摘要:

We have shown that 5-hr preservation using the two-layer (University of Wisconsin solution/perfluorochemical) method at 20 °C allows ATP synthesis and makes it possible to resuscitate a canine pancreas subjected to 90 min of warm ischemia. However, 8 hr of preservation using this method caused a disturbance of vascular microcirculation and did not resuscitate the grafts.The aim of this study was to examine the effect of thromboxane A2 synthesis inhibitor OKY046 on vascular endothelial cells and ATP tissue levels of canine pancreas during preservation using the two-layer (University of Wisconsin solution/perfluorochemical) method at 20 °C, and vascular microcirculation and pancreas viability after transplantation. Graft viability was judged by graft survival following autotransplantation. ATP tissue levels were measured by high-performance liquid chromatography at the end of preservation. Viability of the vascular endothelial cells was judged using nuclear trypan blue uptake of the graft after preservation. Pancreatic tissue perfusion was measured using an H2clearance technique after reperfusion.Pancreas grafts subjected to 90 min of warm ischemia were not viable(0/5). However, 5-hr preservation made it possible to recover the pancreas(5/5); 8-hr preservation was not successful (0/3). ATP tissue levels after 5-hr and 8-hr preservation were 9.40±2.09 and 7.37±1.06μmol/g dry weight, respectively, and OKY046 did not affect ATP synthesis during 8-hr preservation (8.44±0.92 μmol/g dry weight). The percentage of nuclear trypan blue uptake of endothelial cells in 8-hr-preserved grafts was 37.6±11.6% and was significantly higher than the value in 5-hr-preserved grafts (5.0±3.0%;P<0.01). However, OKY046 significantly reduced trypan blue uptake in 8-hr-preserved grafts (8.2±3.6%;P<0.01). Pancreatic tissue perfusion in 8-hr-preserved grafts after 2 hr of reperfusion was 28.5±7.5 ml/min/100 g, and was significantly lower than the value in 5-hr-preserved grafts(57.1±4.4 ml/min/100 g;P<0.01), but OKY046 dramatically improved pancreatic tissue perfusion (97.1±14.6 ml/min/100 g;P<0.01). As a consequence, 8-hr-preserved grafts were resuscitated (4/5).We conclude that OKY046 protects the vascular endothelium during preservation by the two-layer method at 20 °C and consequently improves vascular microcirculation on reperfusion. Together with ATP synthesis, which is essential for repairing damaged cells, the canine pancreas graft subjected to 90 min of warm ischemia is resuscitated during 8-hr preservation by the two-layer method at 20 °C. This method holds promise for pancreas-kidney transplantation from cardiac arrest donors.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The purpose of this study was to compare University of Wisconsin(UW) solution with Euro-Collins (EC) solution in their cold preservation effects on rat limbs. Thirty-six Lewis rat limbs were preserved in EC solution(n=18) or UW solution (n=18) at 4 °C for 72 hr, and grafted orthotopically to a syngeneic rat using microsurgical techniques. The surgeon was blinded to the solution used. We evaluated the vascular patency rate and death rate of both groups at day 7 after surgery and performed histological evaluations of bone, muscle, growth plate, and articular cartilage for each specimen of successful grafts in both groups. The vascular patency rates of the EC and UW groups were 27.7% (5/18) and 11% (2/18), respectively, and showed no significant difference. The death rates of the EC and UW groups were 50%(9/18) and 60% (10/18), which were not significantly different. There were no clear differences in histological viability between both groups, in all tissues exclusive of bone marrow and muscle tissue. Our results showed that in comparing EC and UW solutions, one was not significantly superior to the other as a cold immersion storage medium after a 72 hr ischemia-induced reperfusion injury.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The observation that only a portion of all alginate-polylysine microcapsules are overgrown after implantation suggests that physical imperfections of individual capsules, rather than the chemical composition of the material applied, are responsible for inducing insufficient biocompatibility and thereby fibrotic overgrowth of those capsules. We recently developed a lectin binding assay that allows for quantifying the portion of inadequately encapsulated islets, and demonstrated that inadequately encapsulated islets induce a fibrotic response associated with graft failure.The present study investigates factors influencing the adequacy of encapsulation of pancreatic islets. We applied our lectin binding assay and found that the number of inadequate, and particularly incomplete, capsules is influenced by the following factors. (1) A capsule diameter of 800 μm is associated with a lower percentage of inadequate capsules than smaller (500μm and 600 μm) or larger (1800 μm) capsules. (2) A high rather than low guluronic acid content of the alginate is associated with a lower percentage of inadequate capsules. This can be explained, at least in part, by smaller ranges of swelling and subsequent shrinkage during the encapsulation procedure. (3) An increase in viscosity caused by applying a higher alginate concentration compensates for a low guluronic acid content. This effect of increased viscosity cannot be explained by a reduced range of swelling and shrinkage during the encapsulation procedure.We conclude that alginates with a high guluronic acid content and a viscosity near the filtration limit are preferable in order to minimize the number of inadequate capsules.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

