摘要:

Background.Allogeneic skin transplantation remains a rigorous test of any immune intervention designed to prevent allograft rejection. To date, no single, clinically available immunosuppressant has been reported to induce long-term primary skin allograft survival in primates. We have previously shown that treatment with the humanized CD154-specific monoclonal antibody, humanized 5C8 (hu5C8), induces long-term renal allograft survival in nonhuman primates. In this study, we evaluated the efficacy of hu5C8 in preventing primary skin allograft rejection in rhesus monkeys.Methods.Ten rhesus monkeys were transplanted with full-thickness skin allografts mismatched at both class I and class II major histocompatibility loci. Of these, two were given no treatment, five were treated with hu5C8 alone, and three received hu5C8 combined with whole blood donor-specific transfusion (DST). All recipients also received skin autografts for comparison. Animals were followed by inspection, serial biopsy, mixed lymphocyte culture, and alloantibody determination.Results.Treatment with hu5C8 alone or hu5C8 plus DST greatly prolonged allograft survival. Rejection occurred in the untreated group within 7 days. Mean allograft survival in the monotherapy hu5C8 group was >236 days and in the DST group was >202 days; these differences were not significant. Rejection eventually occurred in most animals. Allograft survival was not correlated with the development of T cell hyporesponsiveness in mixed lymphocyte culture. Rejection was not predicted by the development of donor-specific alloantibody.Conclusion.These results show that treatment with the CD154-specific monoclonal antibody, hu5C8, greatly delays the onset of acute skin allograft rejection.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.Ocular burns cause depletion of limbal stem cells, which leads to corneal opacification and visual loss. Autologous cultured epithelial cells can restore damaged corneas, but this technology is still developing. We sought to establish a culture system that allows preservation of limbal stem cells and preparation of manageable epithelial sheets and to investigate whether such cultures can permanently restore total limbal stem cell deficiency.Methods.We selected a homogeneous group of patients whose limbal cell deficiency was evaluated by scoring the gravity of the clinical picture and the keratin expression pattern. Stem cells, obtained from the limbus of the contralateral eye, were cultivated onto a fibrin substrate and their preservation was evaluated by clonal analysis. Fibrin cultures were grafted onto damaged corneas.Results.Fibrin-cultured limbal stem cells were successful in 14 of 18 patients. Re-epithelialization occurred within the first week. Inflammation and vascularization regressed within the first 3–4 weeks. By the first month, the corneal surface was covered by a transparent, normal-looking epithelium. At 12–27 months follow-up, corneal surfaces were clinically and cytologically stable. Three patients had a penetrating keratoplasty approximately 1 year after restoration of their corneal surface. Their visual acuity improved from light perception or counting fingers to 0.8–1.0.Conclusions.Preservation of limbal stem cells in culture gives new perspectives on the treatment of ocular disorders characterized by complete limbal stem cell deficiency. The multicenter nature of this study and the handiness and ease of long-distance transportation of the fibrin-cultured epithelial sheets suggest that this technology can now be widely applied.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.Although hepatic ischemia-reperfusion (I/R) injury can be reduced by cooling of the ischemic organ, a systematic in vivo analysis of the influence of organ temperature in I/R injury is missing. The aim of this study was to systematically investigate the impact of defined temperatures of the ischemic liver tissue on microvascular I/R injury.Methods.Ischemia of the left liver lobe was induced in C57BL/6 mice for 90 min. The ischemic lobe was placed in a polyethylene well and the temperature was adjusted to 37°C, 26°C, 15°C, and 4°C by superfusion with cooled/warmed saline solution. The ischemia groups (n=7 each) were compared with a sham-operated group (n=7). The sinusoidal perfusion index and the number of leukocytes firmly adherent to the endothelium of postsinusoidal venules were assessed using intravital fluorescence microscopy at 30 min, 120 min, and 240 min of reperfusion, respectively. At the end of the experiment, serum activities of the liver enzymes aspartate