Long-term results of pancreas transplantation under tacrolius immunosuppression.
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BACKGROUND: The long-term safety and efficacy of tacrolimus in pancreas transplantation has not yet been demonstrated. The observation of prolonged pancreatic graft function under tacrolimus would indicate that any potential islet toxicity is short-lived and clinically insignificant. We report herein the results of pancreas transplantation in patients receiving primary tacrolimus immunosuppression for a minimum of 2 years. METHODS: From July 4, 1994 until April 18, 1996, 60 patients received either simultaneous pancreas-kidney transplant (n=55), pancreas transplant only (n=4), or pancreas after kidney transplantation (n=1). Baseline immunosuppression consisted of tacrolimus and steroids without antilymphocyte induction. Azathioprine was used as a third agent in 51 patients and mycophenolate mofetil in 9. Rejection episodes within the first 6 months occurred in 48 (80%) patients and were treated with high-dose corticosteroids. Antilymphocyte antibody was required in eight (13%) patients with steroid-resistant rejection. RESULTS: With a mean follow-up of 35.1+/-5.9 months (range: 24.3-45.7 months), 6-month and 1-, 2-, and 33-year graft survival is 88%, 82%, 80%, and 80% (pancreas) and 98%, 96%, 93%, and 91% (kidney), respectively. Six-month and 1-, 2-, and 3-year patient survival is 100%, 98%, 98%, and 96.5%. Mean fasting glucose is 91.6+/-13.8 mg/dl, and mean glycosylated hemoglobin is 5.1+/-0.7% (normal range: 4.3-6.1%). Mean tacrolimus dose is 6.5+/-2.6 mg/day and mean prednisone dose 2.0+/-2.9 mg/day at follow-up. Complete steroid withdrawal was possible in 31 (65%) of the 48 patients with functioning pancreases. CONCLUSIONS: These data show for the first time that tacrolimus is a safe and effective long-term primary agent in pancreas transplantation and provides excellent long-term islet function without evidence of toxicity while permitting steroid withdrawal in the majority of patients. (+info)
Pediatric renal transplantation under tacrolimus-based immunosuppression.
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BACKGROUND: Tacrolimus has been used as a primary immunosuppressive agent in adult and pediatric renal transplant recipients, with reasonable outcomes. Methods. Between December 14, 1989 and December 31, 1996, 82 pediatric renal transplantations alone were performed under tacrolimus-based immunosuppression without induction anti-lymphocyte antibody therapy. Patients undergoing concomitant or prior liver and/or intestinal transplantation were not included in the analysis. The mean recipient age was 10.6+/-5.2 years (range: 0.7-17.9). Eighteen (22%) cases were repeat transplantations, and 6 (7%) were in patients with panel-reactive antibody levels over 40%. Thirty-four (41%) cases were with living donors, and 48 (59%) were with cadaveric donors. The mean donor age was 27.3+/-14.6 years (range: 0.7-50), and the mean cold ischemia time in the cadaveric cases was 26.5+/-8.8 hr. The mean number of HLA matches and mismatches was 2.8+/-1.2 and 2.9+/-1.3; there were five (6%) O-Ag mismatches. The mean follow-up was 4.0+/-0.2 years. RESULTS: The 1- and 4-year actuarial patient survival was 99% and 94%. The 1- and 4-year actuarial graft survival was 98% and 84%. The mean serum creatinine was 1.1+/-0.5 mg/dl, and the corresponding calculated creatinine clearance was 88+/-25 ml/min/1.73 m2. A total of 66% of successfully transplanted patients were withdrawn from prednisone. In children who were withdrawn from steroids, the mean standard deviation height scores (Z-score) at the time of transplantation and at 1 and 4 years were -2.3+/-2.0, -1.7+/-1.0, and +0.36+/-1.5. Eighty-six percent of successfully transplanted patients were not taking anti-hypertensive medications. The incidence of acute rejection was 44%; between December 1989 and December 1993, it was 63%, and between January 1994 and December 1996, it was 23% (P=0.0003). The incidence of steroid-resistant rejection was 5%. The incidence of delayed graft function was 5%, and 2% of patients required dialysis within 1 week of transplantation. The incidence of cytomegalovirus was 13%; between December 1989 and December 1992, it was 17%, and between January 1993 and December 1996, it was 12%. The incidence of early Epstein-Barr virus-related posttransplant lymphoproliferative disorder (PTLD) was 9%; between December 1989 and December 1992, it was 17%, and between January 1993 and December 1996, it was 4%. All of the early PTLD cases were treated successfully with temporary cessation of immunosuppression and institution of antiviral therapy, without patient or graft loss. CONCLUSIONS: These data demonstrate the short- and medium-term efficacy of tacrolimus-based immunosuppression in pediatric renal transplant recipients, with reasonable patient and graft survival, routine achievement of steroid and anti-hypertensive medication withdrawal, gratifying increases in growth, and, with further experience, a decreasing incidence of both rejection and PTLD. (+info)
Cloning, sequencing, and nucleolar targeting of the basal-body-binding nucleolar protein BN46/51.
(11/2304)
BN46/51 is an acidic protein found in the granular component of the nucleolus of the amebo-flagellate Naegleria gruberi. When Naegleria amebae differentiate into swimming flagellates, BN46/51 is found associated with the basal body complex at the base of the flagella. In order to determine the factors responsible for targeting BN46/51 to a specific subnucleolar region, cDNAs coding for both subunits were isolated and sequenced. Two clones, JG4.1 and JG12.1 representing the 46 kDa and 51 kDa subunits, respectively, were investigated in detail. JG12.1 encoded a polypeptide of 263 amino acids with a predicted size of 30.1 kDa that co-migrated with the 51 kDa subunit of BN46/51 when expressed in yeast. JG4.1 encoded a polypeptide of 249 amino acids with a predicted size of 28.8 kDa that co-migrated with the 46 kDa subunit of BN46/51. JG4.1 was identical to JG12.1 except for the addition of an aspartic acid between positions 94 and 95 of the JG12.1 sequence and the absence of 45 amino acids beginning at position 113. The predicted amino acid sequences were not closely related to any previously reported. However, the sequences did have 26-31% identity to a group of FKPBs (FK506 binding proteins) but lacked the peptidyl-prolyl cis-trans isomerase domain of the FKBPs. Both subunits contained two KKE and three KKX repeats found in other nucleolar proteins and in some microtubule binding proteins. Using 'Far Western' blots of nucleolar proteins, BN46/51 bound to polypeptides of 44 kDa and 74 kDa. The 44 kDa component was identified as the Naegleria homologue of fibrillarin. BN46/51 bound specifically to the nucleoli of fixed mammalian cells, cells which lack a BN46/51 related polypeptide. When the JG4.1 and JG12.1 cDNAs were expressed in yeast, each subunit was independently targeted to the yeast nucleolus. We conclude that BN46/51 represents a unique nucleolar protein that can form specific complexes with fibrillarin and other nucleolar proteins. We suggest that the association of BN46/51 with the MTOC of basal bodies may reflect its role in connecting the nucleolus with the MTOC activity for the mitotic spindle. This would provide a mechanism for nucleolar segregation during the closed mitosis of Naegleria amebae. (+info)
Vasorelaxation and inhibition of the voltage-operated Ca2+ channels by FK506 in the porcine coronary artery.
