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Biomedical subjects

K Yanaga

Publications and source records attributed to K Yanaga.

At least 109 records · Page 6Linked to original sources
PubMed1990

Hepatic artery reconstruction for hepatic artery thrombosis after orthotopic liver transplantation.

We evaluated the efficacy of reconstruction of the hepatic artery for intraoperative or postoperative thrombosis in orthotopic liver transplantation. Of 37 grafts with artery thrombosis, 13 (35.1%, 6 intraoperative and 7 postoperative) underwent reconstruction of the hepatic artery. The arterial flow was reestablished and maintained in 5 (38.5%) of the 13. Recurrent thrombosis in the other 8 grafts developed 2 to 24 days (mean, 13.8 days) after transplantation. Reconstruction was successful in 50% (4/8) of the adults, compared with only 20% (1/5) of the children. Satisfactory results were obtained when a definitive cause of thrombosis could be identified. We conclude that early recognition and correction of the cause of hepatic artery thrombosis during or after orthotopic liver transplantation, especially in adults, is often a graft-saving and lifesaving procedure worthy of consideration.

Adolescent↗
PubMed1990

Development of colon cancer after liver transplantation for primary sclerosing cholangitis associated with ulcerative colitis.

Between February 26, 1981, and July 30, 1987, 36 patients underwent orthotopic liver transplantation for primary sclerosing cholangitis associated with ulcerative colitis. Three of the 36 recipients died within 3 mo because of graft nonfunction or surgical complications. The other 33 (92%) lived for at least 1 yr. Two of the 33 died after 12 and 14 mo, respectively, of recurrent cholangiocarcinoma that was not diagnosed before transplantation. Four other patients died of recurrent liver failure (three cases) or immunoblastic sarcoma (one case) after 14, 21, 36 and 44 mo. Twenty-seven (75%) of the patients are still alive 23 to 81 mo after transplantation. Two patients have been diagnosed as having colorectal cancer 11 and 21 mo respectively, after transplantation, for an overall incidence of 5.6% (2 of 36) and a corrected incidence of 6.5% (2 of 31) if the three early deaths and two later deaths caused by cholangiocarcinomas are excluded. It is not known whether colorectal malignancies were present but undetected at the time of transplantation or whether they developed afterward. It is clear that patients who undergo liver transplantation for primary sclerosing cholangitis associated with ulcerative colitis should have careful follow-up of the colon, including colonoscopy and multiple biopsies of the colorectal mucosa. Whether proctocolectomy should be considered prophylactically after liver transplantation is an unresolved issue.

Adenocarcinoma↗
PubMed1990

Evaluation of protocol before transplantation and after reperfusion biopsies from human orthotopic liver allografts: considerations of preservation and early immunological injury.

Light microscopic, immunohistochemical and ultrastructural analysis of protocol before transplantation and after reperfusion biopsy specimens from 87 randomly selected patients was performed to assess the contribution of preservation and immunological injury to early graft failure. Most biopsy specimens were essentially normal by light microscopy before transplantation, and no particular feature could be relied on to predict function after transplantation. Ultrastructural examination of biopsy specimens before transplantation demonstrated preferential degeneration of sinusoidal lining cells, but no strict correlation was seen between ultrastructural sinusoidal integrity before transplantation and function after transplantation. The presence of zonal or severe focal necrosis and a severe neutrophilic exudate in biopsy specimens after reperfusion presaged a poor early postoperative course in most, but not all, patients. The presence of preformed lymphocytotoxic antibodies had no effect on the early clinical course, but was associated with Kupffer cell hypertrophy in needle biopsy specimens taken after transplantation. No definite evidence was seen of hyperacute rejection as a result of preformed lymphocytotoxic antibodies as detected in conventional assays. These findings suggest that preservation injury accounts for only a subset of grafts that fail to function after transplantation. Other perioperative or "recipient" factors may be of equal or greater importance in early graft dysfunction or failure.

Biopsy↗
PubMed1990

Partial dearterialization of the liver allograft.

The clinical course of five patients with partial dearterialization of their hepatic allografts is described. One patient died and three others suffered serious morbidity as a direct or indirect result of this complication. Partial dearterialization of the liver allograft is a serious and potentially life-threatening complication for which preservation of the complete hepatic arterial supply is important, even if this requires reconstruction of the aberrant vessels.

Adult↗
PubMed1990

Hemodynamic and biochemical changes during normothermic and hypothermic sanguinous perfusion of the porcine hepatic graft.

Using an ex vivo liver sanguinous perfusion system, hemodynamic and biochemical changes of the porcine livers were studied, which were preserved cold (4 degrees C) for 24 hr in University of Wisconsin solution and reperfused with normothermic (37 degrees C) (n = 8) or hypothermic (32 degrees C) (n = 8) blood for 3 hr. Six more livers were reperfused with normothermic blood (37 degrees C) immediately after procurement as controls. The total hepatic blood flow was adjusted to 1 ml/min/g liver weight, in which hepatic artery and portal vein flows were administered at a 1:2 ratio. In livers stored cold for 24 hr in UW solution and perfused normothermically, a statistically higher hepatic artery resistance was exhibited at 30 and 60 min after reperfusion (P less than 0.05), and there was lower bile output (P less than 0.05) at 90 and 120 min as compared to the controls. In livers stored cold for 24 hr in UW solution and perfused hypothermically, as compared to ones perfused normothermically, statistically higher hepatic-artery and portal-vein resistances (P less than 0.05) were observed throughout the perfusion period and 60 min after reperfusion, respectively. In addition, bile output and oxygen consumption of these livers were statistically lower than those of ones perfused normothermically (P less than 0.05). In contrast, chemistries of the perfusate of livers perfused hypothermically were comparable to ones perfused normothermically. Histologic examination of the liver perfused hypothermically demonstrated hepatic arterial and/or portal venous congestion and mild-to-moderate hemorrhage in the portal triads. This study suggests that livers preserved for a prolonged period of time demonstrate a high hepatic arterial resistance shortly after revascularization, and that recipient hypothermia after revascularization may be a risk factor for the development of hepatic arterial thrombosis following liver transplantation.

Animals↗
PubMed1990

Immunodepletion in xenotransplantation.

Xenograft transplantation is perhaps the most immunologically difficult problem in transplantation today. An overwhelming hyperacute rejection reaction (HAR) occurs within minutes of organ implantation. Preformed antibodies are thought to initiate this process. We used a pig-to-dog renal xenograft transplant model and investigated methods of decreasing the severity of hyperacute rejection. Female pigs weighing 15-20 kg were used as donors. Recipients were mongrel dogs weighing 15-25 kg. Experimental dogs were all given a number of treatments of IgG depletion using an antibody removal system (Dupont-Excorim). This machine immunoadsorbs plasma against a column containing immobilized staphylococcal protein A, which is known to bind the IgG Fc receptor. An 84% reduction in the IgG levels and a 71% reduction in IgM levels was achieved. Postoperative assessment was made of urine output, time to onset of HAR, and histopathological examination of the rejected kidneys. Although cross-matches between donor lymphocytes and recipient sera remained strongly positive in the treated dogs, there was a two- to fourfold reduction in the titers. The time to onset of HAR was prolonged in the experimental group, and the urine output was increased slightly. The histopathologic changes in the experimental group generally showed signs of HAR, but of less intensity than in the nonimmunodepleted control group.

Animals↗
PubMed1990

A new liver perfusion and preservation system for transplantation research in large animals.

A kidney perfusion machine, model MOX-100 (Waters Instruments, Ltd, Rochester, MN) was modified to allow continuous perfusion of the portal vein and pulsatile perfusion of the hepatic artery of the liver. Additional apparatus consists of a cooling system, a membrane oxygenator, a filter for foreign bodies, and bubble traps. This system not only allows hypothermic perfusion preservation of the liver graft, but furthermore enables investigation of ex vivo simulation of various circulatory circumstances in which physiological perfusion of the liver is studied. We have used this system to evaluate the viability of liver allografts preserved by cold storage. The liver was placed on the perfusion system and perfused with blood with a hematocrit of approximately 20%, and maintained at 37 degrees C for 3 h. The flows of the hepatic artery and portal vein were adjusted to 0.33 mL and 0.67 mL/g of liver tissue, respectively. Parameters of viability consisted of hourly bile output, oxygen consumption, liver enzymes, electrolytes, vascular resistance, and liver histology. This method of liver assessment in large animals will allow the objective evaluation of organ viability for transplantation and thereby improve the outcome of organ transplantation. Furthermore, this pump enables investigation into the pathophysiology of liver ischemia and preservation.

Animals↗
PubMed1990

Analysis of surgical complications after 397 hepatic transplantations.

The results of 397 consecutive orthotopic hepatic transplantations in 333 recipients were reviewed. One or more surgical complications developed in 172 of 323 patients (55 per cent), excluding ten intraoperative deaths. The six month mortality rate among the patients with surgical complications (55 of 172; 32 per cent) was statistically higher than that among patients without such complications (16 of 151; 11 per cent) (p less than 0.001; chi-square, 58.36). Surgical complications included exploratory laparotomy for bleeding or infection in 74 (22 per cent), reconstruction of the bile duct for biliary obstruction or leakage in 55 (17 per cent), external biliary drainage for biliary leakage in four (1 per cent), tracheostomy in 80 (24 per cent), thoracotomy in 12 (4 per cent) and splenectomy in seven (2 per cent). The incidence of biliary obstruction (16 per cent mortality rate) and leakage (48 per cent mortality rate) was 18 per cent (34 of 193) and 2 per cent (four of 193) each after choledochocholedochostomy, which was 3 per cent (five of 187) and 9 per cent (17 of 187) each after choledochojejunostomy. Biliary obstruction (16 per cent mortality rate) was more common after choledochocholedochostomy (p less than 0.005; chi-square, 23.01), whereas the incidence of more serious biliary leakage (48 per cent mortality rate) was higher after choledochojejunostomy (p less than 0.005; chi-square, 8.97). It is concluded that orthotopic hepatic transplantation remains an unforgiving extensive surgical procedure, in which choledochocholedochostomy remains the first-choice reconstruction of the biliary tract because of its lower mortality.

Adult↗
PubMed1989

Extended preservation of human liver grafts with UW solution.

The fate of 185 cadaveric liver homografts preserved for four to 24 hours with University of Wisconsin (UW) solution was compared with that of 180 grafts preserved for three to 9 1/2 hours with conventional Euro-Collins solution. Although the average preservation time of the UW-preserved livers was almost twice as long as that of the Euro-Collins-preserved livers, the UW-preserved grafts survived at a higher rate; permitted equal patient survival; and had a lower rate of primary nonfunction, a reduced need for retransplantation, and a lower rate of hepatic artery thrombosis. There was no correlation between the time of preservation of UW-preserved grafts up to 24 hours and liver function abnormalities in the first postoperative week. In contrast, livers preserved with Euro-Collins solution for more than five hours had significantly increased perturbations of hepatic function tests. The potential revolutionary effect of the UW solution on liver transplantation is described herein.

Cause of Death↗
PubMed1989

Personal experience with the procurement of 132 liver allografts.

A single donor surgeon's experience procuring the livers from 132 donors is described. Thirty-seven grafts (28.9%) had hepatic arterial anomalies, 19 (14.4%) of which required arterial reconstruction prior to transplantation. Of the 121 grafts evaluated for early function, 103 grafts (85.2%) functioned well, whereas 14 grafts (11.6%) functioned poorly and 4 grafts (3.3%) failed to function at all. The variables associated with less than optimal function of the graft consisted of donor age (P less than 0.05), duration of donor's stay in the intensive care unit (P less than 0.005), abnormal graft appearance (P less than 0.05), and such recipient problems as vascular thromboses during or immediately following transplantation (P less than 0.005). A new preservation fluid, University of Wisconsin solution, allowed safe and longer cold storage of the liver allograft than did Euro-Collins' solution (P less than 0.0001). A parameter of liver allograft viability, which is simple and predictive of allograft function prior to the actual transplant procedure, is urgently needed.

Adolescent↗
PubMed1989

Reversal of hypersplenism following orthotopic liver transplantation.

The purpose of this study was to clarify the effect of orthotopic liver transplantation on hypersplenism. In a 1-year period from July 1, 1986 to June 30, 1987, 196 adult patients underwent 233 orthotopic liver transplantations. Of the 58 patients with hypersplenism who were analyzed in this study, hypersplenism was more commonly associated with postnecrotic cirrhosis than other kinds of liver disease (55.3% (47/85) vs. 14.5% (11/76); p less than 0.001). Postoperative platelet counts were statistically higher than preoperative values (p less than 0.05). The latest platelet counts were more than 100,000/mm3 in 53 patients (91.4%). Of the eight patients whose preoperative and postoperative spleen volumes could be compared, all showed the reduction in the spleen size (p less than 0.02). We conclude that orthotopic liver transplantation, which is a radical surgical procedure for portal hypertension, reverses hypersplenism.

Adult↗