The development of the Belgian paediatric clinical trial network

Paediatric clinical trials are critical to ensure that medications prescribed to children are safe and effective. However, evidence-based dosing and labelling of such medications remain limited, and most clinical trials in paediatrics fail. Factors for lack of trial completion include performance at site level (limited patient recruitment, limited site staff experience and lack of infrastructure), the sponsor team (limited paediatric specific expertise in design, uncertainties on robustness of biomarkers or outcome variables) as well as regulatory and administrative burdens. As a result of the growing demand for site support, the Belgian Paediatric Clinical Research Network (BPCRN) established in 2009 has been relaunched in 2018 to improve paediatric clinical trials, with the support of innovative-medicines-initiative 2 (IMI2) pan-European network conect4children (c4c) and the transatlantic network I-ACT for Children (US).This paper highlights the formation of the BPCRN and the practical insights it offers for advancing paediatric clinical trials through national networks. A national network can improve trial quality, safety and efficiency, provide clinical research expertise, identify suitable sites, and help with troubleshooting of common trial issues. The BPCRN's centralized approach has advanced paediatric clinical trials by streamlining communication and standardizing trial conduct. Challenges and opportunities have arisen, including a relaunch in 2018, orphan medicine trials, and network sustainability. Collaboration between network activities, government support, site-level improvements, efficient communication, and interaction with industry are key to achieve lasting transformation in paediatric medicine research.

Black titania by sonochemistry: A critical evaluation of existing methods

In the field of photocatalysis, the fabrication of black titania is a booming topic, as it offers a system with improved solar light harvesting properties and increased overall efficiency. The darkening of white TiO2 powders can be ascribed to surface hydroxylation, oxygen vacancies, Ti3+ centres, or a combination thereof. A handful of studies suggests these defects can be conveniently introduced by acoustic cavitation, generated during sonochemical treatment of pristine TiO2 powders. In reproducing these studies, P25 TiO2 samples were ultrasonicated for various hours with a power density of 8000 W/L, resulting in powders that indeed became gradually darker with increasing sonication time. However, HAADF-STEM revealed that extensive erosion of the sonotrode tip took place and contaminated the samples, which appeared to be the primary reason for the observed colour change. This was confirmed by UV-Vis DRS and DRIFTS, that showed no significant alteration of the catalyst surface after sonication. EPR measurements showed that only an insignificant fraction of Ti3+ centres were produced, far less than in a TiO2 sample that was chemically reduced with NaBH4. No evidence of the presence oxygen vacancies could be found. The enhanced photocatalytic activities of ultrasonicated materials reported in literature can therefore not be ascribed to the synthesis of actual black (defected) TiO2, but rather to specific changes in morphology as a result of acoustic cavitation. Also, this study underlines the importance of considering probe erosion in sonochemical catalyst synthesis, which is an unavoidable side effect that can have an important impact on the catalyst appearance, properties and performance.

Sunlight-Powered Reverse Water Gas Shift Reaction Catalysed by Plasmonic Au/TiO2 Nanocatalysts: Effects of Au Particle Size on the Activity and Selectivity

This study reports the low temperature and low pressure conversion (up to 160 °C, p = 3.5 bar) of CO₂ and H₂ to CO using plasmonic Au/TiO₂ nanocatalysts and mildly concentrated artificial sunlight as the sole energy source (up to 13.9 kW·m^-2 = 13.9 suns). To distinguish between photothermal and non-thermal contributors, we investigated the impact of the Au nanoparticle size and light intensity on the activity and selectivity of the catalyst. A comparative study between P25 TiO₂-supported Au nanocatalysts of a size of 6 nm and 16 nm displayed a 15 times higher activity for the smaller particles, which can only partially be attributed to the higher Au surface area. Other factors that may play a role are e.g., the electronic contact between Au and TiO₂ and the ratio between plasmonic absorption and scattering. Both catalysts displayed ≥84% selectivity for CO (side product is CH₄). Furthermore, we demonstrated that the catalytic activity of Au/TiO₂ increases exponentially with increasing light intensity, which indicated the presence of a photothermal contributor. In dark, however, both Au/TiO₂ catalysts solely produced CH₄ at the same catalyst bed temperature (160 °C). We propose that the difference in selectivity is caused by the promotion of CO desorption through charge transfer of plasmon generated charges (as a non-thermal contributor).

120 High variation in prediction of developmental competence of bovine oocytes based on visual examination

The quality of an oocyte is often represented by its morphological characteristics. Stringent selection of bovine cumulus–oocyte complexes (COCs) for invitro embryo production (IVP) is regularly based on parameters such as colour and granulation of the ooplasm, density of the surrounding cumulus cells, brightness of the zona pellucida, among other less common parameters. The link between developmental competence and morphology of the COC has been demonstrated in literature in group culture system. However, this has not been yet examined in an individual invitro production system. This study investigates the ability of IVP researchers to predict whether an oocyte will develop into a blastocyst at Day 8 of invitro culture in an individual production system. A set of 29 pictures of immature bovine COCs was presented in duplicates to eight bovine IVP researchers with different institutional backgrounds. The observers were asked if they would select each oocyte for further IVP processing, assuming that only the oocytes with the highest developmental potential can proceed, and thus a stringent selection is warranted. These 29 immature oocytes were matured, fertilized, and cultured individually invitro (using conventional methods) so that their ability to develop into a blastocyst at Day 8 post-fertilization was known. The ability to reach the blastocyst stage was stated as the gold standard and compared with the answers of the observers using kappa statistics and sensitivity (Se) and specificity (Sp) tests. Kappa (κ) for interobserver agreement was κ=0.01 (Se=50%, Sp=53%; positive predictive value=14%, negative predictive value=87%) with 50% accuracy of prediction. The intraobserver agreement was κ=0.69, with κ=1 referring to 100% agreement (Se=87%, Sp=83%), with an accuracy of 85%. The ability of trained embryologists to predict the fate of oocytes’ developmental competence was accurate for only half of the presented oocytes. Additionally, the proportion of false positive (1 − Sp) and false negative (1−Se) predictions was equally distributed. The low positive predictive value might be due to the lower development rates in individual culture systems versus group culture systems, whereas observers are mainly trained to select oocytes for group culture. This study demonstrated the subjective nature of the oocyte selection process that is based on visual examination of COC morphology because interobserver agreement was almost nonexistent. Interpretation of the morphology within an observer remains consequent, represented by the high intraobserver agreement. Consequently, there is a need to develop a new model for the objective determination of oocyte quality for individual IVP. The implementation of machine learning algorithms could objectively enhance oocyte selection and artificial reproductive technologies in extension.

The long-term added value of voiding school for children with refractory non-neurogenic overactive bladder: an inpatient bladder rehabilitation program

INTRODUCTION & BACKGROUND

Despite adequate management, 20% of children with overactive bladder (OAB) syndrome fail to improve their bladder function. To approach the need for alternative strategies, an inpatient bladder rehabilitation 'voiding school' program was established.

OBJECTIVE

The objective of this study was to evaluate the short- and long-term (1-year follow-up) outcome of this voiding school program in children with refractory OAB. In addition, the authors aimed to identify which children achieved the best outcomes with this voiding school program.

STUDY DESIGN

The charts of all children (n = 357, mean age: 9.7 ± 2.0 years, 63.6% boys) with refractory OAB who attended voiding school between 2000 and 2010 were reviewed. A linear mixed model with random intercept was used to evaluate the incontinence (expressed by enuresis and daytime incontinence voiding scores) and maximal voiding volume (MVV).

