Thurid Ahlenstiel - Academia.edu (original) (raw)

Papers by Thurid Ahlenstiel

Kidney International, 2010

The mineral and bone disorder of chronic kidney disease remains a challenging complication in ped... more The mineral and bone disorder of chronic kidney disease remains a challenging complication in pediatric end-stage renal disease. Here, we assessed symptoms, risk factors and management of this disorder in 890 children and adolescents from 24 countries reported to the International Pediatric Peritoneal Dialysis Network Registry. Signs of this disease were most common in North American patients. The prevalence of hyperphosphatemia increased with age from 6% in young infants to 81% in adolescents. Serum parathyroid hormone (PTH) was outside the guideline targets in the majority of patients and associated with low calcium, high phosphorus, acidosis, dialysis vintage and female gender. Serum calcium was associated with dialytic calcium exposure, serum phosphorus with low residual renal function and pubertal status. PTH levels were highest in Latin America and lowest in Europe. Vitamin D and its active analogs were most frequently administered in Europe; calcium-free phosphate binders and cinacalcet in North America. Clinical and radiological symptoms markedly increased when PTH exceeded 300 pg/ml, the risk of hypercalcemia increased with levels below 100 pg/ml, and time-averaged PTH concentrations above 500 pg/ml were associated with impaired longitudinal growth. Hence, the symptoms and management of the mineral and bone disorder of chronic kidney disease in children on peritoneal dialysis showed substantial regional variation. Our findings support a PTH target range of 100-300 pg/ml in the pediatric age group.

Transplantation, 2008

was 4 years (range 0.75-14 years), and the causes were acute hepatitis A in 4 and unknown in 9. S... more was 4 years (range 0.75-14 years), and the causes were acute hepatitis A in 4 and unknown in 9. Short-term complications, documented in 12 children, included mainly hepatic artery thrombosis, which warranted retransplantation in 3 cases, and biliary leaks repaired either by surgery or by invasive radiology. Three patients died during the fi rst month after LDLT of uncontrolled intraoperative bleeding (n=1), sepsis (n=1) and multiorgan failure (n=1). Long term complications were less common, and included ascending cholangitis and graft rejections. Patient survival rate was 69% and 62% at 1 and 5 years, respectively. None of the donors had long term complications. Conclusions: Although the outcomes of LDLT in children with FHF seems inferior to that in children after elective transplantations for chronic liver diseases, the procedure is timely, life-saving and could reduce the dependence on cadaveric donation in this setting.

Transplant International, 2013

Concerns have been raised that mammalian target of rapamycin inhibitors in pediatric transplant r... more Concerns have been raised that mammalian target of rapamycin inhibitors in pediatric transplant recipients might interfere with longitudinal bone growth by inhibition of growth factor signaling and growth plate chondrocyte proliferation. We therefore undertook a prospective nested, case-control study on longitudinal growth over 2 years in steroid-free pediatric renal transplant recipients. Fourteen patients on a steroid-free maintenance immunosuppressive regimen consisting of low-dose everolimus (EVR) in conjunction with low-dose cyclosporine (CsA) were compared to a matched cohort of 14 steroid-free patients on a standard dose mycophenolate mofetil (MMF) regimen in conjunction with a standard dose calcineurin inhibitor (CNI). The mean change in height standard deviation (SD) score in the first study year was 0.31 ± 0.71 SD score in the EVR group compared to 0.31 ± 0.64 SD score in the MMF group (P = 0.20). For the entire study period of 2 years, the change in height SD score in the EVR group was 0.43 ± 0.81 SDS compared to 0.75 ± 0.85 SDS in the MMF group (P = 0.32). The percentage of prepubertal patients experiencing catch-up growth, defined as an increase in height SD score ≥0.5 in 2 years, was similar in the EVR group (5/8, 65%) and the MMF group (6/8, 75%; P = 1.00). Longitudinal growth over 2 years in steroid-free pediatric patients on low-dose EVR and CsA is not different to that of a matched steroid-free control group on an immunosuppressive regimen with standard-dose CNI and MMF. Hence, low-dose EVR does not appear to negatively impact short-term growth in pediatric renal transplant recipients.

Pediatric Nephrology, 2014

Acute antibody-mediated rejection is a diagnostic challenge in renal transplantation medicine. Ho... more Acute antibody-mediated rejection is a diagnostic challenge in renal transplantation medicine. However, it is an important diagnosis to make, since chronic antibody-mediated rejection (CAMR) is the main cause of long-term graft loss. Antibody-mediated rejection is diagnosed by detecting donorspecific antibodies (DSAs) in the blood in combination with observing typical histomorphological signs in kidney biopsy, as described in the Banff classification. Therapy is based on the removal of DSAs by administering intravenous immunoglobulins (IVIGs), plasmapheresis, or immunoadsorption. Reoccurrence of antibodies is diminished by the use of rituximab, increased immunosuppression, and in some cases additional experimental substances. A combination of these techniques has been shown to be successful in the majority of cases of acute and chronic antibody-mediated rejection. Routine DSA monitoring is warranted for early detection of antibody-mediated rejection.

Current Opinion in Organ Transplantation, 2012

The use of everolimus has recently emerged for solid-organ transplantation in children. This revi... more The use of everolimus has recently emerged for solid-organ transplantation in children. This review gives an overview of the relevant studies and clinical trials involving the immunosuppressive effects of everolimus in child organ transplant. The use of everolimus in pediatric organ transplantation is associated with a decrease in calcineurin inhibitor-related toxicity, better renal function, a low number of acute rejections, and an acceptable side-effect profile. Particularly, the use of everolimus reduces the incidence of virus infection and the risk of posttransplant lymphoproliferative disease. Everolimus is an effective agent with several advantages for pediatric solid-organ transplantation. Future prospective, randomized controlled trials will have to be performed in order to validate the findings of these pilot trials.

