high portal vein plasma-to-hepatic vein plasma ratio of 75Se 15 min after 75Se administration and earlier uptake by liver than by other tissues indicated avid hepatic extraction of absorbed selenium from portal vein blood. The results of gel filtration of plasma taken 15 min after 75Se administration suggested that the 75Se was in the form of small molecules with some affinity for protein. Immunoprecipitation studies using plasma indicated that 75Se began to appear in selenoprotein P between 15 and 30 min after intragastric administration. To evaluate the role of the liver in the fate of absorbed selenium, rats with portacaval shunts, in which absorbed selenium bypasses the liver, were compared with sham-operated rats. After intragastric administration of selenium, uptake by the liver and incorporation into selenoprotein P were diminished in rats with portacaval shunts but kidney uptake and urinary excretion were increased. This suggests that hepatic extraction of absorbed selenium from portal vein blood decreases its entrance into the systemic circulation. The results of this study indicate that intestine releases absorbed selenium into portal blood in a small-molecule form, designated A-Se, which is highly extracted by the liver. The liver takes up A-Se better than other tissues because of a high extraction capacity and the fact that it is the first organ through which the blood from the intestine passes.

Absorption↗
PubMed1991

Effect of biliary infection on common bile duct healing in the rat.

It has been postulated that biliary infection plays a role in bile duct stricture formation. The aim of this study was to verify this hypothesis and to evaluate the effect of biliary infection on common bile duct healing. A 3-mm longitudinal choledochotomy was performed in 120 rats and closed with a continuous 11/0 Ethilon suture. Common bile duct division with end-to-end anastomosis using interrupted 11/0 Ethilon sutures was performed in another 30 rats. Biliary infection was achieved in half of the animals with retrograde injection of living 046:K1:H31 strain Escherichia coli recovered from the rat colonic content. All rats with choledochotomy, including those with biliary infection, showed no bile leakage at the suture line, and the bursting pressure at the site of choledochotomy exceeded 40 mmHg as early as 24 h. Rats with common bile duct anastomosis alone showed no stricture formation for up to 6 months after operation. All rats with biliary sepsis developed complete occlusion at the anastomosis. On scanning electron microscopy, the biliary epithelium was well preserved in all rats. The study suggests that in rats with biliary sepsis the risk of bile leakage after primary closure of the common bile duct is negligible, but biliary infection may play a critical role in common bile duct stricture formation.

Anastomosis, Surgical↗
PubMed1991

Liver cirrhosis in rats: regeneration and assessment of the role of phenobarbital.

A common model for producing experimental liver cirrhosis is the administration of CCl4 to phenobarbital (PhB)-stimulated rats. However, concern may arise due to the complex actions of PhB upon liver metabolism. This study examined the role of PhB in the production of CCl4-induced liver cirrhosis in the rat. In addition, regenerative capacity of the liver after partial hepatectomy (PH) or portal branch ligation (PBL) was studied in cirrhotic rats, rats treated with CCl4 alone, and in PhB-treated controls. In rats given PhB throughout the CCl4-induction period, ascitic form of micronodular cirrhosis was found in 93% with only 3% mortality. In contrast, rats pretreated with PhB for only 2 weeks followed by CCl4 alone for 18 weeks did not develop liver cirrhosis. In most of the cirrhotic rats, PH induced hepatic regeneration associated with improved liver histology. PBL was less effective. Treatment with PhB alone for 10 weeks resulted in liver atrophy and reduced hepatic regenerative capacity. Impaired regeneration response was also found in rats treated with CCl4 alone. In conclusion, treatment with PhB throughout the CCl4-induction period seems necessary for the production of liver cirrhosis in rats. However, prolonged treatment with PhB alone results in liver atrophy and an impaired regenerative response. Therefore, though necessary for the cirrhotic model, PhB by itself has negative hepatotrophic influences which questions the thoroughness of the PhB/CCl4 experimental model.

Animals↗
PubMed1991

Phosphatidylcholine prevents postoperative peritoneal adhesions: an experimental study in the rat.

Phosphatidylcholine (PC) is the main constituent of the surface-active material coating peritoneal mesothelium. It may prevent postoperative adhesion formation through production of a lubricant film on mesothelial defects. We therefore examined the effect of its soluble form on surgically induced intraabdominal adhesions in rats. The adhesions were induced at laparotomy by any of four different operative models. PC was administered intraperitoneally (20 mg/rat) or intravenously (20 mg/rat or 50 mg/rat) at the end of the operation and on the second and third postoperative day. It was found that the degree of postoperative adhesion formation was significantly reduced by the intraperitoneal injection of PC in all 4 models. In contrast, no effect was achieved by the intravenous injection of PC, not even at a very high dose level. Our results suggest that soluble PC administered intraperitoneally might be a potent adjunct in postoperative adhesion prevention.

Abdomen↗
PubMed1990

Beneficial effect of hepatic arterialization on hypogonadism in male rats with portacaval shunt.

The effect of portacaval shunt (PCS) with and without hepatic arterialization (HA) upon the liver morphology, hemodynamics, and in relation to testicular weight, histology, and plasma sex steroid levels has been investigated in male rats. PCS rats showed a significant decrease in hepatic blood flow, body and liver weights, together with signs of severe hypogonadism. In contrast, in HA rats the increment in liver blood flow was associated with higher body and liver weights. In spite of total portal blood shunting, a beneficial effect on testicular morphology and an increase in plasma testosterone level were observed. In respect to plasma estradiol levels the intergroup differences could not be evaluated due to large individual variations. This was probably caused by the presence of cross-reactive plasma component(s) masking the level of endogenous estrogen. It is concluded that portosystemic shunting is not of primary importance in the etiology of PCS-related hypogonadism in the male.

Animals↗