ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Lipid peroxidation due to oxygen free radicals (OFR) seems to play a major role in loss of liver graft viability after warm ischemia, preservation, and transplantation. N-acetylcysteine (NAC) is an antioxidant that has a direct effect on OFR, and is also a glutathione precursor, another antioxidant. This study was designed to evaluate the efficacy of NAC in preventing ischemia-reperfusion damage of liver grafts harvested from non-heart-beating donors. Liver transplantation was performed on pigs divided into five groups: group 1 (control group; n=5) received livers from heart-beating donors; livers were subjected to 30 min of warm ischemia in groups 2 (n=3, no NAC) and group 3 (n=3; NAC treatment); warm ischemia time lasted 60 min in groups 4 (n=4; no NAC) and 5 (n=5; NAC treatment). Studied parameters included graft survival for more than 3 days, aspartate aminotransferase plasma levels, liver histology, and hepatic total glutathione concentrations.Graft survival was 100% in groups 1, 2, and 3, 0% in group 4, and 20% in group 5. NAC treatment did not influence initial mean aspartate aminotransferase release which was greater in warm ischemic livers than in controls. NAC treatment had no effect on liver hepatic total glutathione after reperfusion of animals receiving warm ischemic grants. Finally, no effect on liver histology was observed with NAC treatment.Our study suggests that in liver transplantation from non-heart-beating donors, NAC has no effect in both graft viability and lipid peroxidation. The role of OFR in primary dysfunction of transplanted warm ischemic livers remains controversial.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Insulin-dependent diabetes mellitus (IDDM) is the second most prevalent chronic illness of children. Investigation of the treatment of IDDM is hindered by the lack of a reproducible and easily maintained non-human primate model of this disorder.Methods.We induced IDDM in 11 juvenile cynomolgus monkeys after a single (150 mg/kg) intravenous injection of streptozotocin (STZ). All diabetic monkeys were treated with insulin twice daily, based on a sliding scale. Subcutaneous vascular access ports were surgically placed in each monkey to facilitate serial blood sampling and drug administration. Allogeneic pancreatic islet cells from unrelated donors were subsequently transplanted into the mesenteric circulation of all STZ-treated monkeys.Results.Mild, transient nausea and vomiting occurred in all animals after STZ injection; however, no additional signs of toxicity occurred. Within 36 hr, all monkeys required twice daily administration of exogenous insulin to maintain a non-ketotic state. Serum C-peptide levels decreased from >1.2 ng/ml before STZ, to between 0.0 and 0.9 ng/ml after STZ, confirming islet cell destruction. Animals were maintained in an insulin-dependent state for up to 147 days without any observable clinical complications. Subcutaneous vascular access port patency was maintained up to 136 days with a single incidence of local infection. Islet cell transplantation resulted in normoglycemia within 24 hr. Serum C-peptide levels increased (range: 2-8 ng/ml) for 6-8 days in immune competent animals, and for 39-98 days after transplant in immunosuppressed monkeys.Conclusions.IDDM can be consistently induced and safely treated in juvenile cynomolgus monkeys. Chronic vascular access can be maintained with minimal supervision and complications. This model is appropriate for studies investigating potential treatments for IDDM including islet cell transplantation.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Canine stem cell transplantation models have provided important preclinical information for human clinical studies. The recent cloning of cDNA for canine CD34 and the production of monoclonal antibodies that recognize canine CD34 have been the basis for the development of techniques for the large-scale enrichment of canine hematopoietic progenitor cells. In this study, we evaluated the in vivo functional properties of canine bone marrow CD34+ cells after a myeloablative conditioning regimen.Methods.After 920 cGy total body irradiation, three dogs received infusion of autologous CD34+ selected cells from the marrow, three dogs CD34+ depleted autologous marrow cells, and two dogs received CD34+ autologous marrow cells that were immunomagnetically selected and then further purified by cell sorting. In addition, four dogs received allogeneic marrow enriched for CD34+ cells from dog leukocyte antigen-identical littermates to investigate long-term repopulating function of CD34+ cells. Chimerism studies were performed using polymerase chain reaction to detect highly polymorphic microsatellite markers.Results.In three recipients of autologous marrow enriched for CD34+ cells to between 29% and 70% (1.6×106to 3.4×106CD34+ cells/kg), prompt and full hematopoietic recovery occurred, whereas in three dogs that received marrow depleted of CD34+ cells (1×107cells/kg), no hematopoietic recovery was achieved. In two dogs that received highly purified CD34+ cells (purity: 98% and 96%, 0.79×106to 0.547×106CD34+ cells/kg), delayed but full hematopoietic recovery was seen. Three of four allograft recipients of 1.75×106to 6.8×106CD34+ cells/kg engrafted and showed full hematopoietic recovery, whereas one dog rejected the graft. The three long-term survivors showed stable mixed hematopoietic chimerism with predominantly donor hematopoiesis.Conclusions.Transplantation of canine CD34+ cells after lethal total body irradiation provides radioprotection and gives rise to long-term hematopoietic reconstitution. Stable donor/host mixed chimerism was observed in allograft recipients most likely as a result of T-cell depletion of the grafts. Our findings suggest a future role for canine preclinical transplant studies involving in vitro manipulation of hematopoietic progenitor cells.