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.

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Optical smartphone based sensors in the food safety field are systematically reviewed.

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Recommendations on image analysis optimization are given.

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The analytical performance of smartphone based sensors is discussed.

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Available commercial devises are critically compared.

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.

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.

Nephro-urological complications of epidermolysis bullosa in paediatric patients

A small but important proportion of patients with epidermolysis bullosa (EB) may develop significant renal and urological complications which can have a major impact on their morbidity and mortality. During the last 10 years, five of a large group of children with EB under our care, with either dystrophic or junctional types of disease, experienced major nephro-urological complications. Two patients with recessive dystrophic EB (REDB) developed macroscopic haematuria - one had renal failure and underwent a renal biopsy showing IgA nephropathy. A third patient with RDEB also developed renal failure and his biopsy demonstrated postinfectious glomerulonephritis/type III membranoproliferative (mesangiocapillary) glomerulonephritis. Both patients with renal failure underwent peritoneal dialysis. Two patients with junctional EB developed obstructive uropathies, which required bladder reconstruction and the fashioning of a Mitrofanoff channel in one.

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.

Systemic vasculitis: a cause of indeterminate intestinal inflammation

OBJECTIVES

Indeterminate intestinal inflammation may result from a variety of inflammatory conditions in addition to ulcerative colitis and Crohn disease. The primary systemic vasculitides may present with intestinal inflammation and an indeterminate colitis. We set out to describe a series of children with primary systemic vasculitis who initially presented with clinical features suggestive of inflammatory bowel disease (IBD) to establish criteria that might help discriminate between IBD and primary systemic vasculitis.

METHODS

Ten children (6 boys, median age at presentation 8.9 years, range 0.9-14.5 years) satisfied inclusion criteria.

RESULTS

All had abdominal pain, weight loss, diarrhea (6 of 10 bloody) and laboratory evidence of a severe acute phase response. Extraintestinal clinical features included vasculitic rash, renal impairment, myalgia, testicular pain and polyarthritis. Endoscopy showed vascular changes or other macroscopic findings suggestive of vasculitis in 5 of 10 patients. Gut histology revealed indeterminate chronic inflammatory mucosal changes and one patient with small artery fibrinoid necrosis in the submucosal vessels. Extraintestinal biopsy was performed in 6 patients and had a higher yield for the demonstration of vasculitis than intestinal biopsy. The results of selective visceral angiography was suggestive of vasculitis in all patients, but was normal in 7 cases of treatment-unresponsive classic IBD. Treatment comprised corticosteroid and azathioprine in all patients. Cyclophosphamide was given to 7 of 10 patients.

CONCLUSIONS

Extraintestinal manifestations and inflammatory responses that may be disproportionate to the degree of intestinal inflammation provide clues to the presence of an underlying primary systemic vasculitis, and these data suggest that selective visceral angiography plays a key role in the diagnosis of vasculitis in this context. It is important to identify and treat any vasculitic component because failure to do so may result in consequential morbidity or mortality.

EULAR/PReS endorsed consensus criteria for the classification of childhood vasculitides

BACKGROUND

There has been a lack of appropriate classification criteria for vasculitis in children.

OBJECTIVE

To develop a widely accepted general classification for the vasculitides observed in children and specific and realistic classification criteria for common childhood vasculitides (Henoch-Schönlein purpura (HSP), Kawasaki disease (KD), childhood polyarteritis nodosa (PAN), Wegener's granulomatosis (WG), and Takayasu arteritis (TA)).

METHODS

The project was divided into two phases: (1) the Delphi technique was used to gather opinions from a wide spectrum of paediatric rheumatologists and nephrologists; (2) a consensus conference using nominal group technique was held. Ten international experts, all paediatricians, met for the consensus conference. Agreement of at least 80% of the participants was defined as consensus.

RESULTS

Consensus was reached to base the general working classification for childhood vasculitides on vessel size. The small vessel disease was further subcategorised into "granulomatous" and "non-granulomatous." Final criteria were developed to classify a child as HSP, KD, childhood PAN, WG, or TA, with changes introduced based on paediatric experience. Mandatory criteria were suggested for all diseases except WG.

CONCLUSIONS

It is hoped that the suggested criteria will be widely accepted around the world because of the reliable techniques used and the international and multispecialist composition of the expert group involved.

