Factors influencing choice of renal replacement therapy in European paediatric nephrology units

Epidemiology and Outcomes of Children with Kidney Failure Receiving Kidney Replacement Therapy in Australia and New Zealand

Introduction

The incidence and outcomes of kidney replacement therapy (KRT) have been well-studied in adults, but much less so in children. This study aimed to investigate the epidemiology and outcomes of KRT in children in Australia and New Zealand from 2000 to 2020.

Methods

Children aged <18 years initiating KRT in Australia and New Zealand between January 1, 2000 and December 31, 2020 and reported to the Australia and New Zealand Dialysis and Transplant Registry were included. Patient survival, technique-survival, and graft survival were analyzed by Cox regression analyses.

Results

Overall, 1058 children (median [interquartile range (IQR)] age 11 [5-15] years, 41% female, 66% White) were followed-up with for a median period of 12.3 years. First KRT modalities were peritoneal dialysis (PD; 48%), hemodialysis (HD; 34%), and kidney transplantation (KT; 18%). Pre-emptive KT incidence was highest in Caucasian children (80.4%) and lowest in the Indigenous population (3.2%). There was no difference in 5-year patient survival rates between 2011 and 2020 (96.9%, 95% confidence interval [CI] 93.8-98.4) and the preceding decade, 2000-2010 (94.5%, 95% CI 90.4-96.8) (P = 0.79). There was no difference in 5-year death-censored technique survival between 2011 and 2020 (51.2%, 95% CI 39.1-62) and 2000-2010 (48.8%, 95% CI 40.5-56.6) (P = 0.27). However, 5-year derath-censored graft survival was significantly higher in 2011-2020 (88.4%, 95% CI 84.6-91.4) than in 2000-2010 (84.3%, 95% CI 80.4-87.5) (P < 0.001).

Conclusions

PD is the most commonly prescribed KRT modality for children in Australia and New Zealand. Patient-survival, technique-survival, and graft survival rates are excellent and graft survival has improved over the last 2 decades.

Care of the pediatric patient on chronic peritoneal dialysis

Peritoneal dialysis is the most commonly prescribed dialysis modality for infants and young children with kidney failure worldwide. Provision of high-quality care for the pediatric patient on chronic peritoneal dialysis requires a multidisciplinary approach and a strong collaboration with the patient and their caregiver. This article not only reviews current recommendations and advances in the care of pediatric patients on peritoneal dialysis with a focus on the provision of high-quality care and improvement in outcomes, but it also draws attention to health care disparities that exist locally and globally.

Safeguarding children and young people requiring kidney replacement therapy: challenges and potential opportunities

Kidney replacement therapy (KRT) makes considerable physical and psychological demands on children, young people and their families. The impact can be wide-ranging, affecting education, employment, mental health, finances and relationships for both child and caregiver. It is vitally important for those working with these families to recognise the psychosocial challenges they face and to know the range of interventions available. This article explores the psychosocial impact of KRT, considering opportunities to minimise risk and optimise outcomes for children, young people and their families.

Commentary on the NICE guideline on renal replacement therapy and conservative management

NICE Guideline NG107, “Renal replacement therapy and conservative management” (Renal replacement therapy and conservative management (NG107); 2018:1–33) was published in October 2018 and replaced the existing NICE guideline CG125, “Chronic Kidney Disease (Stage 5): peritoneal dialysis” (Chronic kidney disease (stage 5): peritoneal dialysis | Guidance | NICE; 2011) and NICE Technology Appraisal TA48, “Guidance on home compared with hospital haemodialysis for patients with end-stage renal failure”(Guidance on home compared with hospital haemodialysis for patients with end-stage renal failure (Technology appraisal guideline TA48); 2002) The aim of the NICE guideline (NG107) was to provide guidance on renal replacement therapy (RRT), including dialysis, transplant and conservative care, for adults and children with CKD Stages 4 and 5. The guideline is extremely welcomed by the Renal Association and it offers huge value to patients, clinicians, commissioners and key stakeholders. It overlaps and enhances current guidance published by the Renal Association including “Haemodialysis” (Clinical practice guideline: Haemodialysis; 2019) which was updated in 2019 after the publication of the NICE guideline, “Peritoneal Dialysis in Adults and Children” (Clinical practice guideline: peritoneal Dialysis in adults and children; 2017) and “Planning, Initiation & withdrawal of Renal Replacement Therapy” (Clinical practice guideline: planning, initiation and withdrawal of renal replacement therapy; 2014) (at present there are no plans to update this guideline).