aminotransferase/alanine aminotransferase were determined, and tissue specimens were examined by electron microscopy.Results.Core body temperature did not differ significantly between the groups. In the 37°C group, the sinusoidal perfusion index was significantly reduced and the number of adherent leukocytes was significantly increased compared with the sham group. In all hypothermia groups, however, the microcirculatory parameters did not differ from the sham group. Serum activities of aspartate aminotransferase/alanine aminotransferase were significantly increased and hepatocellular integrity was severely affected in the 37°C group as compared with all other groups.Conclusions.These findings demonstrate that in the mouse liver the known protective effect of hypothermia is already encountered at 26°C. Further reduction of temperature did not generate additional protection from I/R injury.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.In human corneal transplantation the value of matching, particularly for MHC class II, is unclear and controversial. The contribution of the direct pathway to T cell activation is also uncertain. We have determined the relative contribution of class I, II and non-MHC antigens to graft rejection and of the direct and indirect pathways to T cell activation in a rat model mimicking human incompatibilities.Methods.DA (RT1a) strain recipients received fully mismatched PVG (RT1c) strain grafts or grafts from one of three recombinant strains bearing DA MHC genes on a PVG background. Graft survival was assessed and the specificity of T cells generated in the draining lymph nodes was determined in mixed lymphocyte (MLR) proliferation assays. To assess the contribution of the direct pathway, fully mismatched graft were performed and allospecific proliferation was measured after depletion of recipient APC from the MLR reaction.Results.There was no significant difference in survival of grafts between the four grades of mismatch, which ranged from a full mismatch to non-MHC mismatches alone (median survival 12.5, 11, 13 and 12.5 days respectively). In conformity with clinical results, strong secondary responses were generated against targets matched for MHC with the recipient. Depletion of recipient APC from a fully allogeneic secondary MLR did not fully abrogate donor-specific proliferation.Conclusions.Class II matching is of no benefit in this model. Strong indirect responses to non-MHC mismatches are sufficient to induce the rapid rejection, but the small numbers of class II+cells in the donor appear sufficient to generate a direct response.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Heme oxygenase-1 (HO-1), a 32-kd microsomal enzyme, is induced as an adaptive response to a wide variety of injurious stimuli. We examined the possible role of HO-1 in cold storage of renal proximal tubular epithelial (RPTE) cells. Hemin, a potent HO-1-inducer, caused a time-dependent increase in HO-1 mRNA and protein expression. Hemin pretreatment of human RPTE cells before cold storage conferred cytoprotection. Increased HO-1 protein was associated with a brisk and early increase in catalytically active iron and a robust increase in cellular ferritin. Deferoxamine, an iron sequestrating antioxidant, prevented hemin-induced iron release and the increase in ferritin, suggesting iron release as an antecedent mechanism for ferritin induction. To verify that the proximate cause of hemin cytoprotection was due to HO-1 induction, we transiently transfected LL-CPK1porcine kidney cells with a HO-1 expression vector before cold storage. HO-1 transfection resulted in increased expression of HO-1 protein and reduced cell injury during cold storage. The novel observation that prior induction of HO-1 prevents cold storage–induced cell injury suggests that a similar strategy may prove efficacious in preventing cold storage–induced organ damage during transplantation.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Introduction.Prostaglandin E1(PGE1) has been demonstrated to reduce ischemia-reperfusion (IR) injury following lung transplantation. However, the cytoprotective mechanisms remain largely unknown. The purpose of this study was to determine whether the mechanism through which PGE1improves IR injury is related to the level of apoptosis or the release of inflammatory cytokines.Methods.In a rat single-lung-transplant model, animals were randomly allocated into four groups of five animals each. Group 1 received normal saline (NS) in the preservation solution and during the 2-hr reperfusion period. Group 2 received NS in the preservation solution