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Using fura-2 fluorometry, the effects of FK506, an immunosuppressant, on changes in cytosolic Ca2+ concentrations ([Ca2+]i) and tension were investigated in porcine coronary arterial strips. The effects of FK506 on the activity of voltage-operated Ca2+ channels were examined by applying a whole cell patch clamp to the isolated smooth muscle cells of porcine coronary artery. FK506 inhibited the sustained increases in both [Ca2+]i and tension induced by 118 mM K+ depolarization and 100 nM U46619 in a concentration-dependent manner (1-30 microM). The extent of inhibition of the K+-induced contraction was greater than that of the U46619-induced contraction. The increases in [Ca2+]i and tension induced by histamine and endothelin- in the presence of extracellular Ca2+ were also inhibited by 10 microM FK506. FK506 (10 microM) had no effect on Ca2+ release induced by caffeine or by histamine in the Ca2+-free solution. FK506 (10 microM) had no effect on the [Ca2+]i-tension relationships of the contractions induced by cumulative increases of extracellular Ca2+ during K+ depolarization or stimulation with U46619. In the patch clamp experiments, FK506 (30 microM) partially inhibited the inward current induced by depolarization pulse from -80 mV to 0 mV. In conclusion, FK506 induces arterial relaxation by decreasing [Ca2+]i mainly due to the inhibition of the L-type Ca2+ channels, with no effect on the Ca2+ sensitivity of the contractile apparatus. (+info)
Failure of calcineurin inhibitors to prevent pressure-overload left ventricular hypertrophy in rats.
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A rapidly emerging body of literature implicates a pivotal role for the Ca2+-calmodulin-dependent phosphatase calcineurin as a cellular target for a variety of Ca2+-dependent signaling pathways culminating in left ventricular hypertrophy (LVH). Most of the recent experimental support for this hypothesis is derived from in vitro studies or in vivo studies in transgenic mice expressing activated calcineurin or mutant sarcomeric proteins. The aim of the present study was to test whether calcineurin inhibitors, cyclosporin A (CsA) and FK 506, prevent pressure-overload LVH using 2 standard rat models: (1) the spontaneously hypertensive rat (SHR) and (2) aortic banding. The major new findings are 2-fold. First, in SHR, LVH (left ventricular weight to body weight ratio) was unaffected by a dose of CsA (5 mg. kg-1. d-1) that was sufficient to raise blood pressure and to inhibit calcineurin-mediated transcriptional activation in skeletal muscle. Second, in rats with aortic banding, LVH was unaffected by FK 506 (0.3 mg. kg-1. d-1) or even higher doses of CsA (10 and 20 mg. kg-1. d-1) that were sufficient to inhibit 90% of total calcineurin phosphatase activity in the hypertrophied myocardium. In the latter experiments, CsA blocked neither the elevated left ventricular end-diastolic pressures, a measure of diastolic function, nor the induction in atrial natriuretic peptide mRNA in the hypertrophic ventricles. Thus, in numerous experiments, systemic administration of potent calcineurin inhibitors did not prevent the development of LVH in 2 classic models of pressure-overload hypertrophy. These results demonstrate that pressure-overload hypertrophy can arise through calcineurin-independent pathways. (+info)
Immunosuppression with FK506 in rat arterial allografts: fate of allogeneic endothelial cells.
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PURPOSE: This study clarified the efficacy of low-dose FK506 and the possibility of discontinuing the use of FK506. METHODS: Fresh carotid arteries were allografted from ACI rats to Lewis rats. FK506 (0.2 mg/kg/day) was given intramuscularly from day 3 after transplantation until the rats were killed (group III), or it was given for 4 weeks and then discontinued (group IV). Isogeneic (group I) and allogeneic (group II) models served as untreated control groups. Grafts were harvested on days 0, 1, 3, 7, 14, 21, 28, 70, and 105 after transplantation. Histological evaluation and measurement of the endothelial cell (EC)-covered area were performed by means of scanning electron microscopy. RESULTS: In group I, ECs were denuded immediately after transplantation and subsequently regenerated within 2 weeks. In group II, after denudation and regeneration of ECs, massive leukocyte adhesion and subsequent destruction of regenerated ECs, followed by intimal hyperplasia, were observed. In group III, FK506 suppressed rejection almost completely, without intimal hyperplasia. In group IV, severe rejection and denudation of regenerated intima appeared 2 weeks after the use of FK506 ended. CONCLUSION: The denudation and regeneration of ECs may play an important role in the process of rejection and graft performance. FK506 proved to be successful in rat arterial allografting, and ECs of donor origin could survive on the allograft as long as FK506 was effective; however, cessation of the use of FK506 resulted in severe destruction of intima. To prevent allograft failure, long-term administration of an immunosuppressant is essential. (+info)
Effects of FK506 in rat and human resistance arteries.
