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Biomedical subjects

William E Harmon

Publications and source records attributed to William E Harmon.

16 recordsLinked to original sources
PubMed2006

Sirolimus pharmacokinetics in pediatric renal transplant recipients receiving calcineurin inhibitor co-therapy.

We have previously reported sirolimus (SRL) pharmacokinetics (PK) in pediatric renal transplant recipients on a calcineurin inhibitor (CNI)-free protocol. We now report pediatric SRL PK in pediatric renal transplant patients receiving SRL + CNI. SRL was dosed to achieve target trough levels between 10 and 20 ng/mL. We performed 49 SRL PK profiles in pediatric renal transplant recipients receiving SRL in combination with either cyclosporine (CsA; 25 profiles), or tacrolimus (TCL; 24 profiles). Ten of the SRL + TCL profiles were obtained from children receiving SRL on a b.i.d. dosing regimen. All other SRL profiles were q.d. regimens. We calculated, the maximum concentration (C(max)), AUC, apparent clearance (aCL; dose/AUC) for dose in mg/m(2), and mean residence time (MRT). SRL levels were measured at 6 and 7 time points for b.i.d. and q.d. dosing, respectively. Regression analysis of SRL trough values vs. AUC showed good correlation in the SRL q.d. + CsA, SRL q.d. + TCL, and SRL b.i.d. + TCL groups (r(2) = 0.95, 0.68, and 0.44, respectively). SRL aCL corrected for body surface area was higher in children aged 0-5 yr receiving SRL with either CsA or TCL. SRL dosing schedule should be tailored to each patient. Higher SRL aCL may be present in younger children when administered with CNI.

Adolescent↗
PubMed2005

A randomized multicenter trial of OKT3 mAbs induction compared with intravenous cyclosporine in pediatric renal transplantation.

Acute rejection leading to renal graft failure is more frequent among children. In patients treated with T cell antibody induction, retrospective data from the pediatric registry show a 22% reduction in the risk of graft failure. We conducted a randomized trial (n = 287) using OKT3 mAbs in one (OKT3) arm and intravenous cyclosporine in the other arm (CYS). Maintenance therapy consisted of randomized, double blind Sandimmune or Neoral together with prednisone and either azathioprine (AZA) or mycophenolate mofetil (MMF). Morbidity, mortality, rejection rates and adverse reactions in the two study arms were similar. Through 4 yr, graft failure was 27% in OKT3 and 19% in CYS (p = 0.15). One-year graft survival was 89.1% in OKT3 and 89.2% in CYS (p = .19). In multivariate analysis, OKT3 had a numerically inferior graft survival (RR = 1.4, CI 0.8-2.2, p = 0.22). In OKT3 graft survival was inferior for children aged 6 yr or younger. Our trial demonstrates that the incidence of acute rejection or graft failure in pediatric patients is not improved by OKT3 induction therapy relative to cyclosporine induction.

Adolescent↗
PubMed2005

Outcome of renal transplantation for Wilms' tumor and Denys-Drash syndrome: a report of the North American Pediatric Renal Transplant Cooperative Study.

In some children with bilateral Wilms' tumor, reduction of tumor burden cannot be accomplished without total nephrectomy. In Denys-Drash syndrome, nephrectomy is required for associated Wilms' tumor or after progression to end stage renal disease secondary to diffuse mesangial sclerosis because of risk of development of Wilms' tumor. Current recommendation is to wait at least 1-2 yr after completion of chemotherapy for Wilms' tumor before renal transplantation. The North American Pediatric Renal Transplant Cooperative Study dialysis (1992-2001) and transplant registries (1987-2002) were analyzed, comparing children 0-18 yr old with Wilms' tumor and Denys-Drash syndrome to other primary diagnoses. There were 37 children with Wilms' tumor and 33 with Denys-Drash syndrome in the dialysis registry. Of these, 10 children with Wilms' tumor and three with Denys-Drash syndrome did not receive a renal transplant and all died. The cause of death was Wilms' tumor in eight children with Wilms' tumor and in one with Denys-Drash syndrome. The transplant registry included 43 children with Wilms' tumor, 43 children with Denys-Drash syndrome, and 7469 patients with other diagnoses. Acute rejection, graft and patient survival profiles from all three groups at 6 months, 1 and 3 yr post-transplant were comparable. There were no graft failures or deaths because of recurrent Wilms' tumor in the Drash group. There was one death with Wilms' tumor in the Wilms' group - a 2.5-yr-old child transplanted after 6 months of dialysis who died of Wilms' <6 months after renal transplantation. In conclusion, most children dialyzed because of Wilms' tumor and Denys-Drash syndrome who did not receive a renal transplant died of Wilms' tumor. However, the outcomes of children with Wilms' tumor and Denys-Drash syndrome who proceeded to renal transplantation are comparable with children with other diagnoses, with no graft failures because of recurrence and only one death from Wilms' tumor in a Wilms' patient who received only a short course of dialysis prior to transplantation. Current practices in children with Wilms' tumor and Denys-Drash syndrome appear to be on target to portend good outcome following renal transplantation.

Adolescent↗
PubMed2005

Pediatric transplantation, 1994-2003.

This article uses OPTN/SRTR data to review trends in pediatric transplantation over the last decade. In 2003, children younger than 18 made up 3% of the 82,885 candidates for organ transplantation and 7% of the 25,469 organ transplant recipients. Children accounted for 14% of the 6,455 deceased organ donors. Pediatric organ transplant recipients differ from their adult counterparts in several important aspects, including the underlying etiology of organ failure, the complexity of the surgical procedures, the pharmacokinetic properties of common immunosuppressants, the immune response following transplantation, the number and degree of comorbid conditions, and the susceptibility to post-transplant complications, especially infectious diseases. Specialized pediatric organ transplant programs have been developed to address these special problems. The transplant community has responded to the particular needs of children and has provided them special consideration in the allocation of deceased donor organs. As a result of these programs and protocols, children are now frequently the most successful recipients of organ transplantation; their outcomes following kidney, liver, and heart transplantation rank among the best. This article demonstrates that substantial improvement is needed in several areas: adolescent outcomes, outcomes following intestine transplants, and waiting list mortality among pediatric heart and lung candidates.

Adolescent↗
PubMed2004

Post-transplant infections now exceed acute rejection as cause for hospitalization: a report of the NAPRTCS.

Newer immunosuppressive agents have dramatically reduced the rates of acute graft rejection (AR) over the last decade but may have exacerbated the problem of post-transplant infections (PTI). We analyzed data from the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) to determine the risks of hospitalization from PTI vs. AR in the years 1987-2000. For patients transplanted in 1987, the AR-associated hospitalization rate exceeded the equivalent hospitalization rate for PTI at both early (1-6 months) and later time points (6-24 months). In contrast, for patients transplanted in the year 2000, the PTI-associated hospitalization rate was twice that for AR-associated hospitalization during each time period. During the first two years post-transplant, rates of AR hospitalization trended significantly downwards (p < 0.001) while rates of PTI-associated hospitalization stayed constant. In the 6-24-month time period post-transplant, the risk of bacterial and viral infection-related hospitalization rose significantly from 1987 to 2000 (p < 0.001 for trend by transplant year). We conclude that the causes of hospitalization at all times up to 24 months post-transplant, including the critical early 6 months, have shifted away from AR to PTI.

Child↗
PubMed2004

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.

Age Distribution↗
PubMed2003

Pretransplant peritoneal dialysis and graft thrombosis following pediatric kidney transplantation: a NAPRTCS report.

Graft thrombosis is a common cause of graft failure in pediatric renal transplantation. Several previous studies, including a North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) review of pretransplant dialysis status and graft outcomes, have described a potential correlation of peritoneal dialysis (PD) and graft thrombosis. This issue is of particular concern for pediatric transplant programs as more than 65% of children with end stage renal disease are treated with PD. We reviewed 7247 pediatric renal transplants performed between 1987 and 2001. Thrombosis was the cause of graft loss in 2.7% (199) of all the transplants performed. Among failed transplants, thrombosis was the third most common cause of graft loss in both index (11.6%) and subsequent transplants (14.5%). Thrombosis becomes the most common cause of graft failure (21%, 61/294) if one looks at transplants in the later cohort, from 1996 to 2001. This change is primarily because of a decrease in the incidence of acute rejection. In the PD group, 3.4% of all grafts were lost as a result of thrombosis. This compares with 1.9% in the hemodialysis group, 2.4% in the pre-emptive transplant group, and 4.1% among patients who received both dialysis modalities. There was a statistically significant difference in thrombosis failure risk in the different dialysis groups (p = 0.005) with those who received only peritoneal dialysis having the highest risk. Additional significant risk factors for graft thrombosis included; cadaver donor source (p < 0.001), cold ischemia time >24 h (p < 0.001), history of prior transplant (p < 0.001), donor age <6 yr (p < 0.001), and >5 pretransplant blood transfusions (p = 0.02). Using stepwise proportional hazards modeling, only pretransplant peritoneal dialysis, >24 h cold ischemia time, prior transplant, and donor age <6 yr were simultaneously associated with an increased risk of thrombosis. We conclude that pretransplant PD is associated with an increased risk of graft thrombosis. Special precautions should be undertaken in pediatric renal transplant patients who have received PD, especially infants and young children.

Child↗
PubMed2003

The report of a national conference on the wait list for kidney transplantation.

In March, 2002, over 100 members of the transplant community assembled in Philadelphia for a meeting designed to address problems associated with the growing number of patients seeking kidney transplantation and added to the waiting list each year. The meeting included representatives of nine US organizations with interests in these issues. Participants divided into work groups addressing access to the waiting list, assigning priority on the list, list management, and identifying appropriate candidates for expanded criteria donor kidneys. Each work group outlined problems and potential remedies within each area. This report summarized the issues and recommendations regarding the waiting list for kidney transplantation addressed in the Philadelphia meeting.

Congresses as Topic↗
PubMed2003

Regulatory CD25+ T cells in human kidney transplant recipients.

Recent evidence suggests that a population of professional regulatory cells, which limit immune responsiveness, exist in rodents and healthy human subjects. However, their role in disease states remains unclear. A proportion of renal transplant recipients do not demonstrate in vitro reactivity toward their mismatched donor-derived HLA-DR antigens; it was therefore hypothesized that this may be due to such regulatory cells. A cohort of 23 renal transplant recipients was studied at a single institution. In patients with no history of acute rejection, 6 (40%) of 15 demonstrated regulation toward the mismatched HLA-DR allopeptides by CD25(+) cells. By contrast, only one (12.5%) in eight of those with a history of acute rejection demonstrated regulation. Interestingly, if the patient assays were stratified according to initial in vitro immune responsiveness toward the mismatched allopeptides, 8 (47.1%) of 17 of patient assays with low allopeptide responsiveness (alloreactive T cell frequencies less than 60/million) demonstrated regulation of indirect pathway alloresponses by CD25(+) cells, whereas 0 of 8 with higher responses (frequencies greater than 60/million) demonstrated no such regulation (P < 0.05 by chi(2) test). The regulatory cells are present in the circulation as early as 3 mo after transplantation and persist for a number of years, despite conventional immunosuppression. Furthermore, induction treatment with anti-IL-2R mAb did not prevent the development of these regulatory CD25(+) cells. Data from two patients suggest that these cells may also play a role in preventing epitope shifting, implicated in the ongoing immune activation contributing to chronic rejection, and that loss of regulation in a given patient may precede an episode of rejection.

Adult↗
PubMed2002

Utility of hemodialysis in maple syrup urine disease.

Maple syrup urine disease (MSUD) is an inborn error of metabolism stemming from a deficiency in 2-ketoacid dehydrogenase and resulting in the systemic accumulation of branched chain amino acids (BCAAs). Affected children may suffer profound developmental and cognitive impairment from exposure to high levels of BCAA and their associated neurotoxic metabolites. Endogenous renal clearance of BCAA is limited and several therapeutic modalities including intensive nutritional regimens, exchange transfusions, peritoneal dialysis, and continuous hemofiltration have been utilized in neonates with MSUD, all of which have had varying success in reducing systemic BCAA levels. In this report, a symptomatic 7-day-old 3-kg neonate with MSUD underwent treatment with a combination of early hemodialysis and aggressive enteral feedings of a metabolically appropriate formula. This approach results in a 75% reduction of systemic toxin levels within 3 h. When compared to other reported modalities of therapy for symptomatic neonates with MSUD, this approach appears to be most efficacious. Moreover, by minimizing the amount of time that an affected neonate is exposed to neurotoxic levels of BCAAs, long-term developmental and cognitive capabilities may be preserved.

Amino Acids, Branched-Chain↗
PubMed2002

Mycophenolate, tacrolimus and post-transplant lymphoproliferative disorder: a report of the North American Pediatric Renal Transplant Cooperative Study.

Tacrolimus (FK506) and mycophenolate mofetil (MMF) have been reported to increase PTLD risk. The NAPRTCS registry database now has several years of data on FK506 and MMF use in pediatric kidney transplantation. We analyzed the data registry to determine if the risk of PTLD was enhanced by the use of MMF or tacrolimus in initial immunosuppression. Data on day 30 therapy in the PTLD group were compared to corresponding data in patients who did not develop PTLD. Data were analyzed using SAS software and a log-rank test for significance. As of October 2000, there were 108 cases of PTLD in 6720 total transplants(1.60%). The use of MMF at day 30 was not a significant risk factor (0. 78% PTLD rate vs. 1.78% in cohort, RR = 1.05, p = 0.89). The relationship of FK506 with PTLD was linked to transplant era, 1987-95 or 1996-2000. In the earlier era, use of FK506 at day 30 was associated with PTLD (seen in 7/15 patients given FK506, RR = 47.7, p < 0.001). However, in the more recent era, there was no such significant association (seen in 3/313 patients given FK506, RR = 1.28, p = 0.692). There have been no cases of PTLD in 197 patients who received both FK506 and MMF at day 30. We conclude that FK506 and MMF use are not currently associated with increased risk of PTLD in pediatric kidney transplants.

Female↗
PubMed2002

The use of a minor as a live kidney donor.

An analysis of the UNOS database suggests a practice pattern that uses live minor kidney donors in clinical circumstances not endorsed by the recommendations of a recent consensus conference on live organ donation. These data reveal that minor donor kidneys were transplanted more frequently to adult than to pediatric recipients, that only 12% of all recipients were identical twins, and that the use of a minor donor provided no better outcome than that expected from an adult donor. Live organ donation from a minor should only be considered when there is no other living donor available and all other opportunities for transplantation have been exhausted.

Adolescent↗
PubMed2002

Post-transplant lymphoproliferative disorder in the United States: young Caucasian males are at highest risk.

We have previously documented Caucasian race and cadaver donor source as risk factors for post-transplant lymphoproliferative disorder (PTLD) development in recipients registered in the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS). We analyzed data from the Scientific Registry of the United Network of Organ Sharing (UNOS) (from January 1988 to December 1999) to determine risk factors for the development of PTLD in all organ systems and its frequency, and we compared these factors to the risk factors in the most recent NAPRTCS database (1987-2000). In the UNOS database, PTLD was reported in 2365 of 205114 organ-transplant recipients (1.2%). PTLD was reported in 3% or more of all intestinal and thoracic organ recipients, but in less than 1% of other abdominal organ recipients. Recipient age < 18 years, Caucasian race and male gender were independent risk factors [Odds Ratios (OR) 2.81, 2.22 and 1.40, respectively, p = 0.0001], but not cadaver donor source. The combination of all three risk factors increased the OR to 8.78. The occurrence of PTLD showed a significant rise per year for heart-lung, kidney, kidney-pancreas and liver transplants, but decreased significantly for heart transplants (p < 0.001). Similar frequencies of PTLD were found in smaller organ-specific registries of heart, intestine, pediatric liver and pediatric kidney transplants. The PTLD incidence per year and incidence density have increased in recent years. Young Caucasian males are at highest risk for PTLD development among solid-organ-transplant recipients. The incidence of PTLD is increasing.

Age Factors↗