and PGE1during the reperfusion period. Group 3 received PGE1in the preservation solution and NS during the reperfusion period. Group 4 received PGE1in the preservation solution and during the reperfusion period.Results.The two groups that received PGE1during the reperfusion period had a significantly higher partial pressure of oxygen (PaO2), lower wet-dry weight ratio, and lower peak airway pressure at the end of the reperfusion period than did the two groups that received NS. In the two groups that received PGE1during the reperfusion period, we observed significantly higher levels of interleukin (IL)-10 in the transplanted lung tissue and plasma and significantly lower levels of tumor necrosis factor (TNF)-&agr;, interferon (IFN)-&ggr;, and IL-12 in lung tissue. The levels of IL-4 and microphage inflammatory protein-2 (MIP-2) were not significantly different between groups. The number of apoptotic cells and the expression of Bcl-2 were not significantly different between groups.Conclusions.PGE1does not decrease the amount of apoptosis after reperfusion and does not significantly upregulate Bcl-2. We have demonstrated that PGE1administered during the reperfusion period reduces IR injury and improves lung function through a mechanism that is likely mediated by a shift between pro- and anti-inflammatory cytokine release.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.Inflammatory cytokines play an important role in the development of experimental obliterative airway disease (OAD) after transplantation. To further determine the immunologic mechanisms associated with OAD development, we used a murine tracheal transplant model in which a single mismatched HLA-A2-transgenic molecule is indirectly recognized by the recipient CD4+ T cells and then determined whether neutralization of several inflammatory cytokines affected the development of OAD.Methods.Tracheas from HLA-A2+ C57BL/6 mice were heterotopically transplanted into C57BL/6 mice. Recipients were treated with neutralizing antibodies against tumor necrosis factor (TNF), interferon-&ggr; (IFN-&ggr;), or interleukin-1 (IL-1). Allograft histology as well as anti-HLA-A2 antibody development and T cell proliferative responses were determined at days +5, +15, +28, and +60.Results.Allografts in untreated and anti-IFN-&ggr;-treated recipients demonstrated full development of OAD by day +28. Allografts in anti-TNF-treated recipients showed no evidence of OAD, even at day +60. Allografts in anti-IL-1-treated recipients showed airway epithelium changes by day +28 but minimal evidence of OAD by day +60. Spleen cells from untreated and anti-IFN-&ggr;-treated recipients showed significantly higher proliferative responses to HLA-A2+ cells, compared with syngeneic recipients (negative controls). In contrast, anti-TNF and anti-IL-1-treated recipients showed significantly lower proliferative responses to HLA-A2+ cells, compared with untreated recipients. Development of anti-HLA-A2 antibodies was detected in all recipients by day +15, with the exception of those treated with anti-TNF.Conclusion.Among the inflammatory cytokines, TNF seems to play a crucial role in the immunopathology of OAD developed after transplantation.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.CA (cancer antigen) 125 is a serologic marker used in the monitoring of ovarian cancer. Elevated levels are also reported in cirrhosis. We evaluated the range of serum CA 125 levels seen before and after liver transplantation, and examined possible factors associated with CA 125 elevation.Methods.We examined prospectively 57 consecutive patients with cirrhosis who underwent liver transplantation. CA 125 levels were also measured in two patients with polycystic liver disease.Results.The mean serum CA 125 level before transplantation was 352±549 u/ml, compared with 46±49 u/ml after transplantation (P<0.001). Multivariate analysis identified the degree of ascites as the only significant predictive variable of preoperative CA 125 level. In five patients who underwent abdominal paracentesis, the mean ascites CA 125 level (951±322 u/ml) was higher than that of the serum (619±290 u/ml) (P<0.003). In 16 hepatectomy specimens, the grade of staining for CA 125 was 0.8±1.4 for the mesothelium of patients with a normal serum CA 125 level, compared with 1.5±1.1 in patients with elevated serum levels (P=0.37). Two patients with severe abdominal distension due to polycystic liver disease but without ascites had elevated serum CA 125 levels.Discussion.CA 125 concentration is elevated in the majority of patients with cirrhosis and normalizes after liver transplantation. It is a reflection of the abdominal distention seen in these patients. Therefore, an elevation in CA 125 should not be considered a contraindication to liver transplantation in the absence of evidence of malignancy.