As a consequence of its large volume, a microencapsulated islet graft can be implanted only into the peritoneal cavity. The graft volume can be reduced by using small capsules. However, reduction of the diameter of the capsules holds a certain risk, because with smaller capsules, more islets may be found to protrude from the capsules. We have developed a lectin binding assay which, after encapsulation, specifically labels islets or parts of islets that are insufficiently immunoprotected as a consequence of inadequate, and particularly incomplete, encapsulation. With this assay, we found that a reduction of the capsule diameter from 800 μm to 500 μm was associated with an increase in the percentage of inadequately encapsulated islets from 6.3±1.2% to 24.2±1.5%. The in vivo significance of this finding was investigated by performing allotransplantations with large diameter(700-800 μm) and small diameter (400-500 μm) capsules. With large-capsule islet grafts, all recipients (n=5) became normoglycemic for 7-16 weeks, whereas with small-capsule islet grafts, only one of seven recipients became normoglycemic. The in vivo significance of inadequate encapsulation was further substantiated by our finding that most large capsules were floating freely in the peritoneal cavity without any cell adhesion, whereas the vast majority of small capsules was found to be adherent to the surface of intra-abdominal organs and infiltrated by immune cell elements characteristic of both an allograft reaction and a foreign body reaction.We conclude that successful use of capsules with small diameters requires further study to determine wyhich factors in the encapsulation procedure should be modified to reduce the number of inadequate small capsules.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