There are several strengths to NICE guideline NG107 and we agree with and support the vast majority of recommendation statements in the guideline. This summary from the Renal Association discusses some of the key highlights, controversies, gaps in knowledge and challenges in implementation. Where there is disagreement with a NICE guideline statement, we have highlighted this and a new suggested statement has been written.

Depression and psychosocial burden among caregivers of children with chronic kidney disease

Background

More attention has recently targeted families of children with chronic kidney diseases displaying depressive symptoms and major psychosocial burden due to the long-standing nature of the illness and its alarming complications. A cross sectional comparative study was conducted to assess the rate of occurrence of both depression severity and psychological burden, personal and role strain in a sample of Egyptian caregivers of children with chronic kidney disease.

Results

Thirty caregivers of children with CKD were enrolled compared to 30 matched controls during a 6-month period. A short pre-designed sheet including socio-demographic data, and general medical, psychiatric and family history was used, and Beck Depression Inventory, Zarit Burden Interview, Holmes and Rahe Socioeconomic Stress Scale, and Occupational Stress Questionnaire were answered.

More than half of the caregivers of children with chronic kidney disease reported moderate depression (53.3%), while 30% and 16.7% reported mild and severe depression respectively. The majority of cases 80% had moderate psychological burden. And 70% of cases reported minimal socioeconomic stress compared to 40% in the control. Logistic regression analysis showed that ZBI and SRRS scores were significantly linked to depression and burden found in caregivers of children with CKD (P = 0.001 and 0.031) respectively.

Conclusion

The rate of occurrence of depression and psychological burden is significantly high in caregivers of children with chronic kidney disease; therefore, this population must be assessed and provided with liaison psychological rehabilitation.

Resident foreign patients receive adequate dialysis but fewer preemptive transplantations: data from the Italian pediatric dialysis registry

BACKGROUND

Sociocultural issues play a key role in children needing kidney replacement therapy (KRT).

METHODS

Data of incident patients < 18 years treated with chronic dialysis or preemptive kidney transplantation (pTx) between 2007 and 2016 were retrospectively collected from the Italian Pediatric Dialysis Registry; KRT modality and outcome were compared between patients with at least one non-Italian parent ("resident foreign patients," RFPs) and those from native parents ("domestic patients," DPs) and between the quinquennium 2007-2011 (period 1) and 2012-2016 (period 2).

RESULTS

We included 448 children (26.8% RFPs). The percentage of RFPs increased from 23 to 30.3% (p = 0.08) from periods 1 to 2. They were younger (6.7 vs. 9.4 years, p = 0.025) and less often treated with pTx (3.3 vs. 13.4%, p = 0.009) than DPs. The percentage of pTx increased from period 1 to 2 in RFPs only (8.4-18.6%, p = 0.006). Independent predictors of a lower probability of pTx were lower age, belonging to RFPs group, starting KRT in period 1 and focal segmental glomerulosclerosis or glomerulopathy as primary kidney disease. Peritoneal dialysis was the preferred dialysis modality in both groups. Age, primary kidney disease, and center size were independently associated with dialysis modality choice. Patient survival, waiting time to Tx, and dialysis modality survival were not different between the two groups.

CONCLUSIONS

The proportion of patients receiving KRT born from immigrant families increased in recent years in Italy. They were younger and less often treated with pTx than domestic patients. In case of dialysis, the outcome was not different between the two groups. Graphical abstract.

Factors influencing the timing of initiation of renal replacement therapy and choice of modality in children with end-stage kidney disease

BACKGROUND

Decision-making in pediatric end-stage renal disease (ESRD) is a complex process for patients, families, and physicians. We evaluated the factors influencing the timing of initiation of renal replacement therapy (RRT) and choice of modality in children with ESRD.

METHODS

We retrospectively reviewed the RRT decision-making process for all children up to 19 years of age with ESRD, who underwent RRT over an 11-year period (2004 to 2014), at a Canadian pediatric tertiary care center. RRT modalities included peritoneal dialysis (PD), hemodialysis (HD), pre-emptive kidney transplant (PKT), and continuous renal replacement therapy (CRRT).

RESULTS

Ninety-two patients progressed to ESRD. RRT was started electively for 58 patients, and urgently for 34 patients. For elective patients, modalities included PD (34%), HD (19%), and PKT (47%). The glomerular filtration rate at initiation of RRT was higher in patients who underwent PKT as opposed to dialysis (11.7 vs. 9.1 ml/min/1.73m²). Medical and quality of life factors, including fatigue and poor concentration, influenced the timing of initiation of elective RRT. Medical factors were primarily important in urgent RRT, including oligoanuria and metabolic disturbances. Medical factors, patient/family preference, and contextual factors such as location of residence influenced choice of modality.

CONCLUSIONS

Our study found that the decision-making process in ESRD is multifactorial and involves not only medical factors, but also assessment of social factors, quality of life, and patient/family preference. Bettering our understanding of this decision-making process will positively impact patients and families through more informed decision-making.

Colostomy in children on chronic peritoneal dialysis

BACKGROUND

This study aimed to evaluate outcome of children on chronic peritoneal dialysis (PD) with a concurrent colostomy.

METHODS

Patients were identified through the International Pediatric Peritoneal Dialysis Network (IPPN) registry. Matched controls were randomly selected from the registry. Data were collected through the IPPN database and a survey disseminated to all participating sites.

RESULTS

Fifteen centers reported 20 children who received chronic PD with a co-existing colostomy. The most common cause of end stage kidney disease was congenital anomalies of the kidney and urinary tract (n = 16, 80%). The main reason for colostomy placement was anorectal malformation (n = 13, 65%). The median age at colostomy creation and PD catheter (PDC) insertion were 0.1 (IQR, 0-2.2) and 2.8 (IQR 0.2-18.8) months, respectively. The colostomies and PDCs were present together for a median 18 (IQR, 4.9-35.8) months. The median age at PDC placement in 46 controls was 3.4 (IQR, 0.2-7.4) months of age. Fourteen patients (70%) developed 39 episodes of peritonitis. The annualized peritonitis rate was significantly higher in the colostomy group (1.13 vs. 0.70 episodes per patient year; p = 0.02). Predominant causative microorganisms were Staphylococcus aureus (15%) and Pseudomonas aeruginosa (13%). There were 12 exit site infection (ESI) episodes reported exclusively in colostomy patients. Seven colostomy children (35%) died during their course of PD, in two cases due to peritonitis.

CONCLUSION

Although feasible in children with a colostomy, chronic PD is associated with an increased risk of peritonitis and mortality. Continued efforts to reduce infection risk for this complex patient population are essential.

Clinical characteristics at the renal replacement therapy initiation of Japanese pediatric patients: a nationwide cross-sectional study

BACKGROUND

Although there is debate regarding the timing of initiation of renal replacement therapy (RRT) in adults with end-stage renal disease, there is a paucity of reliable epidemiological data on pediatric patients. The present study was performed to investigate current practice in Japan with regard to the timing of initiation of RRT in children based on estimated glomerular filtration rate (eGFR).

METHODS

A total of 649 pediatric patients < 20 years old with eGFR at the initiation of RRT between 1 January 2006 and 31 December 2013 were included in the study. Baseline eGFR was calculated for each patient using the Schwartz formula.

RESULTS

eGFR at the start of RRT was 12.1 mL/min/1.73 m² [interquartile range (IQR) 8.4-16.3]. A total of 209 children (32.2%) had high eGFR (eGFR > 15 mL/min/1.73 m²) at the initiation of RRT. Initiation of RRT was more likely in those undergoing preemptive transplantation (PEKT) with high eGFR [odds ratio (OR) 4.16; 95% confidence interval (CI) 1.95-8.90, P < 0.001]. There were 31 deaths of various causes during follow-up, with infections representing the leading causes of death.

CONCLUSIONS

The median eGFR at the initiation of RRT in children showed a wide range of variation. Further studies are needed to investigate the impact of the decision regarding when to initiate RRT in individual pediatric patients.

Vascular Access Choice, Complications, and Outcomes in Children on Maintenance Hemodialysis: Findings From the International Pediatric Hemodialysis Network (IPHN) Registry

RATIONALE & OBJECTIVE

Arteriovenous fistulas (AVFs) have been recommended as the preferred vascular access for pediatric patients on maintenance hemodialysis (HD), but data comparing AVFs with other access types are scant. We studied vascular access choice, placement, complications, and outcomes in children.

STUDY DESIGN

Prospective observational cohort study.

SETTING & PARTICIPANTS

552 children and adolescents from 27 countries on maintenance HD followed up prospectively by the International Pediatric HD Network (IPHN) Registry between 2012 and 2017.

PREDICTOR

Type of vascular access: AVF, central venous catheter (CVC), or arteriovenous graft.

OUTCOME

Infectious and noninfectious vascular access complication rates, dialysis performance, biochemical and hematologic parameters, and clinical outcomes.

ANALYTICAL APPROACH

Univariate and multivariable linear mixed models, generalized linear mixed models, and proportional hazards models; cumulative incidence functions.

RESULTS

During 314 cumulative patient-years, 628 CVCs, 225 AVFs, and 17 arteriovenous grafts were placed. One-third of the children with an AVF required a temporary CVC until fistula maturation. Vascular access choice was associated with age and expectations for early transplantation. There was a 3-fold higher living related transplantation rate and lower median time to transplantation of 14 (IQR, 6-23) versus 20 (IQR, 14-36) months with CVCs compared with AVFs. Higher blood flow rates and Kt/V_urea were achieved with AVFs than with CVCs. Infectious complications were reported only with CVCs (1.3/1,000 catheter-days) and required vascular access replacement in 47%. CVC dysfunction rates were 2.5/1,000 catheter-days compared to 1.2/1,000 fistula-days. CVCs required 82% more revisions and almost 3-fold more vascular access replacements to a different site than AVFs (P<0.001).

LIMITATIONS

Clinical rather than population-based data.

CONCLUSIONS

CVCs are the predominant vascular access choice in children receiving HD within the IPHN. Age-related anatomical limitations and expected early living related transplantation were associated with CVC use. CVCs were associated with poorer dialysis efficacy, higher complication rates, and more frequent need for vascular access replacement. Such findings call for a re-evaluation of pediatric CVC use and practices.

Hemodialysis vascular access and subsequent transplantation: a report from the ESPN/ERA-EDTA Registry

BACKGROUND

Current guidelines advocate use of arteriovenous fistula (AVF) over central venous catheter (CVC) for children starting hemodialysis (HD). European data on current practice, determinants of access choice and switches, patient survival, and access to transplantation are limited.

METHODS

We included incident patients from 18 European countries who started HD from 2000 to 2013 for whom vascular access type was reported to the ESPN/ERA-EDTA Registry. Data were evaluated using descriptive statistics, logistic and Cox regression models, and cumulative incidence competing risk analysis.

