ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Cadaveric kidney transplants with delayed graft function have poorer graft survival by an unknown mechanism. Nitric oxide, produced by nitric oxide synthase (NOS), has a proven role in both recovery of ischemia and promotion of rejection. We therefore wished to study the patterns of NOS activity in a model of renal ischemia. The left renal pedicle of Fisher rats was occluded for 1 hr. Both kidneys were removed at various times and frozen. Renal NOS activity was measured by conversion of [3H]arginine to[3H]citrulline and the content of endothelial NOS isoenzyme (eNOS) was compared by Western blot. NOS activity increased significantly in the left ischemic kidney over the first 24 hr, from a control of 33.8 pmol/min/mg to 79.8 at 2 hr and 56.8 at 24 hr. NOS activity then dropped below baseline, returning to near normal levels at day 21. eNOS content was stimulated over the entire time course, consistent with the presence of an eNOS inhibitor. Oral treatment with the NOS substrate L-arginine at 5 g/L significantly hastened the return of serum creatinine to baseline, if simultaneous contralateral nephrectomy was performed. The lazaroid U74389G given perioperatively also improved renal function and hastened recovery of NOS activity. Because nitric oxide plays an important role in maintaining blood flow during recovery from renal ischemia, the observed decrease in NOS activity may be prevented by perioperative treatment with oral L-arginine and corticosteroids. In addition, U74389G may provide a clinically useful method of minimizing and/or shortening DGF, thereby improving graft function and survival.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Triple therapy with S-adenosylmethionine (SAM) (given to the donor animal, included in University of Wisconsin solution [UW], and added to the reperfusing medium) has been shown to reduce the sequential cold and warm ischemia/reperfusion injuries characteristic of the liver transplantation procedure. To clarify the actions of SAM during different stages of ischemia/reperfusion, we have compared its benefit in five dosage regimens, using perfused rat livers after sequential periods of 24 hr cold and 20 min rewarming ischemia. When added only to UW, the presence of SAM throughout ischemia improved hepatic blood flow by 26% after 15 min of reperfusion versus no treatment (2.32±0.18 vs. 1.84±0.11 ml/min/g liver,P<0.05). SAM also improved blood flow by 23% during the 3-hr perfusion overall (P<0.05). Oxygen consumption and the release of purine nucleoside phosphorylase (PNP) were decreased (bothP<0.05). When added to both UW and the perfusate, SAM additionally increased bile production at 15 min(7.14±1.21 vs. 2.31±0.74 mg/h/g liver,P<0.01). By pretreating the liver donor with SAM in vivo, and including it in the preservation and reperfusing media, it was possible to prolong and amplify the benefits on blood flow(P<0.001) and bile production(P<0.05) and to sustain glucose uptake(P<0.01). An acute exposure to SAM, when used in saline to flush UW from the graft before reperfusion, increased blood flow at 15 min (by 68%) and over a 3-hr period (bothP<0.001), but no indices of metabolic activity were improved. Oxygen consumption and PNP release were both decreased(P<0.05). When added to the perfusate (present throughout reperfusion), SAM increased blood flow at 15 min (58%) and over a 3-hr period (P<0.01 in both cases). Net glucose uptake was increased (P<0.05), whereas oxygen consumption (P<0.001) and PNP release fell(P<0.05). Actions of SAM achieved acutely and over the intermediate- and long-term all seem to underlie its benefits in reducing ischemia/reperfusion injuries.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

For clinical utilization of extracorporeal liver perfusion as an artificial liver assist device, we examined the possibility of long-term xenoperfusion of the pig liver by the continuous administration of prostaglandin E1(PGE1) and insulin.After a 3-hr perfusion period, pig livers that were xenoperfused with human blood exhibited a drastic decrease in the perfusate volume, a progressive elevation of the hepatic artery pressure, a gradual deterioration of bile production, and a marked increase in the release of creatine kinase-BB component. The continuous administration of PGE1(25 μg/hr) and insulin (1 U/hr) significantly improved these derangements(P<0.05) and allowed stable perfusion for up to 9 hr. This manipulation also inhibited leukocyte aggregation in the graft, the characteristic perfusate hemolysis, and acceleration of ketogenesis. Histological examination revealed that the interlobular edema and hemorrhage, characteristics of tissue injuries in xenogeneic hyperacute rejection, were markedly alleviated in the PGE1and insulin-treated group. This study clarifies the finding that the combined administration of PGE1and insulin is effective for long-term xenogeneic extracorporeal liver perfusion, with the graft viability well maintained.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

For studies on the intrahepatic engraftment of transplanted hepatocytes, labeling of donor cells is necessary. Current labeling techniques enable only short-term monitoring of engraftment. In the present study, we describe the use of 5-bromo-2′-deoxyuridine (BrdU) for a more permanent hepatocyte labeling. BrdU is stably incorporated into replicating DNA; consequently, BrdU labeling was performed in regenerating livers. In 10 Lewis rats, a two-thirds partial hepatectomy was performed, followed by continuous, low-dose BrdU administration. This approach provided a fraction of 89±1.5% BrdU-labeled donor hepatocytes, without influencing the efficacy of the ensuing isolation of donor hepatocytes. Subsequently,±1×107isolated hepatocytes were transplanted either intraportally or intrasplenically into syngeneic recipients, and the engraftment of transplanted cells was evaluated in liver lobes at successive time intervals after transplantation. BrdU-positive hepatocytes could be identified and quantitated in recipient livers up to 180 days after transplantation. Repetitive quantitative assessments over time revealed an initial, drastic loss of transplanted cells (<24 hr), followed by a stabilization at approximately 7% of the injected cells. Histological monitoring showed that during this period (<48 hr) the transplanted cells migrate from the portal venules to the liver parenchyma. In recipient livers a homogeneous lobe distribution of hepatocyte engraftment was found 30 days after both intraportal and intrasplenic transplantation. Moreover, no significant difference between the intrahepatic liver cell engraftment of the two transplantation routes was demonstrated. In conclusion, the BrdU-labeling technique of donor hepatocytes enables long-term histological monitoring and quantitative evaluation of the engraftment of transplanted liver cells in recipient livers.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Functioning nephron mass has recently been implicated as a risk factor for development of chronic “rejection” of kidney allografts. Reductions in nephron number below 50% may induce glomerular hypertension and hyperfiltration in surviving units, which in turn lead to graft injury. In the present study, which extends and amplifies our previous investigations, cellular and molecular characteristics of single allografts from F344 donors in bilaterally nephrectomized LEW recipients, our standard experimental model of chronic renal allograft dysfunction, were compared with allografts from recipients where total renal mass was reduced (by ligating branches of the graft renal artery) or restored to normal levels by transplanting or retaining a second kidney. Our findings in this study confirm that progressive proteinuria and structural injury in recipients of single allografts were accentuated in grafts with reduced mass but virtually absent in rats with increased kidney mass. A striking observation was that patterns of cell surface molecule expression, cellular infiltration, and expression of all T cell- and macrophage-associated products studied were all markedly modulated by changes in renal mass. Moreover, several molecules that are up-regulated before evidence of graft injury are down-regulated by providing increased renal mass. These data show that the quantity of functioning renal mass is not only an important independent determinant of the tempo and intensity of chronic renal allograft failure, but also a potent modulator of fundamental cellular and molecular components of a complex process. This phenomenon involves antigen-dependent and antigen-independent elements that ultimately result in chronic allograft failure.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Obliterative bronchiolitis (OB), an important threat to the long-term survival of lung transplant recipients, is characterized histologically by fibroproliferation within small airways. The pathogenesis of OB is thought to involve chronic allograft rejection, and therapy frequently includes augmentation of immunosuppression. We have developed a model that reproduces the pathologic lesion of OB and allows study of interventions designed to limit airway fibrosis. In this model, heterotopic transplantation of murine airways into immune-mismatched recipients results in epithelial abnormalities and fibroproliferation in the airway lumen, changes not seen in heterotopic isografts. Cyclosporine (CsA) inhibits activation and proliferation of T lymphocytes and is commonly administered after lung transplantation. We hypothesized that use of CsA in our model system would reduce fibroproliferation in tracheal allografts. To test this hypothesis, murine tracheas were transplanted heterotopically into allomatched and allomismatched recipients, and then treated with varying doses (5, 10, 15, or 25 mg/kg i.p. q.d.) of CsA. Controls included allografts and isografts not treated with CsA. After 30 days, tracheas were harvested and examined histologically. CsA markedly reduced the development of fibroproliferation in allografts (19% in treated allografts versus 90% in untreated allografts,P<0.0001), but did not reduce inflammation or airway epithelial cell injury. High-dose (25 mg/kg/day) CsA was more effective than lower doses in reducing fibroproliferation (0% in high dose versus 29% in low dose,P=0.04). These findings demonstrate that CsA significantly reduces development of the pathologic lesion of OB, and supports the role of alloimmunity in the pathogenesis of this disease.