Characterization of patients with aHUS and associated triggers or clinical conditions: A Global aHUS Registry analysis

INTRODUCTION

Atypical haemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy (TMA) associated with complement dysregulation; aHUS may be associated with other 'triggers' or 'clinical conditions'. This study aimed to characterize this patient population using data from the Global aHUS Registry, the largest collection of real-world data on patients with aHUS.

METHODS

Patients enrolled in the Global aHUS Registry between April 2012 and June 2021 and with recorded aHUS-associated triggers or clinical conditions prior/up to aHUS onset were analysed. aHUS was diagnosed by the treating physician. Data were classified by age at onset of aHUS (< or ≥18 years) and additionally by the presence/absence of identified pathogenic complement genetic variant(s) and/or anti-complement factor H (CFH) antibodies. Genetically/immunologically untested patients were excluded.

RESULTS

1947 patients were enrolled in the Global aHUS Registry by June 2021, and 349 (17.9%) met inclusion criteria. 307/349 patients (88.0%) had a single associated trigger or clinical condition and were included in the primary analysis. Malignancy was most common (58/307, 18.9%), followed by pregnancy and acute infections (both 53/307, 17.3%). Patients with an associated trigger or clinical condition were generally more likely to be adults at aHUS onset.

CONCLUSION

Our analysis suggests that aHUS-associated triggers or clinical conditions may be organized into clinically relevant categories, and their presence does not exclude the concurrent presence of pathogenic complement genetic variants and/or anti-CFH antibodies. Considering a diagnosis of aHUS with associated triggers or clinical conditions in patients presenting with TMA may allow faster and more appropriate treatment.

Estimating Total Energy Expenditure to Determine Energy Requirements in Free-Living Children With Stage 3 Chronic Kidney Disease: Can a Structured Approach Help Improve Clinical Care?

OBJECTIVE

Malnutrition and obesity are complex burdensome challenges in pediatric chronic kidney disease (CKD) management that can adversely affect growth, disease progression, wellbeing, and response to treatment. Total energy expenditure (TEE) and energy requirements in children are essential for growth outcomes but are poorly defined, leaving clinical practice varied and insecure. The aims of this study were to explore a practical approach to guide prescribed nutritional interventions, using measurements of TEE, physical activity energy expenditure (PAEE), and their relationship to kidney function.

DESIGN AND METHODS

In a cross-sectional prospective age-matched and sex-matched controlled study, 18 children with CKD (6-17 years, mean stage 3) and 20 healthy, age-matched, and gender-matched controls were studied. TEE and PAEE were measured using basal metabolic rate (BMR), activity diaries and doubly labeled water (healthy subjects). Results were related to estimated glomerular filtration rate (eGFR). The main outcome measure was TEE measured by different methods (factorial, doubly labeled water, and a novel device).

RESULTS

Total energy expenditure and PAEE with or without adjustments for age, gender, weight, and height did not differ between the groups and was not related to eGFR. TEE ranged from 1927 ± 91 to 2330 ± 73 kcal/d; 95 ± 5 to 109 ± 5% estimated average requirement (EAR), physical activity level (PAL) 1.52 ± 0.01 to 1.71 ± 0.17, and PAEE 24 to 34% EAR. Comparisons between DLW and alternative methods in healthy children did not differ significantly, except for 2 (factorial methods and a fixed PAL; and the novel device).

CONCLUSION

In clinical practice, structured approaches using supportive evidence (weight, height, BMI sds), predictive BMR or TEE values and simple questions on activity, are sufficient for most children with CKD as a starting energy prescription.

Syndrome of inappropriate secretion of anti-diuretic hormone due to hypothalamic hamartoma: use of tolvaptan

OBJECTIVES

Hypothalamic hamartoma (HH) typically presents with gonadotrophin-dependent precocious puberty and/or seizures. Other endocrine disturbances are rare. We describe an infant with syndrome of inappropriate secretion of anti-diuretic hormone (SIADH) and a HH.

CASE PRESENTATION

A 6-week-old infant presented with seizures and life-threatening hyponatremia. A HH was identified on magnetic resonance imaging. Clinical examination and biochemistry were consistent with SIADH, and serum copeptin was high during hyponatremia, further supporting this diagnosis. Tolvaptan was effective in normalizing plasma sodium and enabling liberalization of fluids to ensure sufficient nutritional intake and weight gain and manage hunger.

CONCLUSIONS

Hyponatremia due to SIADH is novel at presentation of a HH, and can be challenging to diagnose and manage. Successful management of hyponatremia in this case was achieved using tolvaptan.

A Role for Genetic Modifiers in Tubulointerstitial Kidney Diseases

With the increased availability of genomic sequencing technologies, the molecular bases for kidney diseases such as nephronophthisis and mitochondrially inherited and autosomal-dominant tubulointerstitial kidney diseases (ADTKD) has become increasingly apparent. These tubulointerstitial kidney diseases (TKD) are monogenic diseases of the tubulointerstitium and result in interstitial fibrosis and tubular atrophy (IF/TA). However, monogenic inheritance alone does not adequately explain the highly variable onset of kidney failure and extra-renal manifestations. Phenotypes vary considerably between individuals harbouring the same pathogenic variant in the same putative monogenic gene, even within families sharing common environmental factors. While the extreme end of the disease spectrum may have dramatic syndromic manifestations typically diagnosed in childhood, many patients present a more subtle phenotype with little to differentiate them from many other common forms of non-proteinuric chronic kidney disease (CKD). This review summarises the expanding repertoire of genes underpinning TKD and their known phenotypic manifestations. Furthermore, we collate the growing evidence for a role of modifier genes and discuss the extent to which these data bridge the historical gap between apparently rare monogenic TKD and polygenic non-proteinuric CKD (excluding polycystic kidney disease).

A genotype-to-phenotype approach suggests under-reporting of single nucleotide variants in nephrocystin-1 (NPHP1) related disease (UK 100,000 Genomes Project)

Autosomal recessive whole gene deletions of nephrocystin-1 (NPHP1) result in abnormal structure and function of the primary cilia. These deletions can result in a tubulointerstitial kidney disease known as nephronophthisis and retinal (Senior-Løken syndrome) and neurological (Joubert syndrome) diseases. Nephronophthisis is a common cause of end-stage kidney disease (ESKD) in children and up to 1% of adult onset ESKD. Single nucleotide variants (SNVs) and small insertions and deletions (Indels) have been less well characterised. We used a gene pathogenicity scoring system (GenePy) and a genotype-to-phenotype approach on individuals recruited to the UK Genomics England (GEL) 100,000 Genomes Project (100kGP) (n = 78,050). This approach identified all participants with NPHP1-related diseases reported by NHS Genomics Medical Centres and an additional eight participants. Extreme NPHP1 gene scores, often underpinned by clear recessive inheritance, were observed in patients from diverse recruitment categories, including cancer, suggesting the possibility of a more widespread disease than previously appreciated. In total, ten participants had homozygous CNV deletions with eight homozygous or compound heterozygous with SNVs. Our data also reveals strong in-silico evidence that approximately 44% of NPHP1 related disease may be due to SNVs with AlphaFold structural modelling evidence for a significant impact on protein structure. This study suggests historical under-reporting of SNVS in NPHP1 related diseases compared with CNVs.

A novel variant in GATM causes idiopathic renal Fanconi syndrome and predicts progression to end-stage kidney disease

Renal Fanconi syndrome (RFS) is a generalised disorder of the proximal convoluted tubule. Many genes have been associated with RFS including those that cause systemic disorders such as cystinosis, as well as isolated RFS. We discuss the case of a 10-year-old female who presented with leg pain and raised creatinine on a screening blood test. Her mother has RFS and required a kidney transplant in her thirties. Further investigations confirmed RFS in the daughter. Exome sequencing was performed on the affected mother, child, and unaffected father. We identified a novel variant in GATM; c.965G>C p.(Arg322Pro) segregating dominantly in the mother and daughter. We validated our finding with molecular dynamics simulations and demonstrated a dynamic signature that differentiates our variant and two previously identified pathogenic variants in GATM from wildtype. Genetic testing has uncovered a novel pathogenic variant that predicts progression to end stage kidney failure and has important implications for family planning and cascade testing. We recommend that GATM is screened for in children presenting with RFS, in addition to adults, particularly with kidney failure, who may have had previous negative gene testing.