Transplantation, 2013

Thrombotic microangiopathy (TMA) in renal transplants (rTx-TMA) is a serious complication and is ... more Thrombotic microangiopathy (TMA) in renal transplants (rTx-TMA) is a serious complication and is usually either recurrent TMA (RecTMA) due to humoral rejection (HR-TMA) or due to calcineurin inhibitor toxicity (CNI-TMA). Although the triggers are known, our knowledge about the thrombogenic transcriptome changes in the microvessels is rudimentary. We examined the expression of several prothrombotic and antithrombotic genes in 25 biopsies with rTx-TMA (6 RecTMA, 9 HR-TMA, and 10 CNI-TMA) and 8 controls. RNA from microdissected glomeruli of paraffin-embedded tissue was isolated and mRNA transcripts were quantified with real-time polymerase chain reaction after preamplification. Results were correlated with clinicopathologic parameters. Glomerular mRNA expression of KLF2, KLF4, and tPA was lower and that of PAI-1 was higher in rTx-TMA than in the controls. Glomerular mRNA expression of KLF2 and KLF4 correlated with that of tPA and inversely with that of PAI-1 in rTx-TMA. The mRNA expression of complement regulators CD46 and CD59 were higher in rTx-TMA than in the controls. Only in HR-TMA were glomerular ADAMTS13 and CD55 down-regulated. The glomerular capillary bed seems to contribute to all subtypes of rTx-TMA by down-regulation of the endothelial transcription factors KLF2 and KLF4, indicating dedifferentiation with subsequent up-regulation of PAI-1 and down-regulation of tPA, resulting in inhibition of local fibrinolysis. Decreased glomerular expression of ADAMTS13 and CD55 could be an additional pathway toward microthrombosis exclusively in HR-TMA.

Xenotransplantation, 2006

Antigen-specific immunoadsorption combined with rituximab offers the possibility for ABO-incompat... more Antigen-specific immunoadsorption combined with rituximab offers the possibility for ABO-incompatible kidney transplantation without splenectomy. An 8-year-old mentally retarded girl with steroid-resistant nephrotic syndrome and focal segmental glomerulosclerosis due to mitochondriopathy poorly tolerated hemodialysis. Paternal blood group A1B was incompatible with blood group B of the child. Therefore, we decided to perform the first ABO-incompatible renal transplantation in a child in Germany using antigen-specific immunoadsorption. Rituximab (1 x 375 mg/m2) was administered 2 weeks before the first immunoadsorption (Glycosorb) ABO A-column). Triple-drug immunosuppression (tacrolimus, mycophenolate mofetil and prednisolone) was simultaneously started with immunoadsorption. Initial tacrolimus levels were targeted between 15 and 20 ng/ml. Before transplantation, six immunoadsorptions were applied on days -9, -7, -4, -3, -2 and -1. Intravenous immunoglobulin (0.5 g/kg) was administered preoperatively. After transplantation, three immunoadsorptions were performed on days +4, +6 and +8. Before transplantation, antibody (Ab) titers against paternal erythrocytes (20 degrees C) were reduced from 1 : 64 to 1 : 4 by six antigen-specific immunoadsorptions. After transplantation, we performed three more immunoadsorptions and the Ab titers were stable between 1 : 1 and 1 : 8. One, 2 and 8 months later we observed increases in the Ab titer up to 1 : 32 requiring no change in immunosuppressive therapy. No side effects of immunoadsorption were observed. The girl had excellent initial graft function with a serum creatinine of 55 to 70 micromol/l. Two weeks after transplantation, graft biopsy showed no signs of rejection; there was focal positivity for C4d only. Twelve months after transplantation, renal function was stable, with a serum creatinine of 117 micromol/l. Episodes of rejection or severe infections were absent. ABO-incompatible transplantation using antigen-specific immunoadsorption and rituximab may serve as a suitable alternative for children urgently needing renal transplantation and missing a blood group-compatible donor.

Virchows Archiv, 2013

Atypical haemolytic-uremic syndrome (aHUS) is, in most cases, due to hereditary or acquired defec... more Atypical haemolytic-uremic syndrome (aHUS) is, in most cases, due to hereditary or acquired defects in complement regulation and a life-threatening disease. Despite the rapidly grown knowledge about the primary defects in aHUS, the pathogenesis that links complement dysregulation with microthrombus formation in aHUS is still unknown. Thus, we examined the glomerular microvascular expression of pro-and antithrombotic genes. Glomeruli were microdissected from 12 archival paraffinembedded biopsies with aHUS and from seven control biopsies. Glomerular mRNA expression was quantified by single real-time PCR reactions after preamplification. In addition immunostains were performed for plasminogen activator inhibitor 1 (PAI-1) and for tissue plasminogen activator (tPA). Results were compared between cases and controls and with clinical data. Glomeruli in aHUS had increased mRNA expression of antifibrinolytic, prothrombotic PAI-1, antithrombotic thrombomodulin (THBD) and CD73 and decreased expression of profibrinolytic, antithrombotic tPA compared to controls. Impaired fibrinolysis due to increased microvascular expression of the antifibrinolytic PAI-1 in combination with the decreased expression of the profibrinolytic tPA seems to be a final common pathway in renal thrombotic microangiopathy that is also effective in aHUS. The concomitant induction of antithrombotic transcripts likely indicates counterregulatory efforts, demonstrating

Transplantation Journal, 2012

Introduction: Metabolomics is a system approach used also to investigate the metabolic profile by... more Introduction: Metabolomics is a system approach used also to investigate the metabolic profile by multivariate data analysis tools. NMR spectroscopy is a analytical platform for biological matrices, it enables the quick generation of spectral profiles of low molecular weights metabolites. The aim of the work is to control the kidney graft recovery process in an non-invasive way, estimating the process by 1H-NMR spectroscopy and chemometrics on urine samples as they contains metabolites concerning the pathological and clinical state of the patients. Methods: In the study 15 patients (9 males and 6 females) have been followed during the kidney graft recovery process and the first follow up days. Samples have been collected every day, for each patient. In order to develop a model that was able to describe the recovery process from a general point of view, all the data from the patient cohort have been studied together. Results: The chemometric model is able to describe the whole cohort of patients, as each patients follow its own path to recovery, moving to one state to the other only when “time has come“. The model has as many clusters as the clinical states are, and it doesn‘t matter for how long each single patient stay into those clusters because we used a daily based sampling. In order to analyse the changes in metabolic pattern that are connected to the recovery process, we used the typical two steps analytical procedure (often used in metabolomics): first we use an unsupervised technique, Principal Components Analysis, to find trajectories and clustering, then we model the system by using a classification technique, Partial Least Square Discriminant Analysis. The global model, that reveal a clear three stage progress recovery, common to all the patients (figure 1), has been used as a reference model to asses anomalous patients behaviour. The model is made of a first stage, when the kidney is not still working, then a stage characterised by a recovery of the kidney capabilities and functions. These two stages are rather often clearly detached. The third stage is the follow up stage, in that case samples result to be far from the ones collected during the hospital stay. All those stages are characterised by well defined metabolic patterns.

Transplantation Journal, 2012

Transplantation, 2006

Cold ischemia and reperfusion during renal transplantation result in release of reactive oxygen s... more Cold ischemia and reperfusion during renal transplantation result in release of reactive oxygen species. The aim of this study is to examine whether cold storage induced cell injury can be ameliorated by adding flavonoids directly to preservation solutions. Cultured renal tubular epithelial cells (LLC-PK1) were stored in University of Wisconsin (UW) or Euro-Collins (EC) solution at 4 degrees C for 20 hours. Preservation solutions were supplemented with various flavonoids. After rewarming, structural and metabolic cell integrity was measured by lactate dehydrogenase (LDH) release and MTT-test, and lipid peroxidation was assessed from generation of thiobarbituric acid-reactive substances (TBARS). Twenty hours of cold storage resulted in a substantial loss of cell viability in both preservation solutions (in EC: LDH release 92.4+/-2.7%; MTT-test 0.5+/-0.7%). Addition of luteolin, quercetin, kempferol, fisetin, myricetin, morin, catechin, and silibinin significantly reduced cell injury (for luteolin in EC: LDH release 2.4+/-1.6%; MTT-test 110.3+/-10.4%, P<0.01; TBARS-production (related to cold stored control cells) 8.9+/-2.6%). No cytoprotection was found for apigenin, naringenin, and rutin. Protective potency of flavonoids depends on number of hydroxyl-substituents and lipophilicity of the diphenylpyran compounds. Cold storage induced injury of renal tubular cells was substantially ameliorated by adding selected flavonoids directly to preservation solutions.

Pediatric Transplantation, 2008

Recent improvements in immunosuppressive regimens after renal transplantation have increased one ... more Recent improvements in immunosuppressive regimens after renal transplantation have increased one yr graft survival rates to over 90% in adult (1) and paediatric (2) recipients. This improvement is mainly due to the reduction of acute rejection episodes by combined antibody induction therapies plus the use of CNI. However, long-term graft function is reduced by TN. The addition of MMF reversed the progressive loss of GFR in approximately two-thirds of children with TN for at least one yr (3). In many centres, a combination therapy with MMF and a low-dose CNI has become the

Pediatric Transplantation, 2007

Recent improvements in immunosuppressive regimens after renal transplantation have increased one-... more Recent improvements in immunosuppressive regimens after renal transplantation have increased one-yr graft survival rates to better than 90% in adult (1) and pediatric (2) recipients. This improvement is mainly due to the reduction of acute rejection episodes. However, long-term graft survival rates have changed less substantially. TN is the single most important factor for subsequent loss of function (3-5). TN is a multifactorial process based on immunologic and non-immunologic factors (6). Pape L, Ahlenstiel T, Ehrich JHH, Offner G. Reversal of loss of glomerular filtration rate in children with transplant nephropathy after switch to everolimus and low-dose cyclosporine A.

Pediatric Transplantation, 2009

Pediatric Nephrology, 2014

The aim of this study was to analyze the neurological involvement and outcome in pediatric patien... more The aim of this study was to analyze the neurological involvement and outcome in pediatric patients with hemolytic uremic syndrome (HUS) during the 2011 epidemic caused by Escherichia coli O104:H4. Clinical data and data from magnetic resonance imaging (MRI) scans and electroencephalography (EEG) during the acute phase of the disease and during follow-up at 3 and 6 months were analyzed in 50 patients. Twenty-five of these patients underwent neuropsychological testing (WISC IV) during follow-up. Neurological involvement (stupor or coma, seizures, visual disturbances, paresis, myocloni) was initially observed in 14/50 (28%) patients. One patient died. EEG abnormalities were more frequent in patients with neurological involvement than in those without (12/14 vs. 13/25, respectively). Cranial MRI scans were analyzed in nine patients with neurological involvement, of whom five showed abnormal findings. At the 3- and 6-month follow-ups, EEG abnormalities were found in 14/40 (35%) and 7/36 (19%) patients, respectively, whereas 28/42 (67%) and 17/39 (44%) patients, respectively, complained about on-going reduced performance. Neuropsychological testing showed a slightly lower global intelligence quotient in patients with neurological involvement versus those without (113.4 ± 2.8 vs. 119.4 ± 1.8, respectively). Neurological involvement was frequent in our cohort. Accordingly, the incidence of pathological EEG findings was high, even in patients without clinical signs of neurological involvement. Nevertheless, major neurological sequelae were rare, and neuropsychological outcome was favorable after 6 months.

Pediatric Nephrology, 2008

Childhood hemolytic uremic syndrome (HUS) is most often caused by enterohemorrhagic Escherichia c... more Childhood hemolytic uremic syndrome (HUS) is most often caused by enterohemorrhagic Escherichia coli (EHEC). Due to severe hemolysis, red blood cell (RBC) transfusions are often necessary, and anemia is aggravated by low erythropoietin (EPO) levels caused by acute renal failure. In a single center, prospective study, we randomized ten children with EHEC-positive HUS into two therapeutic groups: one receiving EPO treatment (median age 2 years, age range 1-3 years) and the other receiving standard therapy (median age 2 years, age range 1-6 years). Red blood cell transfusions were performed when the hemoglobin level (Hb) fell below 5 mg/dl. The number of RBC transfusions was compared in both groups. The Hb level at admission was comparable between both groups (6.4 vs. 8.1 mg/dl, P>0.05, t-test). However, children in the EPO group required a significantly lower mean number of RBCs than those in the non-EPO group (0.2 vs. 1.4, P<0.04, t-test). Based on these results, we suggest that the early administration of EPO at the time of hemolytic anemia and beginning renal failure may attenuate renal anemia in children with EHEC-induced HUS and thereby reduce the number of RBC transfusions required. The results of this pilot study will have to be confirmed in a larger multicenter trial.

Pediatric Nephrology, 2010

Regional citrate anticoagulation (RCA) has been considered to be a standard component of pediatri... more Regional citrate anticoagulation (RCA) has been considered to be a standard component of pediatric apheresis therapy for more than a decade. However, data on dosing recommendations and evaluations of the effectiveness and safety of anticoagulation are rarely found in published reports. The aim of this retrospective analysis was to present our single-center experience with RCA in pediatric apheresis therapy with the aim of developing an operating procedure. Five children aged 7-14 years underwent a total of 72 (range 3-44) therapeutic apheresis sessions with RCA in the form of immunoadsorption therapy (2 patients), low-density lipoprotein (LDL)-apheresis (1 patient), and plasmapheresis (two patients). A 3% citrate solution was used. Citrate flow was started at 4.0% of the blood flow velocity and was adapted to match post-filter ionized calcium levels ≤ 0.30 mmol/l. Once the patient&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s ionized calcium fell to &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;1.05 mmol/l, an intravenous 10% calcium gluconate solution was administered. Twenty pediatric apheresis patients who received standard heparinization, matched for age, body surface area, processed plasma volume, and blood flow velocity, were enrolled in the study as a comparison group. No side effects were experienced in 72 apheresis session. The 3% citrate solution had to be reduced gradually during the apheresis session and was infused at a mean of 2.8-3.8% of the blood flow rate. Serum bicarbonate levels before and after the apheresis session with RCA [23.9 (range 18.9-30.1) vs. 26.3 (20.2-33.0) mmol/l, respectively] were significantly different (p=0.013). All patients required intravenous calcium substitution to maintain serum calcium levels within the physiological range. Due to the administration of the 3% citrate solution and calcium, all patients significantly gained weight during the procedure, with a median weight gain of 2.5% (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). The extra fluid load caused problems in patients with kidney failure. Our regimen with RCA is safe, feasible, and effective in pediatric therapeutic apheresis therapy. For RCA in apheresis, we recommend (1) a citrate (3%) flow of 3.3% of the blood flow, (2) prophylactic intravenous calcium substitution from the beginning, and (3) a more highly concentrated citrate solution in the case of oliguric patients.

Pediatric Nephrology, 2010

Recent years has seen an increasing use of regional citrate anticoagulation in pediatric dialysis... more Recent years has seen an increasing use of regional citrate anticoagulation in pediatric dialysis. Several approaches have been described for monitoring anticoagulation in the extracorporeal circuit, such as serum citrate levels, post-filter ionized calcium (iCa), and activated coagulation time (ACT). However, no standard recommendations have yet been established for applying any of these parameters, especially for iCa. The objective of this retrospective analysis was to establish adequate coagulation management using post-filter iCa values. Normal values for ACTester-based ACT were established using a group of 64 children who were divided into two subgroups, with one subgroup comprising children without chronic kidney disease or coagulation disorder (age 1.2-17.5 years, median 9.7 years) and one consisting of 32 uremic patients (age 0.6-17.5 years, median 13.7 years). In a second group of 13 patients (aged 7-17 years), all of whom were undergoing high-flux dialysis (HD) with regional citrate anticoagulation (RCA), we assessed 73 post-filter blood samples for ionized calcium and ACT. A receiver operating characteristic graph was used to identify the iCa threshold needed to achieve adequate anticoagulation. Normal values for ACT were 90 s [2 standard deviations (SD) 72-109] in healthy children and 94 s (2 SD 75-113) in the uremic children. There was no statistically significant difference between the groups. In the children undergoing HD with RCA, the post-filter iCa level correlated with ACT (r = -0.94, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). A post-filter iCa level of &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or = 0.30 mmol/l reliably predicted an ACT &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;120 s. Our citrate protocol [citrate 3% rate (ml/h) approximately blood flow rate (ml/min) x 2] meets the established criteria with a high sensitivity. Based on these results, we conclude that the post-filter iCa level can be reliably used for the management of extracorporeal anticoagulation with citrate in pediatric HD. We recommend the application of our citrate prescription protocol in the setting of pediatric intermittent hemodialysis.

Pediatric Nephrology, 2012

Background No adequate statistical model has been established to estimate future glomerular filtr... more Background No adequate statistical model has been established to estimate future glomerular filtration rate (GFR) in children after kidney transplantation (KTX). Equations based on simple linear regression analysis as used in adults are not established in children. Methods An optimal prognostic model of GFR was generated for 63 children at 3-7 years after KTX. The main regression model for prediction of the log-transformed GFR (logGFR) included the mean monthly change of GFR in the period 3-24 months after KTX (ΔGFR), the baseline GFR at 3 months (bGFR), and an intercept. Additionally, we investigated if the inclusion of cofactors leads to more precise predictions. The model was validated by leaveone-out cross-validation for years 3-7 after KTX. Prognostic quality was determined with the mean squared error (MSE) and mean absolute error (MAE). Results were compared with the simple linear regression model used in adults. Results The following statistical model was calculated for every prognosis year (i03, …, 7): Y i ¼ b i0 þ b i1 Á X i1 þ b i2 Á X i2 þ " i logðGFR i Þ ¼ b i0 þ b i1 Á ΔGFR þ b i2 Á bGFR Comparison of the new statistical model and the simple linear model for adults led to relevantly lower MSEs and MAEs for the new model (year 7: New model: MSE 0.1, MAE 0.3/adult model: MSE 1069, MAE 18). The benefit of inclusion of cofactors was not relevant. Conclusions This statistical model is able to predict longterm graft function in children with very high precision.

Kidney International, 2010

The mineral and bone disorder of chronic kidney disease remains a challenging complication in ped... more The mineral and bone disorder of chronic kidney disease remains a challenging complication in pediatric end-stage renal disease. Here, we assessed symptoms, risk factors and management of this disorder in 890 children and adolescents from 24 countries reported to the International Pediatric Peritoneal Dialysis Network Registry. Signs of this disease were most common in North American patients. The prevalence of hyperphosphatemia increased with age from 6% in young infants to 81% in adolescents. Serum parathyroid hormone (PTH) was outside the guideline targets in the majority of patients and associated with low calcium, high phosphorus, acidosis, dialysis vintage and female gender. Serum calcium was associated with dialytic calcium exposure, serum phosphorus with low residual renal function and pubertal status. PTH levels were highest in Latin America and lowest in Europe. Vitamin D and its active analogs were most frequently administered in Europe; calcium-free phosphate binders and cinacalcet in North America. Clinical and radiological symptoms markedly increased when PTH exceeded 300 pg/ml, the risk of hypercalcemia increased with levels below 100 pg/ml, and time-averaged PTH concentrations above 500 pg/ml were associated with impaired longitudinal growth. Hence, the symptoms and management of the mineral and bone disorder of chronic kidney disease in children on peritoneal dialysis showed substantial regional variation. Our findings support a PTH target range of 100-300 pg/ml in the pediatric age group.

Transplantation, 2008

was 4 years (range 0.75-14 years), and the causes were acute hepatitis A in 4 and unknown in 9. S... more was 4 years (range 0.75-14 years), and the causes were acute hepatitis A in 4 and unknown in 9. Short-term complications, documented in 12 children, included mainly hepatic artery thrombosis, which warranted retransplantation in 3 cases, and biliary leaks repaired either by surgery or by invasive radiology. Three patients died during the fi rst month after LDLT of uncontrolled intraoperative bleeding (n=1), sepsis (n=1) and multiorgan failure (n=1). Long term complications were less common, and included ascending cholangitis and graft rejections. Patient survival rate was 69% and 62% at 1 and 5 years, respectively. None of the donors had long term complications. Conclusions: Although the outcomes of LDLT in children with FHF seems inferior to that in children after elective transplantations for chronic liver diseases, the procedure is timely, life-saving and could reduce the dependence on cadaveric donation in this setting.

Transplant International, 2013

Concerns have been raised that mammalian target of rapamycin inhibitors in pediatric transplant r... more Concerns have been raised that mammalian target of rapamycin inhibitors in pediatric transplant recipients might interfere with longitudinal bone growth by inhibition of growth factor signaling and growth plate chondrocyte proliferation. We therefore undertook a prospective nested, case-control study on longitudinal growth over 2 years in steroid-free pediatric renal transplant recipients. Fourteen patients on a steroid-free maintenance immunosuppressive regimen consisting of low-dose everolimus (EVR) in conjunction with low-dose cyclosporine (CsA) were compared to a matched cohort of 14 steroid-free patients on a standard dose mycophenolate mofetil (MMF) regimen in conjunction with a standard dose calcineurin inhibitor (CNI). The mean change in height standard deviation (SD) score in the first study year was 0.31 ± 0.71 SD score in the EVR group compared to 0.31 ± 0.64 SD score in the MMF group (P = 0.20). For the entire study period of 2 years, the change in height SD score in the EVR group was 0.43 ± 0.81 SDS compared to 0.75 ± 0.85 SDS in the MMF group (P = 0.32). The percentage of prepubertal patients experiencing catch-up growth, defined as an increase in height SD score ≥0.5 in 2 years, was similar in the EVR group (5/8, 65%) and the MMF group (6/8, 75%; P = 1.00). Longitudinal growth over 2 years in steroid-free pediatric patients on low-dose EVR and CsA is not different to that of a matched steroid-free control group on an immunosuppressive regimen with standard-dose CNI and MMF. Hence, low-dose EVR does not appear to negatively impact short-term growth in pediatric renal transplant recipients.

Pediatric Nephrology, 2014

Acute antibody-mediated rejection is a diagnostic challenge in renal transplantation medicine. Ho... more Acute antibody-mediated rejection is a diagnostic challenge in renal transplantation medicine. However, it is an important diagnosis to make, since chronic antibody-mediated rejection (CAMR) is the main cause of long-term graft loss. Antibody-mediated rejection is diagnosed by detecting donorspecific antibodies (DSAs) in the blood in combination with observing typical histomorphological signs in kidney biopsy, as described in the Banff classification. Therapy is based on the removal of DSAs by administering intravenous immunoglobulins (IVIGs), plasmapheresis, or immunoadsorption. Reoccurrence of antibodies is diminished by the use of rituximab, increased immunosuppression, and in some cases additional experimental substances. A combination of these techniques has been shown to be successful in the majority of cases of acute and chronic antibody-mediated rejection. Routine DSA monitoring is warranted for early detection of antibody-mediated rejection.

Current Opinion in Organ Transplantation, 2012

The use of everolimus has recently emerged for solid-organ transplantation in children. This revi... more The use of everolimus has recently emerged for solid-organ transplantation in children. This review gives an overview of the relevant studies and clinical trials involving the immunosuppressive effects of everolimus in child organ transplant. The use of everolimus in pediatric organ transplantation is associated with a decrease in calcineurin inhibitor-related toxicity, better renal function, a low number of acute rejections, and an acceptable side-effect profile. Particularly, the use of everolimus reduces the incidence of virus infection and the risk of posttransplant lymphoproliferative disease. Everolimus is an effective agent with several advantages for pediatric solid-organ transplantation. Future prospective, randomized controlled trials will have to be performed in order to validate the findings of these pilot trials.

