Increased intracranial pressure in a patient with Congenital Heart Defect and Ectodermal Dysplasia (CHDED): Extension of phenotype and review of literature

Congenital heart defect (CHD) is a birth defect that affects the structure of the heart. Although CHD is often multifactorial, it can also be inherited as part of a Mendelian disorder such as in congenital heart defect and ectodermal dysplasia (CHDED). This disorder is caused by de novo variants in PRKD1. Here, we describe a patient with a novel de novo variant of PRKD1 with phenotypic features consistent with CHDED. Previously unreported features were noted including high intracranial pressure (ICP), partial anomalous pulmonary venous return (PAPVR), and bifid uvula. We suggest that these features may be associated with CHDED.

Oral Losartan After Limited Mandibulectomy for Treatment of Desmoid-Type Fibromatosis

Desmoid-type fibromatosis (DF) is a rare soft tissue lesion with an annual incidence of 2 to 4 per million population and peak incidence occurring at approximately 4.5 years of age. While benign, the tumor has a locally aggressive infiltrative growth pattern and a high rate of recurrence. Given the functional and aesthetic implications of excision and reconstruction in the facial skeleton, novel medical treatment options are highly desirable. We describe the case of a 3-year-old boy who presented with an enlarging, asymptomatic mass involving the left mandible. Biopsy revealed an immunohistochemical profile consistent with DF. Despite the high likelihood of recurrence, conservative, mandible-sparing en bloc resection and limited mandibulectomy were performed. Pathological and immunohistochemical analysis of the resection specimen revealed DF with grossly positive margins and elevated expression of angiotensin II type 1 receptor. Postoperative medical treatment with the angiotensin receptor blocker losartan was initiated. The patient remains medically stable and disease progression-free on repeat imaging at 20 months post-resection. We describe for the first time the successful use of the angiotensin blocker losartan following conservative surgery for management of DF.

Optimal Sequencing of Deceased Donor and Live Donor Kidney Transplant Among Pediatric Patients With Kidney Failure

IMPORTANCE

In the US, live donor (LD) kidney transplant rates have decreased in pediatric recipients. Pediatric patients with kidney failure will likely need more than 1 kidney transplant during their lifetime, but the optimal sequence of transplant (ie, deceased donor [DD] followed by LD or vice versa) is not known.

OBJECTIVE

To determine whether pediatric recipients should first receive a DD allograft followed by an LD allograft (DD-LD sequence) or an LD allograft followed by a DD allograft (LD-DD sequence).

DESIGN, SETTING, AND PARTICIPANTS

This decision analytical model examined US pediatric patients with kidney failure included in the US Renal Data System 2019 Report who were waiting for a kidney transplant, received a transplant, or experienced graft failure.

INTERVENTIONS

Kidney transplant sequences of LD-DD vs DD-LD.

MAIN OUTCOMES AND MEASURES

Difference in projected life-years between the 2 sequence options.

RESULTS

Among patients included in the analysis, the LD-DD sequence provided more net life-years in those 5 years of age (1.82 [95% CI, 0.87-2.77]) and 20 years of age (2.23 [95% CI, 1.31-3.15]) compared with the DD-LD sequence. The net outcomes in patients 10 years of age (0.36 [95% CI, -0.51 to 1.23] additional life-years) and 15 years of age (0.64 [95% CI, -0.15 to 1.39] additional life-years) were not significantly different. However, for those aged 10 years, an LD-DD sequence was favored if eligibility for a second transplant was low (2.09 [95% CI, 1.20-2.98] additional life-years) or if the LD was no longer available (2.32 [95% CI, 1.52-3.12] additional life-years). For those aged 15 years, the LD-DD sequence was favored if the eligibility for a second transplant was low (1.84 [95% CI, 0.96-2.72] additional life-years) or if the LD was no longer available (2.49 [95% CI, 1.77-3.27] additional life-years). Access to multiple DD transplants did not compensate for missing the LD opportunity.

CONCLUSIONS AND RELEVANCE

These findings suggest that the decreased use of LD kidney transplants in pediatric recipients during the past 2 decades should be scrutinized. Given the uncertainty of future recipient eligibility for retransplant and future availability of an LD transplant, the LD-DD sequence is likely the better option. This strategy of an LD transplant first would not only benefit pediatric recipients but allow DD kidneys to be used by others who do not have an LD option.

Canadian Society of Nephrology Commentary on the Kidney Disease Improving Global Outcomes 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder

Purpose of review:

(1) To provide commentary on the 2017 update to the Kidney Disease Improving Global Outcomes (KDIGO) 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD); (2) to apply the evidence-based guideline update for implementation within the Canadian health care system; (3) to provide comment on the care of children with chronic kidney disease (CKD); and (4) to identify research priorities for Canadian patients.

Sources of information:

The KDIGO 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of CKD-MBD.

Methods:

The commentary committee co-chairs selected potential members based on their knowledge of the Canadian kidney community, aiming for wide representation from relevant disciplines, academic and community centers, and different geographical regions.

Key findings:

We agreed with many of the recommendations in the clinical practice guideline on the diagnosis, evaluation, prevention, and treatment of CKD-MBD. However, based on the uncommon occurrence of abnormalities in calcium and phosphate and the low likelihood of severe abnormalities in parathyroid hormone (PTH), we recommend against screening and monitoring levels of calcium, phosphate, PTH, and alkaline phosphatase in adults with CKD G3. We suggest and recommend monitoring these parameters in adults with CKD G4 and G5, respectively. In children, we agree that monitoring for CKD-MBD should begin in CKD G2, but we suggest measuring ionized calcium, rather than total calcium or calcium adjusted for albumin. With regard to vitamin D, we suggest against routine screening for vitamin D deficiency in adults with CKD G3-G5 and G1T-G5T and suggest following population health recommendations for adequate vitamin D intake. We recommend that the measurement and management of bone mineral density (BMD) be according to general population guidelines in CKD G3 and G3T, but we suggest against routine BMD testing in CKD G4-G5, CKD G4T-5T, and in children with CKD. Based on insufficient data, we also recommend against routine bone biopsy in clinical practice for adults with CKD or CKD-T, or in children with CKD, although we consider it an important research tool.

Limitations:

The committee relied on the evidence summaries produced by KDIGO. The CSN committee did not replicate or update the systematic reviews.

Natural killer cell response to BK virus infection in polyoma virus-associated nephropathy of renal transplant recipients

The mechanisms of injury and advantage secured by opportunistic infection with polyoma virus in renal transplant patients are not completely known. Patient virus-specific T cells play a large role in elimination of reactivated polyoma virus. Natural killer (NK) cells are early responders in antiviral response. Inflammatory NK-cell antiviral responses involve activation receptors such as killer-cell immunoglobulin-like receptors (KIRs) interacting with host-cell major histocompatibility complex class I molecules, altering cell sensitivity to lysis by NK cells.

In vitro effect of cyclosporin A on primary and chronic BK polyoma virus infection in Vero E6 cells

Cyclosporin A (CsA) is known to possess antiviral activity against several viruses in vitro, but the effect of CsA on BK polyoma virus (BKV) replication has not been examined. We investigated the impact of CsA on primary, chronic, and high-level BKV infection using a cell system of kidney cell origin (Vero E6 cells). During the first 2 h post infection, cells treated with CsA up to 3200 microg/L showed a near-identical BK viral load to untreated cells, with only a very minor reduction in the CsA-treated cells observed at 4 h. In chronic culture, CsA completely suppressed the primary BKV infection peak in a non-dose-dependent manner within the dose range of 200-12,800 microg/L (P<0.05). BKV reactivation was also inhibited in the presence of CsA at doses of 200-3200 microg/L: the mean number of BKV DNA copies/mL remained stable or even decreased slightly compared with a 7-log increase in the non-CsA group (P<0.01). CsA did not influence BKV DNA copies/mL in Vero E6 cells with high-level infection (>10(9) copies/mL). Cellular protein measurements indicated that the antiviral effect of CsA was not a result of cytotoxicity. These findings from a relevant in vitro kidney cell system indicate that CsA suppresses the primary BKV infection peak and inhibits escape to BKV reactivation; these effects are dose independent and not related to cytotoxicity. The intracellular antiviral mode of action of CsA against BKV does not appear to be via inhibition of viral cell entry pathways.

Two formulations of the agricultural pesticide adjuvant, Toximul, reduce the glycogen content of HepG2 cells

Young mice exposed dermally to the Toximul (Tox) class of agricultural pesticide adjuvants have reduced levels of hepatic glycogen, a marker of subclinical toxicity. The present study determined whether these effects on glycogen also occurred in cultured HepG2 cells. Exposure (3 hr) to Tox resulted in significant, concentration-dependent glycogen reductions (up to 70%) relative to control values (76 +/- 3 microg glycogen/mg protein). These reductions did not appear to be due to loss of cell viability, and were reversible with Tox removal. Two different formulations of Tox (3409F and MP-A) differed significantly in the magnitudes of glycogen reduction in the HepG2 cells.

BK virus infection, replication, and diseases in pediatric kidney transplantation

Polyomavirus-associated nephropathy is diagnosed in 2-8% of pediatric renal transplants and often precedes renal allograft dysfunction. Without intervention, however, significant graft dysfunction is observed in more than 50% of cases, although progressive early graft loss is reported in only three of 32 (9%) of cases. No specific treatment is available, but early decrease in immunosuppression is followed by declining human polyomavirus type 1 (BK virus) replication and improved outcome. The data suggest differences between pediatric and adult kidney transplantation. Possibly, pediatric patients might be able to mount a more vigorous BK virus-specific immune response than adult patients under similar modulation of immunosuppression. Also the role of cidofovir and leflunomide is still unresolved in pediatric patients. Larger prospective trials are needed to better define the impact of BK virus immunity for replication and disease as well as the role of reducing immunosuppression with or without cidofovir or leflunomide in pediatric transplant patients.

The pesticide adjuvant, Toximul™, alters hepatic metabolism through effects on downstream targets of PPARα

Previous studies demonstrated that chronic dermal exposure to the pesticide adjuvant (surfactant), Toximul (Tox), has significant detrimental effects on hepatic lipid metabolism. This study demonstrated that young mice dermally exposed to Tox for 12 days have significant increases in expression of peroxisomal acyl-CoA oxidase (mRNA and protein), bifunctional enzyme (mRNA) and thiolase (mRNA), as well as the P450 oxidizing enzymes Cyp4A10 and Cyp4A14 (mRNA and protein). Tox produced a similar pattern of increases in wild type adult female mice but did not induce these responses in PPARalpha-null mice. These data support the hypothesis that Tox, a heterogeneous blend of nonionic and anionic surfactants, modulates hepatic metabolism at least in part through activation of PPARalpha. Notably, all three groups of Tox-treated mice had increased relative liver weights due to significant accumulation of lipid. This could be endogenous in nature and/or a component(s) of Tox or a metabolite thereof. The ability of Tox and other hydrocarbon pollutants to induce fatty liver despite being PPARalpha agonists indicates a novel consequence of exposure to this class of chemicals, and may provide a new understanding of fatty liver in populations with industrial exposure.

Carnitine, acylcarnitine and amino acid profiles analyzed by tandem mass spectrometry in a surfactant/virus mouse model of acute hepatic encephalopathy

Tandem mass spectrometry (MS/MS) was used to analyze multiple serum metabolites for the first time in a surfactant/virus mouse model of acute hepatic encephalopathy (AHE). AHE is characterized by acute liver failure that can lead to potentially lethal increases in intracranial pressure. We have reproduced AHE in young CD-1 mice exposed from postnatal day (P) 2-13 to the industrial surfactant, Toximul 3409F (Tox), and then infected intranasally on P14 with sublethal doses (LD(10-30)) of mouse-adapted human influenza B (Lee) virus (FluB). The sera analyzed by MS/MS were from mice exhibiting typical markers of Tox-mediated potentiation of viral illness, including reduced weights and blood glucose levels. Most metabolite abnormalities were not evident until five days after viral infection (P19), the time corresponding to the onset of weight loss and mortality. Values for fatty acylcarnitines and amino acids in the Tox+FluB-treated mice were either additive or supra-additive relative to the effects of either treatment alone. Amino acid profiles were consistent with those reported for human AHE. None of the treated mice exhibited signs of carnitine deficiency, and propionylcarnitine levels were normal. On P19, mice given combined Tox+FluB treatment had significant increases in levels of both medium- and long-chain acylcarnitines (C6:0-C12:0 and C14:0-C20:0, respectively), including their monounsaturated metabolites. Levels of medium-chain dicarboxylic and long-chain hydroxy-acylcarnitines were also elevated in the combined treatment group. The results of this study indicate a diffuse mitochondrial dysfunction in Tox+FluB-treated mice that results in a serum metabolite profile unique from those observed in classic inherited metabolic disorders.

Utilization of vero cells for primary and chronic BK virus infection

BK virus (BKV) nephropathy has a poor prognosis for renal allograft survival with 30% to 60% risk of allograft loss over 1 year. In the past decade, BKV nephropathy has occurred in 1% to 10% of renal transplant patients, with higher rates observed in patients with increased immunosuppression exposure and renal allograft injury. Vero cells (Green monkey kidney cell origin) were optimized for BKV primary and chronic infection inclusive of culture requirements for 60-day growth and monolayer confluence. Quantification of BKV replication in the culture supernatant (SN) and cells was by real-time polymerase-chain reaction (PCR) using the Roche Lightcycler 2.0. Primary BKV infection of Vero cells is achieved by 2 hour incubation with 6.5 x 10(5) BKV copies with subsequent washing of cells leading to steady-state cellular infection of 10(2) to 10(3) BKV copies. Primary infection is demonstrated within 7 to 10 days by a >10-fold increase of BKV copies in SN. Thereafter, a BKV viral load reduction in SN to a chronic/latent level (<10(2) BKV copies in SN) is observed by 14 days. Vero cells with chronic low-level BKV infection (10(2)-10(3) BKV copies in cells) exhibited reactivation (>10(5) BKV copies in SN) in >72% of late culture wells after 40 days. Vero cells can accommodate primary and chronic BKV infection followed by viral reactivation in late culture. The performance characteristics of 3 different pathogenic BKV strains obtained from patients with BKV nephropathy had infectivity profiles that correlated well the relative clinical profile in this Vero cell culture system.

Evaluation of performance factors affecting two formulations of cyclosporine in pediatric renal transplant patients

Success of renal transplantation in children is largely due to improvements in immunosuppressant therapy since the introduction of calcineurin inhibitors. The aim of this study was to identify possible factors that result in formulation differences in the exposure of pediatric patients to cyclosporine (CsA). We examined the handling of the two major formulations of CsA in a group of pediatric renal transplant recipients. The pharmacokinetic profiles of both formulations were assessed, and the data stratified to assess the effects of age, gender, time posttransplant, and other concomitant drug therapy on the two CsA formulations. The microemulsified formulation (MEC) enhanced bioavailability compared to the older oil-based formulation (CYA), especially at C2, with more predictable and consistent absorption in children. This higher bioavailability allowed a 15% reduction of dosing to achieve equal drug exposure. The concentration achieved by MEC at C2 demonstrated a much higher correlation with area under the concentration curve (AUC) than the concentration at C0. In the case of CYA a strong correlation was obtained between AUC and the concentrations obtained at both C0 and C2. Calcium channel blockers increased AUC(0-8) for both CsA formulations. Norfloxacin and pravastatin cotreatment had no effect on either of the CsA formulations. In contrast, the bioavailability of CsA was increased in boys using MEC formulation but this gender-based difference was absent during the use of CYA. This suggests that caution is required for introduction of new formulations of drugs to pediatric patients to evaluate differential effects of age, gender, and concomitant drug therapy.

Polyoma virus in pediatric renal transplantation

Renal transplantation is the treatment of choice for children with end-stage renal disease. Patient survival and allograft survival have improved with better immunosuppressant regimes to reduce acute allograft rejection but post-transplant infections have been exacerbated. An emerging problematic virus in the past decade is the polyoma virus BKV. The features of BKV including the clinical features in the general and immune compromised population are reviewed and correlated with pediatric studies in the post-transplant population. These features are placed in context with lessons learned about BKV in relevant adult studies.

Pamidronate distribution in pediatric renal and rheumatologic patients

OBJECTIVE

To evaluate the distribution and elimination of pamidronate in a population of pediatric patients with renal and rheumatologic disease.

METHODS

Pamidronate whole blood levels were collected for the first 4 h after first exposure in 7 patients. The relationship between the rate of urinary excretion of pamidronate and bone formation or resorption was examined in 18 patients while receiving pamidronate at a total dose of 1 mg/kg/dose infused intravenously over a 4-h period. The urinary pamidronate clearances were correlated with renal function, calcium levels and measures of bone formation and resorption.

RESULTS

Pamidronate levels reached steady state concentrations of 0.9-1.5 microg/ml within 30 min and the clearance of the drug (mean+/-SE) from blood was 180.0+/-64.2 ml/kg/h with an elimination half-life of less than 1 h. The mean urinary excretion of 31.5+/-2.2% of the administered dose indicated that about 68% of the drug was incorporated into bone, confirming the uptake of pamidronate into bone was similar in pediatric patients compared to that previously reported for adults. Bone specific alkaline phosphatase, which is a marker for bone growth and formation, had significant correlation with the uptake of pamidronate into bone (p=0.002). No correlation was demonstrated with a marker for bone resorption (urinary N-telopeptide/creatinine ratio), or with creatinine clearance or calciuria when assessed 2 months after treatment.

CONCLUSION

Pamidronate at a dose of 1 mg/kg/dose every 2 months appears safe in the short term for pediatric patients, achieves relatively low whole blood pamidronate levels, and has similar skeletal uptake of pamidronate compared to adults.

BK virus nephropathy in a heart transplant recipient: case report and review of the literature

The human polyomavirus BK virus (BKV) remains latent in the urinary tract and may be reactivated in immunocompromised states. BKV is noted to be the etiologic agent of polyomavirus-associated nephropathy (PVAN), which is a significant cause of allograft failure in renal transplant patients. Renal dysfunction following non-renal solid organ transplantation is common and is typically attributed to drug toxicity or patient comorbidities. In this article we describe a case of PVAN in the native kidneys of a heart transplant recipient and review the literature. Although this is only the fourth case reported, BKV nephropathy should be considered in the differential diagnosis of new renal failure following non-kidney solid organ transplantation, as early diagnosis of PVAN is necessary to prevent irreversible renal damage.

Brain cyclosporin A levels are determined by ontogenic regulation of mdr1a expression

Cyclosporin A (CyA) toxicity is a common occurrence in pediatric organ transplant patients. We hypothesized that reduced mdr1a expression in newborn and developing mice would affect CyA accumulation within organs and/or toxicity. For functional studies, CyA was administered (5 mg kg(-1) i.p.) to 1-, 12-, and 19-day, and adult male and female mdr1a+/+ and mdr1a-/- mice. Peak blood CyA was lower in 1-, 12-, and 19-day-old (1000 ng ml(-1)) versus adult (1500 ng ml(-1)) mice but was similar in mdr1a+/+ and mdr1a-/- mice. Kidney mdr1a expression (measured by quantitative polymerase chain reaction) increased 2.5-fold in 19-day-old male and female mice and increased another 4-fold in adult females compared with adult males. Liver mdr1a expression increased 6-fold by day 12 compared with neonatal mice. Thereafter, maintenance of hepatic mdr1a expression in females and a reduction to neonatal levels in males was observed. Kidney/blood (8- to 9-fold) and liver/blood (12- to 15-fold) CyA levels were highest on days 12 and 19 and were not dependent on maturational changes in mdr1a mRNA levels. Adults had higher brain expression of mdr1a mRNA (3-fold), a corresponding 5-fold increase in immunodetectable P-glycoprotein, and 80% lower brain accumulation of CyA compared with 1-day-old mice. Conversely, in mdr1a-null mice, brain/blood CyA was similar in newborn and adult mice. A similar pattern was observed for the brain accumulation of the mdr1a substrate 3H-digoxin. We conclude that the risk for central nervous system drug toxicity could be higher in neonates or young children as a consequence of underdeveloped P-glycoprotein.

Two formulations of the industrial surfactant, Toximul, differentially reduce mouse weight gain and hepatic glycogen in vivo during early development: effects of exposure to Influenza B Virus

Previous studies demonstrated that young mice exposed chronically to industrial surfactant (IS) do not exhibit obvious adverse health effects, but do have persistently reduced body weights and compromised hepatic energy metabolism. The present study examined the time course of effects of two formulations of the Toximul (Tox) class of anionic/nonionic IS on body weights and liver glycogen (+/-virus) during early development. Results showed that effects differed in two commonly used strains of mice. In CFW mice, 12 days' exposure to Tox resulted in retardation of weight gain that was most obvious several days after exposure ceased. In this strain effects were greater with Tox 3409F than with Tox MP-A and appeared to be reversible except when the mice were treated with both Tox 3409F and FluB. Weights of the CD-1 mice were not affected by either Tox treatment alone, but were significantly reduced on postnatal day 20 when Tox exposure had been combined with FluB infection. Postnatal replenishment of hepatic glycogen stores during the first three weeks also occurred at different rates in CFW and CD-1 mice. The effects of Tox (+/-FluB) on glycogen also varied with mouse strain and Tox formulation. In CFW mice, exposure to either formulation resulted in significant (55-59%) reductions in glycogen, although reductions were not evident until nine days after Tox exposure stopped. By contrast, hepatic glycogen in CD-1 mice was reduced both during and after dermal exposure to Tox 3409F, whereas no effect was observed with Tox MP-A. Notably, the 3409F effect was reversible in the CD-1 mice, but reversal did not occur in mice also infected with FluB. Tox MP-A+FluB-treated mice exhibited only a transient glycogen reduction. These results illustrate the importance of mouse strain and formulation specificities in assessing biological effects of xenobiotic surfactants. As well, they emphasize that chronic IS exposure can induce changes in growth and energy substrate availability in young mice that may not be evident unless there is a precipitating cofactor such as a viral infection.

Pamidronate treatment of pediatric fracture patients on chronic steroid therapy

Pediatric nephrology and rheumatology patients with steroid-induced osteopenia are at risk of skeletal fracture. Bisphosphonate therapy has not been routinely advocated as a primary or secondary intervention for steroid-associated fractures in this population. This case control study evaluates the role of pamidronate therapy as a secondary fracture intervention. Children with symptomatic pathological fractures of the axial spine or ribs were treated with pamidronate 1 mg/kg/dose (n=17) IV at 60-day intervals for 1 yr (n=15) or 2 yr (n=2). Bone mineral density of L1-L4 (BMD) was assessed prior to treatment and at six-month intervals, and compared to 17 disease-age-gender-steroid dose-matched control patients. Alkaline phosphatase, calcium, phosphate, PTH, renal biochemistry, and 24-hr urine collections for CrCl, N-telopeptide/creatinine ratio, phosphate excretion, and calcium excretion were obtained every two months in the pamidronate population. Pamidronate caused a first exposure transient flu-like illness lasting <24 h in three patients and one patient had a new pathological fracture. No adverse events of hypocalcemia, allergic reaction or thrombophlebitis were noted. All patients reported improvement of skeletal pain. Despite ongoing steroid treatment, pamidronate significantly increased L1-L4 BMD Z-scores (mean+/-SE) relative to baseline (pamidronate vs control: 0-6 months: 0.27+/-0.14 vs -0.82+/-0.31; 0-12 months: 0.63+/-0.17 vs -0.46+/-0.27; 0-18 months: 0.55+/-0.32 vs 0.17+/-0.27; 0-24 months: 0.15+/-0.21 vs -0.23+/-0.22; 0-30 or 36 months: 0.77+/-0.71 vs -0.68+/-0.25) with repeated measures ANOVA assessment (F=11.27, p=0.0057). This study supports the safety and efficacy of pamidronate in steroid-induced fractures in pediatric nephrology and rheumatology patients.

Paradoxical cyclosporine A requirements in pediatric renal transplants receiving high-dose steroids

The potent immunosuppressant cyclosporine A (CyA) is a mainstay of treatment in the renal transplant population. During episodes of acute allograft rejection, therapy also includes the pulse administration of high-dose steroids such as prednisone or methylprednisolone. Both steroids and CyA are metabolized by the CYP3A4 isoenzyme of the cytochrome P450 catalytic system. On a theoretical basis, high steroid concentrations during a rejection episode could competitively inhibit CyA metabolism, increasing its systemic concentration and decreasing its dose requirements. A database was compiled consisting of pediatric patients who had undergone an acute renal rejection event during the years 1993 to 2003. The severity of rejection events, as well as the CyA and prednisone dosing regimens used during rejection, were assessed using a comprehensive chart analysis. The presence or absence of additional medications that could potentially interact with CyA was also examined. Although some patients responded in the predicted manner, the authors also found that a subgroup of pediatric patients placed on highdose pulse steroid therapy for acute graft rejection required increased amounts of CyA to maintain therapeutic concentrations. The authors recommend monitoring of patients on high-dose steroids for paradoxical CyA requirements intermittently during high-dose steroid treatment to individualize CyA therapy appropriately during renal allograft rejection and thereby maximize efficacy while minimizing potential toxic side effects of CyA such as under-immunosuppression and organ rejection.

Third dose of basiliximab in pediatric renal transplantation

Antibody induction therapy is frequently used in pediatric renal transplantation to reduce risk of early rejection. We previously reported lower rates of human herpes virus type 6 (HHV-6) reactivation in patients receiving monoclonal antibody induction with basiliximab, compared to patients receiving antithymocyte globulin/antilymphocyte globulin treatment. Subclinical rejection events were still present in many patients in the first 6 months after transplantation. This prompted a third dose of basiliximab to be administered at day 21 in addition to the standard two doses given immediately prior to transplantation and on day 4. No significant reduction of subclinical rejections was noted in the 11 patients receiving triple dosing of basiliximab. Two patients developed an allergic reaction responsive to intravenous fluids, steroids, and antihistamines with full resolution within 30 minutes of administration. There was no increase in de novo infection or reactivation of HHV-6 or Epstein-Barr virus in this group compared to patients receiving two doses of basiliximab. The goal of reduction of early subclinical rejection events was not achieved with the third dosing of basiliximab in this initial group of pediatric renal transplant patients. However, 63.6% of patients receiving triple basiliximab remained free of clinical and/or subclinical rejection for the first 6 months posttransplant compared to only 36.4% remaining rejection-free for the same interval in the group who received the conventional two doses of basiliximab.

A comparison of the pharmacokinetics of tacrolimus and microemulsified cyclosporin in paediatric renal transplant recipients

OBJECTIVE

Our objective was to identify common factors that determine the dose of tacrolimus and microemulsified cyclosporin in paediatric renal transplant recipients.

METHODS

The concentration profiles of tacrolimus and cyclosporin in blood were determined in 68 children who had received a renal transplant. To avoid disruption of therapy, measurements were made at 2-h intervals over an 8-h period during normal dosing regimens. Direct comparisons of the two drugs were made in 14 of the subjects who were switched from cyclosporin to tacrolimus.

RESULTS

The ratio of peak to trough levels for tacrolimus was approximately twofold compared with over threefold for cyclosporin. Area under the curve (AUC) for tacrolimus remained relatively constant in each 2-h period of the dosage interval compared with the AUC for cyclosporin, which varied by over twofold in the same time period. In the 14 subjects who received both drugs, there was a poor correlation between C2/C0, C2, t(1/2) and AUC for tacrolimus and cyclosporin in the same individual. In a multivariate analysis, there were no significant associations for tacrolimus concentrations, AUC or C2/C0 with age, gender, calcium-channel blocker, quinolone or statin. For cyclosporin, there was some association for AUC with gender and quinolone use and a weak association with calcium-channel blocker or statin use.

CONCLUSIONS

Tacrolimus and microemulsified cyclosporin display a wide intra- and inter-individual variation in pharmacokinetic properties in young subjects. In the case of absorption represented by the peak-trough ratios, the values for tacrolimus are significantly less than those obtained with cyclosporin. The pharmacokinetic parameters obtained for one of these agents is not predictive for the behaviour of the other in young renal transplant recipients.

Effects of insulin-like growth factor-type 1 on weight gain and hepatic glycogen during early development in a surfactant/virus mouse model of acute liver failure: correlation with mortality

Acute liver failure (ALF) was reproduced in young mice exposed daily for 12 days to the industrial surfactant, Toximul 3409F (Tox), and infected on postnatal day (P) 14 with sublethal doses of mouse-adapted human influenza B (Lee) virus (FluB). Combined Tox + FluB treatment potentiated mortality due to non-necrotic ALF. This study tested the hypothesis that mortality would decline if the known losses in energy production due to compromised fatty-acid beta-oxidation were compensated by pharmacological manipulation of hepatic glycogen stores. Glycogen levels, body weights, and mortality were determined without and with injections of insulin-like growth factor-1 (IGF-1). On P25, 13 days after Tox exposure ceased, glycogen levels (mg/100mg) were: 4.0 (control), 1.7 (Tox), 4.3 (FluB), and 2.9 (Tox + FluB). Corresponding cumulative mortalities were 0, 14, 2, and 38%. Following daily IGF-1 injections from P12 to P17, liver glycogen levels on P25 were: 3.5 (IGF-1), 3.9 (IGF-1 + Tox), 12.3 (IGF-1 + FluB), and 5.6 (IGF-1 + Tox + FluB). Unexpectedly, IGF-1 treatment increased mortality to 67% (IGF-1), 89% (IGF-1 + Tox), 63% (IGF-1 + FluB), and 81% (IGF-1 + Tox + FluB). For all groups there was a significant correlation between mortality and poor weight gain. This is the first report of persistent glycogen reductions after surfactant exposure and withdrawal. Their role in potentiating FluB-induced mortality remains to be established.

Determination of pamidronate in human whole blood and urine by reversed-phase HPLC withfluorescence detection

Pamidronate is a bisphosphonate that is effective in treating bone disease including osteopenia and osteoporosis in adults. A sensitive and reliable method for the analysis of pamidronate in whole blood and urine is key to the development of this drug for use in children. A previously described method for pamidronate analysis serum and urine did not consistently detect the drug at satisfactory levels in whole blood. The procedure involves co-precipitation of the bisphosphonates with calcium phosphate, pre-column derivitization with fluorescamine, HPLC utilizing a Nucleosil C(18) column, and fluorescence detection with excitation at 395 nm and emission at 480 nm. Changes to the original protocol included the use of a new internal standard (alendronate), the optimization of the concentration of ethylenediaminetetraacetic acid (EDTA) for dissolving the precipitate, and the elimination of the acidification step prior to deproteinization. The optimum EDTA concentration, which had a significant effect on the labeling capability of fluorescamine, was determined to be 20 mm.A good separation between pamidronate and alendronate was achieved using a heated (40 degrees C ) Nucleosil C(18), 10 micro m particle size column. The mobile phase was an aqueous solution of 1 mm Na(2)EDTA-methanol (97:3, v/v) adjusted to pH 6.5 using a fl ow-rate of 1 mL/min. Fluorescence detection was set at 395 nm for excitation and at 480 nm for emission. The limit of quantitation for pamidronate was 0.5 micro g/mL in whole blood and 0.1 micro g/mL in urine. The method was applied to both whole blood and urine samples from pediatric patients.

Simulect and HHV-6 in pediatric renal transplantation

Herpes virus reactivation is of increasing interest as we aim to decrease morbidity and mortality in the pediatric renal transplant population. We previously reported increased reactivation of HHV-6 and Epstein Barr virus (EBV) with anti-thymocyte globulin/ALG induction therapy. HHV-6 reactivation and de novo infection has been monitored in 31 consecutive pediatric renal transplant patients receiving antibody induction with Simulect. Human Herpes virus-6 (HHV-6) was correlated with EBV reactivation and de novo infection rates, allograft function at 1 year, donor source and number, and patient age and gender. One HHV-6 de novo infection was associated with an early grade II rejection that was steroid resistant but ATG/ALG responsive. Sixteen of 31 (54.8%) patients had HHV-6 reactivation during the first year and eight patients had a prior reactivation profile before transplant. Thirteen patients (41.9%) were naïve to EBV infection prior to transplant with evidence of primary infection in 11 of 13 patients between 6 weeks and 1 year posttransplant. EBV reactivation was noted in four patients with past immunity to EBV. IgM Ab to EBV or HHV-6 during the first year posttransplant did not correlate with risk of rejection during the first year or graft function one year posttransplant. The only patient with positive HHV-6 IgM Ab in the first posttransplant month was a de novo infection in a 2-year-old boy who was naïve for HHV-6 at the time of transplant. Simulect appears safe in pediatric renal transplant with low risk of HHV-6 or EBV infection in the first 1 to 2 months posttransplant.

Phenotypic heterogeneity in pediatric autosomal dominant polycystic kidney disease at first presentation: a single-center, 20-year review

BACKGROUND

The presentation of autosomal dominant polycystic kidney disease (ADPKD) in childhood provides an insight into comorbidities and potential areas for interventions and investigation.

METHODS

Phenotypic heterogeneity at the time of first presentation was studied with respect to age of diagnosis, mode of presentation, parental inheritance pattern, renal function, associated hypertension, and hyperlipidemia. Fifty-five children (median age of presentation, 8.7 years; 27% < 1 year) with ADPKD from 44 families followed up between March 1983 and March 2003 were reviewed. The diagnosis was based on family history and ultrasound confirmation of cysts. Progression of renal disease was followed over the study period (mean duration of follow-up, 4.9 years).

RESULTS

A family history of ADPKD was known at presentation in 89%, which precipitated the screening diagnostic imaging in 59% of these children. Maternal inheritance was displayed in 51%, whereas 5% had no known family history of ADPKD. Bilateral renal findings were present in 78%. Hypertension (>95(th) percentile for age) was present in 22%, and hyperlipidemia was present in 54%. Renal function was not significantly diminished in 98% of patients with creatinine clearance > or =3rd percentile for age, and 7% had persistent proteinuria (>150 mg/d). No subjects had hepatic, splenic, or pancreatic cysts on ultrasound scan. A subpopulation of 10 patients had features of ADPKD dating back to prenatal ultrasound scans. All prenatal cases were characterized by bilateral renal findings, 90% had a known family history of ADPKD at the time of presentation, and 89% of these patients displayed maternal inheritance. Follow-up studies showed a persistence of hyperlipidemia despite pharmacotherapeutic treatment of hypertension, infrequent proteinuria, and sustained renal function in most patients.

CONCLUSION

The results of this study show that many children at the time of first presentation have a significant prevalence of modifiable risk factors: hypertension, proteinuria, and hyperlipidemia, in the face of normal renal function. The results also show a unique presentation existing in prenatal subjects.

Growth hormone therapy before and after pediatric renal transplant

Children undergoing successful renal transplantation anticipate optimal growth and development. The use of rhGH pre- and post-Tx has been evaluated and supported by randomized control trials. Several strategies are required to maximize the potential benefit of this treatment in the renal population including provision of adequate nutrition intake, following bone parameters with appropriate interventions, and strategies to reduce steroid therapy including utilization of alternate day steroid treatment. Studies are required to further assess the impact of rhGH on renal allograft function, rejection risk, and allograft ultrastructural changes.

Decreased bone mineral density in the pediatric renal transplant population

All renal transplant recipients at our centre have had bone mineral density assessment (BMD) by DEXA scans of their lumbar spine while on the transplant waitlist and at 6-month intervals post-transplant over the past 7 yr. Risk factors for osteopenia and osteoporosis including donor source, dialysis status prior to transplantation, prior renal disease, and biopsy confirmed rejection events and their relationship to BMD of the lumbar spine were assessed. Thirty-nine children transplanted over the past 7 yr were included in this study. In total, 127 BMD longitudinal assessments were performed. From 1990 to 1997, ATG/ALG was used as antibody induction therapy. From 1997 to 2002, Basiliximab was utilized. Cyclosporin A (CyA) was the primary immunosuppressant for most children with tacrolimus as primary (n = 2) and switch for CyA failure or toxicity (n = 16). Prednisone was administered at a dose of 1 mg/kg/day for the first week and tapered to 10 mg/m2/alternate day by 1 month post-transplant. Azathioprine 1.5 mg/kg/day was continued for 1 yr and discontinued in children who were rejection free. All rejections were biopsy confirmed and treated with a prednisone pulse. Using a repeated measures regression analysis, we have found that L1-L4 BMD z score is affected by height and transplant number. It is also related to time relative to transplant in a quadratic fashion. There was an inverse relationship between advancing patient age and L1-L4 BMD z score. L1-L4 BMD z score was not related to weight, pre-existing renal disease, gender, donor source, type of renal replacement therapy prior to transplantation, or rejection events.

Bone mineral density in juvenile dermatomyositis: assessment using dual x-ray absorptiometry

OBJECTIVE

To determine the bone mineral density (BMD) status of our juvenile dermatomyositis (DM) population and to compare the frequency of osteopenia in patients with active disease requiring corticosteroids with that in patients with inactive disease who are not receiving corticosteroids.

METHODS

Medical charts of all children diagnosed as having juvenile DM at our institution between 1989 and 1999 were reviewed for demographic and clinical data, including disease activity and duration of corticosteroid therapy. BMD measurements of the lumbar spine (L1-L4) were performed using dual x-ray absorptiometry (DXA). Z scores were calculated from the BMD data for comparison with published normative data.

RESULTS

A total of 15 patients were assessed: 10 with active disease, and 5 with inactive disease who had not taken corticosteroids for an average of 6.0 years (range 3.4-8.1 years). Baseline BMD measurements demonstrated osteopenia or frank osteoporosis in the majority of patients, including 6 of the 10 patients with active disease and 4 of the 5 patients whose disease was in remission. Fourteen patients had serial BMD measurements. Persistent or worsening osteopenia was documented in all patients who had ongoing active disease, except for 3 patients who had been treated with bisphosphonates because of vertebral compression fractures.

CONCLUSION

Osteopenia is common in patients with juvenile DM, and it usually worsens with ongoing disease. It can persist for many years after the disease enters remission. Bisphosphonates appeared to beneficially affect bone mineralization in our patients. Treatment to prevent the long-term complications of osteoporosis in patients with juvenile DM should be considered and requires further study.

Neuropsychological outcome in children with acquired or congenital renal disease

The neuropsychological abilities of children with congenital ( n=13) or acquired ( n=11) end-stage renal disease (ESRD) were compared. Patients were being treated with or being prepared for dialysis and were awaiting transplantation. None of the children had an identifiable syndrome with associated central nervous system (CNS) dysfunction or had exposure to drugs with known CNS toxicity. There were no group differences in intelligence, academic achievement, behavior, or immediate memory. Children with congenital ESRD had poorer fine motor coordination and more difficulty on tests of verbal and nonverbal long-term memory than children with acquired ESRD. However, the neuropsychological outcome for congenital ESRD is more favorable than previously described. Psychological and education treatment recommendations should be considered.

T-cell/periodic acid-Schiff stain: a useful tool in the evaluation of tubulointerstitial infiltrates as a component of renal allograft rejection

Distinguishing between tubulitis and tubulointerstitial mononuclear cell infiltrates and determining the severity of tubulitis are critical components of diagnosing and grading renal allograft rejection using the 1993 Banff schema, the revised 1997 Banff schema, or the Cooperative Clinical Trials in Transplantation grading system. We describe a novel staining method, the T-PAS stain (CD3 and periodic acid-Schiff), which removes some of the subjectivity in the evaluation of tubulointerstitial infiltrates in renal allograft biopsies. The method simply combines two routine stains, immunoperoxidase staining for T cells (CD3) and periodic acid-Schiff (PAS) staining for tubular basement membrane, on the same section.

Extravesical ureteroneocystostomy with and without internalized ureteric stents in pediatric renal transplantation

The use of ureteric double-J stents and the Lich-Gregoir (extravesical) technique of ureteroneocystotomy have both been shown to decrease the rate of urologic complications in adult kidney transplantation (Tx). There are, however, few studies of the systematic use of stents in pediatric renal Tx. Between 1991 and 1997, 32 consecutive pediatric renal transplant recipients routinely received a 6F-12 cm indwelling double-J stent and were studied prospectively. These patients were compared with 32 consecutive pediatric recipients in whom a stent was not used. The latter were transplanted between 1987 and 1991 and formed the control group. All patients had a Lich-Gregoir ureteroneocystotomy. Stents were removed under general-anesthetic cystoscopy 2 3 weeks after Tx. Immunosuppression for stented patients was polyclonal antibody induction, delayed (7-10 days) cyclosporin A, azathioprine, and prednisone. The control group received the same triple drug regimen but with no induction in 29 of the 32 patients. All patients were followed-up with at least one ultrasound evaluation in the first month, and a renal scan and repeat ultrasound were performed if there was any rise in serum creatinine. In the stented group there were two patients with urinary leak and no obstructions. In the non-stented group there were no leaks and one obstruction. There was no graft loss owing to urologic complications in either group. There were three cases of stent expulsion (all in girls) and one case of stent migration in the posterior urethra (a boy). The 1-yr graft survival rate was 90.6% in the stented group and 65.6% in the non-stented group. The prophylactic use of an indwelling ureteral stent in pediatric renal Tx did not reduce the risk of urinary leakage or obstruction. Stent migration is a common phenomenon and, while not a serious complication, is traumatic to children. Furthermore, removal of an internalized double-J stent requires a general anesthetic. We recommend using a stent for selected patients only.

Kidney graft loss in children: implications for program development

BACKGROUND

Graft survival in children who undergo kidney transplantation is lower than that in adults. The objective of the study was to review the experience of the first 22 years of operation of the regional pediatric kidney transplantation unit for Atlantic Canada, based at the IWK-Grace Health Centre, Halifax, and to use the results to improve graft survival.

METHODS

All cases of kidney transplantation performed at the centre from 1971 to 1992 were reviewed and the data compiled with the use of a predetermined database outline. Data for first transplants were analysed and compared with those in North American databases. Of the 40 graft failures, 19 (48%) occurred within the first 3 months after transplantation, a rate similar to that at other centres. The overall survival rates tended to be slightly lower than those of international databases. The introduction of cyclosporine A as an immunosuppressant, in 1985, did not provide the expected marked improvement in survival. Infection frequently accompanied acute rejection, and there was a delay in treatment of infections and rejection after discharge home. On the basis of these preliminary findings, several program changes were made: 1) a sequential immunosuppression protocol was implemented, 2) the intensity of the medical surveillance was increased for the first 3 months after transplantation, with aggressive treatment of infections and rejections, 3) a dedicated pediatric transplantation team was established as a subset of the adult team and 4) pediatric-specific selection criteria for cadaver donors were formulated. After these changes were implemented, data were collected and analysed up to June 30, 1997.

RESULTS

Graft survival rates at 1, 2 and 5 years improved dramatically. After the beginning of 1993, there were only 2 graft losses among 22 transplants. Only one of these occurred in the first 3 months, and it was due to recurrent disease. Twenty-four rejection episodes occurred (10 in the first 3 months after transplantation), but all were reversed easily with high-dose steroid therapy.

INTERPRETATION

Sequential immunosuppression with close medical surveillance and early aggressive treatment of infection and rejection contribute to a marked improvement in kidney graft survival in children.

Infection concomitant with pediatric renal allograft rejection

Renal allograft rejection episodes are frequent in children and often lead to allograft failure. Frequent association of fever with rejection in our transplant program provoked a prospective evaluation of concurrent infection during rejection episodes. Because cytomegalovirus has an established role in rejection and allograft survival, evaluation of cytomegalovirus and other herpes viruses (human simplex virus type 1, varicella, Epstein-Barr virus, and human herpes virus type 6 [HHV-6]) was undertaken in addition to standard bacterial investigation. A total of 37 patients were followed over a 30-month period. Six of eight rejection episodes were associated with herpes viruses (HHV-6, n = 6, and Epstein-Barr virus, n = 1). Three of the herpes-group-associated rejection episodes were treated with antiviral therapy in addition to pulse steroid treatment, with full recovery. The three patients with HHV-6-associated rejection episodes who were treated with pulse steroids, but no antiviral therapy, developed chronic allograft rejection. The recipient's response to allograft antigens may be influenced by concomitant herpes infection, and specific antiviral therapy appears to be indicated when infection is confirmed in association with rejection. An antiviral treatment program coupled with modulation of standard antirejection immunotherapy has the potential to improve morbidity and mortality in the pediatric renal transplant population.

Norfloxacin interferes with cyclosporine disposition in pediatric patients undergoing renal transplantation

Prophylactic treatment with norfloxacin was initiated in a group of pediatric patients undergoing renal transplantation who were receiving cyclosporine and were susceptible to recurrent urinary tract infections. At discharge from the hospital, the mean daily dose of cyclosporine needed to maintain trough cyclosporine blood levels of 150 to 400 ng/ml was 4.5 mg/kg/day for the patients who received norfloxacin compared with 7.4 mg/kg/day for patients who did not receive the antibiotic. This observation suggested that the clearance of cyclosporine was decreased by the concomitant use of norfloxacin. The effect of norfloxacin on specific drug-metabolizing cytochrome P450 isozymes in vitro was examined to determine if the metabolism and subsequent clearance of cyclosporine and possibly other drugs are altered through a metabolic interaction with norfloxacin. In human liver microsomes, the activity of cytochrome P4503A4, the isozyme that metabolizes cyclosporine in humans, was inhibited by norfloxacin. In rat liver microsomes, norfloxacin inhibited the activity of cytochrome P4503A2, the isozyme responsible for cyclosporine metabolism in this species, but did not alter the activity of the rat cytochrome P450 isozymes 1A, 2E1, and 4A1. The in vitro studies suggest that the lower cyclosporine dose required by pediatric patients who were given norfloxacin was caused by inhibition of the metabolism of cyclosporine.