ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.The major antigen recognized on pig tissue by primate antibodies is a terminal gal&agr;1-3gal carbohydrate structure (gal antigen) present on glycolipids and glycoproteins. The production of animals from somatic cells allows for the inactivation of specific genes. It is anticipated that the complete inactivation of the gene encoding &agr;1-3 galactosyltransferase, the enzyme that synthesizes the gal&agr;1-3gal linkage, will result in loss of that antigen from pig organs and tissue and will provide a survival benefit in pig-to-primate xenotransplants.Methods.Positive-negative selection was used to produce fetal-pig fibroblasts that were a heterozygous knockout (+/−) of the &agr;1-3 galactosyltransferase gene. Nuclear transfer of these cells generated pig embryos and live born pigs with the appropriate genotype. Using a novel selection method with cells from (+/−) embryos, we produced homozygous (−/−) fetal-pig fibroblast cells.Results.Southern blot analysis of the &agr;1-3 galactosyltransferase gene showed that we had produced (+/−) pig embryos, (+/−) live born pigs, and (−/−) pig-fetal fibroblast cells. Fluorescence-activated cell sorter (FACS) analysis with some, but not all, mouse anti-gal monoclonal antibodies and sensitized human serum showed that (−/−) cells still synthesized the gal antigen at 1 to 2% of the level of control heterozygous cells.Conclusions.Fetal-pig fibroblasts homozygous for the knockout of the &agr;1-3 galactosyltransferase gene appear to express low but detectable levels of the gal antigen.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Lung transplantation is an effective therapy plagued by a high incidence of early graft dysfunction, in part because of reperfusion injury. The optimal preservation solution for lung transplantation is unknown. We performed experiments using an isolated perfused rat lung model to test the effect of lung preservation with three solutions commonly used in clinical practice.Methods.Lungs were retrieved from Sprague-Dawley rats and flushed with one of three solutions: modified Euro-Collins (MEC), University of Wisconsin (UW), or low potassium dextran and glucose (LPDG), then stored cold for varying periods before reperfusion with Earle’s balanced salt solution using the isolated perfused rat lung model. Outcome measures were capillary filtration coefficient (Kfc), wet-to-dry weight ratio, and lung tissue levels of adenine nucleotides and cyclic AMP.Results.All lungs functioned well after 4 hr of storage. By 6 hr, UW-flushed lungs had a lower Kfc than LPDG-flushed lungs. After 8 hr of storage, only UW-flushed lungs had a measurable Kfc. Adenine nucleotide levels were higher in UW-flushed lungs after prolonged storage. Cyclic AMP levels correlated with Kfc in all groups.Conclusions.Early changes in endothelial permeability seemed to be better attenuated in lungs flushed with UW compared with LPDG or MEC; this was associated with higher amounts of adenine nucleotides. MEC-flushed lungs failed earlier than LPDG-flushed or UW-flushed lungs. The content of the solution may be more important for lung preservation than whether the ionic composition is intracellular or extracellular.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Our previous studies have suggested a chronically low oxygen tension in transplanted pancreatic islets. The present study tested the hypothesis that this may be coupled to changes in intracellular concentrations of crucial ions within the transplanted islet cells and, thus, their function.Methods.X-ray microanalysis was used for studies of native islet cells and islet grafts residing for 1 day or 1 month in nondiabetic or diabetic recipients.Results.Markedly increased sodium concentrations and decreased potassium concentrations were recorded in all transplanted islet cells, irrespective of whether the grafts had been implanted into nondiabetic or diabetic recipients or whether they were investigated 1 day or 1 month after transplantation. The calcium concentration in 1-day-old islet grafts was similar to that in native islet cells, but it decreased markedly between 1 day and 1 month after transplantation. Again this was seen in both nondiabetic and diabetic recipients.Conclusions.Most probably, the disturbances in graft sodium and potassium concentrations reflect ATP depletion and inhibition of the Na/K-ATPase in the plasma membrane as a result of impeded oxygen supply. The decreased calcium concentrations developing over time in the transplanted islet cells might be potentially detrimental, because calcium plays a fundamental role in the control of a variety of cellular functions, including insulin secretion, in &bgr; cells.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Using in situ fluorescence microscopy with Sprague Dawley rats, we studied the hypothesis of compromised microvascular kidney perfusion on organ harvest in non-heart-beating donors (NHBDs), and we evaluated the potential benefit of an additional preflush with saline solution containing streptokinase. Aortal flush of NHBD kidneys solely with University of Wisconsin solution resulted in a significantly (P<0.05) reduced functional capillary density (FCD) with increased perfusion heterogeneity compared with kidneys of heart-beating controls. This was associated with an increased lactate dehydrogenase (LDH) release on 24 hr postpreservation rinse of the grafts (76.7±18.9 U/L). Warm preflush with low-viscosity Ringer’s lactate (RL) solution alone did not influence the decreased renal FCD and the postpreservation LDH release (76.2±29.1 U/L). In contrast, the addition of streptokinase to the RL preflush solution resulted in a significant (P<0.05) improvement of FCD with values not statistically different from those of heart-beating controls. This was associated with an attenuation of perfusion heterogeneity and a significantly lowered postpreservation LDH release (17.0±2.5 U/L). Furthermore, in transplanted and reperfused NHBD kidney grafts, the use of streptokinase-supplemented RL for preflush during organ harvest significantly (P<0.05) reduced early manifestation of tubular necrosis (29%±8%) when compared with kidneys preflushed exclusively with University of Wisconsin solution (56%±4%). Thus, we conclude that kidney harvest from NHBDs is prone to severe microvascular perfusion deficits, which are likely to preclude successful preservation of organ integrity during cold storage. Temporary fibrinolytic preflush with streptokinase may represent a feasible tool to improve microvascular graft equilibration, which effectively protects the renal integrity during both cold storage and posttransplant reperfusion.