RESULTS

Three hundred ninety-three (55.1%) of 713 children started HD with a CVC and were more often females, younger, had more often an unknown diagnosis, glomerulonephritis, or vasculitis, and lower hemoglobin and height-SDS at HD initiation. AVF patients were 91% less likely to switch to a second access, and two-year patient survival was 99.6% (CVC, 97.2%). Children who started with an AVF were less likely to receive a living donor transplant (adjusted HR, 0.30; 95% CI, 0.16-0.54) and more likely to receive a deceased donor transplant (adjusted HR, 1.50; 95% CI, 1.17-1.93), even after excluding patients who died or were transplanted in the first 6 months.

CONCLUSIONS

CVC remains the most frequent type of vascular access in European children commencing HD. Our results suggest that the choice for CVC is influenced by the time of referral, rapid onset of end-stage renal disease, young age, and an expected short time to transplantation. The role of vascular access type on the pattern between living and deceased donation in subsequent transplantation requires further study.

Renal allograft survival rates in kidneys initially declined for paediatric transplantation

BACKGROUND

The outcome of organs which have been declined for paediatric recipients is not known. This study aimed to determine the outcome of kidneys initially declined for paediatric recipients and establish renal allograft survival in kidneys that were eventually transplanted.

METHODS

Data were obtained from the UK Transplant Registry for all donation after brain death (DBD) kidneys offered and declined to paediatric recipients (< 18 years) in the UK from 2009 to 2014.

RESULTS

Eighty-two percent (503/615) of kidneys initially declined for paediatric transplantation were eventually transplanted, 7% (46/615) of kidneys went to paediatric recipients and 62% (384/615) of kidneys went to adult (kidney only) recipients. The remainder were used for multiple organ transplants. In the 46 kidneys that went to paediatric recipients, 1 and 3-year renal allograft survivals were 89% (95% CI 75.8-95.3%) and 82% (95% CI 67.1-90.6%), respectively. In the 384 kidneys given to adult kidney-only recipients, 1 and 3-year renal allograft survivals were 96% (95% CI 93.5-97.6%) and 94% (95% CI 90.7-96.1%), respectively. Eighty-four percent of the 204 children who initially had an offer declined on their behalf were eventually transplanted and have a functioning graft at a median 3-year follow-up.

CONCLUSIONS

This study reports acceptable short-term renal allograft survival in kidneys that were initially declined for paediatric recipients and subsequently transplanted. Evidence-based guidelines are required to ensure that the most appropriate kidneys are selected for paediatric recipients.

Care of the Pediatric Patient on Chronic Dialysis

Optimal care of the pediatric end-stage renal disease (ESRD) patient on chronic dialysis is complex and requires multidisciplinary care as well as patient/caregiver involvement. The dialysis team, along with the family and patient, should all play a role in choosing the dialysis modality which best meets the patient's needs, taking into account special considerations and management issues that may be particularly pertinent to children who receive peritoneal dialysis or hemodialysis. Meticulous attention to dialysis adequacy in terms of solute and fluid removal, as well as to a variety of clinical manifestations of ESRD, including anemia, growth and nutrition, chronic kidney disease-mineral bone disorder, cardiovascular health, and neurocognitive development, is essential. This review highlights current recommendations and advances in the care of children on dialysis with a particular focus on preventive measures to minimize ESRD-associated morbidity and mortality. Advances in dialysis care and prevention of complications related to ESRD and dialysis have led to better survival for pediatric patients on dialysis.

Effect of center practices on the choice of the first dialysis modality for children and young adults

BACKGROUND

Peritoneal dialysis (PD) remains the modality of choice in children, but there is no clear evidence to support a better outcome in children treated with PD. We aimed to assess factors that have an impact on the choice of dialysis modality in children and young adults in France and sought to determine the roles of medical factors and center practices.

METHODS

We included all patients aged <20 years at the start of renal replacement therapy (RRT), recorded in the French RRT Registry between 2002 and 2013. Hierarchical logistic regression models were used to study the association between the patient/center characteristics and the probability of receiving PD as the first dialysis modality.

RESULTS

We included 806 patients starting RRT in 177 centers, 23 of which were specialized pediatric centers. Six hundred and one patients (74.6 %) started with hemodialysis (HD), whereas 205 (25.4 %) started with PD. A greater probability of PD was found in younger children, whereas starting the treatment in an emergency setting was associated with a low use of PD. We found a significant variability among centers that accounted for 43 % of the total variability. The probability of PD was higher in adult centers and was proportional to the rate of PD in the center.

CONCLUSIONS

Center practices are a major factor in the choice of dialysis modality. This raises concerns about patient and family choices and to what extent doctors may influence the final decision. Further pediatric studies focusing on children's and parents' wishes are needed to provide care as close as possible to patients' and families' expectations.

Psychosocial aspects of children and families treated with hemodialysis

INTRODUCTION

The aim of this study was to analyze the selected psychosocial aspects of chronic kidney disease in children treated with hemodialysis (HD).

METHODS

The study included 25 children treated with HD aged 2 to 18 years and their parents. Data concerning the illness and socio-demographic parameters was collected. We used the Paediatric Quality of Life Inventory (PedsQL) for patients and for their parents the PedsQL-proxy version, General Health Questionnaire (GHQ-12), Berlin Social Support Scales (BSSS), and the Caregivers Burden Scale (CBS) to evaluate health-related quality of life (QoL) of HD children and their primary caregivers.

FINDINGS

In the PedsQL test, the QoL of HD children was lower than in healthy children. Children treated with HD assessed their QoL on the PedsQL questionnaire higher than the primary caregivers, on all subscales as well as an overall health-related QoL. Scoring below 2 on the GHQ-12 test was reported in 56% of mothers, which may indicate that psychological symptoms have intensified. There was no correlation between BSSS, CBS, and GHQ-12.

DISCUSSION

The assessment of QoL in pediatric patients would allow for the earliest possible identification of their nonsomatic problems and irregularities. This could, consequently, contribute to improving QoL in both children with chronic kidney disease and their families.

Health-related quality of life in patients with pediatric onset of end-stage renal disease: state of the art and recommendations for clinical practice

Health-related quality of life (HRQoL) is increasingly recognized as a key outcome in both clinical and research settings in the pediatric population with end-stage renal disease (ESRD). This review aims to: (1) summarize the current knowledge on HRQoL and socioprofessional outcomes and (2) provide strategies for incorporation of HRQoL assessment into clinical practice. Studies report that pediatric patients with ESRD have significantly lower HRQoL scores compared with children with other chronic diseases. Patients treated by dialysis are at particularly high risk for impaired HRQoL. Furthermore, patients more often have impaired neurocognitive functioning and lower academic achievement. Important determinants of impaired HRQoL include medical factors (i.e., receiving dialysis, disabling comorbidities, cosmetic side effects, stunted growth), sociodemographic factors (i.e., female gender, non-Western background) and psychosocial factors (i.e., noneffective coping strategies). Contrary to the situation in childhood, adult survivors of pediatric ESRD report a normal mental HRQoL. Despite this subjective feeling of well-being, these patients have on average experienced significantly more difficulties in completing their education, developing intimate relationships, and securing employment. Several medical and psychosocial strategies may potentially improve HRQoL in children with ESRD. Regular assessment of HRQoL and neurocognitive functioning in order to identify areas in which therapies and interventions may be required should be part of standard clinical care.

Renal transplantation in infants

Renal transplantation (RTx) has become an accepted mode of therapy in infants with severe renal failure. The major indications are structural abnormalities of the urinary tract, congenital nephrotic syndrome, polycystic diseases, and neonatal kidney injury. Assessment of these infants needs expertise and time as well as active treatment before RTx to ensure optimal growth and development, and to avoid complications that could lead to permanent neurological defects. RTx can be performed already in infants weighing around 5 kg, but most operations occur in infants with a weight of 10 kg or more. Perioperative management focuses on adequate perfusion of the allograft and avoidance of thrombotic and other surgical complications. Important long-term issues include rejections, infections, graft function, growth, bone health, metabolic problems, neurocognitive development, adherence to medication, pubertal maturation, and quality of life. The overall outcome of infant RTx has dramatically improved, with long-term patient and graft survivals of over 90 and 80 %, respectively.

Psychosocial support for children and families requiring renal replacement therapy

Chronic kidney disease (CKD) and the need for renal replacement therapy (RRT) can place a great strain on the child and family. As well as the medical and nutritional prescription, each child and family requires an individual psychosocial prescription that requires input from multiprofessional team members. The information needs of each child and family need to be constantly evaluated as well as the choice of therapy in relation to social, psychological and economic factors. Many tertiary units lack adequate "time" to deliver such assessments and coordinate the support and respite care for those on long-term dialysis, especially when significant numbers of children are now accepted onto RRT programmes with co-morbidities. National and international standards are needed for the staffing of comprehensive tertiary paediatric renal units as well as studies evaluating supportive care to families.

Dynamic O-linked N-acetylglucosamine modification of proteins affects stress responses and survival of mesothelial cells exposed to peritoneal dialysis fluids

The ability of cells to respond and survive stressful conditions is determined, in part, by the attachment of O-linked N-acetylglucosamine (O-GlcNAc) to proteins (O-GlcNAcylation), a post-translational modification dependent on glucose and glutamine. This study investigates the role of dynamic O-GlcNAcylation of mesothelial cell proteins in cell survival during exposure to glucose-based peritoneal dialysis fluid (PDF). Immortalized human mesothelial cells and primary mesothelial cells, cultured from human omentum or clinical effluent of PD patients, were assessed for O-GlcNAcylation under normal conditions or after exposure to PDF. The dynamic status of O-GlcNAcylation and effects on cellular survival were investigated by chemical modulation with 6-diazo-5-oxo-L-norleucine (DON) to decrease or O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino N-phenyl carbamate (PUGNAc) to increase O-GlcNAc levels. Viability was decreased by reducing O-GlcNAc levels by DON, which also led to suppressed expression of the cytoprotective heat shock protein 72. In contrast, increasing O-GlcNAc levels by PUGNAc or alanyl-glutamine led to significantly improved cell survival paralleled by higher heat shock protein 72 levels during PDF treatment. Addition of alanyl-glutamine increased O-GlcNAcylation and partly counteracted its inhibition by DON, also leading to improved cell survival. Immunofluorescent analysis of clinical samples showed that the O-GlcNAc signal primarily originates from mesothelial cells. In conclusion, this study identified O-GlcNAcylation in mesothelial cells as a potentially important molecular mechanism after exposure to PDF. Modulating O-GlcNAc levels by clinically feasible interventions might evolve as a novel therapeutic target for the preservation of peritoneal membrane integrity in PD.

Structural links between the renal stem/progenitor cell niche and the organ capsule

A special feature of the renal stem/progenitor cell niche is its always close neighborhood to the capsule during organ development. To explore this link, neonatal kidney was investigated by histochemistry and transmission electron microscopy. For adequate contrasting, fixation of specimens was performed by glutaraldehyde including tannic acid. The immunohistochemical data illustrate that renal stem/progenitor cells are not distributed randomly but are positioned specially to the capsule. Epithelial stem/progenitor cells are found to be enclosed by the basal lamina at a collecting duct (CD) ampulla tip. Only few layers of mesenchymal cells are detected between epithelial cells and the capsule. Most impressive, numerous microfibers reacting with soybean agglutinin, anti-collagen I and III originate from the basal lamina at a CD ampulla tip and line between mesenchymal stem/progenitor cells to the inner side of the capsule. This specific arrangement holds together both types of stem/progenitor cells in a cage and fastens the niche as a whole at the capsule. Electron microscopy further illustrates that the stem/progenitor cell niche is in contact with a tunnel system widely spreading between atypical smooth muscle cells at the inner side of the capsule. It seems probable that stem/progenitor cells are supplied here by interstitial fluid.