This was a multicenter, open-label, concentration-ranging trial of FK506 and cyclosporine in 120 patients undergoing primary cadaveric kidney transplant. Patients were randomized to a cyclosporine-based regimen or to one of three FK506-based regimens designed to achieve low (5-14 ng/ml), medium(15-25 ng/ml), or high (26-40 ng/ml) trough whole blood levels. Corresponding initial doses of FK506 were 0.2, 0.3, and 0.4 mg/kg/day. Patients were evaluated at 42 days after transplant for the occurrence of the first episode of acute rejection or toxicity, necessitating a dosage reduction. There was no significant difference among the three FK506-based regimens and the cyclosporine-based regimen for rejection or toxicity at 42 days. However, the incidence of acute rejection was significantly lower (14% for FK506 and 32% for cyclosporine;P=0.048) for the aggregate of all FK506-treated patients versus cyclosporine. The incidence of neurotoxic and gastrointestinal events was higher among FK506-treated patients during the first month after transplant. A significant trend was observed for increasing toxicity with increasing maximum trough FK506 concentrations(P=0.01) and for decreasing rates of rejection with increasing minimum trough FK506 concentrations(P=0.021). FK506 was effective in preventing early rejection in kidney transplant recipients. The target range of whole blood levels that optimizes efficacy and minimizes toxicity seems to be 5-15 ng/ml. The corresponding recommended initial dose of FK506 for kidney transplant recipients seems to be 0.2 mg/kg/day.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Protocol biopsies were performed to define the histologic response to tacrolimus therapy in patients with refractory acute renal allograft rejection. Renal allograft biopsies were performed at defined intervals after initiation of tacrolimus therapy. Protocol biopsies were performed before tacrolimus therapy (within 48 hr of initiation of therapy) and after 1 week of therapy. If the 1-week biopsy did not show rejection reversal, repeat protocol biopsies were obtained at 1-to 2-week intervals, until histologic reversal was observed. Additional biopsies were obtained at 4 weeks and at 8-12 weeks after initiation of tacrolimus therapy. Indicated biopsies were also performed to evaluate increases in serum creatinine. A total of 92 biopsies were performed in 23 patients (average 4.0 biopsies/patient). Biopsies were performed in each patient immediately before starting tacrolimus therapy (23 biopsies), and 69 biopsies (3.0 biopsies/patient) were performed during tacrolimus therapy. Rejection diagnosis was based on strict Banff criteria. Pretacrolimus biopsies demonstrated mild acute rejection in 64% of patients and moderate acute rejection in 36%. One week after initiation of tacrolimus therapy, protocol biopsies revealed the following: no rejection (60%), improvement (13%), no change (20%), and worsening rejection (7%). Histologic changes at 1 week did not correlate with changes in renal function, as 63% of patients that showed histologic improvement or reversal during the first 2 weeks of therapy did not show improvement in serum creatinine. A lack of histologic improvement (or worsening) at 1 week was demonstrated in a significant proportion of patients(27%); increased tacrolimus dosing provided rejection reversal or improvement in 1-2 weeks in each of these patients. Recurrent rejection was diagnosed on eight biopsies in seven patients, however six episodes were diagnosed by protocol biopsies alone (i.e., in the absence of an elevation in serum creatinine). Delayed improvement in renal function, despite histologic reversal, was likely due to physiologic effects of tacrolimus (i.e., afferent arteriolar vasoconstriction), as histologic evidence of tacrolimus toxicity was not observed during the first 2 weeks of therapy. Histologic evidence of tacrolimus nephrotoxicity (nodular arteriolar hyalinosis) was found in 21% (15 of 69) of biopsies in 39% of patients (9 of 23) at a median time of 60 days(range 12-150 days). Tacrolimus dose and blood levels (by IMx assay) did not correlate with development of clinically silent or clinically evident nephrotoxicity. In conclusion: 1) protocol biopsies provide information that allows individualization of tacrolimus rejection therapy, 2) histologic resolution of rejection often precedes biochemical improvement, 3) histologic evidence of tacrolimus nephrotoxicity is seldom observed in the first 2 weeks of therapy, and 4) clinically silent recurrent rejection and clinically silent tacrolimus nephrotoxicity are observed with significant frequency during tacrolimus therapy for refractory renal allograft rejection.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Different groups of cytokines may initiate or inhibit the rejection process. We used the polymerase chain reaction to study the expression of cytokine mRNA for interleukin (IL)-2, -4, -6 and -10, tumor necrosis factor-α, and interferon-γ in 187 biopsy specimens from 24 human cardiac transplant recipients 5-555 days after transplantation. Cytokine levels in the serum were also measured.Cytokine mRNA was detected in 38.5% of biopsy specimens. IL-10 mRNA was detected more frequently with mild or absent rejection (11.6% in grades 0 and 1-vs. 1.4% in grades 2 and 3,P=0.01). Up to 90 days after transplantation, IL-2 mRNA was detected more frequently with moderate rejection (13% in grades 2 and 3 vs. 0% in grades 0 and 1,P=0.076), and IL-4 mRNA was detected more frequently with mild or absent rejection (16% in grades 0 and 1- vs. 0% in grades 2 and 3,P=0.061). More than 90 days after transplantation, IL-2 mRNA was detected more frequently with mild or absent rejection (10% in grades 0 and 1 vs. 0% in grades 2 and 3,P=0.078).Serum IL-4 levels corresponding to biopsy specimens positive for IL-4 mRNA were higher than those corresponding to specimens negative for IL-4 mRNA (59 pg/ml vs. 32 pg/ml medians,P=0.028).Our results suggest that IL-10 and possibly IL-4 (T helper 2 cytokines) may suppress graft rejection, whereas IL-2 (T helper 1 cytokine) may promote cellular rejection. In addition, cytokine profiles may change with length of time after transplantation. The association of elevated serum levels of IL-4 with increased expression of intragraft IL-4 mRNA may suggest release of this cytokine from the graft into the circulation.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Reperfusion injury has been implicated in the development of primary graft dysfunction (PGD) after liver transplantation. Neutrophil migration and activation may be involved in the pathogenesis of this injury.We studied neutrophil activation and its role in the etiology of PGD by measuring neutrophil elastase by radioimmunoassay, in serial blood samples of 19 patients before, during, and for 24 hr after transplantation. In a subgroup of patients, we also measured soluble thrombomodulin at the same time points as a marker of endothelial damage.The pretransplant elastase level was significantly raised(40.13±4.84 ng/ml, mean ± SEM) compared with levels of healthy controls (18.7±5.6 ng/ml,P<0.05). A marked increase in elastase activity followed reperfusion, with a peak at 2 hr(370±50.5 ng/ml,P<0.01). Thereafter, there was a decline, but elastase remained elevated at 24 hr (186±60.94 ng/ml). The mean increase in neutrophil elastase after reperfusion correlated significantly with markers of graft function (P<0.05) and with the mean rise in soluble thrombomodulin(P=0.042), which increased from a pretransplant level of 81.2±11.32 to 186±50.4 ng/ml, 6 hr after reperfusion(P<0.05).The results of this study indicate that marked neutrophil activation and endothelial cell damage occurs after graft reperfusion during orthotopic liver transplantation, and the degree of activation correlates with markers of graft function, which may suggest a role in the etiology of PGD.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