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Obliterative bronchiolitis is the major cause of long-term morbidity and mortality in heart-lung and lung transplant recipients. There is presently no completely effective therapy for the treatment of obliterative bronchiolitis. We have examined the effects of rapamycin (RPM) on the development of obliterative airway disease in murine recipients of heterotopically transplanted allograft tracheas. In this model, an untreated allograft develops almost complete occlusion of the airway lumen with fibroblastic tissue and collagen scar by day 28 after transplantation. RPM administered intraperitoneally at the time of transplantation or even as late as day 14 after transplantation markedly inhibited obliteration of the airway lumen by fibroblastic tissue. Also, RPM significantly inhibited infiltration of the graft by macrophages. In the RPM-treated animals, the airway was reconstituted with an attenuated squamous epithelium rather than a normal pseudostratified epithelium. No adverse side effects were observed with RPM doses up to 12 mg/kg/day. These findings suggest a potential role for RPM, perhaps in combination with cyclosporine, in preventing and treating obliterative bronchiolitis in heart-lung and lung allograft recipients.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Measuring monoethylglycinexylidide (MEGX) formation after intravenous administration of lidocaine in potential organ donors (MEGX test) has been advocated as a useful test to select donor livers for transplantation, but some groups have demonstrated a low test efficacy. We, therefore, investigated the value of an extended MEGX formation test and the value of other dynamic liver function tests, in selecting suitable human donor livers.In 51 human multi-organ donors, we measured elimination of galactose, indocyanine green, and lidocaine, as well as formation of MEGX, at 15, 30, and 60 min after administration of the test substances. In the early postoperative period, the function of the transplanted liver was then classified as good or poor, as defined by a prothrombin time above or below 65% by day 4 and fibrinogen concentration above or below 300 mg/dl by day 7. Donor characteristics and preservation modalities were very similar between the two groups.Galactose, indocyanine green, and lidocaine metabolism failed to predict good or poor graft function in the early postoperative period. MEGX serum concentrations, however, were significantly higher in the group of donors whose organs functioned well in the recipients, as compared with donors whose organs functioned poorly in the recipients. This was true for MEGX concentrations at 15 min (117±9 vs. 90±9 ng/ml;P=0.03), 30 min (108±8 vs. 86±8 ng/ml;P=0.04), and 60 min (100±6 vs. 73±5 ng/ml;P=0.006). Extending the MEGX formation test from 15 to 60 min improved test efficacy. Maximal MEGX concentration in 9 or up to 12 consecutive blood samples, drawn between 3 and 120 min after lidocaine infusion, was also significantly higher in donors whose organs functioned well, than in donors whose organs functioned poorly (129±10 vs. 101±10 ng/ml;P=0.03).Although the groups with good and poor organ function differed significantly with respect to their MEGX serum concentrations, and although efficacy of the MEGX test was improved by extending the test from 15 to 60 min, the overlap in individual MEGX serum concentrations was still so wide that it is virtually impossible to predict early graft function only on the basis of the MEGX test in the donor. Therefore, the MEGX test, although of potential scientific interest, does not predict early graft function with an accuracy necessary for clinical use.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Identification of risk factors influencing graft survival may lead to the development of models to predict graft outcome. Such models may provide guidance for immunosuppressive therapy, measure posttransplantation outcome, and eventually improve graft survival in high-risk patients. A major risk factor influencing graft survival is allosensitization. However, due to the lack of standardization of lymphocytotoxicity assays, the detection of alloantibodies utilizing this current methodology may not correlate with posttransplant events. Recently, a novel standardized enzyme-linked immunosorbent assay (ELISA) for the detection of anti-HLA class I IgG antibodies was developed. To evaluate the predictive value of this diagnostic test, a retrospective analysis of 124 renal allograft recipients with an 18-month follow-up time was performed. A highly significant(P=0.01) correlation between pretransplant ELISA panel reactive antibody (PRA) results and graft loss was observed. Patients with pretransplant ELISA PRA of >10% had a three times higher risk of graft loss compared with patients who tested negative. No such correlation was observed with complement-dependent cytotoxicity results independent of the reduction of IgM antibodies with dithiothreitol. Similarly, a highly significant correlation of ELISA results with the occurrence of early graft dysfunction was observed. Almost all patients (88%) with a pretransplant ELISA PRA of>50% required posttransplant dialysis, compared with 45% of patients with a pretransplant ELISA PRA of 10-50% and 27% of patients with a pretransplant ELISA PRA of <10%. No such difference was observed with complement-dependent cytotoxicity%PRA values. Analysis of posttransplant specimens by ELISA demonstrated a strong correlation of assay results with graft rejection and graft dysfunction. In summary, these results suggest that detection of anti-HLA class I antibodies by ELISA identifies patients at high risk for graft loss. No other single risk factor of such magnitude has been identified so far.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID