摘要:

Background.The etiology of primary graft nonfunction and dysfunction is unknown but most likely involves Kupffer cell-dependent reperfusion injury. However, the donor operation and surgical technique may also have an effect on the outcome after transplantation. Because liver manipulation during harvest cannot be prevented completely with standard procedures, its effect on survival was assessed here.Methods.Donor livers were harvested from female Sprague-Dawley rats (200-230 g). Briefly, after minimal dissection during the first 12 min, livers were either manipulated gently or left alone for 13 subsequent minutes. At 25 min, all livers were perfused with cold University of Wisconsin solution via the portal vein, and transplantation was performed after cold storage (1 hr). In some rats, Kupffer cells were destroyed with gadolinium chloride or inactivated with dietary glycine before harvest. Survival, proteolytic activity in the rinse effluent, serum transaminases, trypan blue distribution to index microcirculation, and histology were compared.Results.In the nonmanipulated group, survival was 100% after transplantation; however, gentle manipulation decreased survival by 70%. Further, manipulation elevated transaminases fivefold and caused about 20% necrosis. At harvest, proteolytic activity and the time for trypan blue to distribute homogeneously were elevated three- to eightfold by manipulation. Gadolinium chloride and glycine prevented the effects of manipulation on all parameters studied.Conclusion.These data indicate for the first time that brief, gentle manipulation of the donor liver has a marked detrimental effect on survival by priming or activating Kupffer cells. This may represent an important early event in pathogenesis, because Kupffer cells play an important role in primary graft nonfunction.

ISSN:0041-1337    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Background.This study was designed to assess whether the protective effect of ischemic preconditioning can be adapted for myocardium undergoing 6 hr of ischemia.Methods.Eighteen isolated rat hearts were perfused with oxygen-bicarbonated Krebs-Henseleit buffer in the Langendorff mode for 35 min (group A, controls) or perfused in the Langendorff apparatus for 20 min, followed by 5 min of global normothermic ischemia and 10 min of buffer perfusion (group B, preconditioning) or followed by two cycles of 2.5 min of global normothermic ischemia plus 5 min of buffer perfusion (group C, preconditioning). The hearts were then arrested and preserved for 6 hr with Bretschneider's histidine-tryptophan-potassium cardioplegic solution at 4 °C, followed by 30 min of reperfusion. Recovery of cardiac function, postischemic enzyme leakage, and intracellular calcium concentration were compared.Results.After 6 hr of ischemia, the hearts that underwent preconditioning in groups B and C showed better recovery of left ventricular developed pressure(P<0.05), a lower end-diastolic pressure level(P<0.05), less leakage of creatine kinase, and a lower intracellular calcium concentration than those in group A. There were no statistical differences in the rate of recovery of coronary flow.Conclusions.Our study demonstrated that ischemic preconditioning improves myocardial functional recovery after 6 hr of hypothermic preservation in the isolated rat heart. Preconditioning might be useful for preserving the heart against long-term ischemia/reperfusion injury.

ISSN:0041-1337    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Background.Accelerated arteriosclerosis limits the survival of transplanted hearts. We hypothesized that insulin-like growth factor-I (IGF-I) is crucial in accelerating transplant arteriosclerosis. Recently, we reported that exposure to IGF-I prior to transplantation accelerates transplant arteriosclerosis in the rat aorta allograft model. Here, we studied the mechanism whereby IGF-I exposure accelerates transplant arteriosclerosis.Methods.The abdominal aorta was harvested from male Brown Norway rats and exposed to 0, 200, or 500 ng/ml of IGF-I at 37 °C for 30 min prior to transplantation to the abdominal position of male Lewis rats. The allografts were harvested 14 days later and processed for immunohistochemical staining for α-actin, growth factors (IGF-I, IGF-I receptor, platelet-derived growth factor-BB, and basic fibroblast growth factor), and immunological markers (major histocompatibility complex class II antigen, macrophage, and CD4- and CD8- positive T cells).Results.By 14 days, the ex vivo IGF-I donor aorta treatment with IGF-I increased in a concentration-dependent manner the expression of IGF-I and IGF-I receptor in both the intima and the adventitia. In contrast, the expression of platelet-derived growth factor-BB was decreased in a concentration-dependent manner in the intima while basic fibroblast growth factor remained unchanged. The cell-mediated immune response was not affected by IGF-I at 14 days after transplantation, which suggests that the immune events associated with acceleration of transplant arteriosclerosis may occur at an earlier time.Conclusion.Acceleration of transplant arteriosclerosis by exposure to IGF-I is associated with increased IGF-I ligand and receptor expression in the allograft vascular wall. These data further suggest that IGF-I may be a major factor in mediating graft arteriosclerosis.

ISSN:0041-1337    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Background.Immunosuppressive drugs have been associated with the development and progression of acute pancreatitis after organ transplantation. Consequently, a reduction or a change in immunosuppressive therapy has been recommended once posttransplantation pancreatitis has been suspected. However, it is not known which of the available immunosuppressive agents is most harmful to the pancreas and which may be used safely in this situation. The objective of this study was to investigate the effect of different immunosuppressive drugs in various dosages on intrapancreatic protease activation, acinar cell necrosis, and mortality in an improved model of acute necrotizing pancreatitis in the rat. The rat model of acute necrotizing pancreatitis, like posttransplantation pancreatitis, is characterized by ischemia and microcirculatory disorders.Method.Acute pancreatitis was induced in rats by using a combination of low-dose controlled intraductal glycodeoxycholic acid superimposed on intravenous cerulein hyperstimulation. Six hours thereafter, animals were randomized to intravenous therapy with 2, 10, or 50 mg/kg/day prednisolone(PRED); 3, 15, or 60 mg/kg/day cyclosporine A (CsA); 10 mg/kg/day azathioprine(AZA); 0.6 mg/kg/day orthoclone OKT3 (OKT3); or saline. After 36 hr, surviving animals were killed to determine acinar cell necrosis and trypsinogen activation peptides levels (TAP) in blood and ascites.Results.Compared with saline-treated control rats, animals treated with 60 mg/kg/day CsA developed significantly more acinar cell necrosis and had increased amounts of TAP in ascites. Likewise, there was more extensive acinar cell necrosis in animals subjected to AZA therapy. However, this was not associated with incremental TAP. Animals treated with 3 or 15 mg/kg/day CsA, OKT3, or PRED showed no significant changes in these target parameters. Animals given 10 or 50 mg/kg/day PRED even had decreased hematocrit values and produced significantly less ascites than animals in the other groups.Conclusion.The present results suggest that AZA and high doses of CsA aggravate acute pancreatitis and should, therefore, be avoided once posttransplantation pancreatitis has been suspected, whereas lower doses of CsA, OKT3, and PRED may be used safely. PRED can even be used at higher doses as may be required when graft rejection is suspected.

ISSN:0041-1337    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Background.Perigraft immunosuppression with antilymphocyte serum (ALS) and postgraft infusion of donor bone marrow cells (BMC), which induces allograft unresponsiveness in a class I major histocompatibility complex (MHC)-disparate mouse combination, is much less effective in class I and II MHC-disparate strain combinations. Because the thymus plays a central role in the maturation, differentiation, and education of T lymphocytes, which are the principal mediator of allograft responses, we examined whether transplantation of donor-specific thymus combined with adult thymectomy of recipients enhances the tolerogenic effect of ALS and donor BMC infusion in a strongly histoincompatible class I and II MHC-disparate DBA/2-to-B6AF1 mouse strain combination.Methods.Adult thymectomy was performed 4 weeks before grafting. B6AF1 mice received ALS (days -1 and 2), skin allografts (day 0), and BMC and/or thymus grafts (ThyTx) (day 7). Flow cytometric analysis was used to detect donor cells in tolerant mice. Limiting dilution assay was used to calculate the frequencies of precursor cytotoxic T lymphocytes against donor and third-party alloantigens. The presence of suppressor cells was determined by in vivo adoptive transfer assay and in vitro coculture mixed lymphocyte culture.Results.When adult thymectomy and postgraft donor ThyTx were combined with ALS and donor BMC, DBA/2 allograft survival was prolonged with all grafts surviving for >122 days. Third-party (DBA/1) or recipient ThyTx was not effective. The tolerant mice accepted the second donor skin allografts but acutely rejected the third-party grafts. No significant chimerism was detected. Marked reduction of precursor cytotoxic T lymphocyte frequencies continued only against donor alloantigens after second donor and third-party skin grafting. No suppressor cell activity was detected. Immunopathological analysis revealed that the cells in the ThyTx of tolerant mice are of donor origin.Conclusion.Donor ThyTx combined with donor BMC infusion in adult thymectomized, ALS-treated mice induced clonal deletion of donor-reactive T cells.

ISSN:0041-1337    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Background.Immunosuppression in patients with hepatitis C virus (HCV) following orthotopic liver transplantation can lead to significant increases in serum viral loads. Our aim was to analyze the effect of a randomized study of two immunosuppressive agents (tacrolimus vs. microemulsion cyclosporine) on the outcome of HCV patients following orthotopic liver transplantation.Methods.From December 1995 to September 1996, 50 adult patients transplanted for HCV cirrhosis were randomly assigned to receive tacrolimus (Prograf)(group 1, 25 patients) or microemulsion cyclosporine (Neoral) (group 2, 24 patients). All patients received α-interferon after transplantation, and the overall steroid doses were no different between the groups. Serum RNA levels were measured by signal amplification of Chiron. Biopsies were taken when transaminases were greater than 2× base line or when there was an inappropriate response to alterations in immunosuppression regimens.Results.There were more episodes of rejection in the Neoral group, but there were no differences in bacterial and viral infections, nor in the rate of HCV recurrence between the two groups. There were seven deaths in group 1 and eight in group 2. Overall patient and graft survival rates in the Prograf and Neoral groups at 18 months were 72 and 68% and 67 and 64%, respectively.Conclusions.(a) Both immunosuppression regimens had similar HCV recurrence rates; (b) there were no differences in bacterial or opportunistic infections; and (c) patient and graft survival was similar between the two groups.

ISSN:0041-1337    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Background.Acute rejection in liver transplants is one of the commonest causes of liver dysfunction in the early postoperative period. However, the factors involved in liver graft rejection are still unknown. Our study was aimed at ascertaining whether the degree of HLA class I and class II compatibility or pretransplant viral infection have any influence on early acute liver graft rejection.Methods.We reviewed clinical and laboratory data in 190 consecutive patients who underwent a liver transplant. HLA-A, HLA-B, and HLA-DR typing for the establishment of an HLA match score was performed by a standard microcytotoxicity method. The existence of pretransplant viral infection was investigated in sera and biopsy tissue by serologic (hepatitis B virus, hepatitis C virus) and polymerase chain reaction (cytomegalovirus) techniques, respectively. The influence of these two factors in acute rejection and the interaction between them was also analyzed.Results.A strong association between viral infection and acute rejection in the group with partial class I matching was found (odds ratio=7.75;P<0.0009), whereas no correlation was observed in the group with zero class I matching (odds ratio=0.98;P=0.81). The rejection percentage in the group in which partial class I match and viral infections coexisted was 60%, whereas in the partially class I-matched group without pretransplant viral presence it was 16%.Conclusions.These findings suggest a participation of partial HLA class I compatibility in triggering acute rejection in recipients suffering preoperative viral infections and support the idea that HLA class I antigen matching could play a role as a linking element between the MHC-restricted T cell-mediated response to viral infection and the allogenic response in liver transplantation.

ISSN:0041-1337    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Background.Previous reports with short-term follow-up after renal transplantation for IgA nephropathy (IgAN) have suggested an incidence of recurrence up to 50%, an increased recurrence with living-related donors, and the rarity of graft loss due to recurrence. In this study, the long-term results of renal transplantation for IgAN were examined.Methods.Between June 1980 and December 1994, 54 patients (61 renal transplants) with end-stage renal disease due to IgA nephropathy were performed at the University of California San Francisco. Actuarial patient and graft survival were compared with a matched reference group. Correlates of recurrent disease (biopsy confirmed) and graft loss were determined.Results.Patient and graft survival for IgA patients were good (100% and 75%, respectively, at 5 years after transplant). Graft survival was lower in IgA recipients with living-related compared with cadaveric renal allografts(P<0.09) and also with renal allografts well matched at HLA-AB (≤2 AB mismatches) (P<0.09) or HLA-DR(≤1 mismatch) (P<0.01). Recurrence was not correlated with donor status, recipient age, race, gender, or immunosuppression. Recurrence (18 of 61) resulted in substantial graft loss (6 of 18) or deteriorating renal function (4 of 18) at a mean follow-up of 61 months. Mean time to diagnosis of recurrence and subsequent graft loss was 31 and 63 months, respectively. Despite re-recurrence of IgAN in three of five patients who were retransplanted, all have good long-term renal function.Conclusions.Substantial graft loss due to recurrent disease after renal transplantation for IgAN occurs with long-term follow-up. Living-related transplantation and HLA matching do not appear to confer an advantage for graft survival in patients with IgAN. Despite the potential for recurrence, IgAN patients enjoy good long-term graft survival.