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Organ cold storage times may be extended by modifications to organ preservation solutions.Methods.Three preservation solutions were investigated for their ability to maintain viable hepatic bioenergetics in stored pig livers: modified University of Wisconsin (mUW); mUW+adenosine (1.34 g/L), and mUW+iloprost (10−8mol/L), a prostacyclin analogue. Using human liver retrieval and storage techniques, pig livers were stored on ice for either 2 or 16 hr, after which phosphorus-31 spectra were collected every 2 min during the period of cold ischemia and hypothermic reperfusion (HtR). During HtR, metabolite concentration changes associated with phosphomonoesters, inorganic phosphate, γ-nucleotide triphosphate (NTP), and β-NTP were measured for all solutions.Results.After a 2-hr storage, β-NTP regeneration in mUW+iloprost produced +57.7% (P<0.01) more β-NTP, at a faster initial rate of +66.3% (P<0.001), compared with mUW, and mUW+adenosine regenerated +35.6% (P<0.05) more β-NTP, compared with mUW. Storage for 16 hr did not slow the rates of regeneration, and the total NTP produced during the course of the experiment remained unchanged for the respective preservation solutions. Cessation of HtR invoked a net accumulation of nucleotide diphosphate, indicating differential kinetics of adenine nucleotide hydrolysis.Conclusion.This large animal model study suggests significant improvements to human organ preservation solutions using prostacyclin analogues and adenosine with respect to hepatic bioenergetics.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Frequent success in human islet isolation is prevented by the large variability of scarce organ donors; this favors the future utilization of pigs as donors for clinical islet xenotransplantation. Porcine-specific difficulties of islet isolation are attributed to the intrinsic fragility of islets during pancreas digestion.Methods.To preserve islet integrity during efficient pancreas dissociation, porcine pancreata (n=48) were distended after cold storage with cold University of Wisconsin solution containing Liberase HI and digested at 24-28°C using digestion-filtration. Pancreata distended with University of Wisconsin solution containing well-proven crude collagenase and digested at 32-34°C served as controls (n=46). Monolayer Ficolldiatrizoate gradient purification was performed in a Cobe 2991.Results.Purified yield of islet equivalents per pancreas (mean ± SEM) was almost doubled by Liberase HI compared with crude collagenase (526,480±46,560 vs. 270,270±19,420;P<0.0001) and also significantly increased comparing islet equivalents per gram of pancreas (4,210±320 vs. 2,640±245;P=0.0004). Islet integrity was better preserved during Liberase HI digestion compared with crude collagenase digestion as indicated by isolation index (2.1±0.1 vs. 1.4±0.1;P<0.0001). Purity, viability, and in vitro function of islets did not differ between experimental groups. Preserved in vivo function of islets isolated by Liberase HI was demonstrated after subcapsular transplantation into 16 diabetic nude rats.Conclusions.If the problems related to xenograft rejection and xenosis could be solved, low-temperature digestion of porcine pancreata using Liberase HI could serve as an essential prerequisite for successful 1:1 xenotransplantation of pig islets into type 1 diabetic human recipients.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Hepatic support systems that provide detoxification without biliary secretion (i.e., isolated hepatocyte systems) are sufficient to improve encephalopathy and bridge patients to transplantation. However, biliary secretion may be critical when hepatic support attempts to restore function and regeneration of the host liver. The purpose of these studies was to optimize the support liver secretory response to bile acid by either single-vessel (portal vein; PV) or dual-vessel (hepatic artery [HA] + PV) perfusions during extracorporeal porcine liver perfusion.Methods.Extracorporeal porcine liver perfusion of anesthetized pigs was developed using support porcine livers perfused through the PV (n=4) alone and through the HA + PV (n=4) via a venovenous circuit. Support livers were provoked with taurocholate (TC) to enhance bile aqueous and hydrophobic outputs.Results.After cold preservation and reperfusion, both PV and HA + PV livers had initial 1-hr bile aqueous outputs <15% of in vivo flow, with cholesterol (C) and phospholipid (PC) outputs <25% of in vivo flow. Bile flow was significantly greater for recovered HA + PV livers (3.0±0.01 ml/15 min) than PV livers (1.9±0.01 ml/15 min). Despite this, PC output was significantly greater for PV than HA + PV livers. The C/PC ratio of PV livers was twice that of HA + PV livers. TC infusion (48 μmol/kg/15 min) of HA + PV livers demonstrated significantly greater increments in bile flow, PC output, and C output than PV livers.Conclusion.In the unstimulated state, porcine support livers with dual-vessel perfusion generated greater aqueous and C outputs despite diminished PC output than in those with single-vessel perfusion. TC stimulation increased bile flow, PC output, and C output in dual-perfused livers more than in PV livers. HA + PV perfusion of support livers is the preferred technique for removing hydrophobic compounds that require PC transport for excretion or exist in the aqueous phase.