RESULTS & DISCUSSION

This study demonstrated an overall beneficial long-term effect of the inpatient program on day- and night-time incontinence, in which 36.6% of children achieved dryness during day- and night-time. In addition, the mean overall decline in the number of wet nights and days declined with 4 extra dry days and/or nights per week, in comparison with the level of continence before attending the voiding school program. In contrast, only a temporary increase in MVV was seen, however, without relapse incontinence. At last, the authors identified the negative impact of decreasing age, male sex, dysfunctional voiding and nocturnal polyuria on the overall outcome of the inpatient program.

CONCLUSION

An inpatient rehabilitation 'voiding school' program is a successful and safe treatment modality for children with refractory OAB that results in long-term significant increase of continence, as well as amelioration in degree of severity. The worst outcomes of this voiding school program were detected in children with young age, who were boys, or had associated nocturnal polyuria, dysfunctional voiding, and/or faecal incontinence.

Calcium and bone homeostasis in heterozygous carriers of CYP24A1 mutations: A cross-sectional study

BACKGROUND

Bi-allelic CYP24A1 mutations can cause idiopathic infantile hypercalcemia (IIH), adult-onset nephrocalcinosis, and possibly bone metabolism disturbances. It is currently unclear if heterozygous carriers experience clinical problems or biochemical abnormalities. Our objective is to gain insight in the biochemical profile and health problems in CYP24A1 heterozygotes.

STUDY DESIGN

Cross-sectional evaluation of participants. Data of previously reported carriers are reviewed.

SETTING AND PARTICIPANTS

Outpatient clinic of a tertiary care hospital. Participants were eight family members of an infant with a well-characterized homozygous CYP24A1 mutation c.1186C>T p.(Arg396Trp).

OUTCOMES

Serum vitamin D metabolites. Symptoms or biochemical signs of hypercalcemia, hypercalciuria or nephrocalcinosis. Bone health in heterozygous as compared to wild type (WT) subjects.

MEASUREMENTS

Genotyping by Sanger sequencing; vitamin D metabolites by liquid chromatography tandem mass spectrometry; renal, calcium and bone markers by biochemical analyses; presence of nephrocalcinosis by renal ultrasound; bone health by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography.

RESULTS

Six participants were heterozygous carriers of the mutation. None of the heterozygous subjects had experienced IIH. One had a documented history of nephrolithiasis, two others had complaints compatible with this diagnosis. No major differences between WT and heterozygous subjects were found regarding bone health, serum or urinary calcium or 25OHD/24,25(OH)2D ratio. Literature reports on three out of 33 heterozygous cases suffering from IIH. In all three, the 25OHD/24,25(OH)2D ratio was highly elevated. Nephrocalcinosis was frequently reported in family members of IIH cases.

LIMITATIONS

Small sample size, lack of a large control group.

CONCLUSIONS

Our and literature data suggest that most heterozygous CYP24A1 mutation carriers have a normal 25OHD/24,25(OH)2D ratio, are usually asymptomatic and have a normal skeletal status but may possibly be at increased risk of nephrocalcinosis. A review of the available literature suggests that an elevated 25OHD/24,25(OH)2D ratio may be associated with symptoms of IHH, irrespective of carrier status.

Propylthiouracil induced ANCA-associated vasculitis in a 14-year-old girl

BACKGROUND

Antineutrophil cytoplasmic antibodies (ANCAs) are the serologic hallmark of ANCA-associated primary small-vessel vasculitides (AAVs), but these antibodies have also been described in other autoimmune diseases such as inflammatory bowel diseases. Furthermore, different drugs are linked to the induction of ANCA, including propylthiouracil (PTU). However progression into clinical overt vasculitis is less common.

CASE-DIAGNOSIS/TREATMENT

We describe the case of a young girl with Graves' disease presenting with fatigue, fever, episcleritis and arthritis. The unexpected double myeloperoxidase/proteinase 3-ANCA positivity triggered a multidisciplinary diagnostic work-up and resulted in the diagnosis of a clinically overt PTU-induced AAV. After PTU-withdrawal and treatment with high-dose corticosteroids, a favorable clinical and biochemical evolution was obtained.

CONCLUSIONS

The use of PTU in the management of hyperthyroidism is not considered first-line treatment in Europe and is even less commonly used in children. Nevertheless, pediatricians should be aware of the possibility of PTU-induced AAV, especially in the presence of multiple ANCA reactivities. Therefore, the use of this drug should be weighed carefully in children.

Neuropsychological functioning related to specific characteristics of nocturnal enuresis

INTRODUCTION/BACKGROUND

There is a high comorbidity demonstrated in the literature between nocturnal enuresis and several neuropsychological dysfunctions, with special emphasis on attention deficit hyperactivity disorder (ADHD). However, the majority of the psychological studies did not include full non-invasive screening and failed to differentiate between monosymptomatic nocturnal enuresis (MNE) and non-MNE patients.

OBJECTIVE

The present study primarily aimed to investigate the association between nocturnal enuresis and (neuro)psychological functioning in a selective homogeneous patient group, namely: children with MNE and associated nocturnal polyuria (NP). Secondly, the study investigated the association between specific characteristics of nocturnal enuresis (maximum voided volume, number of wet nights and number of nights with NP) and ADHD-inattentive symptoms, executive functioning and quality of life.

STUDY DESIGN

The psychological measurements were multi-informant (parents, children and teachers) and multi-method (questionnaires, clinical interviews and neuropsychological testing).

RESULTS

Thirty children aged 6-16 years (mean 10.43 years, SD 3.08) were included. Of them, 80% had at least one psychological, motor or neurological difficulty. The comorbid diagnosis of ADHD, especially the predominantly inattentive presentation, was most common. According to the teachers, a low maximum voided volume (corrected for age) was associated with more attention problems, and a high number of nights with NP was associated with more behaviour-regulation problems. No significant correlations were found between specific characteristics of enuresis and quality of life. Details are demonstrated in Table.

DISCUSSION

The children were recruited from a tertiary referral centre, which resulted in selection bias. Moreover, NP was defined as a urine output exceeding 100% of the expected bladder capacity for age (EBC), and not according to the expert-opinion-based International Children's Continence Society norm of 130% of EBC. The definition for NP of a urine output exceeding 100% of the EBC is more in line with the recent findings of the Aarhus group.

CONCLUSIONS

For children with MNE and associated NP, a high comorbidity with the predominantly inattentive presentation of ADHD was demonstrated. Children experienced problems with daytime functioning in relation to their wetting problem at night. According to the teachers, a low maximum voided volume was associated with more attention problems, and a high number of nights with NP was associated with more behaviour-regulation problems. Although comorbidity is still the appropriate word to use, the observation favours a more complex pathogenesis of enuresis with a common pathway in the central nervous system, including: neurotransmitters, influencing neuropsychological functioning as well as sleep, circadian rhythm of diuresis and bladder function control.

Sleep fragmentation and increased periodic limb movements are more common in children with nocturnal enuresis

AIM

To determine sleep fragmentation in children with nocturnal enuresis (NE).

METHODS

Paediatricians assessed NE parameters in children referred to an enuresis clinic. Control subjects, matched by age and gender and without incontinence or (un)treated NE, were recruited from the paediatric sleep clinic regardless of their sleep problem. Sleep was investigated by one overnight video-polysomnography in both groups.

RESULTS

The study group comprised 67 children with proven NE (50 boys and 17 girls between six and 16 years: 11.1 ± 2.8 SD). They were matched with 67 control subjects (47 boys and 20 girls aged between six and 16 years: 11.0 ± 2.9 SD). Children with NE had a higher incidence of periodic limb movements associated with cortical arousals in their sleep. They displayed significant higher periodic limb movement index, arousal index and awakening index than the control group.

CONCLUSION

Children with NE displayed higher sleep fragmentation and periodic limb movements in sleep than the control children with a possible sleep disorder without NE. The findings emphasise the central involvement of the pathophysiology of NE and the multifactorial nature of the condition.

Disparities in policies, practices and rates of pediatric kidney transplantation in Europe

We aimed to provide an overview of kidney allocation policies related to children and pediatric kidney transplantation (KTx) practices and rates in Europe, and to study factors associated with KTx rates. A survey was distributed among renal registry representatives in 38 European countries. Additional data were obtained from the ESPN/ERA-EDTA and ERA-EDTA registries. Thirty-two countries (84%) responded. The median incidence rate of pediatric KTx was 5.7 (range 0-13.5) per million children (pmc). A median proportion of 17% (interquartile range 2-29) of KTx was performed preemptively, while the median proportion of living donor KTx was 43% (interquartile range 10-52). The median percentage of children on renal replacement therapy (RRT) with a functioning graft was 62%. The level of pediatric prioritization was associated with a decreased waiting time for deceased donor KTx, an increased pediatric KTx rate, and a lower proportion of living donor KTx. The rates of pediatric KTx, distribution of donor source and time on waiting list vary considerably between European countries. The lack of harmonization in kidney allocation to children raises medical and ethical issues. Harmonization of pediatric allocation policies should be prioritized.

Oral lyophylizate formulation of desmopressin: superior pharmacodynamics compared to tablet due to low food interaction

PURPOSE

Desmopressin is a standard treatment for monosymptomatic nocturnal enuresis. Different formulations are promoted as bioequivalent, although these claims are not supported by comparative pharmacodynamic data in children. Food interaction is known to influence the bioavailability of desmopressin. We compared the pharmacodynamics of the 2 most frequently used desmopressin formulations, tablet and lyophilizate, with a standardized meal, allowing extrapolation to clinical reality, where the interval between evening meal and medication intake is limited for school-age children. We hypothesized there would be a faster pharmacodynamic response, and greater concentrating and antidiuretic activity for the fast dissolving (melt) formulation compared to the tablet with simultaneous food intake.

MATERIALS AND METHODS

Two tests were performed on separate days in identical standardized conditions, starting with a 15 ml/kg water load. After achieving maximal diluting capacity a standardized meal was administered, followed by desmopressin tablet (t test) or melt (M-test). Diuresis rate and urinary osmolality were measured hourly. Paired data from 4 girls and 15 boys with a mean age of 12.1 years were obtained.

RESULTS

In the early response phase more than 25% of patients had a higher diuresis rate with tablet vs melt formulation, reaching statistical significance in the plateau phase (urine collected at hours 3 to 5, p <0.02) and in duration of action (urine collected at hours 5 to 8, p <0.005). For desmopressin melt smaller standard deviations in diuresis rate were remarkable. Concentrating capacity demonstrated no significant differences between formulations in the early response phase, in contrast to the plateau phase (p <0.036) and duration of action (p <0.001).

CONCLUSIONS

With meal combination desmopressin melt formulation has a superior pharmacodynamic profile to tablet, making it more suitable for the younger age group with a limited interval between meal and drug administration.

Renal replacement therapy in acute renal failure in children

Acute renal failure in children differs from adult patients in incidence, pathogenesis and size of the patient, but outcome is significantly better. Specific problems are access and haemodynamic stability. Where increasing reporting on the use of CRRT in children seems to convince that CRRT is the treatment of choice, we have to stress that there is no evidence for this statement. Part of this misunderstanding is that both peritoneal and haemodialysis techniques from chronic renal replacement therapy (RRT) are simply extrapolated to intensive care setting. In this paper we want to elaborate on several adaptations in the dialysis-prescription of both peritoneal dialysis and haemodialysis in the ARF setting, which may improve efficacy and outcome. Introduction of new peritoneal dialysis catheter techniques, the cyclers, bicarbonate solutions, combined glucose/amino acid solutions, and low sodium-solutions have overcome many of the inconveniences of the old CAPD-technique. Slow SLED haemodialysis, with an ambulant Genius haemodialyser, with the use of ultra pure water adds to the benefits of conventional haemodialysis (monitoring, safetyness) to better haemodynamic stability of CRRT techniques.

Nocturnal polyuria is related to 24-hour diuresis and osmotic excretion in an enuresis population referred to a tertiary center

PURPOSE

Primary nocturnal enuresis is a heterogeneous disorder, causing a mismatch between overnight diuresis volume and functional bladder capacity. Despite increasing insights in pathogenesis, lack of efficacy of the available treatments is a major problem. We evaluated characteristics of bladder volume and diuresis rate in patients with nocturnal enuresis referred to a tertiary enuresis center.

MATERIALS AND METHODS

Noninvasive screening including maximal voided volume, 24-hour circadian rhythm of diuresis and osmotic excretion from 1,000 consecutive patients.

RESULTS

Of the patients referred as having monosymptomatic nocturnal enuresis 32% were subsequently classified as having nonmonosymptomatic nocturnal enuresis. Differences in bladder volume and nocturnal diuresis characteristics between the monosymptomatic nocturnal enuresis and nonmonosymptomatic nocturnal enuresis groups were minimal.

CONCLUSIONS

The most common observation is a nocturnal diuresis volume greater than maximal voided volume, which in both groups can be caused by nocturnal polyuria or small bladder volume for patient age. The most striking observation is that the positive correlation between nocturnal diuresis volume rate and nocturnal osmotic excretion and 24-hour fluid intake is significantly higher than with the inversed urinary osmolality overnight, which is not only unexpected based on the theory of the primary suppression of vasopressin levels overnight, but also points to a more important role for nutritional and fluid intake than accepted, if not in the primary pathogenesis, then at least in therapy resistance.

The aromatic cluster in KCHIP1b affects Kv4 inactivation gating

The KChIP1b splice variant has been shown to induce slow recovery from inactivation for Kv4.2 whereas KChIP1a enhanced the recovery. Both splice variants differ only by the insertion of the exon1b, rich in aromatic residues (5/11). We analysed in detail the modifications of Kv4.2 gating induced by the KChIP1b splice variant and the role for the aromatic cluster in KChIP1b in inducing these changes. By substituting alanine for the aromatic residues individually or in combination, we could convert the KChIP1b recovery behaviour into that of KChIP1a. The replacement of one or two aromatic residues resulted in a partial restitution of the KChIP1a recovery behaviour. When three aromatic residues were replaced in the exon1b, the recovery from inactivation was fast with time constants that were similar to those obtained with KChIP1a. Moreover, similar findings were observed for closed state inactivation and for the voltage dependence of inactivation. Thus, reduction of the side chain bulkiness in exon1b resulted in the conversion of the KChIP1b phenotype into the KChIP1a phenotype. These results indicate that the aromatic cluster in exon1b modulates the transitions towards and from the closed inactivated states and the steady state distribution over the respective states.

Partial Response to Intranasal Desmopressin in Children With Monosymptomatic Nocturnal Enuresis is Related to Persistent Nocturnal Polyuria on Wet Nights

PURPOSE

The anti-incontinence effect of desmopressin resides in its concentrating capacity and antidiuretic properties. We compared nighttime urine production on wet and dry nights in a highly selected study population of children with monosymptomatic nocturnal enuresis associated with proved nocturnal polyuria who responded only partially to intranasal desmopressin.

MATERIALS AND METHODS

We retrospectively analyzed 39 home recordings of nocturnal urine production and maximum voided volume in children 7 to 19 years old (median 8.9) with monosymptomatic nocturnal enuresis with nocturnal polyuria who had a partial response to desmopressin. Nocturnal diuresis volume and maximum voided volume were documented at baseline (14 days) and during 3 months of followup.

RESULTS

Baseline nocturnal urine output (439 +/- 39 ml) was significantly higher than the maximum voided volume (346 +/- 93 ml, p <0.01). During desmopressin treatment nocturnal urine output on wet nights (405 +/- 113 ml) differed significantly from that on dry nights (241 +/- 45 ml). During treatment nocturnal urine output on wet nights did not differ from baseline values.