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BACKGROUND: FK506 is widely used in organ transplantation and causes hypertension. However, little is known about the impact of the drug on the cardiovascular system. METHODS: We therefore investigated the effect of FK506 on resistance artery and blood pressure responsiveness to vasoconstrictors and vasodilators. Studies were conducted in vitro using human and murine resistance artery, ex vivo in resistance artery isolated from rats treated with FK506 (6 mg/kg/day), and in vivo in conscious, treated animals. RESULTS: In vitro exposure (24 hr) of human and rat resistance artery to FK506 (1000 ng/ml) increased the sensitivity to norepinephrine (NE) and impaired the response to acetylcholine (Ach) and sodium nitroprusside (SNp). In contrast, arteries isolated from rats given FK506 for eight days showed a reduced sensitivity to NE (P < 0.05) and a normal endothelium-dependent relaxation. Their incubation with L-arginine caused a significant reduction in Ach sensitivity in the FK506 group (P < 0.05) but not in controls, suggesting enhancement of nitric oxide production by the drug. The sensitivity to SNp was reduced, as in the in vitro experiments (P < 0.05). Rats given FK506 for eight days presented blood pressure similar to that in controls but also presented signs of a compensatory response to excess vasodilation: tachycardia (P < 0.01), reduced blood pressure sensitivity to NE and Ach, blunted heart rate response to both agonists, and exaggerated hypotension at high doses of Ach. After 21 days of treatment, blood pressure remained similar to that in controls, but resistance artery showed further functional deterioration, with significant impairment of the maximum responses to Ach and to SNp. CONCLUSION: FK506 presents significant vascular toxicity affecting mainly smooth muscle relaxation and alters vascular hemodynamics. The data suggest that similar cardiovascular changes may occur in transplant patients and represent the forerunner of hypertension often seen with more prolonged use of the drug. (+info)
Protective effect of cyclosporin A and FK506 from nitric oxide-dependent apoptosis in activated macrophages.
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1. Activation of macrophages with lipopolysaccharide (LPS) and low doses of interferon-gamma (IFN-gamma) induced apoptotic death through a nitric oxide-dependent pathway. 2. Treatment of cells with the immunosuppressors cyclosporin A (CsA) or FK506 inhibited the activation-dependent apoptosis. 3. These drugs decreased the up-regulation of p53 and Bax characteristic of activated macrophages. Moreover, incubation of activated macrophages with CsA and FK506 contributed to maintain higher levels of Bcl-2 than in LPS/IFN-gamma treated cells. 4. The inhibition of apoptosis exerted by CsA and FK506 in macrophages was also observed when cell death was induced by treatment with chemical nitric oxide donors. 5. Incubation of macrophages with LPS/IFN-gamma barely affected caspase-1 but promoted an important activation of caspase-3. Both CsA and FK506 inhibited pathways leading to caspase-3 activation. Moreover, the cleavage of poly(ADP-ribose) polymerase, a well established caspase substrate, was reduced by these immunosuppressive drugs. 6. CsA and FK506 reduced the release of cytochrome c to the cytosol and the activation of caspase-3 in cells treated with nitric oxide donors. 7. These results indicate that CsA and FK506 protect macrophages from nitric oxide-dependent apoptosis and suggest a contribution of the macrophage to innate immunity under conditions of immunosuppression of the host. (+info)