Economic Evaluation of Using Daily Prednisolone versus Placebo at the Time of an Upper Respiratory Tract Infection for the Management of Children with Steroid-Sensitive Nephrotic Syndrome: A Model-Based Analysis

BACKGROUND

Childhood steroid-sensitive nephrotic syndrome is a frequently relapsing disease with significant short- and long-term complications, leading to high healthcare costs and reduced quality of life for patients. The majority of relapses are triggered by upper respiratory tract infections (URTIs) and evidence shows that daily low-dose prednisolone at the time of infection may reduce the risk of relapse.

OBJECTIVE

The aim of this study was to assess the cost effectiveness of a 6-day course of low-dose prednisolone at the start of a URTI when compared with placebo.

METHODS

A state-transition Markov model was developed to conduct a cost-utility analysis with the outcome measured in quality-adjusted life-years (QALYs). Resource use and outcome data were derived from the PREDNOS2 trial. The analysis was performed from a UK National Health Service perspective and the results were extrapolated to adulthood. Model parameter and structural uncertainty were assessed using sensitivity analyses.

RESULTS

The base-case results showed that administering low-dose prednisolone at the time of a URTI generated more QALYs and a lower mean cost at 1 year compared with placebo. In the long-term, low-dose prednisolone was associated with a cost saving (£176) and increased effectiveness (0.01 QALYs) compared with placebo and thus remained the dominant treatment option. These findings were robust to all sensitivity analyses.

CONCLUSION

A 6-day course of low-dose prednisolone at the time of a URTI in children with steroid-sensitive nephrotic syndrome has the potential to reduce healthcare costs and improve quality of life compared with placebo.

Hemizygous loss of function mutations in CLCN5 causing end-stage kidney disease without Dent disease phenotype

Dent disease type 1 is suspected in the presence of a complete phenotype of low molecular weight (LMW) proteinuria, hypercalciuria and at least one of the following: nephrocalcinosis, nephrolithiasis, haematuria, hypophosphatemia or chronic kidney disease (CKD). We present two brothers who presented with CKD alone. In the absence of typical clinical features, further assessment of LMW proteinuria and hypercalciuria was not undertaken. Whole-genome sequencing revealed hemizygous loss of function mutations in chloride voltage-gated channel 5 (CLCN5) consistent with Dent disease. Dent disease should, therefore, be considered in patients with an incomplete phenotype, including unexplained CKD alone.

Evaluation of Daily Low-Dose Prednisolone During Upper Respiratory Tract Infection to Prevent Relapse in Children With Relapsing Steroid-Sensitive Nephrotic Syndrome: The PREDNOS 2 Randomized Clinical Trial

IMPORTANCE

In children with corticosteroid-sensitive nephrotic syndrome, many relapses are triggered by upper respiratory tract infections. Four small studies found that administration of daily low-dose prednisolone for 5 to 7 days at the time of an upper respiratory tract infection reduced the risk of relapse, but the generalizability of their findings is limited by location of the studies and selection of study population.

OBJECTIVE

To investigate the use of daily low-dose prednisolone for the treatment of upper respiratory tract infection-related relapses.

DESIGN, SETTING, AND PARTICIPANTS

This double-blind, placebo-controlled randomized clinical trial (Prednisolone in Nephrotic Syndrome [PREDNOS] 2) evaluated 365 children with relapsing steroid-sensitive nephrotic syndrome with and without background immunosuppressive treatment at 122 pediatric departments in the UK from February 1, 2013, to January 31, 2020. Data from the modified intention-to-treat population were analyzed from July 1, 2020, to December 31, 2020.

INTERVENTIONS

At the start of an upper respiratory tract infection, children received 6 days of prednisolone, 15 mg/m2 daily, or matching placebo preparation. Those already taking alternate-day prednisolone rounded their daily dose using trial medication to the equivalent of 15 mg/m2 daily or their alternate-day dose, whichever was greater.

MAIN OUTCOMES AND MEASURES

The primary outcome was the incidence of first upper respiratory tract infection-related relapse. Secondary outcomes included overall rate of relapse, changes in background immunosuppressive treatment, cumulative dose of prednisolone, rates of serious adverse events, incidence of corticosteroid adverse effects, and quality of life.

RESULTS

The modified intention-to-treat analysis population comprised 271 children (mean [SD] age, 7.6 [3.5] years; 174 [64.2%] male), with 134 in the prednisolone arm and 137 in the placebo arm. The number of patients experiencing an upper respiratory tract infection-related relapse was 56 of 131 (42.7%) in the prednisolone arm and 58 of 131 (44.3%) in the placebo arm (adjusted risk difference, -0.02; 95% CI, -0.14 to 0.10; P = .70). No evidence was found that the treatment effect differed according to background immunosuppressive treatment. No significant differences were found in secondary outcomes between the treatment arms. A post hoc subgroup analysis assessing the primary outcome in 54 children of South Asian ethnicity (risk ratio, 0.66; 95% CI, 0.40-1.10) vs 208 children of other ethnicity (risk ratio, 1.11; 95% CI, 0.81-1.54) found no difference in efficacy of intervention in those of South Asian ethnicity (test for interaction P = .09).

CONCLUSIONS AND RELEVANCE

The results of PREDNOS 2 suggest that administering 6 days of daily low-dose prednisolone at the time of an upper respiratory tract infection does not reduce the risk of relapse of nephrotic syndrome in children in the UK. Further work is needed to investigate interethnic differences in treatment response.

TRIAL REGISTRATION

isrctn.org Identifier: ISRCTN10900733; EudraCT 2012-003476-39.

Clonal myelopoiesis promotes adverse outcomes in chronic kidney disease

We sought to determine the relationship between age-related clonal hematopoiesis (CH) and chronic kidney disease (CKD). CH, defined as mosaic chromosome abnormalities (mCA) and/or driver mutations was identified in 5449 (2.9%) eligible UK Biobank participants (n = 190,487 median age = 58 years). CH was negatively associated with glomerular filtration rate estimated from cystatin-C (eGFR.cys; β = -0.75, P = 2.37 × 10-4), but not with eGFR estimated from creatinine, and was specifically associated with CKD defined by eGFR.cys < 60 (OR = 1.02, P = 8.44 × 10-8). In participants without prevalent myeloid neoplasms, eGFR.cys was associated with myeloid mCA (n = 148, β = -3.36, P = 0.01) and somatic driver mutations (n = 3241, β = -1.08, P = 6.25 × 10-5) associated with myeloid neoplasia (myeloid CH), specifically mutations in CBL, TET2, JAK2, PPM1D and GNB1 but not DNMT3A or ASXL1. In participants with no history of cardiovascular disease or myeloid neoplasms, myeloid CH increased the risk of adverse outcomes in CKD (HR = 1.6, P = 0.002) compared to those without myeloid CH. Mendelian randomisation analysis provided suggestive evidence for a causal relationship between CH and CKD (P = 0.03). We conclude that CH, and specifically myeloid CH, is associated with CKD defined by eGFR.cys. Myeloid CH promotes adverse outcomes in CKD, highlighting the importance of the interaction between intrinsic and extrinsic factors to define the health risk associated with CH.

Daily low-dose prednisolone to prevent relapse of steroid-sensitive nephrotic syndrome in children with an upper respiratory tract infection: PREDNOS2 RCT

Background

Most children with steroid-sensitive nephrotic syndrome have relapses that are triggered by upper respiratory tract infections. Four small trials, mostly in children already taking maintenance corticosteroid in countries of different upper respiratory tract infection epidemiology, showed that giving daily low-dose prednisone/prednisolone for 5–7 days during an upper respiratory tract infection reduces the risk of relapse.

Objectives

To determine if these findings were replicated in a large UK population of children with relapsing steroid-sensitive nephrotic syndrome on different background medication or none.

Design

A randomised double-blind placebo-controlled trial, including a cost-effectiveness analysis.

Setting

A total of 122 UK paediatric departments, of which 91 recruited patients.

Participants

A total of 365 children with relapsing steroid-sensitive nephrotic syndrome (mean age 7.6 ± 3.5 years) were randomised (1 : 1) according to a minimisation algorithm based on background treatment. Eighty children completed 12 months of follow-up without an upper respiratory tract infection. Thirty-two children were withdrawn from the trial (14 prior to an upper respiratory tract infection), leaving a modified intention-to-treat analysis population of 271 children (134 and 137 children in the prednisolone and placebo arms, respectively).

Interventions

At the start of an upper respiratory tract infection, children received 6 days of prednisolone (15 mg/m2) or an equivalent dose of placebo.

Main outcome measures

The primary outcome was the incidence of first upper respiratory tract infection-related relapse following any upper respiratory tract infection over 12 months. The secondary outcomes were the overall rate of relapse, changes in background treatment, cumulative dose of prednisolone, rates of serious adverse events, incidence of corticosteroid adverse effects, change in Achenbach Child Behaviour Checklist score and quality of life. Analysis was by intention-to-treat principle. The cost-effectiveness analysis used trial data and a decision-analytic model to estimate quality-adjusted life-years and costs at 1 year, which were then extrapolated over 16 years.

Results

There were 384 upper respiratory tract infections and 82 upper respiratory tract infection-related relapses in the prednisolone arm, and 407 upper respiratory tract infections and 82 upper respiratory tract infection-related relapses in the placebo arm. The number of patients experiencing an upper respiratory tract infection-related relapse was 56 (42.7%) and 58 (44.3%) in the prednisolone and placebo arms, respectively (adjusted risk difference –0.024, 95% confidence interval –0.14 to 0.09; p = 0.70). There was no evidence that the treatment effect differed when data were analysed according to background treatment. There were no significant differences in secondary outcomes between treatment arms. Giving daily prednisolone at the time of an upper respiratory tract infection was associated with increased quality-adjusted life-years (0.9427 vs. 0.9424) and decreased average costs (£252 vs. £254), when compared with standard care. The cost saving was driven by background therapy and hospitalisations after relapse. The finding was robust to sensitivity analysis.

Limitations

A larger number of children than expected did not have an upper respiratory tract infection and the sample size attrition rate was adjusted accordingly during the trial.

Conclusions

The clinical analysis indicated that giving 6 days of daily low-dose prednisolone at the time of an upper respiratory tract infection does not reduce the risk of relapse of steroid-sensitive nephrotic syndrome in UK children. However, there was an economic benefit from costs associated with background therapy and relapse, and the health-related quality-of-life impact of having a relapse.

Future work

Further work is needed to investigate the clinical and health economic impact of relapses, interethnic differences in treatment response, the effect of different corticosteroid regimens in treating relapses, and the pathogenesis of individual viral infections and their effect on steroid-sensitive nephrotic syndrome.

Trial registration

Current Controlled Trials ISRCTN10900733 and EudraCT 2012-003476-39.

Funding

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 3. See the NIHR Journals Library website for further project information.

Ectopic vortex veins and varices in Donnai Barrow syndrome

BACKGROUND

Donnai Barrow Syndrome (DBS) is a rare, multi-system autosomal recessively inherited disorder of relevance to ophthalmologists. To aim to describe the ocular phenotype using multimodal imaging for two cases of genetically confirmed DBS and compare against the published phenotype.

MATERIALS AND METHODS

Retrospective case series of two unrelated patients with DBS and review of the literature. Both cases were referred to our tertiary unit for laser prophylaxis against retinal detachment.

RESULTS

There was extreme high myopia greater than 20 dioptres without rhegmatogenous retinal detachment (RRD). Anterior segment features included iris transillumination and ciliary body hypoplasia. Posterior segment changes included previously described changes of optic nerve hypoplasia and a strikingly abnormal appearance of the fundus consisting of multiple bilateral giant posterior vortex veins (PVV). The mouse model shows a similar phenotype.

CONCLUSIONS

Ectopic vortex veins of the choroid expand the phenotype of DBS and can be helpful in distinguishing the differential diagnosis of high myopia in children. Posterior vortex veins have been described in adult high myopia as acquired but our cases suggest that they could be congenital. Orbital manipulation and hypotony during surgery should be avoided to minimise complications. The evidence to recommend prophylactic laser retinopexy in these cases is inconclusive, and overall we recommend that conservative management should be considered using wide-angle retinal imaging in the clinic.

Tolvaptan use in children and adolescents with autosomal dominant polycystic kidney disease: rationale and design of a two-part, randomized, double-blind, placebo-controlled trial

This report describes the rationale and design of a study assessing tolvaptan in children with autosomal dominant polycystic kidney disease (ADPKD). Phase A is a 1-year, randomized, double-blind, placebo-controlled, multicenter trial. Phase B is a 2-year, open-label extension. The target population is at least 60 children aged 12-17 years, diagnosed by family history and/or genetic criteria and the presence of ≥ 10 renal cysts, each ≥ 0.5 cm on magnetic resonance imaging. Subjects will be allocated into 4 groups: females 15-17 years; females 12-14 years; males 15-17 years; and males 12-14 years. Up to 40 subjects aged 4-11 years may also enroll, provided they meet the entry criteria. Weight-adjusted tolvaptan doses, titrated once to achieve a tolerated maintenance dose, and matching placebo will be administered twice-daily. Assessments include spot urine osmolality and specific gravity (co-primary endpoints), height-adjusted total kidney volume, estimated glomerular filtration rate, pharmacodynamic parameters (urine volume, fluid intake and fluid balance, serum sodium, serum creatinine, free water clearance), pharmacokinetic parameters, safety (aquaretic adverse events, changes from baseline in creatinine, vital signs, laboratory values including liver function tests), and generic pediatric quality of life assessments.Conclusion: This will be the first clinical study to evaluate tolvaptan in pediatric ADPKD. What is Known: • Autosomal dominant polycystic kidney disease (ADPKD) is a genetic disorder causing the development of cysts that impede kidney function over time and eventually induce renal failure • There are few data on the effects of tolvaptan, the only treatment approved for adults to slow disease progression, in pediatric ADPKD patients with early-stage disease What is New: • A phase 3, placebo-controlled study is evaluating tolvaptan over 3 years in children and adolescents with ADPKD • This study is designed to account for challenges of tolvaptan dosing and outcome assessment specific to the pediatric population.

Thrombotic microangiopathy following haematopoietic stem cell transplant

Thrombotic microangiopathy is a potentially lethal complication of haematopoietic stem cell (bone marrow) transplantation. The pathophysiology is incompletely understood, although endothelial damage appears to be central. Platelet activation, neutrophil extracellular traps and complement activation appear to play key roles. Diagnosis may be difficult and universally accepted diagnostic criteria are not available. Treatment remains controversial. In some cases, withdrawal of calcineurin inhibitors is adequate. Rituximab and defibrotide also appear to have been used successfully. In severe cases, complement inhibitors such as eculizumab may play a valuable role. Further research is required to define the pathophysiology and determine both robust diagnostic criteria and the optimal treatment.

Inactivation of AMMECR1 is associated with growth, bone, and heart alterations

We report five individuals with loss-of-function of the X-linked AMMECR1: a girl with a balanced X-autosome translocation and inactivation of the normal X-chromosome; two boys with maternally inherited and de novo nonsense variants; and two half-brothers with maternally inherited microdeletion variants. They present with short stature, cardiac and skeletal abnormalities, and hearing loss. Variants of unknown significance in AMMECR1 in four male patients from two families with partially overlapping phenotypes were previously reported. AMMECR1 is coexpressed with genes implicated in cell cycle regulation, five of which were previously associated with growth and bone alterations. Our knockdown of the zebrafish orthologous gene resulted in phenotypes reminiscent of patients' features. The increased transcript and encoded protein levels of AMMECR1L, an AMMECR1 paralog, in the t(X;9) patient's cells indicate a possible partial compensatory mechanism. AMMECR1 and AMMECR1L proteins dimerize and localize to the nucleus as suggested by their nucleic acid-binding RAGNYA folds. Our results suggest that AMMECR1 is potentially involved in cell cycle control and linked to a new syndrome with growth, bone, heart, and kidney alterations with or without elliptocytosis.

