Smartphone-based optical assays in the food safety field.

Smartphone based devices (SBDs) have the potential to revolutionize food safety control by empowering citizens to perform screening tests. To achieve this, it is of paramount importance to understand current research efforts and identify key technology gaps. Therefore, a systematic review of optical SBDs in the food safety sector was performed. An overview of reviewed SBDs is given focusing on performance characteristics as well as image analysis procedures. The state-of-the-art on commercially available SBDs is also provided. This analysis revealed several important technology gaps, the most prominent of which are: (i) the need to reach a consensus regarding optimal image analysis, (ii) the need to assess the effect of measurement variation caused by using different smartphones and (iii) the need to standardize validation procedures to obtain robust data. Addressing these issues will drive the development of SBDs and potentially unlock their massive potential for citizen-based food control.

T cell activation profiles in Kawasaki syndrome.

Superantigens (SAgs) are potent stimulators of T cells bearing specific Vbeta T cell receptors (TCR) and may play a role in the pathogenesis of Kawasaki syndrome (KS), although despite 15 years of intense study this area remains controversial. Because SAgs can cause Vbeta restricted T cell activation in the absence of Vbeta skewing the aims of this study were to describe a flow cytometric protocol to study both CD4 and CD8 Vbeta repertoires, and CD69 expression across the CD4 and CD8 Vbeta repertoire in children with KS. Sixteen children with KS were studied. There was no significant increase in overall peripheral blood CD4 or CD8 T cell activation as determined by CD69 expression. However, Vbeta restricted CD4 and/or CD8 activation was observed in eight of 11 (72%) of the KS patients, a finding not observed in healthy controls. Thirteen of 16 (81%) of the KS patients had evidence of either Vbeta skewing (particularly CD4 Vbeta2 and Vbeta5.1) and/or Vbeta restricted activation. Three patients had Vbeta restricted activation in the absence of skewing. We suggest that these preliminary observations highlight the many layers of complexity when considering T cell activation in KS, which could explain some of the conflicting studies regarding peripheral blood T cell activation and Vbeta skewing. It is likely that in order to move forward with this debate a combination of detailed microbiological, immunological and molecular techniques applied to individual patients will be required ultimately to prove or refute the SAg hypothesis of KS.

Henoch-Schönlein purpura: recent advances.

Recent developments in relation to Henoch-Schönlein purpura (HSP) include: a) a proposed new classification of childhood vasculitides including new classification criteria for HSP; b) the identification of various, potentially important, genetic polymorphisms in HSP that may be relevant in terms of predisposition to or protection from complications; c) evidence that prophylactic steroid at the onset of disease does not protect against renal or gastrointestinal complications but does seem to have beneficial effects in treating them.

Perinatal renal venous thrombosis: presenting renal length predicts outcome.

BACKGROUND: Renal venous thrombosis (RVT) is the most common form of venous thrombosis in neonates, causing both acute and long term kidney dysfunction. Historical predisposing factors include dehydration, maternal diabetes, and umbilical catheters, but recent reports highlight associations with prothrombotic abnormalities. STUDY: Twenty three patients with neonatal RVT were analysed over 15 years. Predisposing factors, presentation, and procoagulant status were compared with renal outcome using multilevel modelling. RESULTS: Median presentation was on day 1: 19/23 (83%) had pre/perinatal problems, including fetal distress (14), intrauterine growth retardation (five), and pre-identified renal abnormalities (two); 8/18 (44%) had procoagulant abnormalities, particularly factor V Leiden mutations (4/18). Long term abnormalities were detected in 28/34 (82%) affected kidneys; mean glomerular filtration rate was 93.6 versus 70.2 ml/min/1.73 m2 in unilateral versus bilateral cases (difference 23.4; 95% confidence interval 6.4 to 40.4; p = 0.01). No correlation was observed between procoagulant tendencies and outcome, but presenting renal length had a significant negative correlation: mean fall in estimated single kidney glomerular filtration rate was 3 ml/min/1.73 m2 (95% confidence interval 3.7 to -2.2; p = 0.001) per 1 mm increase, and kidneys larger than 6 cm at presentation never had a normal outcome. CONCLUSIONS: This subgroup of neonatal RVT would be better termed perinatal RVT to reflect antenatal and birth related antecedents. Prothrombotic defects should be considered in all patients with perinatal RVT. Kidney length at presentation correlated negatively with renal outcome. The latter, novel observation raises the question of whether larger organs should be treated more aggressively in future.

Cardiovascular status after Kawasaki disease in the UK.

OBJECTIVE: Kawasaki disease (KD) is an acute vasculitis that causes coronary artery aneurysms (CAA) in young children. Previous studies have emphasised poor long-term outcomes for those with severe CAA. Little is known about the fate of those without CAA or patients with regressed CAA. We aimed to study long-term cardiovascular status after KD by examining the relationship between coronary artery (CA) status, endothelial injury, systemic inflammatory markers, cardiovascular risk factors (CRF), pulse-wave velocity (PWV) and carotid intima media thickness (cIMT) after KD. METHODS: Circulating endothelial cells (CECs), endothelial microparticles (EMPs), soluble cell-adhesion molecules cytokines, CRF, PWV and cIMT were compared between patients with KD and healthy controls (HC). CA status of the patients with KD was classified as CAA present (CAA+) or absent (CAA-) according to their worst-ever CA status. Data are median (range). RESULTS: Ninety-two KD subjects were studied, aged 11.9 years (4.3-32.2), 8.3 years (1.0-30.7) from KD diagnosis. 54 (59%) were CAA-, and 38 (41%) were CAA+. There were 51 demographically similar HC. Patients with KD had higher CECs than HC (p=0.00003), most evident in the CAA+ group (p=0.00009), but also higher in the CAA- group than HC (p=0.0010). Patients with persistent CAA had the highest CECs, but even those with regressed CAA had higher CECs than HC (p=0.011). CD105 EMPs were also higher in the KD group versus HC (p=0.04), particularly in the CAA+ group (p=0.02), with similar findings for soluble vascular cell adhesion molecule 1 and soluble intercellular adhesion molecule 1. There was no difference in PWV, cIMT, CRF or in markers of systemic inflammation in the patients with KD (CAA+ or CAA-) compared with HC. CONCLUSIONS: Markers of endothelial injury persist for years after KD, including in a subset of patients without CAA.

Analysis of steroids in urine for differentiation of pseudohypoaldosteronism and aldosterone biosynthetic defect.

The salt-losing syndromes in the neonatal period and early infancy due to adrenal disease can be differentiated by the pattern of excretion of steroids in urine. The presence or absence of metabolites of cortisol, aldosterone, and corticosterone as well as certain precursors can be established in a single analysis of steroids in urine by using gas chromatography with open tubular capillary columns. The profiles of steroid excretion in the urine of 8 infants with renal tubular insensitivity to aldosterone were compared with those in 5 infants with isolated aldosterone biosynthetic defects. The excretion in urine of 18 hydroxytetrahydro-compound A was elevated in all 13 children, but relative to the excretion of tetrahydroaldosterone, a high ratio was found for the biosynthetic defect and clearly distinguished the 2 conditions. Age-related changes in steroid metabolism are described. The diagnosis in each case was supported by clinical investigation together with determinations of PRA and aldosterone concentrations.

Hypertension in a four-year-old child: gas chromatographic and mass spectrometric evidence for deficient hepatic metabolism of steroids.

A 4-yr-old boy with hypertension and hypokalaemic alkalosis had low plasma aldosterone levels and renin activity. The hypertension and hypokalemia responded to spironolactone and triamterene therapy. A partial response to dexamethasone was observed. Analysis of urinary steroid metabolites by gas chromatography-mass spectrometry showed that the excretion of metabolites of deoxycorticosterone and aldosterone was subnormal, and there was no evidence for sizeable excretion of unusual steroids with potential mineralocorticoid activity. The cortisol excretion rate, however, was subnormal, and the relative excretions of individual metabolites of this hormone were not typical. In particular, the excretion of tetrahydrocortisone was markedly reduced, and the excretions of allotetrahydrocortisol and free cortisol and metabolites were elevated. These findings suggest that modified or deficient metabolism of adrenal steroids could give rise to elevated blood pressure. It is not known whether the inappropriate production of unusual cortisol metabolites were responsbile for the high blood pressure or whether the altered metabolism is indicative of similar abnormality in the metabolism of other adrenal steroids, resulting in hyperproduction or extended half-life of minor but highly active mineralocorticoids of unknown structures.

A novel parathyroid hormone (PTH)/PTH-related peptide receptor mutation in Jansen's metaphyseal chondrodysplasia.

Two heterozygous PTH/PTH-related peptide (PTHrP) receptor missense mutations were previously identified in patients with Jansen's metaphyseal chondrodysplasia (JMC), a rare form of short limb dwarfism associated with hypercalcemia and normal or undetectable levels of PTH and PTHrP. Both mutations, H223R and T410P, resulted in constitutive activation of the cAMP signaling pathway and provided a plausible explanation for the abnormalities in skeletal development and mineral ion homeostasis. In the present study we analyzed genomic DNA from four additional sporadic cases with JMC to search for novel activating mutations in the PTH/PTHrP receptor, to determine the frequency of the two previously identified missense mutations, H223R and T410P, and to determine whether different mutations present with different severity of the disease. The H223R mutation was identified in three novel JMC patients and is, therefore, to date the most frequent cause of JMC. In the fourth patient, a novel heterozygous missense mutation was found that changes isoleucine 458 in the receptor's seventh membrane-spanning region to arginine (I458R). In COS-7 cells expressing the human PTH/PTHrP receptor with the I458R mutation, basal cAMP accumulation was approximately 8 times higher than that in cells expressing the wild-type receptor despite impaired surface expression of the mutant receptor. Furthermore, the I458R mutant showed higher responsiveness to PTH than the wild-type receptor in its ability to activate both downstream effectors, adenylyl cyclase and phospholipase C. Like the H223R and the T410P mutants, the I458R mutant had no detectable effect on basal inositol phosphate accumulation. Overall, the patient with the I458R mutation exhibited clinical and biochemical abnormalities similar to those in patients with the previously identified H223R and T410P mutations.

Nitric oxide synthase inhibitors and hypertension in children and adolescents.

OBJECTIVE: To establish the role played by the circulating nitric oxide synthase inhibitors N(G)-monomethyl-L-arginine (L-NMMA), asymmetrical dimethyl arginine (ADMA) and symmetric dimethyl arginine (SDMA) and its association with hypertension of children and adolescents. DESIGN: We measured plasma concentrations of L-NMMA, ADMA and SDMA in 38 hypertensives (median age 7.7 years) and in nine healthy normotensive controls (median age 8.2 years) using high-performance liquid chromatography. In addition, their plasma renin activity was determined. The subjects' glomerular filtration rates were calculated from plasma creatinine and height measurements. To determine the vasoactive potency of the arginine analogues, concentration-response curves were plotted for the responses in isolated endothelium-intact and endothelium-denuded mouse aortic rings that had been pre-contracted by administration of a threshold concentration of phenylephrine. RESULTS: Plasma ADMA and SDMA concentrations in members of the hypertensive group [0.23 +/- 0.03 and 1.37 +/- 0.06 micromol/l, respectively (means +/- SEM)] were significantly higher than those in members of the control group (ADMA 0.10 +/- 0.01 micromol/l and SDMA 1.18 +/- 0.06 micromol/l). Plasma concentrations of L-NMMA were similar in members of the hypertensive (0.21 +/- 0.01 micromol/l) and control (0.18 +/- 0.02 micromol/l) groups. The glomerular filtration rate of the hypertensive group was below normal [70.4 +/- 5.4 ml/min per 1.73 m2 (mean +/- SEM)] and was significantly associated with elevated plasma concentrations of ADMA (r = -0.77, P < 0.001), SDMA (r = -0.38, P = 0.02) and L-NMMA (r = 0.35, P = 0.03). Higher plasma ADMA concentrations were associated with a lower plasma renin activity (r = -0.36, P = 0.04). The vasoactive potencies of ADMA (concentration for half-maximal effect with the endothelium intact 25.4 +/- 7.1 micromol/l) and L-NMMA (concentration for half-maximal effect with the endothelium intact 8.2 +/- 2.9 micromol/l) was significantly (P < 0.05) greater than that of SDMA. Both ADMA and L-NMMA (at 3 micromol/l concentrations) initiated a significant vasocontractile response from baseline (P = 0.03 and P < 0.001, respectively). These effects were absent after the endothelium had been removed. SDMA had no effect. CONCLUSIONS: Plasma ADMA and SDMA levels are increased in hypertensive children. By inference from in-vitro data, ADMA appears to attain sufficient concentrations to produce a significant change in vascular tone and hence might play a role in the pathophysiology of childhood hypertension.

Vasculitis in children and adolescents.

Vasculitis can present in childhood. There is a wide spectrum of disease in vasculitis, with Henoch-Schönlein purpura and Kawasaki disease occurring most commonly; however, macroscopic and microscopic polyarteritis, Wegener's granulomatosis, Takayasu's disease, cutaneous polyarteritis, hypersensitivity angiitis; vasculitis associated with connective tissue disorders, such as dermatomyositis, and a number of other miscellaneous vasculitides are seen. With the current range of investigative and therapeutic tools, it is possible to diagnose and treat the majority of patients although morbidity and mortality is not inconsequential.

Measurement of plasma renin activity by semi-micro radioimmunoassay of generated angiotensin I.

A semi-micro method for determination of plasma renin activity (PRA) by radioimmunoassay of generated angiotensin I (AI) is described. The method permits measurement of PRA on 250 mul of plasma without loss of specificity, sensitivity, accuracy or preision. The small sample size has considerable application in terms of investigation of infants and young children. A reference range was established for healthy children on free diets. There was a 15-fold decline in PRA with age from a mean value of 1404pgAI/ml h-1 (ngAI/1. h-1) in infancy to a mean of 85 pgAI/ml h-1 (ngAI/1. h-1) in adult life.

Renovascular hypertension.

Renovascular disease constitutes approximately 10% of cases of secondary hypertension in childhood. It is associated with neurofibromatosis and a number of other syndromes. Fibromuscular dysplasia is the commonest histopathological finding. Bilateral and intrarenal disease is common and is associated with extrarenal arterial disease in a significant proportion of cases. Utilizing currently available investigative procedures, the nature of the disease can be defined and decisions made regarding appropriate treatment. However, although there is the potential for surgical cure, a substantial number of children still require medical therapy probably due to the high incidence of bilateral and small intrarenal arterial involvement that is not amenable to surgical or angioplasty treatment.

Random zero sphygmomanometer versus automatic oscillometric blood pressure monitor; is either the instrument of choice?

The Hawksley random zero sphygmomanometer was designed to eliminate observer bias and two digit preference. We have measured blood pressure (BP) in a group of 62 young adults (median age 26.1 years, range 20.2-31.3 years) with reflux nephropathy under standardised conditions (that is, in the morning, after a 2 h supine rest, before venepuncture, using a standard 12 x 23 cm adult size cuff appropriate for the machine used) utilising the random zero sphygmomanometer and the automatic oscillometric BP monitor (Dinamap 8100, Critikon). Seven consecutive recordings of right brachial BP at intervals of 2 min were taken using each instrument alternatively, and the first reading was discarded. The first instrument used to measure BP was alternated between patients to eliminate bias on instrument preference. Random zero sphygmomanometer was used as recommended by the manufacturers and Korotkoff phase V was used to measure the DBP. The observer and the equipment used were the same throughout the study period. The mean SBP and DBP were calculated to the nearest 1 mm Hg utilising the three recordings taken by each instrument. The limits of agreement and the repeatability coefficients for each method of measurement were assessed utilising the statistical method described by Bland and Altman in 1986. The correlation coefficients among random zero and automatic oscillometric BP monitor for SBP and DBP measurements were 0.84 and 0.67, respectively. The average BP (mean of random zero and automatic oscillometric BP monitor measurement) plotted against the difference between the two methods of measurement showed no relation between the difference and the average of measurement in the ranges of BP studied, that is, between 100 and 160 mm Hg systolic and 55 and 100 mm Hg diastolic. The mean of difference between random zero and automatic oscillometric BP monitor for SBP was -6.45 (s.d. 6.07) and for DBP +10.77 (s.d. 8.16) mm Hg. The limit of agreement for SBP measurement was +5.69 to -18.59 mm Hg and for DBP was +27.09 to -5.55. The repeatability coefficients of random zero and automatic oscillometric BP monitor for systolic and diastolic measurements were 8.64 and 7.04, and 9.72 and 6.62, respectively. Bland and Altman analysis indicates major differences between the two methods of measurement. The automatic oscillometric BP monitor could on average over-read the systolic by 6.45 mm Hg and under-read the diastolic by 10.77 mm Hg compared with that of random zero. Furthermore, the limits of agreement were wide enough for a normotensive to be inadvertently defined as a hypertensive on machine error alone. This clearly indicates that automatic oscillometric BP monitor and random zero BP measurements cannot be used interchangeably in clinical practice. Furthermore, the repeatability coefficients, which should ideally be zero, are too large for either instrument to be considered as the gold standard for BP measurement, although that of automatic oscillometric BP monitor was superior to that of random zero. This study highlights the importance of using nomograms generated by the same method of measurement for comparison both in paediatric and adult practice for correct interpretation of BP.