The use of the British Isles Lupus Assessment Group (BILAG) index as a valid tool in assessing disease activity in childhood-onset systemic lupus erythematosus

OBJECTIVES

The British Isles Lupus Assessment Group (BILAG) index is a standardized systemic lupus erythematosus (SLE) disease activity assessment. The main aim of this study was to correlate the BILAG index with laboratory measures of disease activity in childhood-onset SLE with and without biopsy-proven lupus nephritis.

METHOD

Prospective observational comparison study of the BILAG index in 21 SLE patients under 18 yr of age over a 12-month period in a tertiary referral paediatric outpatient clinic.

RESULTS

Eleven patients with lupus non-nephritis and 10 patients with lupus nephritis were reviewed. The lupus nephritis patients had significantly (P<0.001) more admissions over a similar time interval since diagnosis. The renal BILAG disease activity scores were significantly greater (P = 0.013) in the lupus nephritis group (range 1-9, median 3.0, compared with 0-3 and 1.0 in the lupus non-nephritis group). The total BILAG scores and patient visual analogue scores (VAS) were higher in the lupus nephritis groups, unlike the lower physician VAS, but these differences were not statistically significant compared with other laboratory indices of disease activity.

CONCLUSIONS

The BILAG index is a useful tool in monitoring disease activity in children and adolescents with SLE. The data collected for the BILAG index can be used serially and effectively by different clinicians over time to enable recording of disease status at sequential assessments. The lower patient VAS in the lupus non-nephritis group was not significant and may reflect the patients' own perception of lethargy at times of increased disease activity.

Vbeta-restricted T cell adherence to endothelial cells: a mechanism for superantigen-dependent vascular injury

OBJECTIVE

To investigate the potential for endothelial cells to operate as superantigen-presenting cells for T cells and the potential for such an interaction to cause endothelial cell activation and injury.

METHODS

Class II major histocompatibility complex (MHC)-positive human umbilical vein endothelial cells (HUVECs) were cocultured for 4 hours with purified T cells and the superantigens staphylococcal enterotoxin B (SEB) or toxic shock syndrome toxin 1 (TSST-1). After staining with fluorescence-conjugated monoclonal antibodies, flow cytometric analysis was performed on the HUVECs and T cells to examine V(beta)-restricted T cell adherence to the endothelial cell monolayer, V(beta)-restricted T cell activation (CD69 up-regulation), surface expression of endothelial cell activation markers, and generation of endothelial microparticles (EMPs).

RESULTS

Coculture of purified T cells with class II MHC-positive HUVECs and either TSST-1 or SEB resulted in V(beta)-restricted CD69 up-regulation by CD4 and CD8 cells (V(beta)2 activation for TSST-1; V(beta)3, V(beta)5.1, and V(beta)12 activation for SEB). Additionally, there was CD4 and CD8 T cell V(beta)-restricted adherence to the HUVEC monolayer at 4 hours. Expression of intercellular adhesion molecule 1, E-selectin, and vascular cell adhesion molecule 1 was up-regulated on the class II MHC-positive HUVECs following exposure to superantigen in the presence of T cells, and there was increased EMP release from activated HUVECs, which occurred earlier and was of greater magnitude than that observed in response to tumor necrosis factor alpha.

CONCLUSION

Class II MHC-positive endothelial cells operate as competent superantigen-presenting cells for CD4 and CD8 lymphocytes in vitro. Dual signaling between endothelial cells and T cells results in V(beta)-restricted activation and adherence to endothelial monolayers and endothelial cell activation and release of EMPs expressing inducible cell adhesion molecules. It is proposed that this mechanism could account in part for the vascular injury associated with superantigen-mediated diseases including Kawasaki disease.

Endothelial and platelet microparticles in vasculitis of the young

OBJECTIVE

Microparticles are released from endothelial cells in response to a variety of injurious stimuli and recently have been shown to be increased in a number of diseases associated with endothelial dysfunction. This study examined endothelial microparticle (EMP) and platelet microparticle (PMP) profiles in children with systemic vasculitis to test the hypothesis that EMPs may provide a noninvasive means of examining endothelial activation or injury.

METHODS

The study cohort comprised 39 children with systemic vasculitis at various stages of disease activity, 24 control children with febrile disease, and a control group of 43 healthy subjects. Plasma was ultracentrifuged at 17,000g for 60 minutes, and the microparticle pellets were examined using flow cytometry.

RESULTS

Plasma from patients with active systemic vasculitis contained significantly higher numbers of E-selectin-positive EMPs compared with that from patients in remission, healthy controls, or febrile disease controls (P = 0.000 for each). A similar result was obtained for the numbers of EMPs expressing the marker CD105. There was also a significant increase in PMPs expressing CD42a in the active vasculitis group as compared with the other groups, but this difference was not significant for PMPs expressing P-selectin. The EMP counts correlated with the Birmingham Vasculitis Activity Score and the acute-phase reactant levels in the patients with systemic vasculitis, but there was a poor correlation overall between EMP counts and the acute-phase reactant levels in the febrile disease controls.

CONCLUSION

EMPs may provide a window to the activated endothelium and could provide important pathophysiologic insights into the vascular injury associated with vasculitis of the young.

T cell Vbeta repertoires in childhood vasculitides

Superantigens (SAgs) are potent stimulators of T cells bearing specific Vbeta T cell receptors (TCR) and may play a role in the aetiopathogenesis of systemic vasculitis, although this remains contentious. To investigate the possible aetiological role of SAgs, this study examined peripheral blood T cell Vbeta repertoires in children with systemic vasculitis. FACS analysis of 17 different peripheral blood T cell Vbeta families was performed in 20 healthy control children, 27 disease control children with nonvasculitic inflammatory disease, 25 children with primary systemic vasculitis, six patients with Kawasaki disease (KD) and six patients with Henoch-Schönlein purpura (HSP). There was a significantly increased variance of CD4 Vbeta12 and Vbeta17, and CD8 Vbeta1 in the primary systemic vasculitis group compared to control and disease controls. Moreover, 80% of the primary systemic vasculitis children had one or more CD4 Vbeta expansions or deletions, compared with 30% of controls (P < 0.002), and 37% of the disease controls (P < 0.002). In the KD group, the mean percentage of CD4 Vbeta2 T cells was higher than in controls or disease controls. In the HSP group, there was no consistent skewing of the T cell Vbeta repertoire. We have observed changes in the T cell Vbeta repertoire in children with vasculitis over and above those observed in disease controls. While these data provide impetus for further research into this contentious field, they do not resolve unequivocally the question of the role of SAgs in childhood vasculitic syndromes.

Arterial distensibility in children and teenagers: normal evolution and the effect of childhood vasculitis

BACKGROUND

Polyarteritis nodosa is a necrotising vasculitis of the medium sized and small muscular arteries. The inflammatory and subsequent reparative processes may alter the arterial mechanical properties. The effect of vasculitic damage on arterial distensibility has never been explored however.

AIM

To determine the normal values and the effect of childhood vasculitis on arterial distensibility in children and teenagers.

METHODS

Distensibility of the brachioradial arterial segment was studied using pulse wave velocity (PWV proportional, variant 1/ radical distensibility), in 13 children with polyarteritis nodosa at a median age of 11.8 (range 4.9-16) years. As a control group, 155 healthy schoolchildren (6-18 years, 81 boys) were studied. PWV was assessed using a photoplethysmographic technique; blood pressure was measured by an automatic sphygmomanometer (Dinamap). Data from patients were expressed as z scores adjusted for age and compared to a population mean of 0 by a single sample t test. Determinants of PWV in normal children were assessed by univariate and multivariate linear regression analyses.

RESULTS

Age, height, weight, and systolic blood pressure correlated individually with the brachioradial PWV. Multivariate analysis identified age as the only independent determinant. Ten of the patients were in clinical remission, while three had evidence of disease activity at the time of study. The PWV in the patient group as a whole was significantly greater than those in healthy children (mean z score +0.99). Raised C reactive protein concentration (>2 mg/dl) in the three patients with active disease was associated with a higher PWV when compared to those in remission (z score +2.78 v +0.45). The diastolic blood pressure of the patients was higher than those of the controls (z score +1.04) while the systolic pressure was similar (z score -0.36).

CONCLUSIONS

PWV in the brachioradial arterial segment increases gradually during childhood independent of body weight, height, mass, and blood pressure. Increased PWV, and hence decreased distensibility, in this peripheral arterial segment occurs in polyarteritis nodosa and is amplified during acute inflammatory exacerbation.

Erythromelalgia: an endothelial disorder responsive to sodium nitroprusside

Erythromelalgia is an unusual syndrome of painful vasodilatation. Aetiopathology is probably different in children and adults. Presentation can be severe and associated with hypertension. Dramatic benefit from infused nitroprusside suggests the disorder could represent a dysfunctional endothelium.

Kawasaki disease: an evidence based approach to diagnosis, treatment, and proposals for future research

This article proposes a clinical guideline for the diagnosis and treatment of Kawasaki disease in the UK based on the best available evidence to date, and highlights areas of practice where evidence is anecdotal or based on retrospective data. Future research as proposed by the London Kawasaki Disease Research Group is outlined, and clinicians are invited to prospectively enroll their suspected cases into this collaborative research project.

Cyclosporin for atopic dermatitis in children

This paper details a UK consensus conference held in London in April 2000 to establish guidelines for the use of cyclosporin A for atopic dermatitis in children. It should be reserved for the severest refractory atopic dermatitis. In view of its potential toxicity, careful monitoring is mandatory, in particular blood pressure and renal function.

Behçet's disease in UK children: clinical features and treatment including thalidomide

OBJECTIVE

To study the clinical spectrum of Behçet's disease (BD) in childhood, and to report our experience of using thalidomide.

METHOD

Ten children, diagnosed with BD, were studied retrospectively.

RESULTS

The median (range) age at first presentation was 4 (1.2-12.0) yr, at diagnosis was 11 (3-15) yr and the follow-up period was 4.1 (0.6-6.3) yr. Oral ulcers were present in all patients (100%), genital ulcers were present in six (60%), peri-anal ulcers were present in three (30%), skin manifestations were present in nine (90%), intracranial hypertension was present in two (20%), mild gastrointestinal symptoms were present in five (50%), joint symptoms were present in six (60%), ocular lesions were present in five (50%), but only one child had anterior and posterior uveitis. Therapeutically, a range of drugs was used, including colchicine, that resulted in good responses in five children. Thalidomide (1 mg/kg/week to 1 mg/kg/day) was used in five children who were unresponsive to other immunosuppressive agents. It resulted in complete remission in three children and less frequent milder oral ulcers in two. Neuropathy developed in two children and in one it was irreversible.

CONCLUSION

BD in children is similar to the disease in adults. Thalidomide provided a useful therapeutic option for severe oral and genital ulceration which was unresponsive to other therapies. Awareness of the danger of axonal neuropathy and teratogenesis at all times during thalidomide therapy is crucial. A low dose is probably as effective as higher doses.

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.

Treatment of severe complicated Kawasaki disease with oral prednisolone and aspirin

We report on 7 patients with severe, complicated Kawasaki disease treated with oral prednisolone, after apparently unsuccessful intravenous immunoglobulin treatment. An additional eighth patient was a Jehovah's Witness, who was given steroid and aspirin as first-line treatment. These findings support a beneficial role for steroids in intravenous immunoglobulin-resistant Kawasaki disease.

Vasculitis from the pediatric perspective

This article reviews the spectrum of vasculitic illness affecting children. Apart from the relatively common vasculitides (Henoch-Schönlein purpura, Kawasaki disease, and in worldwide terms Takayasu disease) there are a number of important but comparatively rare disorders affecting children. As in adults, there is a considerable degree of overlap between the various vasculitic syndromes in childhood. With modern therapeutic agents, the prognosis for many of the childhood vasculitides has improved; however, in spite of this, there remains a not inconsequential morbidity and mortality. It is anticipated that as our knowledge of the immunopathogenesis of this group of disorders expands, classification and treatment of vasculitis in both children and adults will improve.

Vascular endothelial cell activation associated with increased plasma asymmetric dimethyl arginine in children and young adults with hypertension: a basis for atheroma?

The mechanism behind the development of vascular complications of hypertension in the young human remains unclear. To explore the role of vascular endothelium-generated nitric oxide (a known mediator of leucocyte-platelet-endothelial interactions) in this context, we investigated markers of endothelial activation (soluble vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), P-selectin, E-selectin), and von Willebrand factor and the plasma level of the endogenous nitric oxide inhibitor asymmetric dimethyl arginine (ADMA) in a group of 31 (17 male, mean age 9.4 years) hypertensive and 9 (4 male, mean age 9.1 years) healthy, normotensive children and young adults. We found raised levels of ADMA (mean (SEM) 235 (32) n mol/l) and VCAM-1 (median (range) 1237 (675-2700) ng/ml) in the plasma of hypertensive subjects compared with those of normotensives (ADMA, 103 (7) n mol/l and VCAM-1, 1005 (425-1650) ng/ml, respectively). Furthermore, in hypertensive subjects, higher VCAM-1 concentrations (r = 0.66, p < 0.001) and vWF concentrations (r = 0.37, p = 0.04) were significantly associated with a higher plasma ADMA level. Therefore, an isolated increase in plasma VCAM-1 in hypertensives in association with raised ADMA may signify a selective "non-inflammatory" endothelial activation triggered by endothelial nitric oxide synthase inhibition. Since VCAM-1 is implicated in the origins of atherosclerosis, ADMA may be an important contributory factor in increasing the risk of atheroma formation in hypertensive children and young adults.