Factor H autoantibody is associated with atypical hemolytic uremic syndrome in children in the United Kingdom and Ireland

Factor H autoantibodies can impair complement regulation, resulting in atypical hemolytic uremic syndrome, predominantly in childhood. There are no trials investigating treatment, and clinical practice is only informed by retrospective cohort analysis. Here we examined 175 children presenting with atypical hemolytic uremic syndrome in the United Kingdom and Ireland for factor H autoantibodies that included 17 children with titers above the international standard. Of the 17, seven had a concomitant rare genetic variant in a gene encoding a complement pathway component or regulator. Two children received supportive treatment; both developed established renal failure. Plasma exchange was associated with a poor rate of renal recovery in seven of 11 treated. Six patients treated with eculizumab recovered renal function. Contrary to global practice, immunosuppressive therapy to prevent relapse in plasma exchange-treated patients was not adopted due to concerns over treatment-associated complications. Without immunosuppression, the relapse rate was high (five of seven). However, reintroduction of treatment resulted in recovery of renal function. All patients treated with eculizumab achieved sustained remission. Five patients received renal transplants without specific factor H autoantibody-targeted treatment with recurrence in one who also had a functionally significant CFI mutation. Thus, our current practice is to initiate eculizumab therapy for treatment of factor H autoantibody-mediated atypical hemolytic uremic syndrome rather than plasma exchange with or without immunosuppression. Based on this retrospective analysis we see no suggestion of inferior treatment, albeit the strength of our conclusions is limited by the small sample size.

Genomic and clinical profiling of a national nephrotic syndrome cohort advocates a precision medicine approach to disease management

Steroid Resistant Nephrotic Syndrome (SRNS) in children and young adults has differing etiologies with monogenic disease accounting for 2.9-30% in selected series. Using whole exome sequencing we sought to stratify a national population of children with SRNS into monogenic and non-monogenic forms, and further define those groups by detailed phenotypic analysis. Pediatric patients with SRNS were identified via a national United Kingdom Renal Registry. Whole exome sequencing was performed on 187 patients, of which 12% have a positive family history with a focus on the 53 genes currently known to be associated with nephrotic syndrome. Genetic findings were correlated with individual case disease characteristics. Disease causing variants were detected in 26.2% of patients. Most often this occurred in the three most common SRNS-associated genes: NPHS1, NPHS2, and WT1 but also in 14 other genes. The genotype did not always correlate with expected phenotype since mutations in OCRL, COL4A3, and DGKE associated with specific syndromes were detected in patients with isolated renal disease. Analysis by primary/presumed compared with secondary steroid resistance found 30.8% monogenic disease in primary compared with none in secondary SRNS permitting further mechanistic stratification. Genetic SRNS progressed faster to end stage renal failure, with no documented disease recurrence post-transplantation within this cohort. Primary steroid resistance in which no gene mutation was identified had a 47.8% risk of recurrence. In this unbiased pediatric population, whole exome sequencing allowed screening of all current candidate genes. Thus, deep phenotyping combined with whole exome sequencing is an effective tool for early identification of SRNS etiology, yielding an evidence-based algorithm for clinical management.

Unexpected Findings in a Child with Atypical Hemolytic Uremic Syndrome: An Example of How Genomics Is Changing the Clinical Diagnostic Paradigm

CBL is a tumor suppressor gene on chromosome 11 encoding a multivalent adaptor protein with E3 ubiquitin ligase activity. Germline CBL mutations are dominant. Pathogenic de novo mutations result in a phenotype that overlaps Noonan syndrome (1). Some patients with CBL mutations go on to develop juvenile myelomonocytic leukemia (JMML), an aggressive malignancy that usually necessitates bone marrow transplantation. Using whole exome sequencing methods, we identified a known mutation in CBL in a 4-year-old Caucasian boy with atypical hemolytic uremic syndrome, moyamoya phenomenon, and dysmorphology consistent with a mild Noonan-like phenotype. Exome data revealed loss of heterozygosity across chromosome 11q consistent with JMML but in the absence of clinical leukemia. Our finding challenges conventional clinical diagnostics since we have identified a pathogenic variant in the CBL gene previously only ascertained in children presenting with leukemia. The increasing affordability of expansive sequencing is likely to increase the scope of clinical profiles observed for previously identified pathogenic variants and calls into question the interpretability and indications for clinical management.

AMMECR1: a single point mutation causes developmental delay, midface hypoplasia and elliptocytosis

Background

Deletions in the Xq22.3–Xq23 region, inclusive of COL4A5, have been associated with a contiguous gene deletion syndrome characterised by Alport syndrome with intellectual disability (Mental retardation), Midface hypoplasia and Elliptocytosis (AMME). The extrarenal biological and clinical significance of neighbouring genes to the Alport locus has been largely speculative. We sought to discover a genetic cause for two half-brothers presenting with nephrocalcinosis, early speech and language delay and midface hypoplasia with submucous cleft palate and bifid uvula.

Methods

Whole exome sequencing was undertaken on maternal half-siblings. In-house genomic analysis included extraction of all shared variants on the X chromosome in keeping with X-linked inheritance. Patient-specific mutants were transfected into three cell lines and microscopically visualised to assess the nuclear expression pattern of the mutant protein.

Results

In the affected half-brothers, we identified a hemizygous novel non-synonymous variant of unknown significance in AMMECR1 (c.G530A; p.G177D), a gene residing in the AMME disease locus. Transfected cell lines with the p.G177D mutation showed aberrant nuclear localisation patterns when compared with the wild type. Blood films revealed the presence of elliptocytes in the older brother.

Conclusions

Our study shows that a single missense mutation in AMMECR1 causes a phenotype of midface hypoplasia, mild intellectual disability and the presence of elliptocytes, previously reported as part of a contiguous gene deletion syndrome. Functional analysis confirms mutant-specific protein dysfunction. We conclude that AMMECR1 is a critical gene in the pathogenesis of AMME, causing midface hypoplasia and elliptocytosis and contributing to early speech and language delay, infantile hypotonia and hearing loss, and may play a role in dysmorphism, nephrocalcinosis and submucous cleft palate.

Progressive myoclonic epilepsy with Fanconi syndrome

This report illustrates the difficulties in diagnosing complex cases and demonstrates how whole exome sequencing can resolve complex phenotypes.

Positive trends in paediatric renal biopsy service provision in the UK: a national survey and re-audit of paediatric renal biopsy practice

BACKGROUND

Paediatric renal biopsy standards introduced in the UK in 2010 were intended to reduce variation and improve practice. A concurrent national drive was aimed at building robust paediatric nephrology networks to ensure services cater for the needs of the family and minimise time away from home. We aimed to identify current national practice since these changes on behalf of the British Association for Paediatric Nephrology.

METHODS

All UK paediatric nephrology centres were invited to complete a survey of their biopsy practice, including advance preparation. From 1 January to 30 June 2012, a national prospective audit of renal biopsies was undertaken at participating centres comparing practice with the British Association for Paediatric Nephrology (BAPN) standards and audit results from 2005.

RESULTS

Survey results from 11 centres demonstrated increased use of pre-procedure information leaflets (63.6 % vs 45.5 %, P = 0.39) and play preparation (90.9 % vs 9.1 %, P = 0.0001). Audit of 331 biopsies showed a move towards day-case procedures (49.5 % vs 32.9 %, P = 0.17) and reduced major complications (4.5 % vs 10.4 %, P = 0.002). Biopsies with 18-gauge needles had significantly higher mean pass rates (3.2 vs 2.3, P = 0.0008) and major complications (15.3 % vs 3.3 %, P = 0.0015) compared with 16-gauge needles.

CONCLUSIONS

Percutaneous renal biopsy remains a safe procedure in children, thus improving family-centered service provision in the UK.