CONCLUSIONS

Persistence of nocturnal polyuria on wet nights in partial desmopressin responders may be related to an insufficient antidiuretic effect. In addition to poor compliance and suboptimal dosing, the poor bioavailability of intranasal desmopressin may be a pathogenic factor. Further prospective studies are needed.

Renal functional changes in relation to hemodynamic parameters during exercise test in normoalbuminuric insulin-dependent children

AIM

To examine the relationship between filtration fraction and systemic vasculopathy, in normoalbuminuric insulin-dependent diabetic adolescents.

METHODS

We calculated filtration fraction from measured glomerular filtration rate and renal plasma flow during a hypotonic saline perfusion test in 30 normotensive adolescent diabetic patients (9-19 years), with a mean duration of diabetes of 7.4 years. Blood pressure and heart rate were measured in basal conditions, during a 24-h ambulatory monitoring and during a dynamic exercise test on a cycle ergometer and peripheral vascular resistance was calculated.

RESULTS

Filtration fraction was increased in the diabetic children compared with controls (30+/-6% vs. 22+/-4%, p<0.001), while renal plasma flow was significantly lower (453+/-133 mL/min/1.73 m2 vs. 593+/-155 mL/min/1.73 m2, p<0.001). Peripheral vascular resistance was significantly higher at peak exercise in diabetic children compared to controls (16.3+/-1.3 mmHg/L min m2 vs. 11.4+/-0.5 mmHg/L min m2, p<0.01).

CONCLUSION

These results indicate that in young patients with IDDM, without apparent nephropathy or apparent systemic vasculopathy, filtration fraction is increased, suggesting an increased intraglomerular pressure. The associated reduced decrease of peripheral vascular resistance (increased diastolic blood pressure during exercise) suggests that renal functional abnormalities may be partly explained by a systemic vasculopathy, also present in the kidney.

Modulation of HERG gating by a charge cluster in the N-terminal proximal domain

Human ether-a-go-go-related gene (HERG) potassium channels contribute to the repolarization of the cardiac action potential and display unique gating properties with slow activation and fast inactivation kinetics. Deletions in the N-terminal 'proximal' domain (residues 135-366) have been shown to induce hyperpolarizing shifts in the voltage dependence of activation, suggesting that it modulates activation. However, we did not observe a hyperpolarizing shift with a subtotal deletion designed to preserve the local charge distribution, and other deletions narrowed the region to the KIKER containing sequence 362-372. Replacing the positively charged residues of this sequence by negative ones (EIEEE) resulted in a -45 mV shift of the voltage dependence of activation. The shifts were intermediate for individual charge reversals, whereas E365R resulted in a positive shift. Furthermore, the shifts in the voltage dependence were strongly correlated with the net charge of the KIKER region. The apparent speeding of the activation was attributable to the shifted voltage dependence of activation. Additionally, the introduction of negative charges accelerated the intermediate voltage-independent forward rate constant. We propose that the modulatory effects of the proximal domain on HERG gating are largely electrostatic, localized to the charged KIKER sequence.

Abnormal Circadian Rhythm of Diuresis or Nocturnal Polyuria in a Subgroup of Children With Enuresis and Hypercalciuria is Related to Increased Sodium Retention During Daytime

PURPOSE

In a subgroup of children with enuresis an increase in nighttime water and solute excretion has been documented. To investigate if modifications in renal function are involved in nocturnal enuresis, we assessed circadian variation in natriuresis and tubular sodium handling in polyuric hypercalciuric children.

MATERIALS AND METHODS

A total of 10 children with proved hypercalciuria and nocturnal polyuria and 10 age matched controls were included in the study. A 24-hour urine collection was performed in 8 sampling periods for measurement of urinary sodium excretion. Segmental tubular sodium transport was investigated during a daytime oral water load test and calculated according to standardized clearance methodology.

RESULTS

The children with enuresis showed a marked increase in the fractional excretion of sodium during the night (0.93% +/- 0.36%), while daytime sodium excretion was decreased (0.84% +/- 0.23%). Analysis of segmental tubular sodium transport revealed decreased delivery of sodium to distal tubule (C(H2O) + C(Na) = 10.7 ml/100 ml glomerular filtration rate), indicating increased proximal tubular sodium reabsorption but also stimulation of distal sodium reabsorption as demonstrated by increased fractional distal sodium reabsorption (92.9% +/- 2.2%, controls 90.5% +/- 2.9%). Increased distal reabsorption was associated with increased fractional potassium excretion (17.5% +/- 2.7%, controls 13.6% +/- 6.4%), indicating increased distal tubular sodium/potassium exchange.

CONCLUSIONS

No intrinsic defect in renal tubular sodium transport was found, but during the day increased sodium reabsorption in proximal and distal tubules was observed, suggesting extrarenal factors to be involved in altered circadian variation in solute and water excretion by the kidney.

The Daytime Alarm: A Useful Device for the Treatment of Children With Daytime Incontinence

PURPOSE

We present the results of the use of a daytime wetting alarm as treatment for therapy resistant daytime wetting in children with an overactive detrusor.

MATERIAL AND METHODS

In a retrospective study we reviewed the files of 63 children treated with a daytime alarm because of persistent daytime wetting. Results were considered a complete success when the children were completely dry after treatment, a partial success when there was greater than 50% improvement in daytime wetting and a failure when no change was observed in daytime symptoms.

RESULTS

During a study period of 25 months 63 children were treated with a daytime alarm at the department of pediatric urology. The mean treatment period was 14 days. At a followup of 12 months treatment failed in 20 children (32%), 21 (33%) had partial success and 22 (35%) were successfully treated.

CONCLUSIONS

In children with therapy resistant daytime wetting and an overactive detrusor the daytime alarm may be a useful treatment tool. Complete cure of daytime incontinence can be attained in 35% of patients, almost a third have improvement in their complaints and training fails in a third.

The Effect of Botulinum-A Toxin in Incontinent Children With Therapy Resistant Overactive Detrusor

PURPOSE

We determined the effect of detrusor injection of botulinum-A toxin in a cohort of children with therapy resistant non-neurogenic detrusor overactivity. This prospective study included therapy resistant children with overactive bladder.

MATERIAL AND METHODS

During the study period of 19 months 10 boys and 11 girls were included. All patients showed decreased bladder capacity for age, urge and urge incontinence. Main treatment duration before inclusion was 45 months. A dose of 100 U botulinum-A toxin (Botox) was injected in the detrusor.

RESULTS

Side effects were evaluated in all 21 included patients. The side effects reported were 10-day temporary urinary retention in 1 girl and signs of vesicoureteral reflux with flank pain during voiding in 1 boy, which disappeared spontaneously after 2 weeks. No further examinations were done since the boy refused. Two girls experienced 1 episode each of symptomatic lower urinary tract infection. Eight girls and 7 boys with a minimum followup of 6 months represent the study group for long-term evaluation. In this study group after 1 injection 9 patients showed full response (no more urge and dry during the day) with a mean increase in bladder capacity from 167 to 271 ml (p <0.001). Three patients showed a partial response (50% decrease in urge and incontinence) and 3 remained unchanged. Eight of the 9 full responders were still cured after 12 months, while 1 of the initially successfully treated patients had relapse after 8 months. The 3 partial responders and the patient with relapse underwent a second injection with a full response in the former full responder and in 1 partial responder.

CONCLUSIONS

Botulinum-A toxin injection in children with non-neurogenic overactive detrusor is an excellent treatment adjunct, leading to long-term results in 70% after 1 injection.

