Sequential Observation of Fundus Changes in Patients with Long Standing Membranoproliferative Glomerulonephritis Type II (MPGN type II)

Specific fundus changes have been reported in patients with membranoproliferative glomerulonephritis type II (MPGN type II). We studied the clinical course of this retinopathy in four patients who all had a long follow-up with several fundus examinations. Sequential observation was indicative of a slow progression of the retinopathy. Most eyes maintained in the chronic stages a nearly normal visual acuity, and a full visual field despite the existence of marked drusen and atrophic changes. The prognosis however must be somewhat guarded, since choroidal neovascularization developed in three eyes and caused bilateral severe visual loss in one patient.

A comparative prospective study on the use of low concentrate citrate lock versus heparin lock in permanent dialysis catheters

We prospectively evaluated the efficacy and safety of a low concentrate citrate lock versus heparin lock in permanent single lumen hemodialysis catheters. The frequency of clot formation, complete catheter occlusion, flow problems and the use of urokinase as well as catheter infection episodes were monitored during 1370 dialysis sessions in 19 patients, randomised in two study groups. There was a significantly higher number of dialysis sessions with clot formation in the citrate group but regarding the need for urokinase bolus or infusion, complete obstruction of the catheter or local infections, there were no statistically significant differences between groups. The higher incidence of clotting in the citrate locked catheters had no repercussion on dialysis efficiency, effective blood flow or on the use of thrombolytic therapy. We found that low concentrate citrate is as safe as heparin for long-term interdialytic anticoagulation of permanent single lumen hemodialysis catheters but is more efficient from a pharmaco-economic viewpoint.

Transcatheter embolization of biopsy-related vascular injuries in renal allografts: Long-term technical, clinical and biochemical results

Purpose: Biopsy-related vascular injuries in renal transplants are rare, but they can lead to dramatic clinical symptoms prompting immediate treatment. Transcatheter embolization is a known minimally invasive technique to treat some form of arterial bleeding. This study evaluated the efficacy of this technique in iatrogenic biopsy-related vascular lesions in renal allografts.

Material and Methods: Between 1993 and 2001, 13 patients were treated by percutaneous transcatheter intervention. Indications for embolization were hypovolemic shock due to perinephric hematoma (n = 5), persistent macroscopic hematuria (n = 7) and an asymptomatic large intrarenal pseudoaneurysm in 1 patient. Selective angiography revealed an arteriovenous fistula (n = 7), a pseudoaneurysm (n = 6), and perinephric contrast extravasation (n = 4).

Results: In all patients, successful embolization of the feeding artery could be performed; in 11 patients it was performed in one session, in 2 patients an additional session was needed. In 1 patient thrombosis of a segmental artery occurred immediately after embolization, but was successfully treated by short-term in situ thrombolysis. Clinical symptoms disappeared in all patients. Serum creatinine levels (determined 30 and 60 days after embolization, compared to the level before embolization) decreased significantly in 10 patients; a progressive deterioration of the renal function was observed in 3 patients.

Conclusions: Transcatheter embolization is a safe and effective endovascular technique to treat biopsy-related vascular injuries in renal transplants. In the vast majority of cases an immediate clinical success and significant benefit in renal function can be obtained and the longevity of the allograft after successful embolization mainly depends on the natural (medical) outcome.

Long-term exposure to belatacept in recipients of extended criteria donor kidneys

Patients in the BENEFIT-EXT study received extended criteria donor kidneys and a more intensive (MI) or less intensive (LI) belatacept immunosuppression regimen, or cyclosporine A (CsA). Patients who remained on assigned therapy through year 3 were eligible to enter a long-term extension (LTE) study. Three hundred four patients entered the LTE (n = 104 MI; n = 113 LI; n = 87 CsA), and 260 continued treatment through year 5 (n = 91 MI; n = 100 LI; n = 69 CsA). Twenty patients died during the LTE (n = 5 MI; n = 9 LI; n = 6 CsA), and eight experienced graft loss (n = 2 MI; n = 1 LI; n = 5 CsA). Three patients experienced an acute rejection episode (n = 2 MI; n = 1 LI). The incidence rate of serious adverse events, viral infections and fungal infections was similar across groups during the LTE. There were four cases of posttransplant lymphoproliferative disorder (PTLD) from the beginning of the LTE to year 5 (n = 3 LI; n = 1 CsA); two of three PTLD cases in the LI group were in patients who were seronegative for Epstein-Barr virus (EBV(-)) at transplantation. Mean ± SD calculated GFR at year 5 was 55.9 ± 17.5 (MI), 59.0 ± 29.1 (LI) and 44.6 ± 16.4 (CsA) mL/min/1.73 m(2) . Continued treatment with belatacept was associated with a consistent safety profile and sustained improvement in renal function versus CsA over time.

Combined kidney and intestinal transplantation in patients with enteric hyperoxaluria secondary to short bowel syndrome

Kidney transplantation is the treatment of choice for end-stage renal disease whereas indications for intestinal transplantation are currently restricted to patients with irreversible small bowel failure and severe complications of total parenteral nutrition (mostly shortage and infection of venous accesses, major electrolyte disturbances and liver failure). Enteric hyperoxaluria is secondary to certain intestinal diseases like intestinal resections, chronic inflammatory bowel disease and other malabsorption syndromes and can lead to end-stage renal disease requiring kidney transplantation. We report two patients suffering from renal failure due to enteric hyperoxaluria (secondary to extensive intestinal resection) in whom we elected to replace not only the kidney but also the intestine to prevent recurrence of hyperoxaluria in the transplanted kidney.

Post-streptococcal glomerulonephritis: not an extinct disease!

We present the case of a 29-year-old type 1 diabetic patient with the diagnosis of acute post-streptococcal glomerulonephritis. The incidence of this textbook example of acute glomerulonephritis has dropped dramatically in the developed world during the past decades due to the more widespread use of antibiotics. However, the present case illustrates that it is not an extinct disease and that clinicians should be aware of this entity. Particular attention is needed for the fact that the clinical context in which the disease occurs may be different from the classical "post-angina" presentation.

Chronic histological damage in early indication biopsies is an independent risk factor for late renal allograft failure

The impact of early histological lesions of renal allografts on long-term graft survival remains unclear. We included all renal allograft recipients transplanted at a single center from 1991 to 2001 (N = 1197). All indication biopsies performed within the first year after transplantation were rescored according to the current Banff classification. Mean follow-up time was 14.8 ± 2.80 years. In multivariate Cox proportional hazards analysis, arteriolar hyalinosis and transplant glomerulopathy were independently associated with death-censored graft survival, adjusted for baseline demographic covariates. Arteriolar hyalinosis correlated with interstitial fibrosis, tubular atrophy, mesangial matrix increase, vascular intimal thickening and glomerulosclerosis. Clustering of the patients according to these chronic lesions, reflecting the global burden of chronic injury, associated better with long-term graft survival than each of the chronic lesions separately. Early chronic histological damage was an independent risk factor for late graft loss, irrespective whether a specific, progressive disease was diagnosed or not, while T cell-mediated rejection did not. We conclude that individual chronic lesions like arteriolar hyalinosis, tubular atrophy, interstitial fibrosis, glomerulosclerosis, mesangial matrix increase and vascular intimal thickening cannot be seen as individual entities. The global burden of early chronic histological damage within the first year after transplantation importantly affects the fate of the allografts.

Evidence in favor of a severely impaired net intestinal calcium absorption in patients with (early-stage) chronic kidney disease

INTRODUCTION

Calcium and phosphorus are essential to many vital physiological processes. Little is known about the net and fractional intestinal absorption of calcium and phosphorus in patients with chronic kidney disease (CKD) and their clinical and hormonal determinants.

METHODS

Blood and 24-hour urine samples were collected in 20 healthy volunteers (HV) and 72 stable CKD stage 1-4 patients and analyzed for parameters of mineral metabolism including calcidiol, calcitriol, and parathyroid hormone (PTH). Dietary intake was assessed by dietary history.

RESULTS

The 24-hour urinary calcium excretion, as opposed to the phosphorus excretion, showed a stepwise decrease across CKD stages (median of 219, 84, 40, and 22 mg/day in HV and patients with CKD stages 1-2, 3 and 4, respectively). Younger age, high serum calcitriol, and high estimated GFR were associated with a high 24-hour urinary calcium excretion. High serum calcitriol levels and dietary phosphorus intake were associated with a high 24-hour urinary phosphorus excretion. The fractional intestinal calcium absorption, as estimated by the urinary-to-ingested calcium ratio, decreased across CKD stages.

CONCLUSIONS

The 24-hour urinary excretion of calcium, as opposed to phosphorus, is markedly decreased in CKD, even in early-stage disease. This is partly explained by low calcitriol levels and older age. Assuming a neutral calcium balance at the time of urine collection, we infer that net intestinal calcium absorption may be severely impaired in CKD.

Three-year outcomes from BENEFIT-EXT: a phase III study of belatacept versus cyclosporine in recipients of extended criteria donor kidneys

Recipients of extended-criteria donor (ECD) kidneys have poorer long-term outcomes compared to standard-criteria donor kidney recipients. We report 3-year outcomes from a randomized, phase III study in recipients of de novo ECD kidneys (n = 543) assigned (1:1:1) to either a more intensive (MI) or less intensive (LI) belatacept regimen, or cyclosporine. Three hundred twenty-three patients completed treatment by year 3. Patient survival with a functioning graft was comparable between groups (80% in MI, 82% in LI, 80% in cyclosporine). Mean calculated GFR (cGFR) was 11 mL/min higher in belatacept-treated versus cyclosporine-treated patients (42.7 in MI, 42.2 in LI, 31.5 mL/min in cyclosporine). More cyclosporine-treated patients (44%) progressed to GFR <30 mL/min (chronic kidney disease [CKD] stage 4/5) than belatacept-treated patients (27-30%). Acute rejection rates were similar between groups. Posttransplant lymphoproliferative disorder (PTLD) occurrence was higher in belatacept-treated patients (two in MI, three in LI), most of which occurred during the first 18 months; four additional cases (3 in LI, 1 in cyclosporine) occurred after 3 years. Tuberculosis was reported in two MI, four LI and no cyclosporine patients. In conclusion, at 3 years after transplantation, immunosuppression with belatacept resulted in similar patient survival, graft survival and acute rejection, with better renal function compared with cyclosporine. As previously reported, PTLD and tuberculosis were the principal safety findings associated with belatacept in this study population.

In vivo CYP3A activity is significantly lower in cyclosporine-treated as compared with tacrolimus-treated renal allograft recipients

In vitro studies have identified cyclosporine and tacrolimus as CYP3A inhibitors. In the current study in renal allograft recipients, we used intravenously and orally administered midazolam as a drug probe to assess whether the study drugs at doses that are generally used in clinical practice have differential effects on in vivo hepatic and first-pass CYP3A activities. Systemic and apparent oral midazolam clearance were 24% (269 ± 73 vs. 354 ± 102 ml/min, P = 0.022) and 31% (479 ± 190 vs. 688 ± 265 ml/min, P = 0.013), respectively, lower in cyclosporine-treated patients (n = 20) than in matched tacrolimus-treated patients (n = 20). The latter displayed midazolam clearances similar to those in two larger cohorts of nonmatched tacrolimus-treated patients (n = 58 and n = 80) and to those receiving a calcineurin inhibitor-free regimen (n = 6). This implies that in vivo hepatic and first-pass CYP3A activities are significantly lower in patients receiving cyclosporine than in those receiving tacrolimus, indicating that, at the doses generally used in clinical practice, cyclosporine is the stronger of the two with respect to CYP3A inhibition. This observation has important implications in the context of drug-drug interactions in transplant recipients.

A phase III study of belatacept-based immunosuppression regimens versus cyclosporine in renal transplant recipients (BENEFIT study)

Belatacept, a costimulation blocker, may preserve renal function and improve long-term outcomes versus calcineurin inhibitors in kidney transplantation. This Phase III study (Belatacept Evaluation of Nephroprotection and Efficacy as First-line Immunosuppression Trial) assessed a more intensive (MI) or less intensive (LI) regimen of belatacept versus cyclosporine in adults receiving a kidney transplant from living or standard criteria deceased donors. The co-primary endpoints at 12 months were patient/graft survival, a composite renal impairment endpoint (percent with a measured glomerular filtration rate (mGFR) <60 mL/min/1.73 m(2) at Month 12 or a decrease in mGFR > or =10 mL/min/1.73 m(2) Month 3-Month 12) and the incidence of acute rejection. At Month 12, both belatacept regimens had similar patient/graft survival versus cyclosporine (MI: 95%, LI: 97% and cyclosporine: 93%), and were associated with superior renal function as measured by the composite renal impairment endpoint (MI: 55%; LI: 54% and cyclosporine: 78%; p < or = 0.001 MI or LI versus cyclosporine) and by the mGFR (65, 63 and 50 mL/min for MI, LI and cyclosporine; p < or = 0.001 MI or LI versus cyclosporine). Belatacept patients experienced a higher incidence (MI: 22%, LI: 17% and cyclosporine: 7%) and grade of acute rejection episodes. Safety was generally similar between groups, but posttransplant lymphoproliferative disorder was more common in the belatacept groups. Belatacept was associated with superior renal function and similar patient/graft survival versus cyclosporine at 1 year posttransplant, despite a higher rate of early acute rejection.

Pharmacokinetics for once- versus twice-daily tacrolimus formulations in de novo kidney transplantation: a randomized, open-label trial

Tacrolimus, a cornerstone immunosuppressant, is widely available as a twice-daily formulation (Tacrolimus BID). A once-daily prolonged-release formulation (Tacrolimus QD) has been developed that may improve adherence and impart long-lasting graft protection. This study compared the pharmacokinetics (PK) of tacrolimus in de novo kidney transplant patients treated with Tacrolimus QD or Tacrolimus BID. A 6-week, open-label, randomized comparative study was conducted in centers in Europe and Australia. Eligible patients received Tacrolimus QD or Tacrolimus BID. PK profiles were obtained following the first tacrolimus dose (day 1), and twice under steady-state conditions. As secondary objectives, efficacy and safety parameters were also evaluated. Sixty-six patients completed all PK profiles (34 Tacrolimus QD, 32 Tacrolimus BID). Mean AUC(0-24) of tacrolimus on day 1 was approximately 30% lower for Tacrolimus QD than Tacrolimus BID (232 and 361 ng.h/mL, respectively), but was comparable by day 4. There was a good correlation and a similar relationship between AUC(0-24) and C(min) for both formulations. Efficacy and safety data were also comparable over the 6-week period. Tacrolimus QD can be administered once daily in the morning on the basis of the same systemic exposure and therapeutic drug monitoring concept as Tacrolimus BID.

Localization, etiology and impact of calcium phosphate deposits in renal allografts

Hypercalcemia, hypophosphatemia and renal phosphate wasting are common after kidney transplantation. Animal data suggest that these alterations in mineral metabolism may contribute to calcium phosphate (CaPhos) deposition in the kidney and renal dysfunction. We tested the hypothesis that CaPhos deposition is highly prevalent in the early posttransplant period and is related to a disturbed mineral metabolism. For this purpose, biomarkers of mineral metabolism and renal calcium and phosphorus handling were prospectively assessed in 201 renal transplant recipients. CaPhos deposits were observed in 4.6, 30.4 and 24.7% of protocol biopsies obtained at the time of engraftment, and 3 and 12 months thereafter, respectively. In multivariate logistic regression analysis, high calcium and low serum phosphorus levels were independently associated with renal CaPhos deposition at month 3. The extent of CaPhos deposition correlated significantly with the severity of mineral metabolism disturbances. Renal function after a mean follow-up of 33 months was similar in patients with and without CaPhos deposition at month 3. In conclusion, our data demonstrate that CaPhos deposition is highly prevalent in the early posttransplant period and suggest that a disordered mineral metabolism is implicated in its pathogenesis. The clinical relevance of CaPhos deposition remains to be established.

Calcineurin inhibitor minimization in the Symphony study: observational results 3 years after transplantation

The Symphony study showed that at 1 year posttransplant, a regimen based on daclizumab induction, 2 g mycophenolate mofetil (MMF), low-dose tacrolimus and steroids resulted in better renal function and lower acute rejection and graft loss rates compared with three other regimens: two with low-doses of cyclosporine or sirolimus instead of tacrolimus and one with no induction and standard cyclosporine dosage. This is an observational follow-up for 2 additional years with the same endpoints as the core study. Overall, 958 patients participated in the follow-up. During the study, many patients changed their immunosuppressive regimen (e.g. switched from sirolimus to tacrolimus), but the vast majority (95%) remained on MMF. During the follow-up, renal function remained stable (mean change: -0.6 ml/min), and rates of death, graft loss and acute rejection were low (all about 1% per year). The MMF and low-dose tacrolimus arm continued to have the highest GFR (68.6 +/- 23.8 ml/min vs. 65.9 +/- 26.2 ml/min in the standard-dose cyclosporine, 64.0 +/- 23.1 ml/min in the low-dose cyclosporine and 65.3 +/- 26.2 ml/min in the low-dose sirolimus arm), but the difference with the other arms was not significant (p = 0.17 in an overall test and 0.077, 0.039 and 0.11, respectively, in pair-wise tests). The MMF and low-dose tacrolimus arm also had the highest graft survival rate, but with reduced differences between groups over time, and the least acute rejection rate. In the Symphony study, the largest ever prospective study in de novo kidney transplantation, over 3 years, daclizumab induction, MMF, steroids and low-dose tacrolimus proved highly efficacious, without the negative effects on renal function commonly reported for standard CNI regimens.

Free p-cresol is associated with cardiovascular disease in hemodialysis patients

Cardiovascular disease (CVD) is highly prevalent in chronic kidney disease, suggesting that molecules retained in uremia might contribute to this increased risk. We explored the relationship between p-cresol, a protein-bound uremic retention solute, and CVD by comparing the strength of this relationship relative to traditional and novel cardiovascular risk factors. Univariate Cox proportional hazard analysis showed that the free serum p-cresol concentration was significantly associated with CVD when the primary end point was the time to the first cardiovascular event. In multivariate analysis, free p-cresol was significantly associated with CVD in non-diabetics. In diabetic patients, however, a significant relationship between p-cresol and cardiovascular events could not be demonstrated despite their having significantly higher p-cresol levels. Our study shows that free p-cresol is a novel cardiovascular risk factor in non-diabetic hemodialysis patients.

Influenza vaccination is efficacious and safe in renal transplant recipients

Whether influenza vaccination in solid-organ transplant recipients is efficacious remains a controversial issue. Furthermore, theoretical concerns have been raised regarding the safety of vaccination as it might trigger rejection of the allograft. The present prospective trial is aimed at investigating the antibody response and safety of influenza vaccination in renal transplant recipients (RTR). A total of 165 RTR and 41 healthy volunteers were vaccinated with a standard trivalent inactivated influenza vaccine. Hemagglutination-inhibiting (HI) antibodies were quantified before and 1 month after vaccination. Seroprotection (SP) and seroresponse (SR) were defined as a titer > or =40 and a 4-fold rise in HI titer, respectively. Similar SR rates were observed in both groups. Postvaccination SP rates in RTR amounted to 92.7%, 78.7% and 82.9% for A/H1N1, A/H3N2 and B, respectively. High baseline SP rates, most probably reflecting frequent preimmunizations, explain partly the high postvaccination SP rates. SR rate was independently and inversely associated with baseline SP rate. Mycophenolate mofetil (MMF) usage was associated with a 2.6-5-fold lower SR. Nonetheless, these patients showed good postvaccination SP rates. A booster dose did not enhance SP or SR rates. Influenza vaccination neither affected allograft function nor caused rejection episodes. In conclusion, influenza vaccination is efficacious and safe in renal transplantation.

Living donor kidney transplantation: analysis of the first 40 cases performed in UZ Leuven

Living donation kidney transplantation has been popular worldwide to try to increase the donor pool. In Belgium, the rate of living donation kidney transplantation has been traditionally relatively low compared to other countries. This is--in part--due to the relatively higher cadaveric organ offer that is available in Belgium (around 25 donors per million inhabitants), compared to other countries. However, the increasing waiting times on cadaveric waiting list and the superiority of the results of live donation versus cadaveric kidney transplantation have led to a reappraisal of this strategy. In our center a living donation kidney transplant programme was started in 1997. Since then 40 cases of live donation kidney transplantation have been performed and are reported herein.

Posttransplant Epstein-Barr virus-associated myogenic tumors: case report and review of the literature

Epstein-Barr virus (EBV) has been implicated in the pathogenesis of different types of malignancies. While nonmelanoma skin cancers, lymphomas and Kaposi sarcomas are the most frequently reported malignancies after solid organ transplantation, EBV-associated smooth muscle tumors (EBV-SMT) after transplantation are rare and thus far only 18 cases in kidney recipients have been reported. A case of a 51-year-old kidney transplant recipient diagnosed with EBV-SMT is reported together with a review of the literature.

Major coagulation disturbances during fractionated plasma separation and adsorption

Fractionated Plasma Separation and Adsorption (FPSA) is a novel nonbiologic detoxification system for the removal of protein-bound solutes. FPSA is used to bridge patients during fulminant liver failure, either to functional recovery or to liver transplantation. Besides liver failure associated protein bound solutes, several important uremic retention solutes share important protein binding. We observed repeated occlusive thrombosis of the arterio-venous conduit during FPSA in hemodialysis (HD) patients, resulting in acute loss of function. A major reduction of several coagulation factors was demonstrated, exceeding 50% for factor II, factor X and protein C. Broad disturbances of the coagulation system were confirmed in FPSA treated liver failure patients. An ex vivo recirculation model demonstrated nonspecific adsorption of coagulation factors protein S and protein C on the anion exchange cartridge. Direct contact between fractionated plasma and the Prometh02 anion exchanger causes significant adsorption of procoagulant and anti-coagulant factors, associated with clinically relevant adverse events.

Tacrolimus exposure and evolution of renal allograft histology in the first year after transplantation

Tacrolimus has a narrow therapeutic window and is characterized by a large inter-individual variability in bioavailability. The impact of tacrolimus exposure on subclinical evolution of graft histology has not been studied in renal recipients. This analysis included 239 protocol biopsies (obtained at implantation, 3 and 12 months) of 120 consecutive kidney recipients treated with tacrolimus, mycophenolate mofetil (MMF) and corticosteroids. Biopsies were scored according to the Banff 2001 criteria and a chronicity score was calculated. Prospective pharmacokinetic data were included in the analysis (5544 tacrolimus predose blood concentrations and tacrolimus AUC(0-12) at 3 and 12 months). Higher donor age and higher number of human leukocyte antigen-DR (HLA-DR) mismatches were independent predictors of subclinical acute rejection at 3 months, present in 8.7% of patients. The number of HLA-DR mismatches was independently associated with biopsy-proven clinical acute rejection. Biopsy-proven acute rejection episodes and low mean tacrolimus exposure were independently associated with higher increase in chronicity scores between 3 and 12 months after transplantation. This observational study suggests that rejection phenomena and immune-mediated mechanisms remain important in the early progression of chronic allograft pathology. Tacrolimus doses or systemic exposure were not associated with lesions of calcineurin inhibitor nephrotoxicity, suggesting that other factors determine susceptibility to tacrolimus nephrotoxicity.

CYP3A5 and CYP3A4 but not MDR1 single-nucleotide polymorphisms determine long-term tacrolimus disposition and drug-related nephrotoxicity in renal recipients

The impact of CYP3A and MDR1 gene single-nucleotide polymorphisms on long-term tacrolimus disposition and drug-related toxicity has not been assessed. A study was performed in 95 genotyped recipients by measuring (12 and 4 h) concentration-time curves on day 7; 3, 6 months; 1, 2, 3, 4, and 5 years after transplantation. In contrast to recipients carrying the CYP3A4*1/CYP3A5*1 or CYP3A4*1B/CYP3A5*1 genotypes, dose-corrected tacrolimus exposure almost doubled over 5 years in patients with the CYP3A4*1/ CYP3A5*3 genotype (AUC(0-12 h): from 41.7+/-18.7 to 80+/-39.2 ng h/ml/mg; P<0.05), whereas apparent oral steady-state clearance and dose requirements significantly decreased accordingly. The CYP3A4*1/CYP3A5*1 and CYP3A4*1B/CYP3A5*1 genotypes were significantly more frequently associated with the development of biopsy-proven tacrolimus-related nephrotoxicity than the CYP3A4*1/ CYP3A5*3 genotype (37.5 vs 11.2%; P=0.03 and 42.8 vs 11.2%; P=0.02). The lack of a time-related increase in dose-corrected tacrolimus exposure observed with the CYP3A4*1/CYP3A5*1 and CYP3A4*1B/CYP3A5*1 genotypes is associated with tacrolimus-related nephrotoxicity, possibly as a result of higher concentrations of toxic metabolites.

Tertiary 'hyperphosphatoninism' accentuates hypophosphatemia and suppresses calcitriol levels in renal transplant recipients

Hypophosphatemia and inappropriately low calcitriol levels are frequently observed following successful renal transplantation. Fibroblast growth factor-23 (FGF-23) is a recently characterized phosphaturic hormone that inhibits renal 1 alpha-hydroxylase activity and may be involved in the pathogenesis of both phenomena. The following hypotheses were tested: pretransplant FGF-23 predicts posttransplant FGF-23, FGF-23 predicts posttransplant hypophosphatemia and FGF-23 is associated with decreased calcitriol levels independent of renal and parathyroid function. Serum biointact parathyroid hormone (PTH), calcidiol, calcitriol, full-length FGF-23, calcium and phosphate were monitored in 41 renal transplant recipients at the time of transplantation (pre) and 3 months thereafter (post). In addition, serum phosphate nadir in each individual patient was identified and urinary fractional excretion of phosphate (FE(PO4)) at month 3 was calculated. High FGF-23(post) levels were independently associated with high FGF-23(pre), low calcitriol(post) and high calcium(post) levels. FGF-23, but none of the other mineral metabolism indices, was an independent predictor of the phosphate nadir in the early posttransplant period. A high FGF-23(post) level was independently associated with a high FE(PO4). High FGF-23(post) and creatinine levels and low PTH(post) levels were independently associated with low calcitriol(post) levels. In conclusion, our data indicate that persistence of FGF-23 contributes to hypophosphatemia and suboptimal calcitriol levels in renal transplant recipients.

Cyclosporine sparing with mycophenolate mofetil, daclizumab and corticosteroids in renal allograft recipients: the CAESAR Study

Although the calcineurin inhibitors (CNI) cyclosporine (CsA) and tacrolimus are highly effective immunosuppressants, they are associated with serious side effects. There is great interest in immunosuppressive regimens that permit reduction or elimination of CNIs, while maintaining adequate immunosuppression and acceptable acute rejection rates. Patients (n = 536) receiving their first renal allograft were randomized to one of three immunosuppressant regimens: daclizumab, mycophenolate mofetil (MMF), corticosteroids (CS) and low-dose CsA (target trough levels of 50-100 ng/mL), weaned from month 4 and withdrawn by month 6; daclizumab, MMF, CS and low-dose CsA; or MMF, CS and standard-dose CsA. Mean GFR 12 months after transplantation (primary end point) was not statistically different in the CsA withdrawal and low-dose CsA groups (both 50.9 mL/min/1.73 m(2)) vs. the standard-dose CsA group (48.6 mL/min/1.73 m(2)). At 12 months, the incidence of biopsy-proven acute rejection was significantly higher in the CsA withdrawal group (38%) vs. the low- or standard-dose CsA groups (25.4% and 27.5%, respectively; p < 0.05). In summary, a regimen of continuous low-dose CsA with MMF, CS and daclizumab induction is a clinically safe and effective immunosuppressive regimen in renal transplant recipients.

Superior dialytic clearance of β2-microglobulin and p-cresol by high-flux hemodialysis as compared to peritoneal dialysis

Both residual renal and dialytic clearance confer to the total solute clearance in dialysis patients. Dialytic clearances of the middle molecule beta-microglobulin (beta(2)M) and the protein-bound solute p-cresol (pcr) are generally believed to be higher with peritoneal dialysis (PD) as compared to hemodialysis (HD). Supportive data, however, are lacking. We performed a single-center cross-sectional observational study including 70 unselected patients treated with either high-flux HD (n=20) or PD (n=50). Mid-day serum levels (PD) and time-averaged concentrations (HD) of the water-soluble solutes urea nitrogen, creatinine and phosphate, the middle molecule beta(2)M, and the protein-bound solute pcr were determined. Dialytic solute clearances (l/week/1.73 m(2)) were calculated from total dialysate collection during the mid-week session in HD and 24 h dialysate collection in PD. Renal clearances were calculated for each of the respective solutes from a timed urine collection. Total clearances were obtained by summation. HD delivered significantly higher clearances of all retention solutes studied. This superiority was especially pronounced for pcr (30.9+/-62.7 vs 4.4+/-2.3, HD vs PD, P<0.0001) and beta(2)M (28.6+/-6.6 vs 5.8+/-3.1, HD vs PD, P<0.0001). Renal clearances, conversely, were significantly higher in patients on PD. Serum levels of all solutes but pcr were significantly lower in HD than in PD. Both a higher residual renal function and a lower generation rate contribute to the lower pcr levels in PD. In conclusion, superior dialytic clearance of both water-soluble solutes, beta(2)M, and pcr is achieved by high-flux HD as compared to PD.

Free serum concentrations of the protein-bound retention solute p-cresol predict mortality in hemodialysis patients

Based on in vitro data, protein-bound uremic retention solutes have increasingly been recognized to play a pathophysiological role in the uremic syndrome. p-Cresol, a representative of this group of molecules, has been shown to be implicated in uremic immunodeficiency and endothelial dysfunction, potentially linking its serum levels to mortality. Thus far, however, no clinical information on this issue is available. To determine the relationship between p-cresol and all-cause mortality, 175 prevalent hemodialysis (HD) patients were enrolled in a prospective study. At baseline, serum levels of the water-soluble solutes urea, creatinine, and phosphate, the middle molecule beta2-microglobulin, total and free concentrations of the protein-bound solute p-cresol, and several risk factors for mortality were evaluated. During a median follow-up of 34 months, 60 patients died. Baseline comorbidity (Davies score) (hazard ratio (HR), 1.49; 95% confidence interval (95% CI), 1.19-1.86), impaired nutritional status (HR, 4.22; 95% CI, 2.15-8.29), time since initiation of dialysis (HR, 0.98; 95% CI, 0.97-1.00), and higher free concentrations of the protein-bound solute p-cresol (HR, 2.28; 95% CI, 1.12-4.64) were independently associated with mortality (multivariate Cox proportional hazards analysis). Our data suggest that free serum levels of p-cresol, a representative of the protein-bound uremic retention solutes, are associated with mortality in HD patients. These findings may encourage nephrologists to widen their field of interest beyond the scope of small water-soluble uremic solutes and middle molecules.

Acarbose treatment lowers generation and serum concentrations of the protein-bound solute p-cresol: a pilot study

Several protein-bound uremic retention solutes (including p-cresol) originate from colonic bacterial fermentation of protein. Higher colonic availability of carbohydrates drives this process towards lower production of toxic metabolites. Small intestinal alpha-glucosidase inhibitors like Acarbose (Glucobay) enhance the amount of undigested carbohydrates reaching the colon. We studied the effect of Acarbose on generation and serum concentrations of p-cresol. Nine healthy volunteers (age 25 (22-36) years) with a creatinine clearance of 89.6 ml/min/1.73 m(2) (85.5-116.4) were treated with Acarbose for 3 weeks. Dose was gradually increased to reach 300 mg/day after 1 week. Blood sampling, 24-h urine and stool collections on 3 consecutive days were performed before and during the last days of the treatment period. p-Cresol generation was estimated from mean 24-h urinary elimination. Gastrointestinal side effects, if present, were mild to moderate. Serum concentrations of p-cresol declined significantly after Acarbose treatment (before: 1.14 mg/l (0.93-3.03); after: 1.11 mg/l (0.31-1.82); P=0.047). Urinary excretion of p-cresol, reflecting its colonic generation rate, was significantly lower after treatment (before: 29.93 mg/day (6.79-75.19); after: 10.54 mg/day (1.08-30.85); P=0.031). The fecal excretion of nitrogen increased after treatment (before: 1.04 g/day (0.47-2.29); after: 1.99 g/day (0.76-3.08); P=0.047). This pilot study suggests that Acarbose treatment lowers generation and serum concentrations of the protein-bound uremic solute p-cresol. Although further confirmation is warranted, the data may point to a novel treatment option for chronic kidney disease patients in view of the potential toxic effects of p-cresol and related substances.

Tacrolimus combined with two different dosages of sirolimus in kidney transplantation: results of a multicenter study

Tacrolimus combined with mycophenolate mofetil (MMF) is an effective regimen in kidney transplantation. This study compared the efficacy of combining tacrolimus and two different dosages of sirolimus with an established tacrolimus-MMF regimen. Each day in addition to tacrolimus, 325 patients received 2 mg sirolimus (TAC-SRL2 mg), 325 patients received 0.5 mg sirolimus (TAC-SRL0.5 mg) and 327 patients 1 g MMF (TAC-MMF). The initial tacrolimus dose was 0.2 mg/kg/day. Sirolimus patients received loading doses of 6 or 1.5 mg, and daily doses of 2 or 0.5 mg thereafter. Steroid administration was identical for all groups. The incidence of biopsy-proven acute rejection was lower in the TAC-SRL2 mg group (15.7%) compared with the TAC-SRL0.5 mg (25.2%, p = 0.003) and the TAC-MMF groups (22.3%, p = 0.036). Six-month graft survival was 91.0% (TAC-SRL2 mg), 92.6% (TAC-SRL0.5 mg) and 92.4% (TAC-MMF); the respective values for patient survival were 98.1%, 97.8% and 97.9%. Thirty-four patients (10.5%), 19 patients (5.8%) and 16 patients (4.9%) in the TAC-SRL2 mg, TAC-SRL0.5 mg and TAC-MMF groups, respectively, discontinued the study because of adverse events. Hyperlipemia was reported more often in the TAC-SRL2 mg group (24.0%) compared with 19.4% (TAC-SRL0.5 mg) and 11.0% (TAC-MMF; p < 0.05). Combining 2 mg sirolimus/day with tacrolimus results in lower rates of acute rejection, but a higher incidence of adverse events.

Hypertensive brain stem encephalopathy in a patient with chronic renal failure

Hypertensive brain stem encephalopathy is a rare disorder that can be seen in severe hypertensive encephalopathy. Patients with chronic renal failure are more prone to develop this disorder because a mild elevation of the blood pressure can already induce brain changes. It is important to diagnose this entity as soon as possible because the symptoms and brain stem lesions are reversible following treatment and because it is important to exclude brain stem ischemia in the diagnostic work-up. Brain MRI and particularly diffusion weighted images are crucial for this purpose.