Reflux nephropathy and hypertension.

Renal scarring associated with vesico-ureteric reflux (VUR), most commonly detected in young children, is associated with a significant risk of developing hypertension in later life. Hypertension in reflux nephropathy contributes significantly to morbidity including deterioration of renal function. The mechanism of onset of hypertension is not clear although abnormalities of the renin-angiotensin system and sodium/potassium ATPase activity have been described in some cases. It is becoming clear that radiologically detectable renal scars or small kidneys may histologically indicate a variety of diagnoses. Prediction of the risk of developing hypertension in individual cases is difficult and therefore regular follow-up remains the only current means of recognising these subjects. Although prevention of renal scar development in children with VUR may offer some benefit in reducing the incidence of hypertension, there is no uniform action that can definitely achieve this, particularly in the very young, before any urinary infection occurs. Primary VUR seems to be a disorder with mendelian dominant inheritance and location of the gene may offer some hope of early identification within certain families. Timely introduction of preventative measures may then be possible even though reservations exist about their effectiveness.

Abnormalities of erythrocyte sodium transport in reflux nephropathy.

Hypertension is a complication of reflux nephropathy commonly occurring during adolescence and young adult life. We studied cellular sodium transport in an adolescent cohort with this condition as abnormal sodium transport is a feature of human hypertension. Thirty males and 52 females with reflux nephropathy, (median age 20.3 years) had erythrocyte ouabain sensitive sodium-potassium ATPase (Na/K ATPase) pump site number (Bmax) and red cell sodium concentration (RBC Na+) measured in 1988. Six years later, 55 of those had red cell sodium-lithium counter transport (LCT) measured. On both occasions, their renal function and blood pressure (BP) were determined. Bmax in the study group (median 10.3 nmol/l) was significantly less than that of controls (median 11.45 nmol/l). Nine patients who were diagnosed as having hypertension during the 6 year study period appeared to have a lower Bmax compared with that of normotensives in the group. RBC Na+ and LCT of the study group were not significantly different from that of controls. The Na/K ATPase activity is diminished, and sodium-lithium counter transport is unchanged in reflux nephropathy. Further study is needed to ascertain the link between these observations and the onset of high BP.

The measurement of blood pressure and the detection of hypertension in children and adolescents.

Despite the publication of several expert committee guidelines for the measurement of blood pressure (BP) and the diagnosis of hypertension in children and adolescents, it was our perception and clinical experience that there still appeared to be a general lack of standardisation of BP measurement techniques and little consensus on the criteria for diagnosing hypertension. To investigate this further, we have conducted a postal survey of consultant-grade paediatricians who were members of the British Paediatric Association (BPA). A total of 1500 questionnaires were sent out and 708 analysable replies were received (47.1%). This showed that 68.6% of paediatricians routinely measured BP, at least on one occasion, in children or adolescents attending their outpatient clinics, 17.7% started at or soon after birth, 12.3% started at the age of 1 year, 20.0% at 3 years, 12.0% from 7 years of age and 3.5% from the age of 13. Only 60.5% reported that they had a choice of four or more different cuff sizes in their clinic. Forty-one percent of respondents reported that the BP was always or sometimes measured by nurses. Fifty-one percent of respondents measured diastolic BP at the phase of muffling of sound (Korotkoff phase IV), 31.9% used the disappearance of sound (phase V) whilst 15.9% claimed that they measured both end-points. The criteria for diagnosing a child as being hypertensive varied greatly; 17.9% reported that they responded to the systolic BP alone, 13.5% to the diastolic BP alone, 65.9% relied on both pressures, and 2.7% responded to either the systolic or diastolic pressure if it was raised. Furthermore, 12.9% diagnosed hypertension if the BP exceeded the 90th percentile in relation to age and 41.8% used the 95th percentile. However 45.3% of respondents employed a higher dividing line. In hospitalised children, leg blood pressures were measured routinely by 30.3%, although a further 44.0% would do so if aortic coarctation or other vascular diseases were suspected. Despite considerable variation in clinical practice, techniques and criteria, only 11.4% of clinicians would manage the patients themselves, with the remainder referring the child on to the appropriate specialist. The survey suggests a general lack of standardisation of BP measurement techniques and little consensus on the criteria for diagnosing hypertension amongst paediatricians. Simplified, shortened and updated guidelines on hypertension in paediatric practice and research are needed.

Systemic vasculitis.

The systemic vasculitides are comparatively rare but important disorders of childhood. Apart from Henoch-Schönlein purpura, which is the commonest example in paediatric practice, Kawasaki disease is most often encountered. Polyarteritis and Wagener's granulomatosis have a lower incidence but are associated with a high morbidity and mortality. Newer investigative procedures and therapeutic approaches have led to more accurate diagnoses and improved outcome but further advances await a better understanding of the vasculitides: polyarteritis; Kawasaki disease; Wagener's granulomatosis; and ANCA in childhood.

15-year follow-up of reflux nephropathy by imaging.

Reflux nephropathy i. e. renal scarring associated with vesico-ureteric reflux and urinary tract infection is primarily a diagnosis based on renal imaging. It is well known to be associated with hypertension and renal failure. This has led to regular long-term follow-up of patients, clinically and radiologically. We report the findings of renal imaging in a cohort of 37 patients with reflux nephropathy 15 or more years after successful surgical correction of vesico-ureteric reflux. The degree of renal scarring had been assessed and recorded at the beginning of the study utilizing a score on the original X-ray films. The scar scores of the current intravenous urography (IVU) imaging underestimate the degree of scarring in 35% of cases when compared with the previously recorded scar scores of the original IVU images suggesting a reduction in the renal scar score in some cases over the years. In the current review, concomitant renal images obtained by IVU and 99mTc dimercapto succinic acid (DMSA) scanning were in agreement for scar scoring in only 50% of cases. The original scar score by IVU or the current scar score by either technique does not correlate with blood pressure, urine albumin excretion or glomerular filtration rate (GFR). We conclude that serial long-term two-dimensional renal imaging in children with damaged kidneys who no longer have vesico-ureteric reflux, does not provide additional information that will alter clinical management. However, the changes in renal volume and echogenicity were not assessed in this study.

Tubular proteinuria in steroid sensitive multi-relapsing nephrotic syndrome.

The urinary excretion of N-acetyl-beta-D-glucosaminidase (UNAG) and retinol binding protein (URBP) was studied in 65 children with steroid sensitive multirelapsing nephrotic syndrome (MRNS): 28 on cyclosporin A (CyA) therapy, 22 on prednisolone (P), 15 off-treatment and in 32 normal children to assess renal tubular damage or dysfunction. The urinary protein excretion was expressed in relation to that of creatinine (UNAG/UC in mumol pnp/h/mmol; URBP/UC in microgram/mmol). There was a weak but significantly negative correlation between age and both, UNAG/UC (r = -0.38, p < 0.01) and URBP/UC (r = -0.50, p < 0.05) in normal children, but not in nephrotics. In normals and in patients off steroids an association between these two proteins was found (r = 0.38, p < 0.05; r = 0.56, p < 0.05 respectively). Geometric mean UNAG/UC was significantly higher in nephrotics on CyA therapy (26.5 +/- 4.0), and on P (37.0 +/- 7.9) as well as in those off-treatment (16.3 +/- 3.1) compared to normal children (9.3 +/- 3.4). There was a further increase in those with raised urinary albumin: creatinine ratio (UA/UC) (> 0.1 mg/mg). URBP/UC was not increased in any of the groups of children with MRNS. Raised NAG in urine may therefore indicate active nephrotic syndrome rather than being due to the drug therapy.

Renal function following cardiopulmonary bypass surgery in children: a randomized comparison of the effects of gentamicin and cloxacillin with cephalothin.

Renal function was studied in 36 children who were randomly allocated to receive either gentamicin and cloxacillin or cephalothin as prophylactic antibiotic cover for complex cardiopulmonary bypass surgery. Both groups of children developed a similar degree of impairment of glomerular function with significant elevations in plasma creatinine concentrations and urine albumin excretion compared to preoperative levels which tended to resolve by the 5th postoperative day. The urine excretion of N-acetyl-glucosaminidase increased in both groups postoperatively but remained significantly elevated only in those children who had received gentamicin. These findings suggest that whilst gentamicin exerts a demonstrable nephrotoxic effect on the proximal renal tubules it does not contribute significantly to either the incidence or severity of postoperative renal glomerular impairment.