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Mycophenolate mofetil (MMF)-based immunosuppression has reduced the acute rejection rate in adults and in children in the early posttransplantation period. Three-year posttransplantation results have been reported for adults but not for children thus far. In the present open-labeled study, patients 18 years old and younger were evaluated prospectively for up to 3 years after renal transplantation (RTX).Methods.Eighty-six patients receiving MMF in combination with cyclosporine and prednisone without induction were evaluated for patient survival, transplant survival, renal function, arterial blood pressure, adverse events, and opportunistic infections. These patients were compared with a historic control group (n=54) receiving azathioprine (AZA) instead of MMF.Results.Patient survival after 3 years was 98.8% in the MMF group and 94.4% in the AZA group (NS). Intent-to-treat analysis of graft survival demonstrated superiority for MMF (98% vs. 80%; P<0.001). Cumulative acute rejection episodes occurred in 47% of patients in the MMF group versus 61% in the AZA group (P<0.05). Renal function was not significantly different, neither after 3 years nor in the long-term calculation. Antihypertensive medication was administered to 73% to 84% of patients, similar in both groups. Opportunistic infections were recorded only for MMF. Infection rates were comparable to those reported in adults.Conclusions.These results suggest that MMF is safe and beneficial as a longer term maintenance immunosuppressive drug in children and adolescents.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Recent evidence has suggested that inconsistencies in human-islet yields after collagenase digestion are attributed to the activation of endogenous enzymes of the cadaveric donor pancreas. Inhibition of protease activity by Pefabloc (0.4 mM; Roche Biochemicals Inc., Indianapolis, IN) has recently been shown to improve human-islet isolation after prolonged cold storage of the pancreas. In this study, we have hypothesized that this improvement was because of the inhibition of three key serine proteases.Methods.Twenty cadaveric pancreases were perfused in the presence (n=12) and absence (n=8) of Pefabloc added at the time of distention using a customized perfusion device. Samples were collected throughout the digestion process and were assayed for trypsin, chymotrypsin, elastase, and total protease activity.Results.In all cases, the enzyme activity levels remained lower in the presence of Pefabloc as compared with the control samples. There was significantly higher chymotrypsin and elastase activity in the control group, but not trypsin or total protease activity, from the time following loading of the enzyme onto the pancreas until the stopping of the enzymatic digestion phase (dilution).Conclusions.Pefabloc was shown to be an effective protease inhibitor throughout the entire digestion process. Pefabloc supplementation did not significantly effect the dilution time or the islet yield in this study; however, these data show that serine proteases are effectively inhibited by Pefabloc during the clinical islet process.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Activated protein C (APC) exhibits anticoagulant and antiinflammatory properties. We studied the kinetics and magnitude of protein C activation in clinical liver transplantation and the interaction of this activation with neutrophil and monocyte activation.Methods.In 10 patients undergoing liver transplantation, we measured plasma protein C and APC levels, neutrophil and monocyte CD11b and L-selectin expression, and leukocyte differential counts pre-, intra-, and postoperatively. Samples of blood entering and leaving the liver were obtained simultaneously to assess changes across the liver.Results.Protein C level was low preoperatively (65%, range 39%–141%) and remained low throughout surgery. Compared with the preoperative level (107%, range 78%–161%), APC level increased during liver reperfusion (471%, range 183%–917%,P=0.05). A transhepatic decrease in protein C level (−16%, range −45%–5%,P=0.007), but not in APC level, occurred during initial liver reperfusion. At the same time, neutrophil and monocyte activation took place in the liver.Conclusions.Despite protein C deficiency, patients with liver insufficiency are able to maintain normal APC levels. During reperfusion, protein C consumption occurs in the liver without concomitant hepatic release of APC, indicating a shortage of APC in the reperfused liver. The process consuming protein C and APC may be related to the simultaneous ongoing neutrophil and monocyte activation within the liver graft, indicating a regulatory role for APC in inflammation.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.An important long-term consideration for living-donor liver transplantation (LDLT) is the expense compared with cadaveric-liver transplantation. LDLT is a more complex procedure than cadaveric transplantation and the cost of donor evaluation, donor surgery, and postoperative donor care must be included in a cost analysis for LDLT. In this study, we compare the comprehensive cost of LDLT with that of cadaveric-liver transplantation.Methods.All costs for medical services provided at our institution were recorded for 24 LDLT and 43 cadaveric recipients with greater than 1 year follow-up transplanted between August 1997 and April 2000. The donor costs include donors evaluated and rejected, donors evaluated and accepted, donor right hepatectomy costs, and donor follow-up costs (365 days postdonation). LDLT and cadaveric recipient costs include medical care 90 days pre-LDLT, recipient transplant costs, and recipient follow-up costs (365 days posttransplant) including retransplantation. Cost is expressed as an arbitrary cost unit (CU) that is a value between $500 to $1,500.Results.Total LDLT costs (evaluations of rejected donors+evaluations of accepted donors+donor hepatectomy+donor follow-up care for 1 year+pretransplant recipient care [90 days pretransplant]+recipient transplantation+recipient 1-year posttransplant care)= 162.7 CU. Total mean cadaveric transplant costs (pretransplant recipient care [90 days pretransplant]+recipient transplantation [including organ acquisition cost]+recipient 1-year posttransplant care)= 134.5 CU, (P=ns).Conclusions.The total comprehensive cost of LDLT is 21% higher than cadaveric transplantation, although this difference is not significant.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID