The pediatric nephrologist's dilemma: growth after renal transplantation and its interaction with age as a possible immunologic variable

An Integrated Transcriptomic Approach to Identify Molecular Markers of Calcineurin Inhibitor Nephrotoxicity in Pediatric Kidney Transplant Recipients

Calcineurin inhibitors are highly efficacious immunosuppressive agents used in pediatric kidney transplantation. However, calcineurin inhibitor nephrotoxicity (CNIT) has been associated with the development of chronic renal allograft dysfunction and decreased graft survival. This study evaluated 37 formalin-fixed paraffin-embedded biopsies from pediatric kidney transplant recipients using gene expression profiling. Normal allograft samples (n = 12) served as negative controls and were compared to biopsies exhibiting CNIT (n = 11). The remaining samples served as positive controls to validate CNIT marker specificity and were characterized by other common causes of graft failure such as acute rejection (n = 7) and interstitial fibrosis/tubular atrophy (n = 7). MiRNA profiles served as the platform for data integration. Oxidative phosphorylation and mitochondrial dysfunction were the top molecular pathways associated with overexpressed genes in CNIT samples. Decreased ATP synthesis was identified as a significant biological function in CNIT, while key toxicology pathways included NRF2-mediated oxidative stress response and increased permeability transition of mitochondria. An integrative analysis demonstrated a panel of 13 significant miRNAs and their 33 CNIT-specific gene targets involved with mitochondrial activity and function. We also identified a candidate panel of miRNAs/genes, which may serve as future molecular markers for CNIT diagnosis as well as potential therapeutic targets.

Safety and utility of surveillance biopsies in pediatric kidney transplant patients

There is currently no way to diagnose a rejection before a change in serum creatinine. This had led some to start doing SB, but little data exist on the utility and safety of SB in pediatric patients. There is also little known on practice patterns of pediatric nephrologists. A retrospective review of pediatric kidney transplant SB between January 2013 and January 2017 at a single center was performed. A survey went to the PedNeph email list. There were 47 SB; 15 at 6 months, 12 at 1 year, 13 at 2 years, and 7 at 3 years. There were 3 minor (1 gross hematuria and 2 hematomas) and no major complications. On 6-month SB, 1 had SC 1A ACR (6.7%) with no BR ACR. On the 12-month SB, there were 5 with SCBR ACR (41.7%) and 1 with SC AMR (8.3%). On the 2-year SB, there were 4 that had SCBR ACR (30.8%), and 1 with SC AMR (7.7%). On the 3-year SB, 1 had chronic transplant glomerulitis (14.3%). The survey showed that 34.3% of pediatric nephrologists perform SB. SB can be performed safely. By early identification of histological lesions, SB gives us an opportunity for individualized immunosuppressive regimens that may prevent chronic allograft dysfunction and improve long-term graft outcome.

Combined liver and kidney transplantation in children: analysis of renal graft outcome

BACKGROUND

Combined liver-kidney transplantation (CLKT) is the accepted treatment for patients with both liver failure and progressive renal insufficiency. Long-term outcome data for CLKT in children is sparse and controversy exists as to whether simultaneous CLKT with organs from the same donor confers immunologic and survival benefit to the kidney allograft. We report the long-term renal graft outcomes of 40 patients who had simultaneous CLKT.

METHODS

A retrospective analysis of kidney graft survival (time from transplantation to death, return to dialysis or last follow-up event) in all pediatric patients (age < 18 years old) who underwent CLKT from March 1994 to January 2015. A 1:1 ratio of controls (deceased donor kidney recipients from our centre matched for age (±2 years) at transplant, time from transplant (±1 year) and treated with the same immunosuppressive regime) to cases was used to compare outcome. Estimated glomerular filtration rate (e-GFR) was calculated using the Schwartz formula. Survival curves were determined using Kaplan-Meier analysis.

RESULTS

The kidney graft survival for CLKT patients was 87.4, 82, and 82 % at 1, 5, and 10 years; kidney graft survival for isolated KT patients were 97.2, 93, and 93 % at 1, 5, and 10 years (p = NS). There were two acute rejection episodes (5 %) in the CLKT group compared to five (12.5 %) episodes in the isolated KT group. There was no statistically significant difference in e-GFR at 1, 5, and 10 years in the two groups but there was a statistically significantly greater decline in e-GFR in the KT group compared to CLKT group from 5-10 years following transplant.

CONCLUSIONS

There are fewer acute rejection episodes following CLKT compared to isolated KT, and we noted a higher mean e-GFR at 1, 5, and 10 years with significantly lesser decline in e-GFR from 5 to 10 years in the CLKT group.

Histopathological diagnosis of acute and chronic rejection in pediatric kidney transplantation

ABO-compatible as well as ABO-incompatible kidney transplantation are well established in the pediatric population. There are particularities in the histopathological evaluation of pediatric kidney transplant biopsies as for example the recurrence of certain diseases different from the adult population. Furthermore, the challenging transition of pediatric renal transplant recipients to adulthood is associated with an increased rate of non-adherence triggered rejection episodes. With modern immunosuppressive drugs, T-cell-mediated rejection of renal allografts is well controlled. In contrast, antibody-mediated rejection (AMR) is increasingly recognized as one of the major reasons for allograft loss. However, the 2001 diagnostic Banff criteria for antibody-mediated rejection require further refinement, as the morphological spectrum of AMR expands while effective therapeutic strategies are lacking. For example, endarteritis, which traditionally has been attributed to T-cell-mediated rejection, has recently been shown to be part of the AMR spectrum in some cases. Many findings in transplant renal biopsies are not specific for a certain disease but need consideration of differential diagnoses. To use the term "chronic allograft nephropathy" as a diagnostic entity is no longer appropriate. Therefore, the precise identification of specific diseases is paramount in the assessment of transplant renal biopsies in order to enable tailored therapeutic management.

Surveillance biopsies in children post-kidney transplant

Surveillance biopsies are increasingly used in the post-transplant monitoring of pediatric renal allograft recipients. The main justification for this procedure is to diagnose early and presumably modifiable acute and chronic renal allograft injury. Pediatric recipients are theoretically at increased risk for subclinical renal allograft injury due to their relatively large adult-sized kidneys and their higher degree of immunological responsiveness. The safety profile of this procedure has been well investigated. Patient morbidity is low, with macroscopic hematuria being the most common adverse event. No patient deaths have been attributed to this procedure. Longitudinal surveillance biopsy studies have revealed a substantial burden of subclinical immunological and non-immunological injury, including acute cellular rejection, interstitial fibrosis and tubular atrophy, microvascular lesions and transplant glomerulopathy. The main impediment to the implementation of surveillance biopsies as the standard of care is the lack of demonstrable benefit of early histological detection on long-term outcome. The considerable debate surrounding this issue highlights the need for multicenter, prospective, and randomized studies.

Pharmacokinetics, pharmacodynamics, safety, and tolerability of single-dose fingolimod (FTY720) in adolescents with stable renal transplants

Oral fingolimod signals the sphingosine 1-phosphate receptor and this in turn mediates immunomodulatory activity. No data of fingolimod in any pediatric population existed before this study. We put our study results in perspective against data from adult renal transplant patients. We investigated pharmacokinetics and pharmacodynamics of single-dose fingolimod (0.07 mg/kg) and its effects on lymphocytes and heart rate in seven adolescents (14.1 ± 1.6 yr) with stable renal transplants. Blood samples for pharmacokinetics and lymphocytes were collected at screening, baseline, and up to 28 days post-dosing. Cardiac monitoring included 12-lead ECG, 24-h Holter monitoring, and echocardiography. A fingolimod dose of 0.07 mg/kg resulted in mean AUC of 731 ± 240 ng·h/mL and C(max) of 3.6 ± 0.6 ng/mL. Drug exposure was nearly identical to adults receiving the same dose. Absolute lymphocyte count decreased 85% from baseline; average nadir occurred by six h post-dose. Heart rate decreased from 74 bpm (predose mean) to 53 bpm (nadir) three h post-dose. Mean heart rates recovered by Day 14 (75 bpm). Weight-adjusted doses of fingolimod in adolescents resulted in drug exposure similar to adults. Adolescents and adults shared comparable negative chronotropic effects and decreased lymphocyte count. Recovery trajectories of these parameters back to baseline were similar between age groups.

Renal graft outcome after combined liver and kidney transplantation in children: UCLA and UNOS experience

Although it has been described in adults that renal grafts in the context of CLKT have a lower number of AR episodes and improved renal allograft survival, this has never been examined in pediatrics. We performed a single center retrospective case-control study examining 10 patients aged 10+/-6 yr with a CLKT that survived the post-surgery period of six months, and compared outcomes to a group of 20 KO transplants matched for age, era, and immunosuppression. We observed a significant reduction in the incidence of AR episodes in the CLKT group. To evaluate whether or not this experience was reproducible nationally, we performed an analysis of the 1995-2005 UNOS database. As of March 2007, 111 CLKT and 3798 KO transplants were identified from the OPTN/UNOS data. There was a significant improvement in the late kidney graft survival at five yr post-transplant in the CLKT group. These findings support the concept that liver transplantation is immunologically protective of the kidney allograft in CLKT.

Patterns of chronic injury in pediatric renal allografts

BACKGROUND

In pediatric recipients, the pathophysiology of chronic renal allograft injury is poorly understood.

METHODS

We studied the evolution and determinants of tubulointerstitial, vascular, and glomerular injury in 240 pediatric protocol renal allograft biopsies during the first 5 years posttransplant.

RESULTS

Chronic tubulointerstitial injury (ci, ct) developed predominantly during the first 12 months posttransplant, whereas chronic vascular damage (cv, and arteriolar hyalinosis [ah]) and global glomerulosclerosis (gs) became increasingly prevalent at 25 to 36 months and beyond. Chronic interstitial lesions were associated with acute rejection and borderline histology (odds ratio [OR] 2.3, P<0.04), recipient body surface area less than 1.0 m2 (OR 3.6, P<0.05), and obesity (OR 2.0, P<0.03). Determinants of ct were acute rejection (OR 2.6, P=0.02) and acute tubular necrosis (OR 2.8, P<0.04). Vascular fibrous intimal thickening and ah were associated with donor hypertension (OR 3.6, P=0.001) and recipient body surface area less than 1.0 m (OR 2.6, P=0.02), respectively. The severity of ah correlated with the incidence of gs (r=0.32, P<0.0001), with 7.8% gs for ah0, 14.3% gs for ah1, 60.0% gs for ah2, and 95.5% gs for ah3 (median values). Antibody induction conferred protection from ci (OR 0.31, P=0.008), ct (OR 0.33, P=0.002), and ah (OR 0.12, P<0.001) progression.

CONCLUSIONS

By 5 years posttransplant, pediatric renal allografts manifest a substantial burden of tubulointerstitial and microvascular injury. These lesions are associated with donor hypertension, acute inflammation, renal hypoperfusion, obesity, and calcineurin inhibitor toxicity. The pervasiveness and rapid progression of microvascular lesions at 25 to 36 months suggest that attempts at reducing calcineurin inhibitor exposure should be made before two years posttransplant.

Induction therapy in pediatric renal transplant recipients: an overview

Induction therapy to prevent the acute rejection of mismatched allografts with the ultimate aim of prolonging the life of the allograft has been the cornerstone of immunosuppression since the introduction of renal transplantation. Agents used for induction therapy have changed over time. Their role in transplantation is expanding to include corticosteroid avoidance and immunosuppression minimization. This review provides an overview of induction therapies for renal transplantation including historic therapies such as total lymphoid irradiation and Minnesota antilymphocyte globulin, and current therapies with polyclonal and monoclonal antibodies and chemical agents, with special emphasis on children. Data from adult studies, and pediatric studies whenever available, are summarized. A brief summary of experimental therapies with fingolimod and belatacept is provided. Historically, induction therapies were targeted at T cells. The role of induction therapies targeted at B cells is emerging in select groups of patients that include highly sensitized recipients and those receiving transplants from blood group incompatible donors. With the advent of newer maintenance immunosuppressive medications and with very low rates of acute rejection, induction protocols for renal transplantation need to be targeted so that excessive immunosuppression and infections are avoided. Several single-center and registry data analyses in children suggest that the addition of an interleukin (IL)-2 receptor antagonist may improve graft survival compared with no induction. The safety profile of IL-2 receptor antagonists is indistinguishable from that of placebo, with no apparent difference in the incidence of infection or post-transplant lymphoproliferative disease. IL-2 receptor antagonists and polyclonal lymphocyte-depleting antibodies offer equivalent efficacy in standard-risk populations. However, in high-risk patients, acute rejection rates and graft outcomes may be improved with the use of lymphocyte-depleting agents such as Thymoglobulin. However, cytomegalovirus infection and other infections may be more common with this therapy. Therefore, in patients at high risk of graft loss, Thymoglobulin may be the preferred choice for induction therapy, while for all other patients, IL-2 receptor antagonists should be considered the first-line choice for induction therapy. Newer lymphocyte-depleting agents such as alemtuzumab may be better utilized in minimization regimens involving one or two oral maintenance immunosuppressive agents.

Safety and efficacy of a calcineurin inhibitor avoidance regimen in pediatric renal transplantation

Thirty-four children were entered into a pilot trial of calcineurin inhibitor avoidance after living-donor kidney transplantation, the CN-01 study. Patients were treated with anti-CD25 mAb, prednisone, mycophenolate mofetil, and sirolimus. Twenty patients were maintained on the protocol for up to 3 yr of follow-up. One enrolled patient did not receive the transplant because of a donor problem, eight terminated because of one or more rejection episodes, four terminated because of adverse events, and one was lost to follow-up. Two grafts were lost, one as a result of chronic rejection and the other as a result of posttransplantation lymphoproliferative disorder. There were no deaths. The 6- and 12-mo acute rejection rates were 21.8 and 31.5%, respectively. GFR were stable throughout the course of the study, with a slight downward trend by 6 mo after transplantation followed by a slight upward trend to a mean of 70 ml/min thereafter. Early surveillance graft biopsies frequently showed focal interstitial mononuclear cellular infiltrates without overt vasculitis or tubulitis, but these infiltrates disappeared without treatment. Anti-HLA class I and II antibodies were detected in three patients before transplantation, and all three had acute rejections, including the two patients who lost their grafts. De novo anti-HLA Ab production occurred in only one patient after transplantation. There were two episodes of Epstein Barr virus-related posttransplantation lymphoproliferative disorder, one of which developed after the patient had been terminated from the study. It is concluded that calcineurin inhibitor-free immunosuppression can be safe and effective in pediatric living-donor renal transplantation. However, further modifications that are designed to lessen early rejection rates and decrease complications should be tested before this approach is used routinely.

RABBIT ANTITHYMOCYTE GLOBULIN AS INDUCTION IMMUNOTHERAPY FOR PEDIATRIC DECEASED DONOR KIDNEY TRANSPLANTATION

PURPOSE

There is scant literature describing the long-term outcome of the use of antithymocyte globulin induction immunotherapy in pediatric deceased donor kidney transplants. We retrospectively studied the long-term results and safety of antithymocyte globulin as induction immunotherapy in all children undergoing transplantation at our institution since 1991.

MATERIALS AND METHODS

A total of 120 kidney transplants were performed in 95 patients 18 years or younger between January 1986 and December 1998. Patients were divided into 2 groups. The control group (63 patients) received cyclosporine, azathioprine and prednisolone, while the treatment group (59 patients) received rabbit antithymocyte globulin (RATG) induction immunotherapy for 6 to 10 days, combined with cyclosporine, azathioprine and prednisolone.

RESULTS

Actuarial patient survival rates at 1, 3, 5 and 10 years were 96%, 95%, 95% and 90%, respectively. Actuarial graft survival rates at 1, 3, 5 and 10 years were 76%, 69%, 64% and 49%, respectively. The 1, 3, 5 and 10-year graft survival rates in the control group were 62%, 57%, 51% and 36%, respectively, compared to 90%, 82%, 79% and 69%, respectively, in the RATG group (p = 0.001). There was a significant difference in the incidence of graft loss secondary to acute cellular rejection between the control and RATG groups (19.7% vs 3.3%, p = 0.008). There was no difference in infectious complications between the control and RATG groups (13% vs 20%, p = 0.33), and there was no case of post-transplant lymphoproliferative disorder encountered in either group.

CONCLUSIONS

The use of rabbit antithymocyte globulin in pediatric deceased donor kidney transplant recipients resulted in significant improvement in graft survival and was relatively safe.

Anesthesia for pediatric renal transplantation with and without epidural analgesia--a review of 7 years experience

BACKGROUND

Few objective data exist describing current anesthesia practice for pediatric renal transplantation. We describe here, the experience from an Australian tertiary pediatric center that has continued an active pediatric renal transplantation program after relocation in 1995. Areas of interest include preoperative status, fluid management, hemodynamic stability, perioperative complications, and the use of epidural analgesia. In particular, the influence of perioperative epidural analgesia on hemodynamic stability is addressed.

METHODS

A retrospective review of anesthesia records of all patients undergoing pediatric renal transplantation performed at the Children's Hospital at Westmead (CHW), from November 1995 to October 2002 was carried out.

RESULTS

Fifty-three pediatric renal transplants were performed in 50 patients. Average age and weight were 10.2 years (range: 1-18 years) and 31.4 kg (range: 9-66 kg), respectively. A total of 14 recipients were less than or equal to 6 years of age. Twenty-four children were recipients of cadaveric transplants, 29 children received kidneys from living related donors. Few children presented with severe anemia (two patients) gross electrolyte abnormalities (three patients) or uncontrolled hypertension. Intraoperatively, all children had central venous pressure monitoring and only four had invasive arterial blood pressure monitoring. Average intraoperative fluid administration was 88 ml x kg(-1) (range: 30-190). Twenty-three children received blood transfusions intraoperatively. Postoperative analgesia was provided using an epidural infusion in 39 patients and an opioid infusion/patient controlled analgesia in the remainder. There was a tendency to greater hemodynamic stability in the group, which received intra-operative epidural analgesia. Half the patients who had epidural analgesia required parenteral opioid supplementation. Five patients had postoperative pulmonary edema. Minor postoperative adverse events included epidural associated motor block (three cases) and opioid related oversedation (one patient). No perioperative mortality or major morbidity was recorded.

CONCLUSIONS

Anesthesia for renal transplantation in pediatric patients at CHW is safe and effective using a selected range of drugs and techniques. Pretransplant medical optimization, careful preoperative assessment, adequate monitoring and precise fluid management together with appropriate postoperative analgesia typify the perioperative care of CHW renal transplant recipients.

Pediatric transplantation

Analysis of the OPTN/SRTR database demonstrates that, in 2002, pediatric recipients accounted for 7% of all recipients, while pediatric individuals accounted for 14% of deceased organ donors. For children fortunate enough to receive a transplant, there has been continued improvement in outcomes following all forms of transplantation. Current 1-year graft survival is generally excellent, with survival rates following transplantation in many cases equaling or exceeding those of all other recipients. In renal transplantation, despite excellent early graft survival, there is evidence that long-term graft survival for adolescent recipients is well below that of other recipients. A causative role for noncompliance is possible. While the significant improvements in graft and patient survival are laudable, waiting list mortality remains excessive. Pediatric candidates awaiting liver, intestine, and thoracic transplantation face mortality rates generally greater than those of their adult counterparts. This finding is particularly pronounced in patients aged 5 years and younger. While mortality awaiting transplantation is an important consideration in refining organ allocation strategies, it is important to realize that other issues, in addition to mortality, are critical for children. Consideration of the impact of end-stage organ disease on growth and development is often equally important, both while awaiting and after transplantation.

Short sirolimus half-life in pediatric renal transplant recipients on a calcineurin inhibitor-free protocol

Immunosuppression with SRL may provide an opportunity to avoid long-term exposure to the nephrotoxicity of CNI. Thus, we have initiated an experimental protocol of IL-2r antibody induction, prednisone, MMF and SRL in pediatric renal transplant recipients (median age 15.5 yr, IQR 8.5, range 1.3-21.7). The recipients were treated with daclizumab every 2 wk for the first 2 months, prednisone on a tapering schedule, MMF at 1200 mg/m(2)/day and SRL given b.i.d. The SRL was dosed to achieve defined target whole blood 12-h trough levels. We performed 24 SRL PK profiles in 13 stable pediatric renal transplant recipients at 1 and 3 months post-transplant. Half-life (T(1/2)) and terminal T(1/2) were 9.7 (7.1-24.6) and 10.8 (4.4-95.2) hours (median, range) respectively at month 1, and were 9.6 (5-17.8) and 12.1 (4.7-71.0) hours respectively at month 3. SRL trough levels correlated with AUC (r(2) = 0.84, p < 0.001). There was no relationship between SRL and mycophenolic acid (MPA) AUC values (r(2) = 0.04). During the first 3 months post-transplant only one patient experienced severe neutropenia and another patient had subclinical (histologic) evidence of a mild acute rejection episode with no change in renal function. We conclude that the T(1/2) of SRL in pediatric renal transplant recipients not treated with CNI is much shorter than what has been reported for adults, due to rapid metabolism. We conclude that children require SRL dosing every 12 h, higher doses and frequent drug monitoring to achieve target SRL concentrations.

Paediatric renal transplantation--a 15 year experience

OBJECTIVE

To review the outcome of paediatric renal transplantation over a period of 15 years in a developing country.

METHODS

This is a retrospective study of 63 children, less than 15 years of age, who underwent living-related renal transplantation in Christian Medical College and Hospital Vellore between 1984 and 1996.

RESULTS

The records of 12 patients were not adequate for detailed analysis. Parents were the donors for these children in 84.3% of cases. The most common known cause of end-stage renal disease in these children was reflux nephropathy. Combinations of cyclosporine, azathioprine and prednisolone were used as immunosuppressive drugs. Complications occurred in 16 patients. During the follow-up period, eight patients died and two returned to receiving haemodialysis. Patient survival was 92% at the end of 1 year and 90% at the end of 3 years. Graft survival was 88% and 86% at 1 and 3 years, respectively.

CONCLUSION

Our study validates the concept of renal transplantation as optimal therapy with adequate medical, social and functional rehabilitation for children with end-stage renal disease. Our study also indicates that vesicoureteric reflux appears to be underdiagnosed and should be actively pursued to prevent complications.