Combined therapy with atorvastatin and calcineurin inhibitors: no interactions with tacrolimus

Increased systemic exposure to statins and consequent risk for complications has been reported in patients concomitantly treated with cyclosporin A (CsA). This has been ascribed to inhibition of drug catabolism by cytochrome P450 3A4 (CYP3A4) or drug transport by P-glycoprotein (PGP) and organic anion transporting polypeptide (OATP1B1). It is not known whether the combination of statins and tacrolimus (Tac) also suffers from this drawback. Therefore, a pharmacokinetic study of atorvastatin and its metabolites was performed in 13 healthy volunteers after 4 days' treatment, and after short (12 h) concomitant exposure to CsA and Tac. A complementary assessment of overall CYP, and hepatic and intestinal CYP3A4+PGP activity was performed after each treatment episode and compared to baseline (no drugs). Systemic exposure to atorvastatin acid and its metabolites was significantly increased when administered with CsA. In contrast, intake of Tac did not have any impact on atorvastatin pharmacokinetics. Concomitantly, a profound decrease of hepatic and intestinal PGP and an increase of intestinal CYP3A4 were noted with CsA, whereas no effect was seen after atorvastatin therapy with or without Tac. Based on these findings treatment with Tac appears a safer option for patients needing a combination of statins and calcineurin inhibitors.

Different evolution of trough and dose levels during the first year after transplantation for tacrolimus versus cyclosporine

At present, the two calcineurin inhibitors-cyclosporine (CsA) and tacrolimus (FK506)-are among the most frequently used immunosuppressants in clinical transplantation. Both drugs share variable oral bioavailability, which necessitates intense drug monitoring. This variability is attributed to large interindividual differences in drug catabolism by cytochrome P450 3A4/5 (CYP3A4/5) and drug efflux by P-glycoprotein (PGP). In addition, the activity of both CYP3A4 and PGP can vary substantially within the same individual due to environmental factors such as concomitant intake of inducing/inhibiting medications (eg, rifampicin/sporanox) or food substances (eg, grapefruit juice). More recently, an inducing effect of methylprednisolone on intestinal and hepatic CYP3A4 has been shown. Also, an influence of gender on CYP3A4 activity (being higher in women) has been reported. Once CsA and FK506 are absorbed and reach the bloodstream, both drugs are avidly bound to erythrocytes (up to 95% for FK506 and 50% for CsA) and plasma proteins, leaving only a small fraction of circulating active drug. This phenomenon also limits further hepatic catabolism and hence clearance of drug, which is influenced by hematocrit and levels of plasma proteins such as albumin. The aim of the present study was to compare the influence of changing steroid doses, hematocrit, and albumin on trough and dose levels of FK506 versus CsA during the first year after transplantation. In addition, the evolution of trough and dose levels of FK506 versus CsA was stratified according to gender.

Combined therapy with atorvastatin and calcineurin inhibitors: no interactions with tacrolimus

Increased systemic exposure to statins and consequent risk for complications has been reported in patients concomitantly treated with cyclosporin A (CsA). This has been ascribed to inhibition of drug catabolism by cytochrome P450 3A4 (CYP3A4) or drug transport by P-glycoprotein (PGP) and organic anion transporting polypeptide (OATP1B1). It is not known whether the combination of statins and tacrolimus (Tac) also suffers from this drawback. Therefore, a pharmacokinetic study of atorvastatin and its metabolites was performed in 13 healthy volunteers after 4 days' treatment, and after short (12 h) concomitant exposure to CsA and Tac. A complementary assessment of overall CYP, and hepatic and intestinal CYP3A4+PGP activity was performed after each treatment episode and compared to baseline (no drugs). Systemic exposure to atorvastatin acid and its metabolites was significantly increased when administered with CsA. In contrast, intake of Tac did not have any impact on atorvastatin pharmacokinetics. Concomitantly, a profound decrease of hepatic and intestinal PGP and an increase of intestinal CYP3A4 were noted with CsA, whereas no effect was seen after atorvastatin therapy with or without Tac. Based on these findings treatment with Tac appears a safer option for patients needing a combination of statins and calcineurin inhibitors.

Immunosuppressive Drugs After Simultaneous Pancreas-Kidney Transplantation

INTRODUCTION

We report the early and late secondary effects of tacrolimus or cyclosporine-microemulsion (ME), in combination with mycophenolate mofetil (MMF), and rATG.

PATIENTS AND METHODS

One hundred three patients were randomly assigned to tacrolimus (initial oral dose 0.2 mg/kg) and 102 to cyclosporine-ME (initial daily oral dose 7 mg/kg). All patients received 4 days of concomitant rATG induction therapy [ATG-Fresenius Biotech GmbH (ATG-F) daily dose of 4 mg/kg or Thymoglobulin-Genzyme/Sangstat (Thymo-S) 1.25 mg/kg], MMF (2 to 3 g per day), and short-term corticosteroids.

RESULTS

Thymo-S was associated with a transiently lower white cell count in the first 3 months compared with ATG-F, while ATG-F caused a lower albeit transient early nadir in platelet count. Both polyclonal preparations were well tolerated; they did not differ with respect to clinically relevant side effects such as infections and malignancies. Higher cyclosporine-ME trough levels were associated with pancreas graft thrombosis. Study withdrawal was more frequent among patients on cyclosporine-ME therapy, because of toxicities, graft loss, and lack of efficacy, the last being the cause of subsequent switch to tacrolimus. Tacrolimus-treated patients were mainly withdrawn from the study due to MMF discontinuation.

CONCLUSION

Short-term induction therapy in combined kidney-pancreas transplantation is effective and well tolerated. Tacrolimus causes fewer pancreas graft losses and fewer drug discontinuations due to side effects. When MMF is combined with tacrolimus, dose reductions and discontinuations are common.