The emergency management of severe hypertension

Severe hypertension in childhood is a life-threatening clinical problem that carries with it not only serious sequelae of inadequate treatment but equally serious complications of over enthusiastic therapy. The majority of cases have some form of underlying renal disease. Therapeutic success is achieved by slow and safe reduction of blood pressure with the immediate target of avoiding hypertensive sequelae yet allowing preservation of target organ function. Short-acting parenteral antihypertensives are recommended along with careful blood pressure monitoring to prevent complications arising through loss of autoregulatory control.

Urinary supersaturation of calcium oxalate and phosphate in patients with X-linked hypophosphatemic rickets and in healthy schoolchildren

Nephrocalcinosis (NC) is a complication of the treatment of X-linked hypophosphatemic rickets (XLHR). Some studies have found that treated patients have enteric hyperoxaluria caused by phosphate therapy and have implicated calcium oxalate, whereas others have found only calcium phosphate in renal biopsy tissue.

AIM AND METHODS

We aimed to study the urinary supersaturation of calcium oxalate and calcium phosphate and to determine whether these measures are risk factors for NC. We collected 24-hour urine samples from 20 patients (12 girls) with XLHR, mean +/- SD age 8.2 +/- 4.7 years, and from 79 age-matched members of a healthy control group prospectively.

RESULTS

The median 24-hour urine excretions of oxalate, phosphate, and citrate (mmol/1.73 m(2) per day) were significantly increased in patients compared with the control group (oxalate 0.38 vs 0.28, P =. 0012; phosphate 63.1 vs 25.8, P <.0001; citrate 4.18 vs 2.7, P =. 0002). However, no significant differences were seen in the calcium oxalate or calcium phosphate between patients and the control group. No significant differences were seen in 24-hour urine calcium or magnesium excretion between patients and the control group; however, 8 patients had hypercalciuria. A significant higher urine volume in patients compared with the normal group (826 mL/m(2) 24-hour vs 597 mL/m(2) 24-hour; P <.005) was found. Twelve patients had NC at the time of investigation, and although the oxalate excretion was significantly higher in these patients, no significant difference was seen in the relative supersaturation of calcium oxalate monohydrate (CaC(2)O(4).H(2)O) compared with the 8 without NC.

CONCLUSIONS

Although 24-hour urine oxalate and phosphate excretion are increased in treated patients with XLHR, there is no increase in the supersaturation of either calcium oxalate or phosphate. Determination of the supersaturation of calcium oxalate or calcium phosphate does not predict the development of NC in XLHR.

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.

Vascular endothelium and nitric oxide in childhood hypertension

Vascular endothelium releases nitric oxide (NO), an important vasodilator that is continuously synthesised by the constitutive enzyme, endothelial nitric oxide synthase (NOS). This maintains a constant vasodilator tone which is diminished in adult hypertension, due to reduced endothelium-dependent vascular relaxation, which is NO dependent. In childhood, however, hypertension is often secondary, and normalisation of blood pressure by removal of cause (e.g. renal artery stenosis, catecholamine-producing tumour) suggests reversibility of endothelial dysfunction, if it is present. Raised plasma levels of endogenous inhibitors have been found, especially in children with secondary hypertension due to renal parenchymal and renovascular disease, and may contribute to hypertension by more than just inhibition of vascular NO release; e.g. by reduction of glomerular filtration rate and promotion of salt and water retention. These inhibitors also modulate renin release, which may be of relevance in cardiovascular physiology, and may also interfere with the anti-platelet properties of NO, increasing the likelihood of vascular thrombotic events. NO inhibitors also promote endothelial activation, with increased expression of adhesion molecules that may form seedlings of atherosclerosis. In chronic renal impairment, accumulation of NO inhibitors may contribute to hypertension. Efficient long-session dialysis helps better interdialysis control of blood pressure in these subjects, independent of salt and water removal, suggesting that removal of such vasoactive agents may be important for efficient blood pressure control. There are a few studies assessing NO generation in hypertensive children via plasma nitrite and nitrate, the NO end products, which suggest normal or increased production as opposed to a reduction, perhaps as a compensatory phenomenon. In the treatment of hypertension, nitroprusside and nitrates exert their actions via NO donation. Excessive production of NO (usually via inducible NOS) or excessive administration (nitrovasodilators) can be cytotoxic and may cause hypotension and shock, as in severe sepsis. NOS inhibitors and NO therefore appear to play a crucial role in aetiology, complications and therapy of childhood hypertension.

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.

Antineutrophil cytoplasmic antibodies in Wegener's granulomatosis

The prevalence of antineutrophil cytoplasmic antibodies (ANCA) was studied in 12 children with Wegener's granulomatosis. The serum samples were taken in the active phase of disease and were screened for ANCA by indirect immunofluorescence with normal neutrophils and enzyme linked immunosorbent assay (ELISA) using crude neutrophil extract, proteinase 3, myeloperoxidase, cathepsin G, lactoferrin, and elastase as antigens. Of these 12 patients, 10 wre positive for ANCA in the active phase of their illness, and they showed a predominantly cytoplasmic ANCA staining pattern on indirect immunofluorescence. There were high titres of ANCA directed against crude neutrophil extract, proteinase 3, myeloperoxidase, and cathepsin G. IgM isotypes occurred as commonly as IgG isotypes. Therefore, screening for ANCA is usually but not invariably positive in children with Wegener's granulomatosis. Specific diagnosis still relies on clinical and pathological features, and the value of ANCA in the diagnosis of paediatric Wegener's granulomatosis requires further study.

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.

Performance of a new blood pressure monitor in children and young adults: the difficulties in clinical validation

The aim of this study was to assess the performance of a new ambulatory blood pressure monitor (Dynapulse 5000A) in children and young adults. The reference methods, i.e. the mercury-Doppler (Hg-D) method of blood-pressure measurement (recommended for less than 5-year-old children by the British Hypertension Society criteria) and the mercury-auscultation (Hg-A) technique (recommended for 5 years and above) were initially compared utilizing 132 concomitant systolic blood pressure (SBP) readings taken among 44 subjects (3 in each) aged 2-30 years. Hg-D over-read SBP above that of the conventional Hg-A by a mean of 5.25 mmHg (95% confidence interval (CI) 4.11, 6.4). This difference in measurement between the two techniques was also significantly (p = 0.01) related to age. [Difference in mmHg = 7.83 (95% CI 5.53, 10.12) -0.30 (95% CI -0.54, -0.07) age in years.] The Dynapulse 5000A was therefore validated only against Hg-D throughout the age range and was undertaken utilizing 468 concomitant resting SBP measurements taken among 59 subjects (supine or sitting) using a 'T' system. The Dynapulse was found to give higher SBP readings (average 13.5 mmHg) than Hg-D sphygmomanometry. Although the differences were not dependent on the age of the child, the pulse rate or the body mass index, there was a significant drift in the differences with time (-0.05 mmHg/day). Repeatability of each of the measurement methods calculated utilizing two or three consecutive recordings taken at 1-min intervals showed that variability between repeated measurements made with the Dynapulse (14.8%) was greater than for Hg-D. Repeatability coefficient of the Hg-D (11.2%) was also less than ideal for a reference method. We conclude that Dynapulse 5000A over-reads SBP above that detected by Hg-D, but cannot be fairly graded by British Hypertension Society criteria due to the inconsistency and poor repeatability of the recommended reference methods.

Childhood vasculitis

Vasculitis can and does occur in childhood. Apart from the relatively common vasculitides (Henoch-Schönlein purpura, Kawasaki disease and in world wide terms Takayasu disease) there are a number of important but comparatively rare disorders affecting children. These include macroscopic and microscopic polyarteritis, cutaneous polyarteritis, Wegener's granulomatosis, Churg-Strauss syndrome, primary angiitis of the central nervous system, hypersensitivity angiitis, hypocomplimentaemic urticarial vasculitis, vasculitis associated with various connective tissue disorders and vasculitis associated with conditions such as Behçets syndrome, familial Mediterranean fever and Cogan's syndrome. Distinguishing these conditions from other disorders is often difficult and requires clinical acumen and appropriate investigative procedures. With modern therapeutic agents, it is possible to implement appropriate therapy but in spite of this, there remains a not inconsequential morbidity and mortality.