Immunosuppressive therapy for paediatric transplant patients: pharmacokinetic considerations

Immunosuppressive therapy in paediatric transplant recipients is changing as a consequence of the increasing number of available immunosuppressive agents. Generic and other new formulations are now emerging onto the market, clinical experience is growing, and it is expected that clinicians should tailor immunosuppressive protocols to individual patients by optimising dosages and drugs according to the maturation and clinical status of the child. Most information about the clinical pharmacokinetics of immunosuppressive drugs in paediatrics is centred on cyclosporin, tacrolimus and mycophenolate mofetil in renal and liver transplant recipients; data regarding other immunosuppressants and transplant types are limited. Although the clinical pharmacokinetics of these drugs in paediatric transplant recipients are still under investigation, it is evident that the pharmacokinetic parameters observed in adults may not be applicable to children, especially in younger age groups. In general, patients younger than 5 years old show higher clearance rates irrespective of the organ transplanted or drug used. Another important factor that frequently affects clearance in this patient population is the post-transplant time. In accordance with these findings, and in contrast with the usual under-dosage in children, the need for higher dosages in younger recipients and during the early post-transplant period seems evident. To achieve the best compromise between prevention of rejection and toxicity, dosage individualisation is required and this can be achieved through therapeutic drug monitoring (TDM). This approach is particularly useful to ensure the cost-effective management of paediatric transplant recipients in whom the pharmacokinetic behaviour, target concentrations for clinical use and optimal dosage strategies of a particular drug may not yet be well defined. Although TDM may be a tool for improving immunosuppressive therapy, there is little information concerning its positive contribution to clinical events, including outcomes, for paediatric patients. Substantial information to support the use of TDM exists for cyclosporin and, to a lesser extent, for tacrolimus, but a diversity of options affects their implementation in the clinical setting. The role of TDM in therapy with mycophenolate mofetil and sirolimus has yet to be defined regarding both methods and clinical indications. Pharmacodynamic monitoring appears more suited to other immunosuppressants such as azathioprine, corticosteroids and monoclonal or polyclonal antibodies. If coupled with pharmacokinetic measurements, such monitoring would allow earlier and more precise optimisation of therapy. Very few population pharmacokinetic studies have been carried out in paediatric transplant patients. This type of study is needed so that techniques such as Bayesian forecasting can be applied to optimise immunosuppressive therapy in paediatric transplant patients.

Review of select transplant subpopulations at high risk of failure from standard immunosuppressive therapy

Despite improvements in short-term graft and patient survival rates for solid organ transplants, certain subgroups of transplant recipients experience poorer clinical outcome compared to the general population. Groups including pediatrics, African-Americans, diabetics, cystic fibrosis patients, and pregnant women require special considerations when designing immunosuppressive regimens that optimize transplant outcomes. Problems specific to pediatric transplant recipients include altered pharmacokinetics of immunosuppressive drugs, such as cyclosporine (CsA) and tacrolimus (poor absorption, increased metabolism, rapid clearance), the need to restore growth post-transplantation, and a high incidence of drug-related adverse effects. African-Americans have decreased drug absorption and bioavailability, high immunologic responsiveness, and a high incidence of post-transplant diabetes mellitus. Diabetics and cystic fibrosis patients exhibit poor absorption of immunosuppressive agents, which may lead to underimmunosuppression and subsequent graft rejection. Pregnant women undergo physiologic changes that can alter the pharmacokinetics of immunosuppressives, thus requiring careful clinical management to minimize the risks of either under- or overimmunosuppression to mother and child. To achieve an optimal post-transplant outcome in these high-risk patients, the problems specific to each group must be addressed, and immunosuppressive therapy individualized accordingly. Drug formulation greatly impacts upon pharmacokinetics and the resultant level of immunosuppression. Thus, a formulation with improved absorption (e.g., CsA for microemulsion), higher bioavailability, and less pharmacokinetic variability may facilitate patient management and lead to more favorable outcomes, especially in groups demonstrating low and variable bioavailability. Other strategies aimed at improving transplant outcome include the use of higher immunosuppressive doses, different combinations of immunosuppressive agents, more frequent monitoring, and management of concurrent disease states.

A decade of living donor transplantation in North American children: the 1998 annual report of the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS)

This report of the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) covers the years 1987-1997, and analyzes data on 2,904 living donor (LD) transplants performed in 2,779 patients. Since 1991, approximately 300 LD transplants have been performed each year at the participating centers of the NAPRTCS. Caucasian children account for 72% of all LD recipients while African-American children constitute only 11%. There has been a gradual decline in the number of transplants performed in children under the age of 6 years from a peak of 30% in 1987, to 21% in 1997. Preoperative calcineurin inhibitor therapy has dropped from 71% in 1987 to 38% in 1997. Through 1996, at six months post-transplant 97% of recipients were receiving prednisone, 88% were maintained on cyclosporin A, and 79% were receiving azathioprine. Of patients transplanted in 1997, 47% are maintained on mycophenolate and 10% are maintained on tacrolimus. By day 15, 20% of index transplant patients have had an acute rejection and by the end of the first year 47% have had a rejection episode. Among patients transplanted in 1995-1996, 40% had a rejection in the first year. Nine per cent of rejection episodes are irreversible in children under 2 years of age and 5% of the episodes are irreversible in 25-year-old children. Estimated graft survival probability at 1 year is 91%, at 3 years it is 84% and at 5 years it is 78.5%. Rejection accounts for 33% of graft loss and recurrence constitutes another 10%. Influential prognostic variables for graft survival are race (African-American vs. others, relative risk (RR) = 2.0, p < 0.001), > 5 random transfusions (RR = 1.6, p < 0.001, T cell induction therapy (RR = 0.78, p = 0.01), and later year of entry (1989-1990 vs. 1994-1995, RR = 0.95, p = 0.04). Patient survival at 1 and 3 years was 97% and 96.5%, respectively, however, the 3-year patient survival of children under 2 years was 89%. The mean height deficit baseline (n=2,677) was -1.86, at 1 year post-transplant (n=1,459) it was -1.80, and at 5 years post-transplant (n=592) it was -2,06. This report, devoted specifically to LD pediatric transplants, raises the issues regarding the use of immunosuppression such as preoperative calcineurin inhibitors and T-cell antibodies. Studies to address the high incidence of chronic rejection and recurrence of original disease are necessary. Additional areas of concern are the high infant mortality and continued growth retardation post-transplantation.

Safety of kidney biopsy in pediatric transplantation: a report of the Controlled Clinical Trials in Pediatric Transplantation Trial of Induction Therapy Study Group

BACKGROUND

Historically, young children undergoing renal transplantation have lower allograft survival than adults, and potential causes of this are being addressed by the North American Pediatric Renal Transplant Cooperative Study through the National Institutes of Health-sponsored study Cooperative Clinical Trials in Pediatric Transplantation. Included in this study is evaluation of surveillance renal biopsies (SB) and clinically indicated biopsies (CB). Few data exist in children to identify the risk involved with renal transplant biopsies.

METHODS

Questionnaires were mailed to 21 participating centers asking for descriptions of adverse events associated with kidney biopsies, with choices limited to none, gross hematuria, perinephric hematoma, and other. Further clinical details were obtained from review of medical records of all patients with reported adverse events. Data were collected from 19 centers on 126 patients.

RESULTS

Eighty-six patients had undergone 212 biopsies (75 SB and 137 CB). Nine biopsy-related adverse events were reported (4.2%): three SB (4.0%) and six CB (4.4%). Gross hematuria was reported in six patients (2.8%): two SB (2.7%) and four CB (2.9%). A perinephric hematoma was reported in one patient. Two patients with intraperitoneal kidneys developed significant bleeding after biopsy and required transfusions and surgical exploration. No patient lost kidney function or required nephrectomy after biopsy. No difference was noted in adverse events between SB at day 5 or 12 versus CB.

CONCLUSION

Evaluation of transplanted kidney tissue may provide important information for the care of the transplantation patient. This analysis suggests that transplanted kidney biopsies can be performed with minimal risks in pediatric patients.

Paediatric kidney transplantation

Renal transplantation is the optimal form of renal replacement therapy leading to substantial improvement in the quality of life. It has rapidly become the standard treatment for end-stage renal disease in children. However, despite impressive short-term results significant long-term problems remain unsolved. Because of the lack of effective treatment for chronic rejection and common recipient noncompliance, allograft half-life has not improved significantly during the last decade. A paediatric recipient is likely to need several retransplantations in adulthood. Moreover, the immunosuppressive drugs used today have potentially serious side-effects including nephrotoxicity and de novo malignancy. These are especially relevant for paediatric recipients who will continue to receive therapy for several decades. Most therapeutic protocols used for children are derived from those used for adults. However, the metabolic differences between an adult and a growing and developing paediatric transplant recipient are not always adequately appreciated before these new therapies are initiated. In the near future, we are likely to see new and more efficient drugs become available. It is important that we try to understand their properties in children and use them and our current arsenal on an individual basis aiming at optimal graft survival but also at avoiding unnecessary adverse effects.

Calcineurin activity in children with renal transplants receiving cyclosporine

BACKGROUND

The major immunosuppressive effect of cyclosporine is through the inhibition of calcineurin, an enzyme important in the activation of T lymphocytes. In children, neither calcineurin activity nor its inhibition by cyclosporine (CsA) has been investigated.

METHODS

Calcineurin activity, was measured in stable pediatric renal transplant patients, with healthy children used as controls. Whole blood CsA concentrations were measured by monoclonal radioimmunoassay. Simultaneous calcineurin and CsA levels were measured before and 1, 2, 3.5, 5, and 12 hr after their routine morning CsA dose.

RESULTS

Calcineurin activity was approximately 50% inhibited at trough blood concentrations (148 microg/L); moreover, inhibition increased as CsA concentrations rose and declined as concentrations fell. Maximum calcineurin inhibition was about 70% at concentrations of about 431 microg/L. Linear regression analysis revealed a significant correlation between mean CsA blood concentration and the mean degree of inhibition of calcineurin activity (P=0.005, one-tailed).

CONCLUSION

We conclude that inhibition of calcineurin activity by CsA in pediatric renal transplant recipients correlates with CsA blood concentrations.

Influence of donor and recipient ages and sex on graft function after pediatric renal transplantation

BACKGROUND

Adult donor grafts adapt to the smaller size of the child recipient by reducing their absolute glomerular filtration rate (GFR) (ml/min). The question arises whether these grafts can increase the absolute GFR when the child recipient grows or whether a child donor graft can better increase its function. The aim of this study was to evaluate the influence of donor and recipient ages and sex on renal function.

METHODS

Eighty-five children and adolescents, aged 0.4-20.5 years at transplantation, were monitored annually, by GFR and effective renal plasma flow (ERPF), determined by clearances of inulin and para-aminohippuric acid. The patients received 90 grafts from donors aged 3-67 years. Follow-up time was around 5 years.

RESULTS

Absolute GFR and ERPF (ml/min) of grafts from donors <20 years of age (all cadaveric donor grafts) increased during follow-up, resulting in a constant relative GFR and ERPF (ml/min/1.73 m2), whereas absolute GFR and ERPF of grafts from donors >20 years of age remained constant during follow-up, resulting in a significant decrease in relative values. Relative GFR and ERPF fell during follow-up in young recipients (<12 years of age), but remained constant in older recipients (>12 years). Donor and recipient sex did not influence renal function.

CONCLUSIONS

Child donor grafts seem better able to increase their function with the growth of the child recipient than adult grafts. However, the limited access to pediatric grafts and the fact that pediatric cadaveric grafts might involve technical problems in connection with grafting restrict their use.

Growth rates in pediatric dialysis patients and renal transplant recipients

We compared growth rates by modality over a 6- to 14-month period in 1,302 US pediatric end-stage renal disese (ESRD) patients treated during 1990. Modality comparisons were adjusted for age, sex, race, ethnicity, and ESRD duration using linear regression models by age group (0.5 to 4 years, 5 to 9 years, 10 to 14 years, and 15 to 18 years). Growth rates were higher in young children receiving a transplant compared with those receiving dialysis (ages 0.5 to 4 years, delta = 3.1 cm/yr v continuous cycling peritoneal dialysis [CCPD], P < 0.01; ages 5 to 9 years, delta = 2.0 to 2.6 cm/yr v CCPD, chronic ambulatory peritoneal dialysis (CAPD), and hemodialysis, P < 0.01). In contrast, growth rates in older children were not statistically different when comparing transplantation with each dialysis modality. For most age groups of transplant recipients, we observed faster growth with alternate-day versus daily steroids that was not fully explained by differences in allograft function. Younger patients (<15 years) grew at comparable rates with each dialysis modality, while older CAPD patients grew faster compared with hemodialysis or CCPD patients (P < 0.02). There was no substantial pubertal growth spurt in transplant or dialysis patients. This national US study of pediatric growth rates with dialysis and transplantation shows differences in growth by modality that vary by age group.

Blood transfusions in liver recipients: a conundrum or a clear benefit in the cyclosporine/tacrolimus era?

Blood transfusions are common in patients with end-stage liver disease (ESLD), and their effects on sensitization, rejection, and liver graft survival are not well known. These effects were examined in 121 recipients of primary liver grafts, surviving > or = 30 days. Ninety-six (79%) patients received transfusions before transplantation. Transfusion recipients had significantly fewer severe or recurrent rejection episodes (18%), compared with patients who did not receive transfusions (42%, P=0.006), if the first transfusion was > or = 90 days before the transplant. Patients with alcoholic ESLD (n=49) had significantly fewer severe rejection episodes when compared with the nonalcoholic (n=72) patients (12% vs. 35%, P=0.004). The transfusion benefit was, however, more apparent and significant in the nonalcoholic (26% vs. 56% in nontransfused, P=0.02) than among the alcoholic recipients (6% vs. 25%, P=0.1). This finding is, most likely, due to a combination of a higher rate of severe rejection and the statistical power of the larger number of recipients in the nonalcoholic group. This finding is further corroborated by a multivariate analysis in which blood transfusions retained their benefit (P<0.05) independent of recipient's age and diagnosis. Graft and patient survival were not significantly different in the transfused versus nontransfused groups. Transfusion recipients had a higher panel antibody (11.4+/-23.4 vs. 2.7+/-8.1, P<0.02) but no increased risk of a positive crossmatch. In liver recipients, blood transfusions diminish the risk of rejection independent of recipient's age and the cause of ESLD.

Factors influencing short-term and long-term pediatric renal transplant survival

OBJECTIVE

To determine the patient and donor characteristics important for short-term and long-term renal transplant survival at Cincinnati Children's Hospital Medical Center.

METHODS

Cumulative transplant survival was calculated and univariate analysis of graft survival performed on 206 transplants done since 1970 in 148 pediatric patients. Grafts to black recipients were analyzed separately. Short-term graft survival is defined as 1-year allograft survival and long-term graft survival as graft half-life (t1/2) survival for allografts functioning after the first posttransplant year.

RESULTS

One-year graft survival of living-related donor (LRD) and cadaver donor (CAD) transplants was 77% and 62%, respectively. Graft t1/2 was 11.2 years for LRD and 9.8 years for CAD grafts. The CAD 1-year graft survival when the recipient or donor was younger than 7 years was 36% and 41%, respectively. The LRD 1-year graft survival to children younger than 7 years was 88% versus 75% in older children. Graft survival at 1 year was similar for CAD primary and retransplants (60% vs 65%), but graft t1/2 better for CAD primary grafts (17.8 years vs 5.0 years, P < 0.001). Preemptive LRD grafts performed similarity at 1 year and better over the long term compared with patients who had long-term dialysis (85% vs 74%, P = NS; and 16.9 years vs 8.0 years, p < 0.001). Preemptive CAD grafts did poorly, with 1-year graft survival of 38%. Administration of Cyclosporine A (CsA) improved CAD 1-year graft survival (76% vs 54%, p < 0.001) but not long-term survival. Thirty grafts to 24 black children had a 1-year survival of 48%, with no graft surviving more than 5 years.

CONCLUSIONS

Living-related donor transplantation should be aggressively pursued for young children. If a LRD is unavailable and the young child's medical condition is stable, delay in CAD transplantation should be considered, with dialysis before transplant. Use of CsA improves 1-year pediatric graft survival, but does not improve graft survival after 1 year at the Children's Hospital Medical Center. New strategies to improve graft survival in black children should be pursued.

Long-term cyclosporin A pharmacokinetic profiles in pediatric renal transplant recipients

To study the long-term effect of cyclosporin A (CyA), 94 6-h and 29 12-h pharmacokinetic profiles were evaluated in 32 children at least 1 year after renal transplantation. Children weighing less than 25 kg needed significantly higher doses of CyA than those weighing more than 25 kg (9.8 vs 5.3 mg/kg per day; P < 0.001) to achieve similar trough levels (TL). The average dose of CyA required to achieve the target TL declined gradually with time after transplantation. The average area under the curve over 6 h (AUC/6) correlated strongly with the AUC/12 (r = 0.967; P < 0.001). The AUC/6 of patients with biopsy-proven CyA toxicity was significantly higher than for those without toxicity (Mann-Whitney U-test P < 0.05) despite similar TL. We conclude that AUC monitoring for 6 h provides valuable information not only on TL but also on the absorption and elimination characteristics of CyA as well as on the potential for CyA toxicity.

Renal transplantation in young children

AIMS

To review the outcome of renal transplantation in small children treated with triple immunosuppression at a single Australian centre.

METHODS

The medical records of all children under the age of five years undergoing renal transplantation from 1988 were reviewed. The duration of follow-up was 30 months (range 18-36).

RESULTS

Six children received seven renal allografts (five living-related [LR] and two cadaveric [CD]). They had a median age of 3.75 years (range 1.5-4.9) and weight of 11.6 kg (9.1-14.5) at the time of transplantation. All patients received an immunosuppressive regime involving cyclosporin A, azathioprine and prednisolone. There were no deaths. The only graft lost was a CD graft (severe acute rejection within one week of transplantation). Hypertension occurred in all recipients and usually required more than one antihypertensive drug for treatment. Renal function measured by serum median creatinine concentration (range) was 0.05 mmol/L (0.03-0.11) at three months (n = 6) and 0.10 mmol/L (0.07-0.22) at 30 months (n = 4). Growth estimated from median (range) height standard deviation scores was -1.97 (-1.36-(-4.04)) at three months (n = 6) and -1.90 (-1.74-2.50) at 30 months (n = 4). No patient was entirely weaned from prednisolone. Cyclosporin A side effects included hirsutism (five patients), gingival hyperplasia (six patients) and nephrotoxicity (three patients).

CONCLUSIONS

Satisfactory patient and graft survival can be accomplished in this recipient age group. The results compare with other international experience and accumulating Australian experience. Hypertension and poor skeletal growth were consistent observations. The long-term outcome of renal function using triple immunosuppression remains to be determined.

Effects of growth hormone on kidney function in pediatric transplant recipients

Recent evidence suggests that treatment with recombinant human growth hormone (rhGH) after a successful kidney transplant improves the growth rate of children with short stature. We prospectively investigated eight children (6 boys, 2 girls), focusing on acute rejection episodes and changes in serum creatinine levels during rhGH treatment. The children (mean age 11.6 +/- 3.4 years) received rhGH daily (0.04-0.05 mg/kg subcutaneously). Seven patients completed at least 12 months (20 +/- 8 months) of rhGH treatment. Their mean serum creatinine level was 1.3 +/- 0.7 mg/dl 12 months before, and increased to 3.4 +/- 4.2 mg/dl after 12 months of rhGH treatment, but did not achieve statistical significance (P = 0.06). Their mean calculated glomerular filtration rate was 58 +/- 20 ml/min per 1.73 m2 12 months before, and decreased to 38 +/- 21 ml/min per 1.73 m2 after 12 months of rhGH treatment, but did not achieve statistical significance (P = 0.08). Of the seven patients, two developed acute rejection after 5 and 6 rejection-free years; three lost their grafts and returned to dialysis. These preliminary observations describe untoward renal events in children receiving rhGH treatment after a kidney transplant.

Flow cytometry: its use in pediatric renal transplantation utilizing polyclonal induction

Induction protocols for pediatric renal transplant recipients commonly utilize polyclonal or monoclonal agents in sequence with additional immunosuppression. Polyclonal agents Minnesota antilymphoblast globulin (MALG), anti-thymocyte globulin (ATGAM) effect both T and B cells while monoclonal agents (OKT3) are T-cell specific. Flow cytometric analysis of T-cell subsets has become the marker of adequacy of immunosuppression during OKT3 therapy, yet to date no marker exists to measure the adequacy of immunosuppression with polyclonal agents. At the University of Michigan, flow cytometric analysis in pediatric renal transplant recipients undergoing polyclonal induction reveals that CD3, CD4, and CD8 suppression initially occurs. As opposed to OKT3, a rebound of CD3 cells occurs despite daily use of a polyclonal agent in sequence with additional immunosuppressives. During these analyses, a single kidney was lost which flow cytometry failed to predict. No significant difference in flow cytometric patterns occurred when comparing ATGAM to MALG induction. Flow cytometry utilized during polyclonal induction in pediatric renal transplant recipients revealed a variety of T-cell suppression patterns but failed to demonstrate persistence of suppression. Despite this lack of suppression as indicated by flow cytometry, a 97% 1 year allograft survival rate exists in the pediatric transplant program at the University of Michigan Medical Center. Therefore, the role of flow cytometry during polyclonal induction has yet to be well defined.

Growth of children following the initiation of dialysis: a comparison of three dialysis modalities

Maintenance dialysis usually serves as an interim treatment for children with end-stage renal disease (ESRD) until transplantation can take place. Some children, however, may require dialytic support for an extended period of time. Although dialysis improves some of the problems associated with growth failure in ESRD (acidosis, uremia, calcium, and phosphorus imbalance), many children continue to grow poorly. Therefore, three different dialysis modalities, continuous ambulatory peritoneal dialysis (CAPD), cycler/intermittent peritoneal dialysis (CPD), and hemodialysis (HD), were evaluated with regard to their effects on the growth of children initiating dialysis and remaining on that modality for 6-12 months. Growth was best for children undergoing CAPD when compared with the other two modalities with regard to the following growth parameters: incremental height standard deviation score for chronological age [-0.55 +/- 2.06 vs. -1.69 +/- 1.22 for CPD (P < 0.05) and -1.80 +/- 1.13 for HD (P < 0.05)]; incremental height standard deviation score for bone age [-1.68 +/- 1.71 vs. -2.45 +/- 1.43 for CPD (P = NS) and -2.03 +/- 1.28 for HD (P = NS)]; change in height standard deviation score during the dialysis period [0.00 +/- 0.67 vs. -0.15 +/- .29 for CPD (P = NS) and -0.23 +/- .23 for HD (P = NS)]. The reasons why growth appears to be best in children receiving CAPD may be related to its metabolic benefits: lower levels of uremia, as reflected by the blood urea nitrogen [50 +/- 12 vs. 69 +/- 16 mg/dl for CPD (P < 0.5) and 89 +/- 17 for HD (P < 0.05)], improved metabolic acidosis, as indicated by a higher serum bicarbonate concentration [24 +/- 2 mEq/l vs. 22 +/- 2 for CPD (P < 0.05) and 21 +/- 2 for HD (P < 0.05)]. In addition, children undergoing CAPD receive significant supplemental calories from the glucose absorbed during dialysis. CAPD, and possibly, other types of prolonged-dwell daily peritoneal dialysis appear to be most beneficial for growth, which may be of particular importance for the smaller child undergoing dialysis while awaiting transplantation.

Growth after conversion to alternate-day corticosteroids in children with renal transplants: a single-center study

During the 1980s all children with growth potential and stable/adequate renal function at 6-9 months after kidney transplantation underwent conversion to alternate-day corticosteroids in an attempt to maximize growth. Conversion was attempted in 79 of 160 children who received allografts during this decade and was considered successful if they remained on alternate-day prednisone for more than 1 year, with a calculated creatinine clearance of at least 75% of the pre-conversion baseline value. Conversion succeeded in 55 children but failed in 24. Growth was markedly improved among those successfully converted when compared with the failure group, as measured by standard deviation score for growth velocity based on chronological age (+0.94 +/- 1.58 vs. -0.86 +/- 1.53, P < 0.001) and bone age (+0.49 +/- 0.61 vs. -1.24 +/- 1.47, P < 0.001). The improved growth among the successfully converted patients is believed to have been related to the combined effects of lower corticosteroid dose (0.36 +/- 0.16 vs. 0.48 +/- 0.21 mg/kg per day, P < 0.02) and better renal function (calculated creatinine clearance 87 +/- 32 vs. 47 +/- 21 ml/min per 1.73 m2, P < 0.001) at 1 year post conversion. Two factors appeared to improve the likelihood of successful conversion: the use of cyclosporine and receiving a live-related rather than cadaver transplant. Cyclosporine was associated with improvement in the overall rate for successful conversion in all recipients, from 59% to 83% (P < 0.05). Recipients of allografts from live-related donors underwent successful conversion in 90% of cases compared with 58% receiving cadaver allografts (P < 0.05). (ABSTRACT TRUNCATED AT 250 WORDS)

Combined pancreas and kidney transplantation normalizes protein metabolism in insulin-dependent diabetic-uremic patients

In order to assess the combined and separate effects of pancreas and kidney transplant on whole-body protein metabolism, 9 insulin-dependent diabetic-uremic patients (IDDUP), 14 patients after combined kidney-pancreas transplantation (KP-Tx), and 6 insulin-dependent diabetic patients with isolated kidney transplant (K-Tx), were studied in the basal postabsorptive state and during euglycemic hyperinsulinemia (study 1). [1-14C]Leucine infusion and indirect calorimetry were utilized to assess leucine metabolism. The subjects were studied again with a combined infusion of insulin and amino acids, given to mimic postprandial amino acid levels (study 2). In the basal state, IDDUP demonstrated with respect to normal subjects (CON): (a) higher free-insulin concentration (17.8 +/- 2.8 vs. 6.8 +/- 1.1 microU/ml, P < 0.01) (107 +/- 17 vs. 41 +/- 7 pM); (b) reduced plasma leucine (92 +/- 9 vs. 124 +/- 2 microM, P < 0.05), branched chain amino acids (BCAA) (297 +/- 34 vs. 416 +/- 10 microM, P < 0.05), endogenous leucine flux (ELF) (28.7 +/- 0.8 vs. 39.5 +/- 0.7 mumol.m-2.min-1, P < 0.01) and nonoxidative leucine disposal (NOLD) (20.7 +/- 0.2 vs. 32.0 +/- 0.7 mumol.m-2. min-1, P < 0.01); (c) similar leucine oxidation (LO) (8.0 +/- 0.1 vs. 7.5 +/- 0.1 mumol.m-2.min-1; P = NS). Both KP-Tx and K-Tx patients showed a complete normalization of plasma leucine (116 +/- 5 and 107 +/- 9 microM), ELF (38.1 +/- 0.1 and 38.5 +/- 0.9 mumol.m-2.min-1), and NOLD (28.3 +/- 0.6 and 31.0 +/- 1.3 mumol.m-2.min-1) (P = NS vs, CON). During hyperinsulinemia (study 1), IDDUP showed a defective decrease of leucine (42% vs. 53%; P < 0.05), BCAA (38% vs. 47%, P < 0.05), ELF (28% vs. 33%, P < 0.05), and LO (0% vs. 32%, P < 0.05) with respect to CON. Isolated kidney transplant reverted the defective inhibition of ELF (34%, P = NS vs. CON) of IDDUP, but not the inhibition of LO (18%, P < 0.05 vs. CON) by insulin. Combined kidney and pancreas transplanation normalized all kinetic parameters of insulin-mediated protein turnover. During combined hyperinsulinemia and hyperaminoacidemia (study 2), IDDUP showed a defective stimulation of NOLD (27.9 +/- 0.7 vs. 36.1 +/- 0.8 mumol.m-2.min-1, P < 0.01 compared to CON), which was normalized by transplantation (44.3 +/- 0.8 mumol.m-2.min-1).

Triple immunosuppression with subsequent prednisolone withdrawal: 6 years' experience in paediatric renal allograft recipients

Thirty-four children (< or = 15 years of age) with end-stage renal failure received 39 renal allografts between 1985 and 1991 and were treated with cyclosporin A (CyA), azathioprine and low-dose prednisolone (PNL). We aimed to withdraw PNL by 6 months after transplantation. Median duration of follow-up was 2 years 4 months (range 0.1 month to 6 years 4 months). There were no deaths. Crude graft survival for living-related grafts (n = 9) was 100%, although only 1 patient has been followed for > 2 years. For cadaveric grafts (n = 30), 1- and 5-year actuarial graft survivals were 90% and 79% respectively. At 12 months posttransplant, the median (range) glomerular filtration rate for all patients was 63 (19-109) ml/min per 1.73 m2 (n = 25) and at 5 years was 48 (17-64) ml/min per 1.73 m2 (n = 9). Complications observed included rejection episodes which occurred after discontinuation of PNL. Long-term (after 12 months), 28% of patients remain on PNL. Hypertension was present in more than 50% of patients. Severe CyA nephrotoxicity was not seen. Catch-up growth as determined by the change (delta) in mean height standard deviation score (Ht-SDS) was noted at 1 year [delta SDS/year = +0.60; P < 0.001 (n = 18)] and at 2 years [delta SDS/year = +0.27; P < 0.01 (n = 16)] in pre-pubertal patients. The median Ht-SDS at 2 years for pre-pubertal children was -0.71 SD and growth velocity did not improve thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Causes of kidney allograft loss in a large pediatric population at a single center

At our institution, 521 kidney transplants were performed in 429 children (mean age 8.7 +/- 5.6-years) between 1969 and 1991. Of these transplants, 408 were primary, 113 were retransplants, 347 were living related, 171 were cadaver, and 3 were living nonrelated. Immunosuppression consisted of prednisone, azathioprine, and Minnesota antilymphocyte globulin (non-CSA) in 339 patients, total lymphoid irradiation in 8, and, more recently, cyclosporine (CSA) in addition in 168 patients. Average follow-up was 8.8 +/- 6.0 years. Actuarial graft survival in the non-CSA versus CSA groups at 1 year was 77.0% versus 85.7%; at 5 years, 59.6% versus 71.9%. Of 136 non-CSA patients, causes of graft loss at 5 years included: chronic rejection in 55 (40.4%), acute rejection in 27 (19.9%), recurrent disease in 16 (11.8%), technical complications in 8 (5.9%), infectious complications in 4 (2.9%), other causes in 5 (3.7%), and death with a functioning graft in 21 (15.4%). Of 40 CSA patients, causes of graft loss at 5 years included: chronic rejection in 16 (40.0%), acute rejection in 8 (20.0%), recurrent disease in 6 (15.0%), technical complications in 3 (7.5%), other causes in 2 (5.0%), and death with a functioning graft in 5 (12.5%). The causes of graft loss did not significantly differ in the non-CSA and CSA groups. Chronic rejection was the most common cause of graft loss in both groups. Research focusing on chronic rejection is needed to improve graft outcome in pediatric kidney transplantation.

New immunosuppressive agents for pediatric transplantation

Pediatric transplantation has always been challenging for transplant surgeons. Although the higher immunoreactivity and the faster metabolism showed by this unique population when compared with adults requires a heavy immunosuppressive regimen, the possibility of disrupting the delicate balance of correct psychophysical development calls for a regimen of more selective and less toxic immunosuppressive drugs. In the past decade several new drugs have been investigated and some of them appear to be very promising, although pleiotropic toxicities have not yet been eliminated. An appropriate pharmacokinetic approach and the evaluation of synergistic multi-drug combinations by rigorous mathematical models would lead to highly selective immunosuppressive regimens which may result in virtually no toxicity.

Factors predictive of sustained growth in children after renal transplantation. The North American Pediatric Renal Transplant Cooperative Study

To ascertain growth and rehabilitation of children after transplantation, the North American Pediatric Renal Transplant Cooperative Study collected growth data on renal transplant recipients. From January 1987 through December 1990, a total of 1553 children with one or more transplants were entered into the study by its 75 participating centers. Of these, the first 300 children with a functioning graft and 2 years of linear growth data form the cohort for this study. For the total cohort of 300 patients, the mean (+/- SEM) baseline height z score was -2.41 +/- 0.09, and the change in z score determined after 2 years was 0.18 +/- 0.06 (p < 0.01). Children in the age group from birth to 1 year had the maximal deficit and had the maximal improvement in z score, gaining about 1 SD (p < 0.01). For the 2- to 5-year-old group, the change in z score was about 0.5 SD (p < 0.001). No improvement in z score was noted for children 6 to 17 years of age. Each increase in serum creatinine concentration of 90 mumol/L (1 mg/dl) was associated with -0.17 decrease in the z score (p < 0.001). Gender, donor source, history of previous transplantation, and prior dialysis were not associated with a significant change in the z score; thus the increased rate of growth during the first 2 post-transplantation years occurred mainly in subjects less than 6 years of age.

A single center experience with renal transplantation in young children

Results of pediatric renal transplantation have been variable. We evaluated our experience with renal transplantation in children less than 5 years old to determine its safety and efficacy. Of the 428 renal transplants done at our institution from August 1983 to December 1989, 14 were performed in 13 children 13 to 50 months old (mean age 34 months). All of the patients were small for age with height standard deviation scores ranging from -1.7 to -4.5. Patient survival, allograft survival and statural growth were used as determinants of successful outcome. Followup was complete in all patients, including renal function studies and serial height measurements. Growth velocity standard deviation scores were calculated. Patient survival was 100%. Allograft survival was 100% 2 to 7.3 years after transplantation for living related donor recipients whereas 1-year graft survival was poor (40%) for cadaveric graft recipients. Of 10 patients with good graft function at 1 year 9 demonstrated improvement in the height standard deviation score. Seven of 10 patients demonstrated significant catch-up growth (growth velocity standard deviation score greater than 0, p = 0.04). Our study supports the safety and efficacy of renal transplantation in young children. Early transplantation using living-related donor organs is the optimal therapy to prevent growth retardation and allow the young child with end stage renal disease to have a normal life.

Hepatic allograft rejection: new developments in terminology, diagnosis, prevention, and treatment

Hepatic allograft rejection remains a major cause of morbidity related to the need for increased immunosuppression and continues to be a principal cause of late failure of the graft. Hepatic allograft rejection is defined on the basis of morphologic findings; cellular rejection is defined as portal or periportal hepatitis with nonsuppurative cholangitis or endotheliitis (or both), and ductopenic rejection is defined as loss of interlobular and septal bile ducts, typically in at least 50% of the portal tracts. The overall incidence of episodes of cellular rejection, which usually occur within the first 2 weeks after liver transplantation, varies from 50 to 100%. Ductopenic rejection occurs in approximately 8% of patients who undergo initial liver transplantation and is usually diagnosed between 6 weeks and 6 months after transplantation. Induction and maintenance immunosuppression with triple-drug (cyclosporine, prednisone, and azathioprine) therapy and other combinations that include antilymphocyte preparations, however, has decreased the incidence of both cellular and ductopenic rejection. In patients experiencing episodes of cellular rejection, high-dose intravenously administered corticosteroid therapy yields the best response and is associated with a lower incidence of ductopenic rejection than is low-dose and orally administered corticosteroid therapy. The correlation between degree of biochemical liver dysfunction and presence of histologic rejection is minimal early after transplantation. Histologic severity of rejection, however, suggests which patients will require more immunosuppression and which patients may need antilymphocyte therapy for controlling the rejection episode. With the availability of new immunosuppressive agents, distinguishing patients at high risk for rejection is important. The goals for use of new immunosuppressive agents and regimens are to improve graft and patient survival, to decrease the incidence of cellular and ductopenic rejection, and to minimize side effects and complications.

Outcome of renal transplantation in children less than two years of age

Twenty-two renal transplants were performed in 21 children less than two years of age at Children's Hospital. Fourteen were from living related donors and eight were from cadaveric donors. The five year patient and graft survivals of these recipients were compared to all other pediatric recipients between two and 18 years of age who received renal transplants over the same time period. Five year graft survival for recipients less than two years of age was 86% following living-related donor transplantation and 38% following cadaver donor transplantation. Older pediatric recipients aged between two and 18 years had a five year graft survival of 73% following living-related donor renal transplantation, which was similar to that for recipients less than two years of age. Although older cadaveric recipients had a comparable five year graft survival to younger recipients, at 42%, the patterns of graft loss were different. Graft failures in young recipients occurred within the first seven months post-transplant, whereas the older recipient's grafts failed more gradually. Actuarial five-year patient survival in recipients less than two years of age was 86% following living-related donor renal transplantation and 70% following cadaver-donor renal transplantation. Recipients less than two years of age had a poorer patient survival than older recipients following both living-related donor renal transplantation (P = 0.06) and cadaver-donor renal transplantation (P less than 0.05). These findings suggest that the graft survival of living-related donor renal transplantation in recipients less than two years of age is better than that of cadaver-donor renal transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)