Transplantation, 2013

Thrombotic microangiopathy (TMA) in renal transplants (rTx-TMA) is a serious complication and is ... more Thrombotic microangiopathy (TMA) in renal transplants (rTx-TMA) is a serious complication and is usually either recurrent TMA (RecTMA) due to humoral rejection (HR-TMA) or due to calcineurin inhibitor toxicity (CNI-TMA). Although the triggers are known, our knowledge about the thrombogenic transcriptome changes in the microvessels is rudimentary. We examined the expression of several prothrombotic and antithrombotic genes in 25 biopsies with rTx-TMA (6 RecTMA, 9 HR-TMA, and 10 CNI-TMA) and 8 controls. RNA from microdissected glomeruli of paraffin-embedded tissue was isolated and mRNA transcripts were quantified with real-time polymerase chain reaction after preamplification. Results were correlated with clinicopathologic parameters. Glomerular mRNA expression of KLF2, KLF4, and tPA was lower and that of PAI-1 was higher in rTx-TMA than in the controls. Glomerular mRNA expression of KLF2 and KLF4 correlated with that of tPA and inversely with that of PAI-1 in rTx-TMA. The mRNA expression of complement regulators CD46 and CD59 were higher in rTx-TMA than in the controls. Only in HR-TMA were glomerular ADAMTS13 and CD55 down-regulated. The glomerular capillary bed seems to contribute to all subtypes of rTx-TMA by down-regulation of the endothelial transcription factors KLF2 and KLF4, indicating dedifferentiation with subsequent up-regulation of PAI-1 and down-regulation of tPA, resulting in inhibition of local fibrinolysis. Decreased glomerular expression of ADAMTS13 and CD55 could be an additional pathway toward microthrombosis exclusively in HR-TMA.

Xenotransplantation, 2006

Antigen-specific immunoadsorption combined with rituximab offers the possibility for ABO-incompat... more Antigen-specific immunoadsorption combined with rituximab offers the possibility for ABO-incompatible kidney transplantation without splenectomy. An 8-year-old mentally retarded girl with steroid-resistant nephrotic syndrome and focal segmental glomerulosclerosis due to mitochondriopathy poorly tolerated hemodialysis. Paternal blood group A1B was incompatible with blood group B of the child. Therefore, we decided to perform the first ABO-incompatible renal transplantation in a child in Germany using antigen-specific immunoadsorption. Rituximab (1 x 375 mg/m2) was administered 2 weeks before the first immunoadsorption (Glycosorb) ABO A-column). Triple-drug immunosuppression (tacrolimus, mycophenolate mofetil and prednisolone) was simultaneously started with immunoadsorption. Initial tacrolimus levels were targeted between 15 and 20 ng/ml. Before transplantation, six immunoadsorptions were applied on days -9, -7, -4, -3, -2 and -1. Intravenous immunoglobulin (0.5 g/kg) was administered preoperatively. After transplantation, three immunoadsorptions were performed on days +4, +6 and +8. Before transplantation, antibody (Ab) titers against paternal erythrocytes (20 degrees C) were reduced from 1 : 64 to 1 : 4 by six antigen-specific immunoadsorptions. After transplantation, we performed three more immunoadsorptions and the Ab titers were stable between 1 : 1 and 1 : 8. One, 2 and 8 months later we observed increases in the Ab titer up to 1 : 32 requiring no change in immunosuppressive therapy. No side effects of immunoadsorption were observed. The girl had excellent initial graft function with a serum creatinine of 55 to 70 micromol/l. Two weeks after transplantation, graft biopsy showed no signs of rejection; there was focal positivity for C4d only. Twelve months after transplantation, renal function was stable, with a serum creatinine of 117 micromol/l. Episodes of rejection or severe infections were absent. ABO-incompatible transplantation using antigen-specific immunoadsorption and rituximab may serve as a suitable alternative for children urgently needing renal transplantation and missing a blood group-compatible donor.

Virchows Archiv, 2013

Atypical haemolytic-uremic syndrome (aHUS) is, in most cases, due to hereditary or acquired defec... more Atypical haemolytic-uremic syndrome (aHUS) is, in most cases, due to hereditary or acquired defects in complement regulation and a life-threatening disease. Despite the rapidly grown knowledge about the primary defects in aHUS, the pathogenesis that links complement dysregulation with microthrombus formation in aHUS is still unknown. Thus, we examined the glomerular microvascular expression of pro-and antithrombotic genes. Glomeruli were microdissected from 12 archival paraffinembedded biopsies with aHUS and from seven control biopsies. Glomerular mRNA expression was quantified by single real-time PCR reactions after preamplification. In addition immunostains were performed for plasminogen activator inhibitor 1 (PAI-1) and for tissue plasminogen activator (tPA). Results were compared between cases and controls and with clinical data. Glomeruli in aHUS had increased mRNA expression of antifibrinolytic, prothrombotic PAI-1, antithrombotic thrombomodulin (THBD) and CD73 and decreased expression of profibrinolytic, antithrombotic tPA compared to controls. Impaired fibrinolysis due to increased microvascular expression of the antifibrinolytic PAI-1 in combination with the decreased expression of the profibrinolytic tPA seems to be a final common pathway in renal thrombotic microangiopathy that is also effective in aHUS. The concomitant induction of antithrombotic transcripts likely indicates counterregulatory efforts, demonstrating

Transplantation Journal, 2012

Introduction: Metabolomics is a system approach used also to investigate the metabolic profile by... more Introduction: Metabolomics is a system approach used also to investigate the metabolic profile by multivariate data analysis tools. NMR spectroscopy is a analytical platform for biological matrices, it enables the quick generation of spectral profiles of low molecular weights metabolites. The aim of the work is to control the kidney graft recovery process in an non-invasive way, estimating the process by 1H-NMR spectroscopy and chemometrics on urine samples as they contains metabolites concerning the pathological and clinical state of the patients. Methods: In the study 15 patients (9 males and 6 females) have been followed during the kidney graft recovery process and the first follow up days. Samples have been collected every day, for each patient. In order to develop a model that was able to describe the recovery process from a general point of view, all the data from the patient cohort have been studied together. Results: The chemometric model is able to describe the whole cohort of patients, as each patients follow its own path to recovery, moving to one state to the other only when “time has come“. The model has as many clusters as the clinical states are, and it doesn‘t matter for how long each single patient stay into those clusters because we used a daily based sampling. In order to analyse the changes in metabolic pattern that are connected to the recovery process, we used the typical two steps analytical procedure (often used in metabolomics): first we use an unsupervised technique, Principal Components Analysis, to find trajectories and clustering, then we model the system by using a classification technique, Partial Least Square Discriminant Analysis. The global model, that reveal a clear three stage progress recovery, common to all the patients (figure 1), has been used as a reference model to asses anomalous patients behaviour. The model is made of a first stage, when the kidney is not still working, then a stage characterised by a recovery of the kidney capabilities and functions. These two stages are rather often clearly detached. The third stage is the follow up stage, in that case samples result to be far from the ones collected during the hospital stay. All those stages are characterised by well defined metabolic patterns.

Transplantation Journal, 2012

Transplantation, 2006

Cold ischemia and reperfusion during renal transplantation result in release of reactive oxygen s... more Cold ischemia and reperfusion during renal transplantation result in release of reactive oxygen species. The aim of this study is to examine whether cold storage induced cell injury can be ameliorated by adding flavonoids directly to preservation solutions. Cultured renal tubular epithelial cells (LLC-PK1) were stored in University of Wisconsin (UW) or Euro-Collins (EC) solution at 4 degrees C for 20 hours. Preservation solutions were supplemented with various flavonoids. After rewarming, structural and metabolic cell integrity was measured by lactate dehydrogenase (LDH) release and MTT-test, and lipid peroxidation was assessed from generation of thiobarbituric acid-reactive substances (TBARS). Twenty hours of cold storage resulted in a substantial loss of cell viability in both preservation solutions (in EC: LDH release 92.4+/-2.7%; MTT-test 0.5+/-0.7%). Addition of luteolin, quercetin, kempferol, fisetin, myricetin, morin, catechin, and silibinin significantly reduced cell injury (for luteolin in EC: LDH release 2.4+/-1.6%; MTT-test 110.3+/-10.4%, P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01; TBARS-production (related to cold stored control cells) 8.9+/-2.6%). No cytoprotection was found for apigenin, naringenin, and rutin. Protective potency of flavonoids depends on number of hydroxyl-substituents and lipophilicity of the diphenylpyran compounds. Cold storage induced injury of renal tubular cells was substantially ameliorated by adding selected flavonoids directly to preservation solutions.

Pediatric Transplantation, 2008

Recent improvements in immunosuppressive regimens after renal transplantation have increased one ... more Recent improvements in immunosuppressive regimens after renal transplantation have increased one yr graft survival rates to over 90% in adult (1) and paediatric (2) recipients. This improvement is mainly due to the reduction of acute rejection episodes by combined antibody induction therapies plus the use of CNI. However, long-term graft function is reduced by TN. The addition of MMF reversed the progressive loss of GFR in approximately two-thirds of children with TN for at least one yr (3). In many centres, a combination therapy with MMF and a low-dose CNI has become the

Pediatric Transplantation, 2007

Recent improvements in immunosuppressive regimens after renal transplantation have increased one-... more Recent improvements in immunosuppressive regimens after renal transplantation have increased one-yr graft survival rates to better than 90% in adult (1) and pediatric (2) recipients. This improvement is mainly due to the reduction of acute rejection episodes. However, long-term graft survival rates have changed less substantially. TN is the single most important factor for subsequent loss of function (3-5). TN is a multifactorial process based on immunologic and non-immunologic factors (6). Pape L, Ahlenstiel T, Ehrich JHH, Offner G. Reversal of loss of glomerular filtration rate in children with transplant nephropathy after switch to everolimus and low-dose cyclosporine A.

Pediatric Transplantation, 2009

Pediatric Nephrology, 2014

The aim of this study was to analyze the neurological involvement and outcome in pediatric patien... more The aim of this study was to analyze the neurological involvement and outcome in pediatric patients with hemolytic uremic syndrome (HUS) during the 2011 epidemic caused by Escherichia coli O104:H4. Clinical data and data from magnetic resonance imaging (MRI) scans and electroencephalography (EEG) during the acute phase of the disease and during follow-up at 3 and 6 months were analyzed in 50 patients. Twenty-five of these patients underwent neuropsychological testing (WISC IV) during follow-up. Neurological involvement (stupor or coma, seizures, visual disturbances, paresis, myocloni) was initially observed in 14/50 (28%) patients. One patient died. EEG abnormalities were more frequent in patients with neurological involvement than in those without (12/14 vs. 13/25, respectively). Cranial MRI scans were analyzed in nine patients with neurological involvement, of whom five showed abnormal findings. At the 3- and 6-month follow-ups, EEG abnormalities were found in 14/40 (35%) and 7/36 (19%) patients, respectively, whereas 28/42 (67%) and 17/39 (44%) patients, respectively, complained about on-going reduced performance. Neuropsychological testing showed a slightly lower global intelligence quotient in patients with neurological involvement versus those without (113.4 ± 2.8 vs. 119.4 ± 1.8, respectively). Neurological involvement was frequent in our cohort. Accordingly, the incidence of pathological EEG findings was high, even in patients without clinical signs of neurological involvement. Nevertheless, major neurological sequelae were rare, and neuropsychological outcome was favorable after 6 months.

Pediatric Nephrology, 2008

Childhood hemolytic uremic syndrome (HUS) is most often caused by enterohemorrhagic Escherichia c... more Childhood hemolytic uremic syndrome (HUS) is most often caused by enterohemorrhagic Escherichia coli (EHEC). Due to severe hemolysis, red blood cell (RBC) transfusions are often necessary, and anemia is aggravated by low erythropoietin (EPO) levels caused by acute renal failure. In a single center, prospective study, we randomized ten children with EHEC-positive HUS into two therapeutic groups: one receiving EPO treatment (median age 2 years, age range 1-3 years) and the other receiving standard therapy (median age 2 years, age range 1-6 years). Red blood cell transfusions were performed when the hemoglobin level (Hb) fell below 5 mg/dl. The number of RBC transfusions was compared in both groups. The Hb level at admission was comparable between both groups (6.4 vs. 8.1 mg/dl, P>0.05, t-test). However, children in the EPO group required a significantly lower mean number of RBCs than those in the non-EPO group (0.2 vs. 1.4, P<0.04, t-test). Based on these results, we suggest that the early administration of EPO at the time of hemolytic anemia and beginning renal failure may attenuate renal anemia in children with EHEC-induced HUS and thereby reduce the number of RBC transfusions required. The results of this pilot study will have to be confirmed in a larger multicenter trial.

Pediatric Nephrology, 2010

Regional citrate anticoagulation (RCA) has been considered to be a standard component of pediatri... more Regional citrate anticoagulation (RCA) has been considered to be a standard component of pediatric apheresis therapy for more than a decade. However, data on dosing recommendations and evaluations of the effectiveness and safety of anticoagulation are rarely found in published reports. The aim of this retrospective analysis was to present our single-center experience with RCA in pediatric apheresis therapy with the aim of developing an operating procedure. Five children aged 7-14 years underwent a total of 72 (range 3-44) therapeutic apheresis sessions with RCA in the form of immunoadsorption therapy (2 patients), low-density lipoprotein (LDL)-apheresis (1 patient), and plasmapheresis (two patients). A 3% citrate solution was used. Citrate flow was started at 4.0% of the blood flow velocity and was adapted to match post-filter ionized calcium levels ≤ 0.30 mmol/l. Once the patient&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s ionized calcium fell to &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;1.05 mmol/l, an intravenous 10% calcium gluconate solution was administered. Twenty pediatric apheresis patients who received standard heparinization, matched for age, body surface area, processed plasma volume, and blood flow velocity, were enrolled in the study as a comparison group. No side effects were experienced in 72 apheresis session. The 3% citrate solution had to be reduced gradually during the apheresis session and was infused at a mean of 2.8-3.8% of the blood flow rate. Serum bicarbonate levels before and after the apheresis session with RCA [23.9 (range 18.9-30.1) vs. 26.3 (20.2-33.0) mmol/l, respectively] were significantly different (p=0.013). All patients required intravenous calcium substitution to maintain serum calcium levels within the physiological range. Due to the administration of the 3% citrate solution and calcium, all patients significantly gained weight during the procedure, with a median weight gain of 2.5% (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). The extra fluid load caused problems in patients with kidney failure. Our regimen with RCA is safe, feasible, and effective in pediatric therapeutic apheresis therapy. For RCA in apheresis, we recommend (1) a citrate (3%) flow of 3.3% of the blood flow, (2) prophylactic intravenous calcium substitution from the beginning, and (3) a more highly concentrated citrate solution in the case of oliguric patients.

Pediatric Nephrology, 2010

Recent years has seen an increasing use of regional citrate anticoagulation in pediatric dialysis... more Recent years has seen an increasing use of regional citrate anticoagulation in pediatric dialysis. Several approaches have been described for monitoring anticoagulation in the extracorporeal circuit, such as serum citrate levels, post-filter ionized calcium (iCa), and activated coagulation time (ACT). However, no standard recommendations have yet been established for applying any of these parameters, especially for iCa. The objective of this retrospective analysis was to establish adequate coagulation management using post-filter iCa values. Normal values for ACTester-based ACT were established using a group of 64 children who were divided into two subgroups, with one subgroup comprising children without chronic kidney disease or coagulation disorder (age 1.2-17.5 years, median 9.7 years) and one consisting of 32 uremic patients (age 0.6-17.5 years, median 13.7 years). In a second group of 13 patients (aged 7-17 years), all of whom were undergoing high-flux dialysis (HD) with regional citrate anticoagulation (RCA), we assessed 73 post-filter blood samples for ionized calcium and ACT. A receiver operating characteristic graph was used to identify the iCa threshold needed to achieve adequate anticoagulation. Normal values for ACT were 90 s [2 standard deviations (SD) 72-109] in healthy children and 94 s (2 SD 75-113) in the uremic children. There was no statistically significant difference between the groups. In the children undergoing HD with RCA, the post-filter iCa level correlated with ACT (r = -0.94, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). A post-filter iCa level of &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or = 0.30 mmol/l reliably predicted an ACT &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;120 s. Our citrate protocol [citrate 3% rate (ml/h) approximately blood flow rate (ml/min) x 2] meets the established criteria with a high sensitivity. Based on these results, we conclude that the post-filter iCa level can be reliably used for the management of extracorporeal anticoagulation with citrate in pediatric HD. We recommend the application of our citrate prescription protocol in the setting of pediatric intermittent hemodialysis.

Pediatric Nephrology, 2012

Background No adequate statistical model has been established to estimate future glomerular filtr... more Background No adequate statistical model has been established to estimate future glomerular filtration rate (GFR) in children after kidney transplantation (KTX). Equations based on simple linear regression analysis as used in adults are not established in children. Methods An optimal prognostic model of GFR was generated for 63 children at 3-7 years after KTX. The main regression model for prediction of the log-transformed GFR (logGFR) included the mean monthly change of GFR in the period 3-24 months after KTX (ΔGFR), the baseline GFR at 3 months (bGFR), and an intercept. Additionally, we investigated if the inclusion of cofactors leads to more precise predictions. The model was validated by leaveone-out cross-validation for years 3-7 after KTX. Prognostic quality was determined with the mean squared error (MSE) and mean absolute error (MAE). Results were compared with the simple linear regression model used in adults. Results The following statistical model was calculated for every prognosis year (i03, …, 7): Y i ¼ b i0 þ b i1 Á X i1 þ b i2 Á X i2 þ " i logðGFR i Þ ¼ b i0 þ b i1 Á ΔGFR þ b i2 Á bGFR Comparison of the new statistical model and the simple linear model for adults led to relevantly lower MSEs and MAEs for the new model (year 7: New model: MSE 0.1, MAE 0.3/adult model: MSE 1069, MAE 18). The benefit of inclusion of cofactors was not relevant. Conclusions This statistical model is able to predict longterm graft function in children with very high precision.