Mesalazine interstitial nephritis presenting as colitis ulcerosa exacerbation

Mesalazine is the first line treatment in paediatric inflammatory bowel disease (IBD). There are several reports in the literature about nephrotoxicity (1/150 treated patients), from renal insufficiency to reversible nephritis. It is currently advised to follow creatinine in patients treated with mesalazine during the first 5 years of treatment; however this may reveal the problem too late. As demonstrated in this paediatric case, a high degree of clinical suspicion is needed to diagnose the side effects before irreversible kidney damage occurs. Since the treatment of IBD exacerbation and mesalazine induced interstitial nephritis is based upon steroids, delayed diagnosis of the latter is at risk.

Retrospective Analysis of Efficacy and Tolerability of Tolterodine in Children with Overactive Bladder

OBJECTIVE

To evaluate the efficacy and tolerability of tolterodine in children with an overactive bladder, treated in a single incontinence centre.

MATERIALS AND METHODS

A retrospective analysis of a database of a total of two hundred and fifty-six patients (175 boys and 81 girls, age range 3 years to 17 years, mean age 8.33 years) with urodynamically confirmed bladder overactivity was performed. All children received tolterodine tartrate (dose range of 0.5-4 mg orally). In group I (n=205) tolterodine tartrate replaced anticholinergic drugs (AC) (oxybutinin chloride or oxyphencyclimin hydrochloride). A subgroup of patients switched because of intolerance due to serious adverse events (60.4%) or because of lack of improvement in micturition variables (39.6%). In group II tolterodine was prescribed as initial therapy (n=51). Tolerability was assessed by a standardised questionnaire on adverse events at every outdoor clinic visit. Efficacy assessment was based on micturition diary variables, mean change of maximum bladder capacity and number of incontinence episodes/24 h.

RESULTS

The mean treatment time was 9.32 months with a range from 1.5 months to 23.4 months. The final dose was 0.1mg/kg orally daily divided into two doses. In group I central nervous system disorders (81%) were the most common adverse events, 26.2% showed flushing, 12.2% accommodation problems and 25.2% had gastrointestinal complaints (constipation, encopresis, abdominal pain). Withdrawal of the non-selective antimuscarinic drug resulted in total recovery from adverse events. Introduction of tolterodine in group I and II caused no serious adverse events. Nine patients (3.5%) reported side-effects and only two discontinued treatment. There were no reports of flushing, troubles of visual accommodation, hyperpyrexia. In group I we observed a mean decrease in urgency by 38.7%, a mean increase in maximal bladder capacity by 33.6% and the number of incontinence episodes decreased by 64.8%. In group II we observed equivalent values with a significant (p<0.001) change in maximal bladder capacity (49.7%), incontinence episodes (64.8%) and micturition episodes/24 h.

CONCLUSIONS

The results of this retrospective analysis suggest that tolterodine is well tolerated in children and offers an effective treatment for urinary symptoms due to overactive bladder. Tolterodine is superior to non-selective antimuscarinic drugs, with respect to adverse events, allowing more compliance and more effective treatment in children.

Distal nephron sodium-potassium exchange in children with nephrotic syndrome

While recent literature data suggest that a primary impairment in sodium excretion is the basic abnormality in the pathogenesis of edema formation in the nephrotic syndrome, there is ample evidence that functional hypovolemia contributes to stimulation of renal sodium and fluid retention. Vasoactive hormones such as renin and aldosterone are involved in this process. Discrimination between both mechanisms would be possible by assessment of aldosterone bioactivity and will have therapeutical consequences by indicating the need for administration of i.v. albumin or diuretics. In this paper, several indices of aldosterone bioactivity were assessed in 85 patients with minimal lesion nephrotic syndrome (118 measurements were performed in patients while in remission and 210 following relapses), and in 41 nephrotic patients with different types of nephropathy and were related to plasma renin and aldosterone levels. A better correlation was found between log aldosterone and U(K+)/U(Na+) + U(K+) ratio than with other parameters measuring renal potassium handling such as transtubular potassium gradient, fractional excretion of potassium and urine K+/urine Na+ or urine K+ creatinine ratios. In patients with renal sodium retention (FE(Na)% less than 0.5), an U(K+)/U(Na+) + U(K+) ratio higher than 0.60 identifies patients with increased aldosterone levels and indicates functional hypovolemia. This index may therefore be used to assess which patients will benefit from i.v. albumin administration.

The role of pelvic-floor therapy in the treatment of lower urinary tract dysfunctions in children

The pelvic-floor is under voluntary control and plays an important role in the pathophysiology of lower urinary tract (LUT) dysfunctions in children, especially of non-neuropathic bladder sphincter dysfunction. The following therapeutic measures can be applied to try to influence the activity of the pelvic-floor during voiding: proprioceptive exercises of the pelvic-floor (manual testing), visualization of the electromyographic registration of relaxation and contraction of the pelvic-floor by a curve on a display (relaxation biofeedback), observation of the flow curve during voiding (uroflow biofeedback), learning of an adequate toilet posture in order to reach an optimal relaxation of the pelvic-floor, an individually adapted voiding and drinking schedule to teach the child to deal consciously with the bladder and its function and a number of simple rules for application at home to increase the involvement and motivation of the child. In children however with persisting idiopathic detrusor instability additional therapeutic measures may be necessary to improve present urologic symptoms (incontinence problems, frequency, urge) and to increase bladder capacity. Intravesical biofeedback has been used to stretch the bladder and seems to be useful in case of sensory urge. Recently a less invasive technique, called transcutaneous electrical nerve stimulation (TENS), has been applied on level of S3 with promising results in children with urodynamicaly proven detrusor instability, in which previous therapies have failed.

Does monosymptomatic enuresis exist? A molecular genetic exploration of 32 families with enuresis/incontinence

OBJECTIVE

s To confirm linkage to microsatellite markers on chromosome 8q, 12q, 13q and 22q in families with nocturnal enuresis/incontinence segregating with an autosomal dominant pattern, and to determine if there is an association between the clinical subtype and these linked loci.

PATIENTS AND METHODS

Families with at least three members with nocturnal enuresis in two generations were included in the study. The index patient was > or = 7 years old and had evidence of bladder dysfunction; all other family members were > or = 5 years old. Bladder dysfunction in the index patients was documented by video-urodynamics when indicated. A nycthemeral rhythm of diuresis was documented in all index patients. The clinical diagnosis of all family members was based on a questionnaire on voiding problems and micturition habits, uroflowmetry, measurement of functional bladder capacity and nocturnal diuresis. Linkage was analysed using an autosomal dominant model with a gene frequency equal to 0.05 and a penetrance of 0.9.

RESULTS

Thirty-two families with nocturnal enuresis/incontinence (one with four, 25 with three and six with two generations) were included. The mean number of persons included per family was 10 and on average five members were symptomatic. Linkage of nocturnal enuresis to a region on chromosome 22q11 was found in nine families, to 13q13-14 in six and to 12q in four. There was no convincing evidence for linkage to chromosome 8q. Clinical findings in the proband and their family members with possible linkage to a given locus were heterogeneous, and hence no clear genotype/phenotype correlation could be postulated.

CONCLUSION

These findings support the hypothesis of the genetic and phenotypic heterogeneity of nocturnal enuresis/incontinence. Putative linkage was confirmed to the same chromosomal loci as in previous studies of 'monosymptomatic' enuresis and different phenotypes were linked to the same loci.

Obligatory heterotetramerization of three previously uncharacterized Kv channel alpha-subunits identified in the human genome

Voltage-gated K(+) channels control excitability in neuronal and various other tissues. We identified three unique alpha-subunits of voltage-gated K(+)-channels in the human genome. Analysis of the full-length sequences indicated that one represents a previously uncharacterized member of the Kv6 subfamily, Kv6.3, whereas the others are the first members of two unique subfamilies, Kv10.1 and Kv11.1. Although they have all of the hallmarks of voltage-gated K(+) channel subunits, they did not produce K(+) currents when expressed in mammalian cells. Confocal microscopy showed that Kv6.3, Kv10.1, and Kv11.1 alone did not reach the plasma membrane, but were retained in the endoplasmic reticulum. Yeast two-hybrid experiments failed to show homotetrameric interactions, but showed interactions with Kv2.1, Kv3.1, and Kv5.1. Co-expression of each of the previously uncharacterized subunits with Kv2.1 resulted in plasma membrane localization with currents that differed from typical Kv2.1 currents. This heteromerization was confirmed by co-immunoprecipitation. The Kv2 subfamily consists of only two members and uses interaction with "silent subunits" to diversify its function. Including the subunits described here, the "silent subunits" represent one-third of all Kv subunits, suggesting that obligatory heterotetramer formation is more widespread than previously thought.

Voiding disorders in severely mentally and motor disabled children

PURPOSE

We evaluated the voiding and continence patterns in severely mentally and motor disabled children.

MATERIALS AND METHODS

The hetero-anamnestic, uroflometer and morning urine concentration profile results of 17 girls and 21 boys with severe mental and motor disability were evaluated in a prospective study.

RESULTS

Of the children 20 (52.7%) suffered daytime and/or nighttime wetting and 18 (47.4%) were continent. Daytime and nighttime wetting occurred in 85.7% of children with tetraparesis and in 66.6% of those with an IQ between 46 and 55, representing the highest incidence rates. Bladder capacity was too small for age (mean deficit 145 ml.) in 92% of the children. Uroflowmetry demonstrated a dysfunctional pattern in 60.7% of patients. Dysfunctional voiding occurred in 100% of children with coordination disorders and in 87.5% of those with an IQ between 46 and 55, representing the highest incidence rates. The morning urine concentration profiles showed an osmolality of at least 1,021 mOsm./kg. in all cases.

CONCLUSIONS

Although we found a remarkably high incidence of dysfunctional voiding, no correlation between the uroflow and continence patterns could be found. Restricted fluid intake, due to swallowing problems and insufficient hydration, causes an important bladder capacity deficit in most patients. Becoming continent is determined by motor disability, especially the degree of mobility, rather than by mental development.

Transcutaneous neuromodulation for the urge syndrome in children: a pilot study

PURPOSE

Neuromodulation has been used to treat voiding dysfunction in adults. Due to its invasiveness it has rarely been used in children until now with the availability of transcutaneous neurostimulation. We evaluated clinical effects of transcutaneous neuromodulation on detrusor overactivity in children with the urge syndrome.

MATERIALS AND METHODS

Between May 1, 1998 and February 28, 1999, 15 girls (mean age 10.2 years) and 26 boys (mean age 10.7 years) with proved detrusor hyperactivity on videourodynamic study underwent neuromodulation. All children had been given anticholinergic therapy previously. Neurostimulation only was used in children in whom anticholinergics had no effect and those who had significant side effects. Anticholinergics were continued in children in whom they had a partial effect. Stimulation of 2 Hz. was applied for 2 hours every day. Surface electrodes were placed at the level of sacral root S3. After 1 month of trial stimulation those children who responded continued the treatment for 6 months, and were evaluated every 2 months.

RESULTS

Of the 41 children 15 boys and 13 girls responded after 1 month of trial therapy with an increase in bladder capacity, decrease in urgency, decrease in incontinence and/or better sensitivity. Of the 13 children who did not respond 9 lacked motivation and 4 had no clinical effect despite motivation. After 6 months of therapy a significant increase in bladder capacity, decrease in voiding frequency and decrease in incontinence periods were noted. Adverse effects were not observed. One year after therapy relapse was noted in 7 patients, leaving 21 of 41 children definitively cured.

CONCLUSIONS

Although preliminary, our results indicate that transcutaneous neuromodulation can improve symptoms of detrusor overactivity, as response to stimulation was noted in 76% of our patients and 56% were cured after 1 year. This therapeutic option is attractive for children because of its noninvasiveness and absence of adverse effects.

One thousand video-urodynamic studies in children with non-neurogenic bladder sphincter dysfunction

OBJECTIVE

To ascertain the aetiology and epidemiology of non-neurogenic bladder sphincter dysfunction (NNBSD) by assessing the results of prospective video-urodynamic studies (VUD) in 1000 children.

PATIENTS AND METHODS

During a 4-year study period (January 1995 to December 1998) 1000 children prospectively underwent VUD to further define their NNBSD. After a noninvasive screening assessment consisting of a history, voiding diary, clinical examination, urine analysis, ultrasonography and uroflowmetry, those children who would benefit from further VUD were selected. The selection criteria included a history of urinary tract infection (UTI), a small bladder capacity not responding to training, dysfunctional uroflow, ultrasonographic abnormalities and resistance to therapy. During the study period 3500 children were screened for incontinence problems, including monosymptomatic nocturnal enuresis; 1000 of these were selected for VUD (524 boys and 476 girls).

RESULTS

The urodynamic diagnosis was of normal bladder-sphincter function in 62 (6.2%, male : female 44 : 56), urge syndrome in 582 (58%, 58 : 42), dysfunctional voiding in 316 (32%, 49 : 51) and 'lazy bladder' in 40 (4%, 20 : 80). Boys diagnosed with a 'lazy bladder' were younger than those with urge syndrome and dysfunctional voiding. Girls with dysfunctional voiding were younger than those with urge syndrome. The incidence of UTI was significantly higher in girls than in boys; boys with NNBSD had no greater risk for UTI and in girls the general risk was 34%. Only in girls with a lazy bladder was there a significantly higher incidence of UTI (53%). Reflux occurred equally in all groups, with an overall incidence of 15%. The incidence of obstipation was significantly higher in girls with a lazy bladder, and overall was 17%.

CONCLUSION

These results from a large series provide a new insight into the epidemiology and pathophysiology of NNBSD. The age distribution provides evidence against a dysfunctional voiding sequence. The risk of developing UTI in NNBSD is greater only in girls. In children with a lazy bladder the risk is also significantly higher, indicating that residual urine is a greater risk factor than detrusor instability. Urge syndrome and dysfunctional voiding in girls carry the same risk for developing UTI, indicating that bladder instability is a higher risk factor for UTI than detrusor sphincter discoordination. All dysfunctions carry an equal risk for developing secondary reflux. Children with NNBSD have different primary diseases but all have a common risk of incontinence, UTIs, reflux and obstipation.

[Differences in the profile of nycthemeral diuresis]

Monosymptomatic enuresis in childhood can be divided in two subtypes by a nycthemeral diuresis profile, including urinary volume and osmolality. The first one is characterized by an abnormal circadian diuresis cycle, responsible for nocturnal polyuria and/or low urinary overnight osmolality, there is a good response to desmopressin; the other one is the so-called cognitive or idiopathic type, which provides a poor response to desmopressin.

[Urination disorders revealing posterior urethral valve: clinical aspects]

One hundred sixty-four boys presenting with voiding dysfunction without any obvious uropathy or neuropathy were enrolled in a prospective study. Nine (5.5%) were suspected to have urethral valves after video-urodynamic assessment, later confirmed by cystoscopy. Those with proven posterior urethral valves were compared to a control group of boys without urethral obstruction. There was no difference in anamnesis nor clinical presentation between the two groups. Even on uroflowmetry the urethral valves were not suspected; only the urodynamic assessment could distinguish the obstructed from the non-obstructed boys. Although there remains controversy about the existence of posterior urethral valves in functional voiding disorders in boys, we could demonstrate that after a complete prospective screening such a rare combination occurs in around 5% of the cases.

Pelvic-floor therapy and toilet training in young children with dysfunctional voiding and obstipation

OBJECTIVE

To analyse experience in treating young children (4-5 years old) with urodynamically confirmed voiding dysfunction, using a noninvasive training programme.

PATIENTS AND METHODS

Between January 1996 and October 1997, 20 children (all < 5 years old, mean age 4.45 years, 18 girls and two boys, mean ages 4.44 and 4.5 years, respectively) with voiding dysfunction were treated. Three children showed filling phase dysfunction alone (bladder instability), six emptying phase dysfunction alone (dysfunctional voiding) and 11 showed both filling and emptying phase dysfunction. Sixteen children had incontinence problems (three diurnal, two nocturnal and 11 diurnal and nocturnal). Eight children had a history of recurrent urinary tract infections and 12 girls had vaginal irritation. Four children were referred for perineal pain caused by spasms of the pelvic floor. Eight children had encopresis based on chronic obstipation. Therapy consisted of keeping a voiding and drinking chart, instructions on proper toilet posture, daily rules for application at home, and if possible relaxation biofeedback of the pelvic-floor muscles. Therapy was considered successful if incontinence and other urological symptoms resolved. The treatment of encopresis is also discussed.

RESULTS

Of the 20 children, 13 had a good result; they all became dry during the day and night, and encopresis resolved. Six children had moderate success; in one, nocturnal incontinence persisted, and in two diurnal and nocturnal incontinence continued. In two children encopresis persisted and in one the faecal incontinence ameliorated. In one child the therapy was prematurely interrupted because of lack of motivation.

CONCLUSION

This experience suggests that a noninvasive training programme is applicable in very young children with symptoms of dysfunctional elimination of urine and faeces.

Uraemic guanidino compounds inhibit gamma-aminobutyric acid-evoked whole cell currents in mouse spinal cord neurones

Guanidine, creatinine (CTN), methylguanidine (MG) and guanidinosuccinic acid (GSA) are four endogenous guanidino compounds with proven neuroexcitatory actions, and putative pathophysiological significance as uraemic toxins. The effects of these uraemic guanidino compounds, were studied on whole-cell current evoked by gamma-amino butyric acid (GABA) on mouse spinal cord neurones in vitro. CTN, MG and GSA concentration dependently blocked GABA-evoked current with calculated IC50 values (+/-SE) of 9.6 +/- 0.9, 9.7 +/- 1.5 and 5.1 +/- 0.4 mM, respectively. CTN, MG and GSA were shown to block inward and outward currents to the same extent, demonstrating voltage independent block of GABA-evoked current by these compounds. Guanidine, however, evoked inward whole-cell currents, which were almost completely blocked by strychnine, indicating that the guanidine-evoked current might have been due to glycine receptor activation.

Effects of competitive NMDA receptor antagonists on excitatory amino acid-evoked currents in mouse spinal cord neurones

The effects of CGP 37849 [DL-(E)-2-amino-4-methyl-5-phosphono-3-pentenoate] and its ethylester CGP 39551 on whole-cell currents evoked by the endogenous excitatory amino acids, L-glutamate and L-aspartate, were studied in cultured mouse spinal cord neurones. Although CGP 37849 was the more potent compound, both antagonists inhibited 20 microM L-aspartate or 2 microM L-glutamate currents concentration-dependently and reversibly. We calculated IC50 values of 370 +/- 180 nM for CGP 37849 and 2200 +/- 140 nM for CGP 39551 (inhibition of L-aspartate current), and 210 +/- 25 nM for CGP 37849 and 6000 +/- 4700 nM for CGP 39551 (inhibition of L-glutamate current). Both CGP 37849 and CGP 39551 selectively blocked N-methyl-D-aspartate (NMDA)-evoked inward current. Current evoked by 5 microM kainate or 5 microM alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) was unaffected by 10 microM CGP 39551. Current evoked by NMDA was concentration-dependently blocked by CGP 39551 with an IC50 of 2100 +/- 220 nM. After application of 10 microM CGP 37849, 17 +/- 6% of the current evoked by 5 microM L-glutamate remained. This residual current was due to non-NMDA receptor activation since application of 25 microM 2-amino-5-phosphonovalerate (APV) together with CGP 37849 did not significantly alter the residual current, whereas application of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) with CGP 37849 did significantly inhibit this current. Clamping cells at potentials ranging from -80 to +60 mV showed a linear potential--current relationship for the 20 microM L-aspartate-evoked current with reversal potential around 0 mV. The proportion of the L-aspartate current antagonized by CGP 37849 or CGP 39551 appeared to be independent of clamping potential. The concentration--current relationship of L-aspartate in the absence of the antagonists showed an EC50 of 49 +/- 14 microM. Upon application of 1 microM CGP 37849 and 10 microM CGP 39551, the L-aspartate concentration--current curve shifted to higher concentrations, and resulted in a 5- and 13-fold increase in the EC50 of L-aspartate, respectively, whereas Imax was not changed by application of the antagonists. Thus, the potent NMDA antagonists CGP 37849 and CGP 39551 were shown to inhibit excitatory amino acid responses specifically by competitive binding to the neurotransmitter recognition site of the NMDA receptor. Selective, competitive antagonism of L-glutamate- and L-aspartate-evoked NMDA receptor responses probably underlies the effects of CGP 37849 and CGP 39551 such as their anticonvulsant, neuroprotectant and antidepressant actions.

Anomalies of the external urethral meatus in girls with non-neurogenic bladder sphincter dysfunction

OBJECTIVE

To investigate in a prospective study the clinical and urodynamic characteristics associated with the correlation previously reported between non-neuropathic bladder sphincter dysfunction and minimal meatal deformities in girls.

PATIENTS AND METHODS

From January 1995 to June 1996 all girls referred for urodynamics to investigate non-neuropathic bladder sphincter dysfunction were examined for meatal anomalies. Two types of meatal anomalies were recognized, i.e. hypospadias, in which the urethral meatus is displaced dorsally and meatal web or covered hypospadias, in which there is a mucosal web on the dorsal side of the urethral meatus that deflects the urinary stream anteriorly. The girls presenting with minimal meatal deformities were compared with those presenting a normal meatal configuration for their history and video-urodynamic features.

RESULTS

During the study, 288 girls were referred for video-urodynamics; 88 presented with meatal anomalies (24 hypospadias and 64 covered hypospadias) and comprised the study group; all other girls were considered as the control group. Incontinence during the day was more frequent in the study group (56%) than in the control group (34%) (P=0.003). Nocturnal enuresis was more frequent in the control group (87%) than in the study group (68%, P=0.006). Urge was more frequent in the study group (80%) than in the control group (65%, P=0.02), as was anterior deflection of the urinary stream (voiding over the toilet rim), in 48% and 4.5%, respectively (P<0.001). On video-urodynamics, dysfunctional voiding (detrusor sphincter dyscoordination during voiding) was more frequent in the study group (59%) than in the control group (38%, P=0.009), and vaginal voiding was more frequent in the study group (40%) than in the control group (11.5%, P<0.001).

CONCLUSION

Girls presenting with meatal anomalies have more severe dysfunction, as estimated by urodynamics. Although the natural history of these anomalies and the incidence in the normal population is not known, it is thought that there is an aetiological correlation between the functional voiding disorders and the meatal anomaly. Surgical treatment to correct the anomalies is proposed.

Effects of the competitive N-methyl-D-aspartate antagonist CGP 37849 and its ethylester CGP 39551 on N-methyl-D-aspartate-evoked whole-cell currents in cultured spinal neurones and on vestibular stimulation-induced seizures in EL mice

The competitive N-methyl-D-aspartate (NMDA) antagonist DL-2-amino-4-methyl-5-phosphono-3-pentenoic acid (CAS 127910-31-0, 4-methyl-APPA, CGP 37849) and its ethyl ester (CAS 127910-32-1, CGP 39551) potently block NMDA-evoked whole-cell current on mouse spinal neurones in primary dissociated cell cultures with IC50 (+/- SE) values of 189 +/- 9 nmol/l (CGP 37849) and 2100 +/- 220 nmol/l (CGP 39551), respectively. The compounds dose-dependently blocked vestibular stimulation-induced convulsions in EL mice, 2 h after oral administration, with ED50 (95% CI) values of 135 (78-236) mumol/kg (CGP 37849) and 65 (45-94) mumol/kg (CGP 39551). In male Swiss albino mice, performance in the step-through passive avoidance procedure was dose-dependently impaired with ED50 (95% CI) values of 85 (56-157) mumol/kg (CGP 37849) and 27 (18-42) mumol/kg (CGP 39551). In addition performance of these animals in the rotarod test of motor coordination was impaired, 2 h after oral administration of CGP 39551, with an ED50 (95% CI) of 142 (100-201) mumol/kg. These findings demonstrate anticonvulsant activity in these potent NMDA antagonists after oral administration with CGP 39551 possessing greater relative potency. However, the unfavourable ratio of therapeutic dose versus dose inducing memory or motor impairment supports the prevailing notion that such adverse effects of the presently available compounds preclude the use of NMDA antagonists as long-term therapies.

Combined use of urinary alpha1-microglobulin and 99mTc DMSA scintigraphy in the diagnosis and follow-up of acute pyelonephritis and cystitis in children

OBJECTIVES

In the absence of specific symptomatology in children and neurogenic bladder disease patients, the early diagnosis of acute pyelonephritis is a challenge. The aim of the present study was to determine if dimercaptosuccinic acid (DMSA) lesion-positive (acute pyelonephritis) patients have elevated urinary alpha1-microglobulin (alpha1-MG) excretion (no false negatives) and if DMSA lesion-negative (cystitis) patients have normal urinary alpha1-MG excretion (no false positives).

METHODS

A selected population of 62 children above 3 months of age with a proven urinary tract infection were administered a DMSA scan. A control scan was performed after the acute phase of the illness, and the diagnosis of pyelonephritis (n = 44) was made retrospectively. The urinary alpha1-MG was determined by immunonephelometry.

RESULTS

The urinary alpha1-MG-creatinine ratio was highly sensitive (98%) and specific (100%) and correlated with the DMSA scintigraphy images. Only 1 of the 44 patients with pyelonephritis and all of the cystitis patients (n = 18) had a normal urinary alpha1-MG (<10 mg/g). The drop in absolute DMSA uptake correlated significantly (r = 0. 758, p < 0.001) with the urinary alpha1-MG-creatinine ratio. The urinary alpha1-MG-creatinine ratio was significantly higher (p < 0. 02) in bilateral than in unilateral pyelonephritis.

CONCLUSION

DMSA lesion-positive (acute pyelonephritis) patients have elevated urinary alpha1-MG excretion and DMSA lesion-negative (cystitis) patients have normal urinary alpha1-MG excretion.

A K+ channel splice variant common in human heart lacks a C-terminal domain required for expression of rapidly activating delayed rectifier current

We have cloned HERG USO, a C-terminal splice variant of the human ether-à-go-go-related gene (HERG), the gene encoding the rapid component of the delayed rectifier (IKr), from human heart, and we find that its mRNA is approximately 2-fold more abundant than that for HERG1 (the originally described cDNA). After transfection of HERG USO in Ltk- cells, no current was observed. However, coexpression of HERG USO with HERG1 modified IKr by decreasing its amplitude, accelerating its activation, and shifting the voltage dependence of activation 8.8 mV negative. As with HERG USO, HERGDeltaC (a HERG1 construct lacking the C-terminal 462 amino acids) also produced no current in transfected cells. However, IKr was rescued by ligation of 104 amino acids from the C terminus of HERG1 to the C terminus of HERGDeltaC, indicating that the C terminus of HERG1 includes a domain (</=104 amino acids) that is critical for faithful recapitulation of IKr. The lack of this C-terminal domain not only explains the finding that HERG USO does not generate IKr but also indicates a similar mechanism for hitherto-uncharacterized long QT syndrome HERG mutations that disrupt the splice site or the C-terminal. We suggest that the amplitude and gating of cardiac IKr depends on expression of both HERG1 and HERG USO.

Use-dependent block of Ih in mouse dorsal root ganglion neurons by sinus node inhibitors

1. The sinus node inhibitors UL FS 49 and DK-AH 269 reduce heart rate by slowing diastolic depolarization rate in the sino-atrial (SA) node, which might originate from the use-dependent blockade of a hyperpolarization-activated current If. A hyperpolarization-activated current Ih, which is present in many types of neurons, is similar to If. We studied the effects of these drugs on Ih in cultured mouse dorsal root ganglion (DRG) neurons. 2. With the whole-cell patch-clamp technique use-dependent block of Ih was observed. The steady-state block following a voltage-clamp pulse train (1-s steps from -38 to -108 mV applied at 0.5 Hz) was dependent on drug concentration and showed an apparent Kd of 0.1 and 0.79 microM with DK AH 269 and UL-FS 49 respectively. 3. The rate of block increased linearly with drug concentration. The rate of recovery from block was, however, much slower compared to cardiac tissue. 4. There was no significant effect of UL-FS 49 on the activation curve. 5. At high concentrations of UL-FS 49 a clear association of the drug with the open channel was observed. 6. When the cell was stimulated at a frequency of 3 Hz, a distinct hyperpolarization was observed in the presence of extracellular Cs+ or when Ih was blocked with UL-FS 49, but not in the absence of Cs+ and UL-FS 49. 7. These results indicate that Ih protects the cell against hyperpolarizations and subsequent inexcitability. The action of the drugs on the hyperpolarization-activated current in cardiac and neuronal tissue show some similarities; however, some pronounced differences indicate that different subtypes of the channel might exist.

Pelvic-floor therapy in girls with recurrent urinary tract infections and dysfunctional voiding

OBJECTIVE

To analyse the treatment of girls with recurrent urinary tract infections (UTIs, at least two periods confirmed) and urodynamically confirmed dysfunctional voiding with pelvic-floor therapy.

PATIENTS AND METHODS

Forty-two girls with recurrent UTIs were treated prospectively during a study period of 18 months. Training consisted of an individually adapted voiding and drinking schedule, pelvic-floor relaxation biofeedback, instructions on toilet behaviour and biofeedback uroflowmetry; residual urine was estimated by ultrasonography. All the girls received prophylactic antibiotics during treatment and those girls with urodynamically proven detrusor instability (33) received anticholinergics. Therapy was considered successful when the girls remained free of infection with no further prophylactic antibiotics for at least 6 months.

RESULTS

Four girls younger than 6 years all suffered nocturnal and diurnal incontinence and two had reflux. Treatment was effective for recurrent UTI in all and the reflux resolved in two. All four girls became dry during the day and one became dry at night. In the 38 girls older than 6 years, the treatment was successful for recurrent UTI in 24 from the out-patient and in all three from the clinical programme. Reflux, which was seen in six of these girls, resolved in five; one girl underwent bilateral reimplantation. Incontinence was treated in all 23 girls with incontinence problems before treatment (four of whom were initially dry). Twelve girls needed a wetting alarm to become dry during the night. In four girls the treatment was effective for recurrent UTI but the incontinence persisted; in seven the treatment was considered unsuccessful as they all had UTIs after treatment; all remained incontinent. Reflux persisted in all four girls in this group who had reflux before treatment.

CONCLUSION

The training programme was effective in treating recurrent UTI in 35 of 42 girls (83%). The persistence of incontinence problems is a bad prognostic factor for the recurrence of UTI after the training programme. Pelvic-floor therapy seems a reasonable and meaningful component in the treatment of recurrent UTIs in which detrusor-sphincter dyssynergia plays a role.