Basal metabolic rate in children with chronic kidney disease and healthy control children

BACKGROUND

Meeting energy requirements of children with chronic kidney disease (CKD) is paramount to optimising growth and clinical outcome, but little information on this subject has been published. In this study, we examined basal metabolic rate (BMR; a component of energy expenditure) with the aim to determine whether it is related to kidney function independently of weight, height and lean body mass (LBM).

METHODS

Twenty children with CKD and 20 healthy age- and gender-matched control children were studied on one occasion. BMR was measured by indirect open circuit calorimetry and predicted by the Schofield equation. Estimated glomerular filtration rate (eGFR) was related to BMR and adjusted for weight, height, age and LBM measured by skinfold thickness.

RESULTS

The adjusted BMR of children with CKD did not differ significantly from that of healthy subjects (1296 ± 318 vs.1325 ± 178 kcal/day; p = 0.720). Percentage of predicted BMR also did not differ between the two groups (102 ± 12% vs. 99 ± 14%; p = 0.570). Within the CKD group, eGFR (mean 33.7 ± 20.5 mL/min/m(2)) was significantly related to BMR (β 0.3, r = 0.517, p = 0.019) independently of nutritional status and LBM.

CONCLUSIONS

It seems reasonable to use estimated average requirement as the basis of energy prescriptions for children with CKD (mean CKD stage 3 disease). However, those who were sicker had significantly lower metabolic rates.

Factors influencing success of clinical genome sequencing across a broad spectrum of disorders

To assess factors influencing the success of whole-genome sequencing for mainstream clinical diagnosis, we sequenced 217 individuals from 156 independent cases or families across a broad spectrum of disorders in whom previous screening had identified no pathogenic variants. We quantified the number of candidate variants identified using different strategies for variant calling, filtering, annotation and prioritization. We found that jointly calling variants across samples, filtering against both local and external databases, deploying multiple annotation tools and using familial transmission above biological plausibility contributed to accuracy. Overall, we identified disease-causing variants in 21% of cases, with the proportion increasing to 34% (23/68) for mendelian disorders and 57% (8/14) in family trios. We also discovered 32 potentially clinically actionable variants in 18 genes unrelated to the referral disorder, although only 4 were ultimately considered reportable. Our results demonstrate the value of genome sequencing for routine clinical diagnosis but also highlight many outstanding challenges.

Eculizumab in atypical haemolytic uraemic syndrome with severe cardiac and neurological involvement

BACKGROUND

Atypical haemolytic uraemic syndrome (aHUS) is a rare disorder usually caused by dysregulation of the alternative complement pathway. Uncontrolled complement activation results in systemic complement-mediated thrombotic microangiopathy (TMA) and subsequent multi-organ damage. The two most common extrarenal complications comprise neurological and cardiovascular involvement. Eculizumab, a humanised anti-C5 monoclonal antibody, has recently been introduced as a therapy for this condition.

CASE-DIAGNOSIS/TREATMENT

A 19-month-old child suffering from aHUS with severe neurological involvement, dilated cardiomyopathy and renal impairment requiring dialysis received eculizumab as first-line treatment, initiated within 12 h of admission, resulting in significant improvements in her neurological state and normalisation of cardiac and renal function. These positive outcomes have been sustained with fortnightly eculizumab therapy (at the time of writing, on-going for 1 year). No further complications of TMA have occurred.

CONCLUSION

Severe cardiac involvement in a child with aHUS is an important indication for prompt, first-line treatment with eculizumab, resulting in rapid normalisation of cardiac function.

Short course daily prednisolone therapy during an upper respiratory tract infection in children with relapsing steroid-sensitive nephrotic syndrome (PREDNOS 2): protocol for a randomised controlled trial

BACKGROUND

Relapses of childhood steroid-sensitive nephrotic syndrome (SSNS) are treated with a 4- to 8-week course of high-dose oral prednisolone, which may be associated with significant adverse effects. There is a clear association between upper respiratory tract infection (URTI) and relapse development. Previous studies in developing nations have suggested that introducing a 5- to 7-day course of daily prednisolone during an URTI may prevent a relapse developing and the need for a treatment course of high-dose prednisolone. The aim of PREDNOS 2 is to evaluate the effectiveness of a 6-day course of daily prednisolone therapy during an URTI in reducing the development of a subsequent relapse in a developed nation.

METHODS/DESIGN

The subjects will be 300 children with relapsing SSNS (≥2 relapses in preceding year), who will be randomised to receive either a 6-day course of daily prednisolone or no change to their current therapy (with the use of placebo to double blind) each time they develop an URTI over 12 months. A strict definition for URTI will be used. Subjects will be reviewed at 3, 6, 9 and 12 months to capture data regarding relapse history, ongoing therapy and adverse effect profile, including behavioural problems and quality of life. A formal health economic analysis will also be performed. The primary end point of the study will be the incidence of URTI-related relapse (3 days of Albustix +++) following the first infection during the 12-month follow-up period. DNA and RNA samples will be collected to identify a potential genetic cause for the disease. Subjects will be recruited from over 100 UK centres with the assistance of the Medicines for Children Research Network.PREDNOS 2 is funded by the National Institute for Health Research Health Technology Assessment Programme (11/129/261).

DISCUSSION

We propose that PREDNOS 2 will be a pivotal study that will inform the future standard of care for children with SSNS. If it is possible to reduce the disease relapse rate effectively and safely, this will reduce the morbidity and cost associated with drug treatment, notwithstanding hospital admission and parental absence from employment.

TRIAL REGISTRATION

Current Controlled Trials (ISRCTN10900733).

Children with nephrotic syndrome have greater bone area but similar volumetric bone mineral density to healthy controls

BACKGROUND

Glucocorticoid use has been associated with an increased fracture risk and reduced bone mineral density (BMD), particularly in the trabecular compartment. However the contribution of the underlying inflammatory disease process to these outcomes is poorly understood. Childhood nephrotic syndrome (NS) typically follows a relapsing-remitting course often requiring recurrent courses of glucocorticoids, but with low systemic inflammation during remission. NS therefore represents a useful clinical model to investigate the effects of glucocorticoids on BMD and bone geometry in childhood.

METHODS

Children with NS were compared to age and sex matched healthy controls. Body composition and areal BMD (whole body, lumbar spine and hip) were assessed by DXA. Peripheral quantitative computed tomography (pQCT) scans were obtained at metaphyseal (4%) and diaphyseal (66%) sites of the tibia to determine volumetric BMD and bone cross-sectional geometry. Lifetime cumulative glucocorticoid exposure was calculated from medical records.

RESULTS

29 children with NS (55% male, age 10.7±3.1years) were compared to 29 healthy controls (55% male, age 11.0±3.0years). The children with NS were of similar height SDS to controls (p=0.28), but were heavier (0.65±1.28SDS vs -0.04±0.89SDS, p=0.022) and had greater body fat percentage SDS (0.31±1.01 vs -0.52±1.10, p=0.008). Tibial trabecular and cortical vBMD were similar between the two groups but bone cross-sectional area (CSA) was significantly greater in children with NS at both the metaphysis (954±234mm(2) vs 817±197mm(2), p=0.002) and diaphysis (534.9±162.7mm(2) vs 463.2±155.5mm(2), p=0.014). Endosteal and periosteal circumferences were greater in children with NS than controls (both p<0.01), resulting in reduced cortical thickness (2.4±0.7mm vs 2.8±0.7mm, p=0.018), but similar cortical CSA (p=0.22). The differences in cortical geometry were not statistically significant when weight was included as a confounding factor. There were no associations between cumulative steroid exposure, duration of NS or number of relapses and any bone parameter.

CONCLUSIONS

Tibial bone CSA is increased in children with NS. We speculate that this is a compensatory response to increased body weight. Defects in trabecular BMD were not identified in this cohort of children with NS.

Eculizumab therapy for atypical haemolytic uraemic syndrome due to a gain-of-function mutation of complement factor B

BACKGROUND

Atypical haemolytic uraemic syndrome (aHUS) is caused by dysregulated complement activation. A humanised anti-C5 monoclonal antibody has recently become available for treatment of this condition

CASE-DIAGNOSIS/TREATMENT

We present the first description of an infant with an activating mutation of complement factor B successfully treated with eculizumab. On standard doses she had evidence of ongoing C5 cleavage despite a good clinical response.