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Mixed allogeneic bone marrow chimerism induces tolerance to solid organ grafts. Although we previously reported that partially ablative conditioning with 700 cGy of total body irradiation (TBI) is sufficient to allow for bone marrow engraftment in mice, we determined that a minimum of 1000 cGy was required in the rat. Because T cells and NK cells are critical in bone marrow graft rejection, our purpose was to examine whether targeting of radioresistant NK cells and/or T cells in the recipient hematopoietic microenvironment would reduce the TBI dose required for engraftment of allogeneic rat bone marrow.Methods.Wistar Furth rats received either anti-NK3.2.3 monoclonal antibodies on days −3 and −2, antilymphocyte serum on day −5, a combination of both or no pretreatment. TBI was performed on day 0 and rats were reconstituted with 100×106T cell-depleted bone marrow cells from ACI donors.Results.Engraftment of T cell-depleted rat bone marrow was readily achieved in animals conditioned with 1000 cGy TBI alone (12/12) and the level of donor chimerism averaged 89%. At 900 cGy TBI alone only one of eight recipients engrafted. In striking contrast, 11 of 12 animals pretreated with anti-NK monoclonal antibodies and irradiated with 900 cGy showed donor chimerism at a mean level of 41%. No further enhancement of bone marrow engraftment could be achieved when recipients were pretreated with antilymphocyte serum alone or antilymphocyte serum plus anti-NK monoclonal antibodies. Mixed allogeneic chimeras exhibited stable multilineage chimerism and donor-specific tolerance to subsequent cardiac allografts.Conclusion.Specific targeting of radioresistant host NK cells allows for a significant reduction of the TBI dose required for allogeneic bone marrow engraftment.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Transjugular intrahepatic portosystemic shunting (TIPS) has become an effective treatment for the complications of portal hypertension. We assessed the feasibility and outcome of TIPS in liver transplant recipients.Methods.During the period from December 1992 to January 1998, eight adults presenting recurrent hepatitis C virus (five patients) and hepatitis B virus (one patient) infection, veno-occlusive disease (one patient), and secondary biliary cirrhosis (one patient) had TIPS because of refractory ascites (five patients), bleeding esophageal varices (one patient), refractory hepatic hydrothorax (one patient), retransplantation (two patients), and redo-biliary surgery (one patient).Results.In two patients, the procedure was difficult due to cavo-caval implantation. Ascites, hydrothorax, and variceal bleeding were controlled in all patients. Moderate to severe encephalopathy developed in four patients; two patients had worsening of their existing encephalopathy. Three of five patients treated with cyclosporine needed a drastic dose reduction due to the development of severe side effects. No long-term survivor developed shunt stenosis or occlusion. Two patients did moderately well at 6 and 14 months, respectively; the former died due to chronic rejection while waiting for a retransplantation. Three did well at 14, 36, and 28 months, respectively; the latter patient died of liver failure 32 months after TIPS. One jaundiced patient died after 1.5 months due to necrotic pancreatitis. Two patients died after 4 and 8.5 months, respectively, due to liver failure; the latter was doing well until 7 months after TIPS.Conclusions.TIPS is feasible in transplant recipients in cases of decompensated allograft cirrhosis, of allograft veno-occlusive disease or when retransplantation or redo-biliary surgery are scheduled in the presence of portal hypertension. At transplantation, the surgeon should keep in mind the eventuality of a later TIPS procedure. Close immunosuppression monitoring is warranted because modified metabolization of cyclosporine (and probably tacrolimus) may cause serious side effects.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.In Japan, the relative risk for renal cell carcinoma (RCC) in renal transplants was about 80-fold higher than that in the general population. Depressed immune surveillance due to the use of immunosuppressive agents was considered to cause cancer. Before renal transplantation, a vast majority of patients received hemodialysis, a known causative factor for acquired cystic disease of kidney (ACDK). Because ACDK is also considered to predispose to RCC, at least two risk factors for cancer accumulate in renal transplants.Methods.In our study, clinicopathological features together with p53 gene mutations were analyzed in 218 patients with RCC: 22 received dialysis followed by renal transplantation, 39 received dialysis alone, and 157 sporadic RCC. P53 mutations were analyzed on DNA extracted from paraffin-embedded specimens with use of single strand conformation polymorphism, followed by direct sequencing.Results.RCC in transplants shared several clinico-pathological features with those in dialysis patients, which included small size and multiplicity of tumor, relatively high frequency of presence of ACDK, and papillary type of RCC. p53 gene mutations were infrequent in RCC of any clinical setting.Conclusions.Atrophic kidney at the end-stage of renal failure and under dialysis have lesions of ACDK that might predispose to RCC in dialysis and transplant patients.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID