Analysis of the functional muscle-bone unit of the forearm in patients with phenylketonuria by peripheral quantitative computed tomography.

Bone disease in patients with phenylketonuria (PKU) is incompletely characterized. We therefore analyzed, in a cross-sectional study radius macroscopic bone architecture and forearm muscle size by peripheral quantitative computed tomography (pQCT) and muscle strength by hand dynamometry in a large cohort (n = 56) of adolescent and adult patients with PKU aged 26.0 ± 8.9 (range, 11.8-41.5) years. Data were compared with a reference population (n = 700) from the DONALD study using identical methodology. We observed a significant reduction of cortical thickness (z-score -1.01 ± 0.79), Strength-Strain Index (SSI) (z-score -0.81 ± 1.03), and total bone mineral density (BMD) of the distal radius (z-score -1.05 ± 1.00). Mean muscle cross-sectional area (z-score -0.98 ± 1.19) and muscle grip force (z-score -0.64 ± 1.26) were also significantly reduced, indicating an impaired muscular system as part of the clinical phenotype of PKU. SSI positively correlated (r = 0.53, P < 0.001) with the corresponding muscle cross-sectional area in the reference population; however, the regression line slope in PKU patients was less steep (P < 0.001), indicating that bone strength is not adequately adapted to muscle force. In conclusion, the radial bone in PKU patients is characterized by reduced bone strength in relation to muscular force, decreased cortical thickness, and impaired total BMD at the metaphyseal site. These alterations indicate a mixed bone defect in PKU, both of which are due to primary alterations of bone metabolism and to secondary alterations in response to neuromuscular abnormalities.

Epidemiology and morbidity of Epstein-Barr virus infection in pediatric renal transplant recipients: a multicenter, prospective study.

BACKGROUND: The epidemiology and morbidity of Epstein-Barr virus (EBV) infection in pediatric renal transplant recipients have been characterized insufficiently. METHODS: In a prospective, multicenter study among 106 pediatric kidney allograft recipients aged 11.4 ± 5.9 years, we investigated the epidemiology of EBV infection and the relationship between EBV load, EBV serology, and EBV-related morbidity (posttransplant lymphoproliferative disease [PTLD] or symptomatic EBV infection, defined as flu-like symptoms or infectious mononucleosis). RESULTS: EBV primary infection occurred in 27 of 43 (63%) seronegative patients and reactivation/reinfection in 28 of 63 (44%) seropositive patients. There was no association between the degree or duration of EBV load and EBV-related morbidity: The vast majority (17 of 18 [94%]) of patients with a high, persistent EBV load remained PTLD-free throughout a follow-up of 5.0 ± 1.3 years, while 2 of 3 (66%) patients with EBV-related PTLD exhibited only a low EBV load beforehand. Eight of 18 (44%) patients with a high, persistent EBV load remained asymptomatic during a follow-up of 5.3 ± 2.9 years. Multivariate analysis identified the EBV high-risk (D(+)/R(-)) serostatus (odds ratio [OR], 7.07; P < .05), the presence of human leukocyte antigen (HLA)-DR7 (OR, 5.65; P < .05), and the intensity of the immunosuppressive therapy (OR, 1.53; P < .01) as independent risk factors for the development of a symptomatic EBV infection. CONCLUSIONS: Presence of EBV high-risk seroconstellation, HLA-DR7, and intensity of immunosuppressive therapy are significant risk factors for a symptomatic EBV infection, whereas there is no close association between the degree or duration of EBV load and EBV-related morbidity. Clinical Trials Registration. NCT00963248.

Soluble CD30 and ELISA-detected human leukocyte antigen antibodies for the prediction of acute rejection in pediatric renal transplant recipients.

Biomarker-based post-transplant immune monitoring for the prediction of impending graft rejection requires validation in specific patient populations. Serum of 28 pediatric renal transplant recipients within the framework of a well-controlled prospective randomized trial was analyzed pre- and post-transplant for soluble CD30 (sCD30), a biomarker reflecting mainly T-cell reactivity, and anti-human leukocyte antigen (anti-HLA) antibody reactivity, a biomarker for B-cell activation. A sCD30 concentration ≥40.3 U/ml on day 14 was able to discriminate between patients with or without biopsy-proven acute rejection (BPAR) with a sensitivity of 100% and a specificity of 76%. Six of seven patients (86%) with BPAR showed a sCD30 above this cut-off, whereas only 3/21 patients (14%) without BPAR had a sCD30 above this cut-off (P = 0.004). For pre- and post-transplant anti-HLA class II reactivities by enzyme-linked immunosorbent assay, a cut-off value of 140 optical density was able to discriminate rejecters from nonrejecters with a sensitivity of 86% or 71% and a specificity of 81% or 90%, respectively. Withdrawal of steroids was associated with a approximately twofold higher serum sCD30 compared to controls, but did not affect anti-HLA reactivities. An increased post-transplant sCD30 serum concentration and positive pre- and post-transplant anti-HLA class II reactivities are informative biomarkers for impending BPAR in pediatric renal transplant recipients. (TWIST, Clinical Trial No: FG-506-02-43).

(Val-)Ganciclovir prophylaxis reduces Epstein-Barr virus primary infection in pediatric renal transplantation.

Epstein-Barr virus (EBV) primary infection constitutes a serious risk for pediatric transplant recipients, particularly as regards the development of EBV-related post-transplant lymphoproliferative disease (PTLD). Currently, there is no established prophylactic regimen. We investigated the association between chemoprophylaxis with valganciclovir (VGCV) or ganciclovir (GCV) and the incidence of EBV viremia in EBV-naïve pediatric renal transplant recipients (R-) who had received a graft from an EBV-positive donor (D+) and are therefore at high risk of EBV primary infection. In a prospective, multicenter trial (n = 114), we compared a cohort on chemoprophylaxis (n = 20) with a similar control cohort without chemoprophylaxis (n = 8). Over the 1-year study period, antiviral prophylaxis with VGCV/GCV was associated with a significantly decreased incidence of EBV primary infection: 9/20 patients (45%) in the prophylaxis group experienced an EBV primary infection compared to 8/8 controls (100%) (P < 0.0001). Chemoprophylaxis was associated with a significantly lower EBV viral load (P < 0.001). Type or intensity of immunosuppressive therapy did not influence the occurrence of EBV primary infection or the level/persistence of EBV viral load. Chemoprophylaxis with VGCV/GCV is associated with a reduced incidence of EBV viremia in high-risk pediatric kidney allograft recipients in the first year post-transplant. (ClinicalTrials.gov number: NCT00963248).

Combined phase I/II study of imexon (AOP99.0001) for treatment of relapsed or refractory multiple myeloma.

Imexon [AOP99.0001 (4-imino-1,3-diazobicyclo[3. 1. 0]-hexan-2-one)] belongs to a novel class of promising anticancer agents that induce tumor apoptosis through oxidative stress. Clinical experience since the late 1960s has provided initial evidence for a clinical antitumor activity. Our open-label, multicenter phase I clinical trial was designed to further investigate the adverse event (AEs) profile and pharmacokinetics of AOP99.0001 in pretreated myeloma patients and collect initial data on the potential clinical efficacy in this indication. Thirty-six patients with relapsed or refractory myeloma, who had been pretreated with at least two lines of therapy earlier, were included. Imexon was applied intravenously on 5 consecutive days for 2 weeks (d1-5 and d8-12) for a 3-week cycle. The plasma half-life of AOP99.0001 and its active metabolite AOP99.0002 was found to be approximately 1.2 and 2.6 h, respectively. The mean duration of treatment with Imexon was 6.8 weeks in a dose range between 50 and 1000 mg/m without reaching dose-limiting toxicity. Drug-related AEs occurring with a frequency of greater than 10% were fatigue, nausea, constipation, headache, asthenia, anemia, thrombocytopenia, leukopenia and creatinine increase. A total of nine severe adverse events occurred in three patients. No mortality was encountered when patients were on treatment with Imexon. Preliminary antimyeloma efficacy of AOP99.0001 was observed with 1 minimal response, 12 (36%) stable disease responses, and all other evaluable patients had progressive disease. Remarkably, the patient with minimal response also experienced a complete clinical resolution of myeloma-associated polyneuropathy. Overall, Imexon was safe and well tolerated in the dose range investigated. Imexon showed minor clinical activity as a single agent in heavily pretreated myeloma patients. On account of its unique mechanism of action, favorable toxicity profile, initial clinical evidence for antimyeloma activity, and its known synergistic activity in combination with approved agents for myeloma treatment, AOP99.0001 is recommended for future clinical studies in combination regimens in multiple myeloma.

Enterococcal peritonitis in children receiving chronic peritoneal dialysis.

BACKGROUND: Peritonitis is a common complication of chronic peritoneal dialysis (CPD) and can be associated with technique failure. Enterococcus is an uncommon peritoneal pathogen in children receiving CPD but represents a potential therapeutic challenge due to its innate resistance to cephalosporins and emerging resistance to glycopeptides. METHODS: The International Pediatric Peritonitis Registry is a global consortium of 47 paediatric dialysis centres designed to address validation of the International Society for Peritoneal Dialysis paediatric peritonitis treatment guidelines. Between 2001 and 2004, peritonitis episodes were assessed in 392 participating children receiving CPD. RESULTS: Among the 392 patients, 340 episodes of culture-positive peritonitis were evaluated. Twenty of these episodes were due to Enterococcus species (5.9%). There were no clinical characteristics uniquely associated with enterococcal peritonitis at presentation. After 3 days of therapy, 75% of patients were pain free, 95% had decreased effluent cloudiness and 90% were afebrile. Only one patient required a catheter exchange, and all patients experienced full functional recovery. Despite broad in vitro resistance to cephalosporins and 21% resistance to glycopeptides, neither in vitro resistance pattern nor choice of empiric antibiotic regimen affected short- or long-term outcomes. CONCLUSIONS: Enterococci are likely responsible for ∼6% of culture-positive peritonitis episodes in children receiving CPD. Although it was not possible to identify patients with enterococcal peritonitis based on presentation, clinical response was not associated with in vitro resistance patterns, and patients who initially received a cephalosporin-based empiric regimen until culture results are available are likely to respond quickly and have full functional recovery.

Improved growth and cardiovascular risk after late steroid withdrawal: 2-year results of a prospective, randomised trial in paediatric renal transplantation.

BACKGROUND: Long-term corticosteroid treatment impairs growth and increases cardiovascular risk factors. Hence, steroid withdrawal constitutes a major topic in paediatric renal transplantation and maintenance immunosuppression. METHODS: The lack of data from randomised controlled trials caused us to conduct the first prospective, randomised, multicentre study on late steroid withdrawal among paediatric kidney allograft recipients treated with standard-dose cyclosporine microemulsion (CsA) and mycophenolate mofetil (MMF) for 2 years. Forty-two low- or regular-immunologic risk patients were randomly assigned, >or=1 year post-transplant, to continue taking or to withdraw steroids over 3 months. RESULTS: Two years after steroid withdrawal, they showed a longitudinal growth superior to controls [mean height standard deviation score (SDS) gain, 0.6 +/- 0.1 SDS versus -0.2 +/- 0.1 SDS (P < 0.001)]. The prevalence of the metabolic syndrome declined significantly (P < 0.05), 2 years after steroid withdrawal, from 39% (9/23) to 6% (1/16). Steroid-free patients had less frequent arterial hypertension (50% versus 93% (P < 0.05)) and required fewer antihypertensive drugs [0.6 +/- 0.2 versus 1.5 +/- 0.3 (P < 0.05 versus control)]. Additionally, they had a significantly improved carbohydrate and lipid metabolism with fewer hypercholesterolaemia and hypertriglyceridaemia (P < 0.05 versus control). Patient and graft survival amounted to 100%. Allograft function remained stable 2 years after steroid withdrawal. The incidence of acute rejections was similar in the steroid-withdrawal group (1/23, 4%) and controls (2/19, 11%). CONCLUSION: Late steroid withdrawal in selected CsA- and MMF-treated paediatric kidney transplant recipients improves growth, mitigates cardiovascular risk factors and reduces the prevalence of the metabolic syndrome, at no increased risk of acute rejection or unstable graft function.

Initial evaluation of a biochemical cystic fibrosis newborn screening by sequential analysis of immunoreactive trypsinogen and pancreatitis-associated protein (IRT/PAP) as a strategy that does not involve DNA testing in a Northern European population.

BACKGROUND: Ethical concerns and disadvantages of newborn screening (NBS) for cystic fibrosis (CF) related to genetic testing have raised controversies and impeded implementation of CF NBS in some countries. In the present study, we used a prospective and sequential immunoreactive trypsinogene (IRT)/pancreatitis-associated protein (PAP) strategy, with IRT as first and PAP as second tier, and validated this biochemical approach against the widely used IRT/DNA protocol in a population-based NBS study in southwest Germany. METHODS: Prospective quantitation of PAP and genetic analysis for the presence of four mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene most prevalent in southwest Germany (F508del, R553X, G551D, G542X) were performed in all newborns with IRT > 99.0th percentile. NBS was rated positive when either PAP was ≥1.0 ng/mL and/or at least one CFTR mutation was detected. In addition, IRT > 99.9th percentile was also considered a positive rating. Positive rating led to referral to a CF centre for testing of sweat Cl(-) concentration. FINDINGS: Out of 73,759 newborns tested, 98 (0.13%) were positive with IRT/PAP and 56 (0.08%) with IRT/DNA. After sweat testing of 135 CF NBS-positive infants, 13 were diagnosed with CF. Detection rates were similar for both IRT/PAP and IRT/DNA. One of the 13 diagnosed CF newborns had a PAP concentration <1.0 ng/mL. CONCLUSIONS: Sequential measurement of IRT/PAP provides good sensitivity and specificity and allows reliable and cost-effective CF NBS which circumvents the necessity of genetic testing with its inherent ethical problems.

Pharmacodynamic monitoring of cyclosporine A by NFAT-regulated gene expression and the relationship with infectious complications in pediatric renal transplant recipients.

Pharmacokinetic monitoring of CsA is unsatisfactory, because at comparable CsA blood concentrations, the frequency and severity of adverse effects vary considerably among patients. We have therefore recently developed a precise, reliable, and robust whole-blood pharmacodynamic assay that measures the suppression of CsA-target genes in T lymphocytes. Because of the different characteristics of CsA pharmacokinetics in children and the higher propensity for infectious complications, this assay requires validation in the pediatric patient population. We therefore quantified in a prospective study of 45 pediatric renal transplant recipients the residual expression of NFAT-regulated genes in lymphocytes by RT-PCR and correlated these findings with the frequency of recurrent infections in the maintenance period post-transplant. Patients with recurrent infections showed a significantly stronger inhibition of NFAT-regulated gene expression (18.2%) than patients without recurrent infections (31.7%; p = 0.012). This difference was specific, because various PK parameters of CsA and the concomitant immunosuppressive therapy were comparable between patients. Multivariate regression analysis showed that patient age and residual NFAT-regulated gene expression were the only independent determinants of recurrent infections. By ROC curve analysis, a cutoff value of 23% residual NFAT-regulated gene expression had the highest sensitivity (71.1%) and specificity (65.4%) for the discrimination of patients with and without recurrent infections. Pharmacodynamic monitoring of CsA by measurement of residual NFAT-regulated gene expression in T lymphocytes has the potential to identify over-immunosuppressed pediatric renal transplant recipients and is therefore a useful tool for the optimization of CsA therapy.

Gram-negative peritonitis in children undergoing long-term peritoneal dialysis.

BACKGROUND: The proportion of gram-negative causative organisms in peritoneal dialysis-associated peritonitis is increasing. Little published information for this complication exists in children. The objective of this study is to evaluate the clinical presentation, early and late response to treatment, and identification of factors influencing the outcome of gram-negative peritonitis (GNP) in children. STUDY DESIGN: Case series. SETTING AND PARTICIPANTS: 104 children (aged 7.9 +/- 5.9 years) with 121 GNP episodes reported to the International Pediatric Peritonitis Registry from October 2001 through December 2004. PREDICTORS: Patient, clinical, bacteriological, and treatment features. OUTCOMES: Initial response to empirical treatment was assessed after approximately 72 hours of therapy. Final outcome was judged according to the occurrence of death, technique failure, relapse, need for catheter exchange, and a composite end point defining full functional recovery. RESULTS: 44% of episodes of GNP occurred in children younger than 5 years. Causative organisms included Pseudomonas species, 21%; Klebsiella species, 18%; Escherichia coli, 17%; and Acinetobacter species, 12%. Thirty-two percent of organisms classified as gram-negative were not identified further. Clinical manifestations were severe and uniform for all causative gram-negative agents. A substantial proportion (20%) of organisms were resistant to ceftazidime, with resulting suboptimal response to empirical therapy. By day 3 of initial empiric treatment, 85% of children with GNP had improved clinically (39%, complete resolution; 46%, improvement in symptoms), 10% showed poor response, and 5% had worsening of symptoms. Multivariate analysis identified severe abdominal pain, use of a single-cuff catheter, and intermittent (versus continuous) intraperitoneal ceftazidime administration as independent predictors of worse initial response to treatment. Full functional recovery was achieved in 86% of episodes. Nineteen patients (16%) required catheter removal, 11 (9%) experienced a relapse, 7 (6%) discontinued peritoneal dialysis therapy permanently, and 3 died. Lack of clinical improvement after 72 hours of therapy (odds ratio, 5.39; P < 0.01) and the presence of an exit-site infection (odds ratio, 7.69; P = 0.01) independently increased the risk of an incomplete functional recovery. LIMITATIONS: The study was not designed to assess absolute incidence figures or risk factors for the development of GNP in children. CONCLUSIONS: GNP is a significant complication of long-term peritoneal dialysis therapy in children, and a substantial proportion of affected children are at risk of permanent sequelae. Because results of empiric treatment with ceftazidime are suboptimal in the setting of this infection, alternative antimicrobial agents should be reconsidered.

MEG versus EEG: influence of background activity on interictal spike detection.

The comparative sensitivity of EEG and magnetoencephalography (MEG) in the visual detection of focal epileptiform activity in simultaneous interictal sleep recordings were investigated. The authors examined 14 patients aged 3.5 to 17 years with localization-related epilepsy. Simultaneous 122-channel whole-head MEG and 33-channel EEG were recorded for 20 to 40 minutes during spontaneous sleep. The EEG and MEG data were separated and four blinded independent reviewers marked the presence and timing of epileptic discharges (ED) in the 28 data segments. EEG and MEG data were matched and spikes identified by at least three reviewers were classified in three categories according to the following criteria: type 1 MEG > EEG, type 2 EEG > MEG (type 1/2: difference of three or more raters), and type 3 EEG = MEG (three or more raters each). The presence of simultaneous sleep changes was visually determined for every single EEG-segment. Spikes with high spatiotemporal correlation were averaged and subjected to single dipole analysis of peak activity in EEG. Out of 4704 marked patterns, 1387 spikes fulfilled the above criteria. In fact, more spikes were unique to MEG (689) than to EEG (136) and to the combination of both modalities (562). ED were detected predominantly by MEG in eight patients and by EEG in two patients. The presence of vertex waves and spindles lead to a significantly higher number of spikes identified only in MEG. Averaging of type 1 spikes produced clear spike activity in EEG in 9 of 12 cases. On the contrary, only 2 of 10 type 2 spikes were visible in MEG after averaging. Dipoles of spikes visible in MEG showed a more tangential orientation compared with more radial dipoles of type 2 spikes. Spike characteristics, e.g., dipole orientation, are a key factor for a sole EEG representation. Exclusive MEG detection is more likely influenced by overlapping background activity in EEG. Because MEG is indifferent to radial activity, i.e., sleep changes, a higher ratio of spikes unique to MEG compared with EEG is detected in the case of overlapping sleep changes.

Percutaneous endoscopic gastrostomy in children on peritoneal dialysis.

OBJECTIVE: Insertion of percutaneous endoscopic gastrostomies (PEG) in patients on chronic peritoneal dialysis (PD) has been reported to be contraindicated due to an increased risk of morbidity and mortality. However, no systematic survey on this topic has yet been published. DESIGN: Retrospective multicenter study. SETTING: 23 pediatric dialysis units associated with the working group Arbeitsgemeinschaft für Pädiatrische Nephrologie (APN). DATA SOURCE: A structured questionnaire on clinical details of PD patients who had undergone PEG insertion or open gastrostomy (OG) since 1994 was distributed to all pediatric dialysis units of the APN. RESULTS: 27 PD patients (20 males) from 12 centers in whom PEG insertion was performed after Tenckhoff catheter introduction were evaluated. Age at intervention ranged from 0.25 to 10.9 years (median 1.3 years). Most patients were malnourished, with standard deviation score (SDS) for body weight between -4.2 and -0.6 (median -2.2). Major complications were early peritonitis < 7 days after PEG in 10/27 (37%) patients, episodes of fungal peritonitis in 7/27 (26%) patients, 4 cessations of PD and change to hemodialysis, and 2 associated deaths. However, in 14 patients, no such problems were encountered and, in 4 patients, early peritonitis effectively treated with intraperitoneal antibiotics was the only major complication. Thus, in 18/27 (67%) patients, PD was successfully reinitiated shortly after PEG insertion. Among all participating centers, only two OG procedures were reported during the study period, illustrating a clear preference for the PEG over the OG procedure among members of the APN. CONCLUSION: PEG insertion following PD initiation carries a high risk for fungal peritonitis and potential PD failure; however, complication rates in this largest reported series were lower than previously described. Antibiotic and antifungal prophylaxis, withholding PD for 2 - 3 days, and gastrostomy placement by an experienced endoscopy team are suggested precautions for lowering the risk of associated complications. When gastrostomy placement does not occur prior to or at the time of initiating PD, the risks and benefits of percutaneous versus open placement must be carefully weighed.

The international pediatric peritonitis registry: a global Internet-based initiative in pediatric dialysis.

OBJECTIVES: Recommendations for the management of peritoneal dialysis-associated peritonitis in children have recently been developed by an International Society for Peritoneal Dialysis (ISPD) expert committee. The International Pediatric Peritonitis Registry (IPPR) was established in October 2001 as a global consortium of 47 pediatric dialysis centers in order to assess the validity of these guidelines. DESIGN: The IPPR is an internet-based registry collecting data on pediatric peritonitis episodes treated according to the ISPD guidelines. Data on 375 episodes have been collected as of July 2004. DATA ACQUISITION: Detailed data are obtained online on the diagnosis of peritonitis, antibiotic and adjunctive therapy, as well as on possible risk factors and treatment results. CONCLUSIONS: Final data analysis of the IPPR will yield extensive information on the treatment and outcome of peritoneal dialysis-associated peritonitis in children.

Altered temporal organization of plasma insulin oscillations in chronic renal failure.

Chronic renal failure (CRF) is associated with mechanistically unexplained impaired insulin sensitivity. Erratic insulin secretory patterns typify other states of insulin resistance. We sought to investigate possible alterations of plasma insulin oscillations in CRF. We assessed high- and low-frequency insulin and glucose oscillations in 7 male CRF patients and 11 controls by multiparametric deconvolution analysis and cluster analysis, approximate entropy (ApEn) statistic, and cross-ApEn statistics. Insulin sensitivity was appraised by euglycemic hyperinsulinemic clamps. Despite impaired glucose disappearance rates in CRF, fasting and 24-h mean insulin and glucose concentrations did not differ between patients and controls. However, patients showed a 2.5-fold increase of insulin elimination half-life, reduced frequency of both rapid (6.1 +/- 0.4 vs. 7.1 +/- 0.2 h(-1), P < 0.001) and slow oscillations of insulin release (0.54 +/- 0.11 vs. 0.71 +/- 0.1 h(-1), P < 0.001), lack of acceleration and paradoxically more orderly slow insulin and glucose pulses after meals, and increased temporal coupling between insulin and glucose patterns (cross-ApEn: 0.58 +/- 0.13 vs. 1.37 +/- 0.23, P < 0.001). Postprandial glucose intolerance was inferable by prolonged and amplified blood glucose excursions despite exaggerated insulin bursts of almost 3-fold higher area. In summary, CRF is associated with a complex disruption of the temporal organization of insulin release, which differs from abnormalities observed to date in other states of insulin resistance.

Circadian rhythm of glucose uptake in cultures of skeletal muscle cells and adipocytes in Wistar-Kyoto, Wistar, Goto-Kakizaki, and spontaneously hypertensive rats.

Hypertension and noninsulin-dependent diabetes mellitus are usually associated with marked glucose intolerance. Hypertensive and even nonhypertensive diabetic individuals display disturbances of the normal circadian blood pressure rhythm. However, little is known about circadian changes of the glucose uptake in muscle and fat cells, the major glucose utilizing tissues. Therefore, we investigated circadian rhythms of glucose uptake in primary muscle and fat cell cultures of hypertensive and type II diabetic rats and their respective control strains. 2-Deoxy-D-(1-3H)glucose uptake was measured over 48 h after synchronization of cells by means of medium change with and without addition of insulin, phloretine, and/or staurosporine. The circadian changes of glucose uptake were assessed by fitting cosine curves to the uptake values. Insulin stimulation of deoxyglucose uptake was only present in control animals, not in hypertensive and diabetic rats. Deoxyglucose uptake displayed a circadian rhythm in control animals, and was markedly disturbed in hypertensive and diabetic animals. Blocking of glucose transporters by phloretine abolished the circadian pattern of deoxyglucose uptake indicating a role of glucose transporters in its generation. Inhibition of kinases by staurosporine inhibited the insulin-stimulated deoxyglucose uptake, but did not dampen the circadian rhythmicity of basal deoxyglucose uptake. The generation of the circadian rhythm of glucose uptake in muscle and fat cell cultures is therefore probably insulin independent and independent of protein kinases. In summary, our results show for the first time: (a) a circadian rhythm of deoxyglucose uptake in glucose utilizing muscle and fat cells in vitro, (b) a disruption of this rhythm in cells of hypertensive and diabetic rats.

Methodological issues in assessing the incidence of peritoneal dialysis-associated peritonitis in children.

OBJECTIVES: To evaluate the distribution of peritonitis incidence and assess the usefulness of patient-specific peritonitis rates in children. DESIGN: 49 children on automated peritoneal dialysis (PD) followed during a 2-year observation period. SETTING: Single-center, academic children's hospital. PATIENTS: 49 children aged 2 months to 18 years; 24 prevalent, 25 incident during the observation period. Cumulative observation time was 639 patient-months. MAIN OUTCOME MEASURES: Cohort-specific peritonitis incidence, median patient-specific peritonitis incidence, mean peritonitis incidence by gamma-Poisson (negative binomial) modeling, peritonitis-free survival by Kaplan-Meier life-table analysis. RESULTS: 68 new peritonitis episodes and 21 relapses occurred in 27 patients. The distribution of patient-specific peritonitis incidence was bimodal, with a large group experiencing no or very few episodes, and another cluster around 1 episode per 6-9 months. Overall cohort-specific peritonitis incidence was 1.28, median subject-specific incidence 0.99, and mean incidence according to negative binomial modeling 1.04 (95% confidence interval 1.02-1.06) episodes per patient-year. Median peritonitis-free survival time was 6.9 months. In those patients who developed peritonitis, subject-specific peritonitis incidence was inversely correlated with patient age (r = -0.42, p < 0.05) and duration of chronic PD at last observation (r = -0.42, p < 0.05). CONCLUSIONS: Since the distribution of peritonitis in children is non-Gaussian, the average risk of peritonitis is more accurately expressed by the median of the individual subject-specific peritonitis rates or by the mean incidence estimate obtained by the negative binomial distribution model. The assignment of a personal peritonitis risk to each patient permits risk factor analysis by routine statistical methods, even in smaller populations.

Relapsing peritonitis in children who undergo chronic peritoneal dialysis: a prospective study of the international pediatric peritonitis registry.

BACKGROUND AND OBJECTIVES: The International Pediatric Peritonitis Registry (IPPR) was established to collect prospective data regarding peritoneal dialysis (PD)-associated peritonitis in children. In this report, we present the IPPR results that pertain to relapsing peritonitis (RP). DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This was an online, prospective entry into the IPPR of data that pertain to peritonitis cases by participating centers. RESULTS: Of 490 episodes of nonfungal peritonitis, 52 (11%) were followed by a relapse. There was no significant difference between RP and non-RP in distribution of causative organisms and antibiotic sensitivities. Initial empiric therapy-ceftazidime with either first-generation cephalosporin or glycopeptide (vancomycin or teicoplanin)-was not associated with relapse. Switching to monotherapy with a first-generation cephalosporin on the basis of culture results was associated with higher relapse rate (23%) than other final antibiotic therapies (0 to 9%). Culture-negative RP was less likely to have a satisfactory early treatment response than non-RP (82 versus 98%). Young age, single-cuff catheter, downward-pointing exit site, and chronic systemic antibiotic prophylaxis were additional independent risk factors for RP in the multivariate analysis. Compared with non-RP, RP was associated with a lower rate of full functional recovery (73 versus 91%), higher ultrafiltration problems (14 versus 2%), and higher rate of permanent PD discontinuation (17 versus 7%). CONCLUSIONS: This is the largest multicenter, prospective study to date to examine RP in children. In addition, this is the first report in the literature to examine specifically the relationship of postempiric antibiotic treatment regimens to the subsequent risk for relapse.

Prospective, randomized trial on late steroid withdrawal in pediatric renal transplant recipients under cyclosporine microemulsion and mycophenolate mofetil.

BACKGROUND: : Many transplant centers practice late steroid withdrawal after pediatric renal transplantation, but evidence-based data on the overall risk-to-benefit ratio in this patient population are lacking. METHODS: : We therefore conducted the first prospective, randomized, open-label multicenter study to validate this strategy: 42 low-immunologic risk pediatric kidney allograft recipients, aged 10.3+/-4.3 years, on cyclosporine microemulsion, mycophenolate mofetil, and corticosteroids were randomly assigned, more than or equal to 1-year posttransplant, to continue steroids or to withdraw over 3 months. This report contains the 1-year results. RESULTS: : In response to steroid withdrawal, patients experienced a significant catch-up growth with a mean standardized height gain of 0.3+/-0.1 standard deviation score (SDS) per year (P<0.05 vs. control), whereas mean height SDS in the control group did not change (0.0+/-0.1 SDS). Standardized body mass index declined significantly by 0.68+/-0.23 SDS after steroid withdrawal, but rose significantly by 0.26+/-0.34 SDS in the control group. Patients off steroids had less frequent arterial hypertension (50% vs. 87.5% (P<0.05) and significantly lower serum cholesterol (by 21%) and triglyceride values (by 36%) than control patients. Patient and graft survival were 100%. The incidence of acute rejection episodes in the steroid-withdrawal group was 1 of 23 (4%) compared with 1 of 19 (5%) in controls. Transplant function remained stable in both groups. CONCLUSION: : Late steroid withdrawal in low-immunologic risk European pediatric kidney transplant recipients on cyclosporine microemulsion and mycophenolate mofetil is not associated with an increased rate of acute rejection episodes, enables catch-up growth and ameliorates cardiovascular risk factors.

Peritonitis in children who receive long-term peritoneal dialysis: a prospective evaluation of therapeutic guidelines.

In children who are on chronic peritoneal dialysis, peritonitis is the primary complication compromising technique survival, and the optimal therapy of peritonitis remains uncertain. An Internet-based International Pediatric Peritonitis Registry was established in 47 pediatric centers from 14 countries to evaluate the efficacy and safety of largely opinion-based peritonitis treatment guidelines in which empiric antibiotic therapy was stratified by disease severity. Among a total of 491 episodes of nonfungal peritonitis entered into the registry, Gram-positive organisms were cultured in 44%, Gram-negative organisms were cultured in 25%, and cultures remained negative in 31% of the episodes. In vitro evaluation revealed 69% sensitivity of Gram-positive organisms to a first-generation cephalosporin and 80% sensitivity of Gram-negative organisms to a third-generation cephalosporin. Neither the risk factors assumed by the guidelines nor the choice of empiric therapy was predictive of either the early treatment response or the final functional outcome of the peritonitis episodes. Overall, 89% of cases achieved full functional recovery, a portion after relapsing peritonitis (9%). These data serve as the basis for new evidence-based guidelines. Modification of empiric therapy to include aminoglycosides should be considered.

SRL-based immunosuppression vs. CNI minimization in pediatric renal transplant recipients with chronic CNI nephrotoxicity.

Because calcineurin inhibitor (CNI)-induced nephrotoxicity contributes significantly to late renal allograft loss, sirolimus (SRL)-based, CNI-free maintenance immunosuppression has been advocated, but data in the pediatric population are scarce. We therefore analyzed the efficacy and safety of an SRL-based immunosuppressive regimen plus mycophenolate mofetil (MMF) and corticosteroids vs. CNI minimization (mean dose reduction by 39%) plus MMF and corticosteroids in 19 pediatric recipients with biopsy-proven CNI-induced nephrotoxicity in a single-center case-control study. In the SRL group, we observed, one yr after study entry, an improvement of glomerular filtration rate (GFR) by 10.3 +/- 3.0 mL/min/1.73 m2 (p < 0.05 vs. baseline) in seven of 10 patients and a stabilization in the remaining three, while in the CNI minimization group GFR improved by 17.7 +/- 7.1 mL/min/1.73 m2 (p < 0.05) in six of nine recipients and stabilized in the remaining three. No patient in either group experienced an acute rejection episode. The main adverse event under SRL therapy was a transient hyperlipidemia in 70% of patients. In pediatric renal transplant recipients with declining graft function because of CNI-induced nephrotoxicity, CNI withdrawal and switch to SRL-based therapy or CNI minimization are associated with a comparable improvement of GFR after 12 months of observation.