CONCLUSIONS

Eculizumab is effective therapy for aHUS associated with factor B mutations, but recommended doses may not be adequate for all patients.

Cisplatin-induced haemolytic uraemic syndrome associated with a novel intronic mutation of CD46 treated with eculizumab

A 2-year-old patient with a neuroblastoma developed haemolytic uraemic syndrome (HUS) following treatment with cisplatin and carboplatin. Following treatment with eculizumab, there was a substantial improvement in renal function with the recovery of the platelet count and the cessation of haemolysis. Subsequent investigations showed a novel, heterozygous CD46 splice site mutation with reduced peripheral blood neutrophil CD46 expression. Withdrawal of eculizumab was followed by the recurrence of disease activity, which resolved with re-introduction of therapy. Abnormal regulation of complement may be associated with other cases of cisplatin-induced HUS and treatment with eculizumab may be appropriate for other affected individuals.

Does dysregulated complement activation contribute to haemolytic uraemic syndrome secondary to Streptococcus pneumoniae?

We describe two patients with haemolytic uraemic syndrome (HUS) associated with invasive Streptococcus pneumoniae infection. Both patients had transiently reduced serum concentrations of complement C3. One had reduced expression of CD46 and never recovered renal function. No constitutive defect in regulation of the alternative pathway of complement activation was demonstrated in the second patient but there was an apparent improvement in her condition after administration of eculizumab. The most widely accepted mechanism for pneumococcal HUS is endothelial cell damage by pre-formed antibodies against the Thomsen-Friedenreich antigen. This explanation does not bear rigorous scrutiny. We postulate that transiently dysregulated complement activation may play a role in the pathogenesis of pneumococcal disease. We further postulate that the mechanism could be enhanced binding of factor H to the neuraminidase-altered surface of endothelial cells or reduced binding of factor H to the endothelial cell surface mediated by competitive binding of factor H by pneumococcal surface protein C (pspC).

Simultaneous sequencing of 24 genes associated with steroid-resistant nephrotic syndrome

BACKGROUND AND OBJECTIVES

Up to 95% of children presenting with steroid-resistant nephrotic syndrome in early life will have a pathogenic single-gene mutation in 1 of 24 genes currently associated with this disease. Others may be affected by polymorphic variants. There is currently no accepted diagnostic algorithm for clinical genetic testing. The hypothesis was that the increasing reliability of next generation sequencing allows comprehensive one-step genetic investigation of this group and similar patient groups.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study used next generation sequencing to screen 446 genes, including the 24 genes known to be associated with hereditary steroid-resistant nephrotic syndrome. The first 36 pediatric patients collected through a national United Kingdom Renal Registry were chosen with comprehensive phenotypic detail. Significant variants detected by next generation sequencing were confirmed by conventional Sanger sequencing.

RESULTS

Analysis revealed known and novel disease-associated variations in expected genes such as NPHS1, NPHS2, and PLCe1 in 19% of patients. Phenotypically unexpected mutations were also detected in COQ2 and COL4A4 in two patients with isolated nephropathy and associated sensorineural deafness, respectively. The presence of an additional heterozygous polymorphism in WT1 in a patient with NPHS1 mutation was associated with earlier-onset disease, supporting modification of phenotype through genetic epistasis.

CONCLUSIONS

This study shows that next generation sequencing analysis of pediatric steroid-resistant nephrotic syndrome patients is accurate and revealing. This analysis should be considered part of the routine genetic workup of diseases such as childhood steroid-resistant nephrotic syndrome, where the chance of genetic mutation is high but requires sequencing of multiple genes.

Microbiological aspects of the UK National Institute for Health and Clinical Excellence (NICE) guidance on urinary tract infection in children

The publication in August 2007 of the UK National Institute for Health and Clinical Excellence (NICE) guidance on urinary tract infection in children provided a fresh and useful review of the management of this condition. However, it has also resulted in some controversy. In particular, the advice to use urgent microscopy for rapid screening of urine in children >or=3 months but <3 years of age has presented practical problems for some laboratories in staffing this service out of hours. Further discussion between microbiologists, paediatricians and primary care doctors regarding this recommendation is required. In addition, the abandoning of routine antibiotic prophylaxis following a first-time urine infection has caused some debate. The evidence around these issues is reviewed, as well as the differences in the laboratory processing and interpretation of paediatric urines compared with urine specimens from adults. General measures to reduce the risk of recurrence are also discussed. As mentioned in the NICE guidance, microbiologists should continue to emphasize the basic principles, particularly the importance of obtaining an accurate diagnosis from a well-collected and well-transported urine specimen.

Hemolytic uremic syndrome associated with invasive pneumococcal disease: the United kingdom experience

OBJECTIVE

To describe the presentation, management, and outcome of 43 cases of pneumococcal-associated hemolytic uremic syndrome (P-HUS). An increased incidence of P-HUS has been noted in the United Kingdom between January 1998 and May 2005.

STUDY DESIGN

Cases with microangiopathic hemolytic anemia (Hb <10 g/dL with fragmented RBCs), thrombocytopenia (platelet count < 130 x 10(9)/L), acute renal impairment with oliguria and elevated plasma creatinine for age, confirmed or suspected pneumococcal infection and/or T-activation were included.

RESULTS

The median age at presentation was 13 months (range, 5-39 months). Pneumococcus was identified in 34 of 43 cases; T-activation was identified in 36 of 37 cases. Twelve strains were serotyped: serotypes 3 (n = 2), 6A (n = 2), 12F (n = 1), 14 (n = 1), 19A (n = 6). Empyema was present in 23 of 35 pneumonia cases; 13 cases had confirmed (9) or suspected (4) pneumococcal meningitis; 36 cases required dialysis (median, 10 days; range, 2-240 days). The mortality rate was 11%, comprising 3 cases of meningitis, 1 case of sepsis and 1 case of pulmonary embolism at 8 months follow up while on dialysis. Follow-up data were available for 35 of 38 patients who survived (median follow-up period, 9 months; range, 1-63 months); of these, 10 patients had renal dysfunction, 1 patient was dialysis-dependent, 5 patients had hypertension and 8 patients had at least 1+ proteinuria on urinalysis.

CONCLUSION

P-HUS has increased compared with historic surveys (0/288 in 1985-1988; 8/413 in 1997-2001, 43/315 in 1998-May 2005). Early mortality remains high (8-fold that of VTEC-induced HUS). Ten of 12 strains identified would not be covered by the PCV7 vaccine.

Acute renal failure in a patient with paroxysmal cold hemoglobinuria

Acute renal failure following auto-immune hemolysis is rare. We report a child with acute paroxysmal cold hemoglobinuria (PCH) complicated by renal failure. She was treated by peritoneal dialysis and red blood cell transfusion. After 2 weeks she had made a complete recovery with a normal blood count and renal profile, and the peritoneal dialysis catheter was removed. Extensive investigation, including an analysis of heme oxygenase-1 gene promoter region polymorphisms, failed to identify a cause for the renal failure in this patient.

Rituximab therapy for steroid-dependent minimal change nephrotic syndrome

We present a patient with steroid-sensitive but high-dose steroid-dependent nephrotic syndrome who was treated with rituximab. For 9 months following therapy she had undetectable CD19 cells in the peripheral circulation. She remained in remission during this period even though therapy was reduced to low-dose, alternate day prednisolone only. After 9 months, CD19 cells were once again detectable. Shortly after CD19 cells became detectable again she relapsed. We conclude that B-lymphocytes play a central role in the pathogenesis of idiopathic minimal change nephrotic syndrome (MCNS) and that rituximab may have a useful role in the management of steroid-dependent patients.

Laparoscopic renal biopsy in obese children

Percutaneous kidney biopsy is routinely used to obtain renal tissue for histological examination. It is usually successful and has very few contraindications. We describe two children with clinical obesity in whom the percutaneous approach failed to yield renal tissue for histology. They underwent successful laparoscopic kidney biopsies that yielded adequate renal tissue for diagnosis, although the first attempt in one patient yielded renal medulla necessitating a repeat biopsy. We recommend that laparoscopic kidney biopsies should be considered in obese children when percutaneous kidney biopsies are considered impossible.

Tubulointerstitial nephritis and uveitis in monozygotic twin boys

We describe monozygotic male twins who developed tubulointerstitial nephritis and uveitis (TINU) almost 2 years apart. They presented with non-specific symptoms and were noted to have glycosuria and renal impairment. Both children have uveitis. One had biopsy-proven interstitial nephritis and the other had biochemical evidence of transient tubular dysfunction. While the renal parameters improved, they are still under treatment for uveitis. The occurrence of TINU in identical twins at an interval of just under 2 years supports a strong genetic element in the aetiology of this syndrome. We believe this is the first report of male twins with TINU.

Urinary L-lactate excretion is increased in renal Fanconi syndrome

BACKGROUND

Measurement of l-lactate in body fluids is an established clinical tool to identify disorders of cellular respiration. However, there is very little known about the clinical value of urinary lactate measurements. We investigated urinary lactate excretion in children with renal Fanconi syndrome.

METHODS

Freshly voided urine samples were obtained from children with Fanconi syndrome and controls both with and without renal disease. Urine lactate was estimated by conversion to pyruvate in the presence of lactate dehydrogenase and NAD. The NADH produced was measured photometrically. Urine lactate was factored for urine creatinine.

RESULTS

Children with Fanconi syndrome had a significantly higher urine lactate/creatinine ratio [mean: 84 x 10(-2) mmol/mmol; 95% confidence interval (CI): 40.8-127.1 x 10(-2) mmol/mmol] than healthy controls (mean: 1.3 x 10(-2) mmol/mmol; CI: 1.1-1.5 x 10(-2) mmol/ mmol) and those with a variety of renal diseases (mean: 3.1 x 10(-2) mmol/mmol; CI: 1.8-4.5 x 10(-2) mmol/mmol).

CONCLUSIONS

Urinary lactate is increased in Fanconi syndrome. The increase is likely to be due to reduced lactate co-transport in the proximal tubule. Urinary lactate/creatinine has clinical utility as a sensitive test of disordered proximal renal tubular function.

Acute renal tubular dysfunction in association with Salmonella enteritidis

A thirteen-year-old boy presented with acute renal tubular dysfunction after an infection with salmonella enteritidis. The child recovered following treatment with ciprofloxacin for a week.

Bilateral multicystic kidneys--an unusual case

Multicystic dysplasia of the kidneys is a condition whose prognosis is good as it usually presents unilaterally. Bilateral cases are usually fatal in utero. We report a case of bilateral multicystic dysplasia of the kidneys where the lower moiety of the right kidney was spared cystic change. The patient had normal renal function and, following conservative management, remains alive and well 6 months later.

Hypertension: a cause of growth impairment

The effects of high blood pressure on growth are not fully understood and while hypertension may be associated with failure to thrive, hypertension causing failure to thrive in children is poorly documented. We describe four children presenting with failure to thrive due to hypertension consequent to various aetiologies. Control of hypertension with appropriate therapy resulted in improved growth. The exact pathogenesis of failure to thrive in hypertensive children is not known. These cases demonstrate the importance of careful measurement of blood pressure in children with failure to thrive.

Bacterial infection in children with HIV: a prospective study from Cape Town, South Africa

Invasive bacterial infection in children infected with the human immunodeficiency virus (HIV) is common. South African data on this problem are limited. Over 1 year we prospectively studied 108 HIV-infected children hospitalized for 136 presumed infective episodes. Blood culture was positive in 24.8% of episodes. Streptococcus pneumoniae predominated (14/30 positive blood cultures); one-third of isolates showed resistance to penicillin. Acute lower respiratory tract infection accounted for 44% of clinical diagnoses, a bacterial cause being established for 23.8% of these. Age and stage of HIV infection did not influence the likelihood of a positive culture. A high proportion of presumed infective episodes requiring hospitalization of young HIV-infected children have a bacterial cause. Blood culture appears to be a useful method of obtaining the microbiological information required to focus antibiotic therapy.

Effects of long-term high-altitude hypoxia on isolated fetal ovine coronary arteries

OBJECTIVE

To examine the effects of long-term high-altitude hypoxia on the contractile properties of isolated fetal coronary arteries.

METHODS

Maximal contractile responses (T(max)) to 90 mmol/L KCl and the thromboxane A(2) mimetic U46619 were measured in proximal (PLCx) and distal left circumflex (DLCx), left anterior descending (LAD), and right coronary arterial (RCA) rings from high-altitude and control fetuses. Paired studies were conducted with and without nitric oxide synthase (NOS) inhibitors, Nomega-nitro-L-arginine and Nomega-nitro-L-arginine ester.

RESULTS

In high-altitude fetuses, 90 mmol/L KCl T(max) responses in both intact and NOS-blocked rings decreased by approximately 62% in PLCx, approximately 59% in DLCx, approximately 57% in LAD, and approximately 47% in RCA (n = 9-18/group; P <.05). High-altitude vessels also exhibited decreased sensitivity to U46619. NOS blockade potentiated T(max) to U46619 in the high-altitude RCA segments and augmented T(max) to U46619 in high-altitude RCA compared with its treated control counterpart (P <. 05).

CONCLUSION

These results suggest that nitric oxide influences the pharmacologic responsiveness of the RCA to U46619. Furthermore, long-term high-altitude hypoxia significantly alters the contractile capabilities of fetal coronary arteries. These observations may partially explain the maintained redistribution of cardiac output to the fetal heart during exposure to long-term high-altitude hypoxia.

Ca(2+) sensitivity of fetal coronary arteries exposed to long-term, high-altitude hypoxia

OBJECTIVE

To determine the contribution of decreased calcium responsiveness of fetal coronary arteries to decreased contractile responses to potassium and the thromboxane A(2) analogue U46619 in these arteries after exposure to chronic hypoxemia.

METHODS

Concentration-response curves to Ca(2+) in beta-escin-permeabilized left circumflex (LCx), left anterior descending (LAD), and right coronary artery (RCA) rings from high-altitude (HA) and control (CON) fetuses were measured. In a second set of beta-escin-permeabilized coronary artery rings, the effect of U46619 on Ca(2+) sensitivity was tested.

RESULTS

Maximum Ca(2+)-activated force (T(max)) was decreased in HA LCx (CON 0.091+/-0.010 versus HA 0.057+/-0.006 g/cm(2); P<.05) and HA LAD (CON 0.065+/-0.012 versus HA 0.031+/-0.007 g/cm(2); P <.05). No significant difference was observed in the RCA. There was no change in the pD(2) (-log EC(50)) values between CON and HA coronary rings. The Ca(2+) sensitizing effect of U46619 on submaximal Ca(2+)-activated force was lower only in the HA LCx (CON 0.044+/-0.010 versus HA 0.023+/-0.006 g/cm(2) at 10(-5) mol/L; P<.05).

CONCLUSION

These results indicate that maximum tension development in response to Ca(2+) was decreased in the HA LCx and LAD but not the RCA; however, Ca(2+) sensitivity of the contractile apparatus was unaltered in all of them. Decreased Ca(2+) responsiveness may partially explain the decreased contractile capability of fetal LCx and LAD during long-term, high-altitude intrauterine hypoxemia.

A randomized, clinical evaluation of the safety and efficacy of a novel oral irrigator

PURPOSE

To evaluate the safety and efficacy of the Braun Oral-B OxyJet (MD15) Oral Irrigator when used as an adjunct to manual brushing.

MATERIALS AND METHODS

64 subjects with mild-to-moderate gingivitis entered this randomized, parallel-group, examiner-blind 8-week study. Subjects were assigned to use either the MD15 and a manual brush, or a manual brush alone. Both groups brushed twice daily; the MD15 subjects, in addition to brushing, also used the irrigator in the evening. Subjects were scored at baseline, week 4 and week 8 at up to 168 oral sites for gingival inflammation (modified gingival index), gingival bleeding (angular bleeding index), and plaque (modified plaque index).

RESULTS

No adverse events related to study treatment were reported. Use of the MD15 in conjunction with manual brushing resulted in significant (P < 0.05) decreases from baseline in the plaque index at week 8, the gingival index at week 4, and the bleeding index at weeks 4 and 8. The gingival index was also decreased from baseline at week 8, but this was not statistically significant (P = 0.069). The control group also showed significant decreases from baseline for the gingival index at week 8 and the bleeding index at weeks 4 and 8, but plaque scores were not significantly reduced. Although use of the MD15 plus brushing significantly reduced plaque levels from baseline, while brushing alone did not, the difference between the two groups did not achieve statistical significance (P = 0.065). Differences between the groups with respect to the gingival and bleeding indices were also not statistically significant. It is concluded that use of the OxyJet Oral Irrigator in conjunction with manual brushing is safe, reduces plaque and improves gingival health.

Efficacy of a chlorine dioxide-containing mouthrinse in oral malodor

Studies have suggested that when chlorine dioxide is contained in a mouthrinse, it neutralizes volatile sulfur compounds in mouth air. The efficacy of a chlorine dioxide-containing mouthrinse in the reduction of oral malodor was evaluated in a randomized, controlled, double-blind, parallel group study of 31 men and women. Subjects with a maximum odor pleasantness score of < or = -1 (slightly unpleasant/stale) on a 7-point ordinal scale at both screening and baseline were randomized to treatment with the chlorine dioxide-containing rinse (n = 16) or distilled water (negative control) (n = 15). Oral malodor was evaluated at baseline (prerinse) and at 2, 4, 8, 24, 48, 72, and 96 hours postrinse by both a trained, previously calibrated panel of organoleptic judges and a factory-calibrated portable sulfide monitor. The sulfide monitor measured concentrations of volatile sulfur compounds in the subjects' mouth air 3 minutes after completion of the organoleptic assessment at each time point. The correlation between the organoleptic assessments and log-transformed sulfide monitor values was evaluated. With the chlorine dioxide mouthrinse, a statistically significant improvement in odor pleasantness, reduction in odor intensity, and reduction in oral volatile sulfur compound concentrations compared to the water control were evident at 2 hours postrinse and persisted through 8 hours postrinse. The mean (+/- SD) odor pleasantness improved from -1.25 +/- 0.31 at baseline to -0.73 +/- 0.33 at 2 hours postrinse in the chlorine dioxide group compared to -1.40 +/- 0.38 at baseline to -1.31 +/- 0.67 at 2 hours in the control group (P < 0.01). Odor pleasantness reached its maximum change from baseline to 0.63 +/- 0.45 at 8 hours postrinse. The mean (+/- SD) log-transformed sulfide monitor measurement decreased from 5.40 +/- 0.29 at baseline to 5.17 +/- 0.13 at 2 hours postrinse in the chlorine dioxide group, but increased from 5.47 +/- 0.40 at baseline to 5.56 +/- 0.54 at 2 hours in the control group (P < 0.01). As measured by the sulfide monitor, the mean volatile sulfur compound concentration in the chlorine dioxide group reached its minimum level at 8 hours postrinse (change from baseline in the log-transformed Halimeter measurement of -0.35 +/- 0.31). Thus, this study demonstrates that a one-time use of a chlorine dioxide-containing mouthrinse significantly improves mouth odor pleasantness, reduces mouth odor intensity, and reduces volatile sulfur compound concentrations in mouth air for at least 8 hours after use.

Cocaine induces apoptosis in fetal myocardial cells through a mitochondria-dependent pathway

In the present study, we examined the direct cytotoxic effects of cocaine on fetal cardiac myocytes. Cocaine treatment of cultured fetal rat (21 days) myocardial cells (FRMCs) induced a time- and concentration-dependent increase in apoptotic cells in FRMCs. Cocaine induced surface exposure of phosphatidylserine in FRMCs at 12-h treatment and increased apoptotic cells up to 96 h. Corresponding DNA fragmentation induced by cocaine in these cells was demonstrated in situ by terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling assay and by electrophoresis of labeled DNA fragments, showing the characteristic apoptotic ladders. The pD(2) and maximum increase of cocaine-induced apoptosis in FRMCs were 4.3 and 3.2-fold, respectively. Both caspase-9 and caspase-3 inhibitors (Z-LEHD-FMK and Ac-DEVD-CHO, respectively) blocked cocaine-induced apoptosis. In addition, cyclosporin A inhibited cocaine-induced apoptosis in a concentration-dependent manner with an IC(50) value of 0.1 microM. The maximum of 86% inhibition was obtained with 3 microM cyclosporin A. Cocaine induced the release of cytochrome c from the mitochondria and increased its levels in the cytosol by 3.1-fold. In accordance, the level of cytochrome c in the mitochondria fraction decreased by approximately 60%. Cocaine-induced translocation of cytochrome c was inhibited by cyclosporin A. The results indicate that cocaine has a direct cytotoxic effect on fetal cardiomyocytes by inducing apoptosis in the cells. Furthermore, the release of cytochrome c from the mitochondria and its subsequent activation of caspase-9 and caspase-3 play a key role in cocaine-induced apoptosis.

Quantitative electron microscopic study of the hypoxic fetal sheep heart

In order to determine the effects of chronic, high-altitude hypoxia on the ovine fetal heart, we exposed pregnant ewes to 3,820 m beginning at 30 days gestation. We previously showed that following approximately 110 days of hypoxia the fetal heart showed significant reduction in cardiac output (76% of control) and contractility, and elevated levels of citrate synthase and lactate dehydrogenase. To investigate ultrastructural influences on these observed physiologic changes at altitude, we hypothesized that the volume densities of myofibrils and mitochondria, and glycogen content would be reduced in the ovine fetal heart and that this may contribute to contraction and cardiac output deficits in hypoxia. Mitochondria and myofibril volume density were determined by standard point-counting techniques and glycogen content was determined by biochemical analysis. The glycogen content from the hypoxic right ventricle (4.8 +/- 0.3%) was significantly lower than in control right ventricle (6.8 +/- 0.5%) and both left ventricles (hypoxia, 7.2 +/- 0.5; control, 7.8 +/- 0. 4%). Total mitochondrial volume density was also significantly reduced following hypoxia (15.5 +/- 0.7%) compared to controls (16.9 +/- 0.4%). As is common in the ovine fetal heart, the myofibril volume density of the right ventricle from both groups was significantly higher than the left ventricle (RV, 58.6 +/- 1.6; LV 54.3 +/- 0.9%). However, it was not different between control and high altitude. In support of our hypothesis, we may speculate that deficits in the quantity of myocyte glycogen and mitochondria contribute to the observed reduction in cardiac output and contractility, despite the upregulation of citrate synthase and lactate dehydrogenase. In contrast, myofibril volume density was unchanged.

Effects of long-term, high-altitude hypoxia on the capillarity of the ovine fetal heart

To determine the effect of chronic hypoxia on myocardial capillarity, we exposed pregnant ewes to an altitude of 3,820 m from day 30 to day 139 of gestation and compared the fetus to low-altitude (approximately 300 m) controls. We hypothesized that capillarity would increase in the hypoxic myocardium to optimize oxygen and metabolite flux to hypoxic tissues. Fetal hearts were fixed by retrograde aortic perfusion and processed for microscopy and stereological evaluation. Fiber cross-sectional area and capillary density were measured and standardized to sarcomere length. Capillary volume density and capillary diameter were measured, capillary-to-fiber ratio and capillary length density were calculated, and the capillary anisotropy coefficient was obtained from a table of known values. Capillary-to-fiber ratio, capillary volume density, and the capillary anisotropy coefficient were not different between hypoxia and control groups. Capillary diameter was significantly larger in the right compared with the left ventricle of hypoxic but not control hearts; fiber cross-sectional area tended to be larger in the right ventricle of both groups, but this was not significant. As a result of larger fiber size, capillary density and capillary length density were significantly smaller in the right ventricle of hypoxic but not control fetal hearts. Contrary to our hypothesis, the ovine fetus does not show morphological adaptation in the myocardium after approximately 109 days of high-altitude hypoxic stress.