FK506 (tacrolimus) is a safe and effective immunosuppressant for the prevention of organ rejection after organ transplantation. FK506 has a relatively narrow therapeutic index and the correlation of dose to blood concentration is poor as a result of moderate variability in pharmacokinetic parameters between patients. Therapeutic monitoring of whole blood FK506 drug concentrations has been used in an effort to determine whether a relationship exists between concentrations of FK506 in the blood and the development of toxicity or the risk for organ rejection. An analysis of the relationship between FK506 blood levels and the occurrence of toxicity and rejection was carried out using data from four recent clinical trials. Trough FK506 levels within a 7-day window before the onset of rejection or toxicity were analyzed using logistic regression models. In kidney transplant patients (n=92), a significant correlation between FK506 levels and the incidence of both toxicity (P=0.01) and rejection(P=0.02) was seen. In liver transplant patients from three clinical trials, FK506 levels correlated well with the incidence of toxicity (P≤0.01); however, there was no significant relationship between FK506 levels and the incidence of rejection. It is concluded that therapeutic monitoring of whole blood FK506 levels may be useful for minimizing the risks of both toxicity and rejection in kidney transplant patients and for minimizing the risk of toxicity in liver transplant recipients.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Fungal infections are associated with a high mortality rate after liver transplantation. To describe risk factors for fungal infections, 405 consecutive liver transplant recipients were analyzed. Forty-five patients(11%) developed invasive fungal infection. Median posttransplantation time to the first episode was 60 days. Pathogens wereCandidaspecies (spp) (n=24, 53%),Cryptococcus neoformans(n=10, 22%),Aspergillusspp (n=6, 13%),Rhizopusspp (n=1), and others (n=4). Presentations of infection included disseminated (n=9), intra-abdominal (n=9), esophageal(n=9), lung (n=8), blood (n=6), and central nervous system infections (n=3), and sinusitis with esophagitis (n=1). Eighteen patients (40%) with invasive fungal infection died, and 13 (72%) of these deaths were attributable to fungi. Mortality in the nonfungal infection group was 12%. Univariate analysis identified separate risk factors forCandida(intra-abdominal bleeding),Aspergillus(fulminant hepatitis), and cryptococcal (symptomatic cytomegalovirus infection) infections. In both univariate and multivariate analyses, a high intratransplant transfusion requirement and posttransplant bacterial infection were identified as significant risk factors for all types of fungal infection. The risk factor analysis reported here suggests that different pathogenic processes lead toCandidaand non-Candidainfection in liver transplant recipients. Their identification should prompt specific prophylactic measures to reduce morbidity and mortality in this population.

ISSN:0041-1337    

出版商:OVID    

年代:1996

数据来源: OVID