ISSN:0041-1337    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Background.The preservation of sufficient quantities of islets for human transplantation has proven to be a tenacious problem for researchers and transplant programs. Beyond the variables associated with islet procurement, there is the problem of tissue storage before transplantation. Cryopreservation has been adopted as a method for long-term islet storage that allows for recovery of viable tissue. However, there is significant tissue loss during the process and the possibility that long-term viability may be compromised. An alternate method of prolonged culture at 24 °C was initially introduced as a means of reducing islet antigenicity. Although successful in the short term, prolonged culture with serum-based media has also resulted in a significant loss of tissue. In this study, we report the successful use of an ITS+ Premix-supplemented serum-free media for prolonged islet culture and its comparison to fetal bovine serum-supplemented media and to cryopreservation.Methods.Pancreata were procured from cadaveric organ donors, and islets were isolated using our own modification of the automated method of Ricordi. Aliquots from a series of human islet isolations were cultured in parallel in(A) CMRL + ITS (serum-free media; SFM) or (B) CMRL + 10% fetal bovine serum(standard media) and compared with cryopreserved and thawed tissue.Results.Our results show that SFM allows for the long-term culture of islet tissue. For time points up to 2 months, islets cultured in SFM showed recovery ratios greater than those for standard serum-supplemented media. At 1 week and 1 month, islet recovery ratios were greater for SFM-cultured islets than for cryopreserved tissue. Viability studies confirmed that the SFM-cultured islets were able to respond to glucose stimulation (stimulation index 0.8-21.2). Additionally, in vivo results using cultured islets in a patient demonstrated good islet function, with a 1-month stimulation index of 4.02 in response to an intravenous glucose tolerance test.Conclusion.We conclude that this culture modification represents a method by which functional islet tissue can be maintained in long-term culture and successfully transplanted.

ISSN:0041-1337    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Background.Methods to quantitate the effects of immunosuppressive drugs on immune reactivity might be helpful for monitoring immunosuppressive treatment. Cyclosporine (CsA) inhibits the induction of cytokine synthesis in T cells, and measurement of interleukin (IL)-2 production might constitute a parameter of this drug's effect.Methods.We determined the percentages of CD4+and CD8+lymphocytes producing IL-2 upon stimulation by phorbol myristate acetate and calcium ionophore in whole blood culture, using immunostaining of intracytoplasmatic and membrane markers, followed by multiparameter flow cytometry. A total of 38 clinically stable transplant patients on various immunosuppressive protocols were studied.Results.The percentage of CD4+T cells producing IL-2 was strongly reduced in patients compared with healthy controls (23%[range, 3-68%] vs. 59.0% [range, 41-70%];P=0.000035). The percentage of CD4+T cells producing IL-2 was negatively correlated with the CsA level(Rc=-0.0821,P=0.00002297) but not with prednisolone or azathioprine doses. Fewer CD8+T cells produced IL-2 in transplant patients compared with controls, but the difference failed to reach statistical significance. The percentage of CD8+T cells capable of producing IL-2 was inversely correlated to CsA levels(Rc=-0.0375,P=0.0011).Conclusions.These data suggest that the functional effects of CsA in transplant recipients can be quantitatively determined and that the capacity of CD4+T cells to produce IL-2 upon stimulation constitutes a functional parameter of CsA effects on the immune system. Prospective studies are required to determine whether this method is useful for clinical monitoring.

ISSN:0041-1337    

出版商:OVID    

年代:1998

数据来源: OVID