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Increased QT dispersion (QTd), predicting patients with risk of malignant arrhythmia, have recently been reported in hemodialysis patients (HDp). In this prospective study, we aimed to investigate changes in QTd and signal averaged-ECG (SAECG) in HDp after transplantation. Twenty-seven HDp (M/F:18/9, mean age 30±8 years) and 24 controls (M/F:14/10, mean age 33±6 years) were included. All QT parameters (QTmax, Qtmin, and QTd) were increased in HDp. QTmax and QTd started to decrease at the first month after transplantation. Percentage change in QTd at the third month was significantly correlated with percentage change in LV mass index (r=0.45,P=0.04), serum calcium (r=−0.47,P=0.02) and intact parathyroid hormone (r=0.68,P=0.01). In multivariate regression analysis, only percent chance in LV mass index was retained as significant. As for analysis of SAECG, 4 of the 23 (17%) HDp has abnormal late potentials which disappeared after transplantation. HDp with LV hypertrophy had higher filtered-QRS duration compared to patients without hypertrophy (110±12 vs. 97±11 msec,P=0.01). It was concluded that increased QTd and presence of late potentials improved early after renal transplantation. These changes were mainly associated with the regression of the LV mass.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.Liver graft size, anatomy of the bile duct and the vascular inflow and outflow are essential for living related liver transplantation (LRLT). Preoperative delineation of those variations that would change the operative procedure to achieve a successful result especially in an emergency condition.Purpose.Our aim was to develop a rapid and noninvasive imaging diagnostic method for the detection of anatomical variants that is mandatory for a safe operation when selecting potential liver transplant living donors. We used a different magnetic resonance (MR) imaging technique, which enabled to us to exploit the anatomical landmark of the liver, signal enhancement of blood flow in the abdomen, and the intrahepatic biliary routes inside the liver. Then, with the help of Advantage Window workstation reconstruction, the reconstructed single vascular or biliary systems were displaced in a three-dimensional fashion and the whole examination finished within 30 min.Methods.Modification of the standard MR technique was performed on a superconductive 1.5T whole body image scanner, MR arteriogaphy, venography, and cholangiography with three-dimensional reconstruction in evaluating the anatomy of the hepatic arteries, hepatic veins, portal venous system, bile ducts, and liver size in potential liver transplant living donors. These anatomical structures were compared with traditional imaging methods.Results.In all 38 cases, as well as delineation of the portal vein detail to the segmental level was satisfactorily obtained in this MR study. The images were well displayed in a three-dimensional fashion, which had good correlation with images from traditional imaging modalities and operative findings. In 86.8% cases, the MR arteriography was well matched with the celiac angiography. Of those 17 operative cases, estimation of liver volume was well correlated with the liver graft within 3.9–12.5% variation. In the major hepatic vein, we obtained 100% accuracy and 88.2% in the minor branches. Of 12 donors received intraoperative cholangiography during liver donation, good correlation of biliary anatomy was achieved. One donor was excluded from graft donation due to the complicated arterial supply to the left liver. According to the anatomical variation, surgical procedures in graft harvesting and anastomosis were readjusted and no major complications were found in those donors and all recipients survived after liver transplantation.Conclusion.MR volumetry, venography, angiography, and cholangiography with three-dimensional reconstruction is sufficient for all major imaging evaluation. It may replace the traditional conventional catheter angiography, computed tomography, sonography and endoscopic retrograde cholangiography as a single investigation in the evaluation of the potential liver transplant donors. Angiography is only valuable in suboptimal cases and intraoperative cholangiography is only performed in biliary ductile variants.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID