Simon Heales

Publications of Simon Heales

• Erratum to: Urine analysis of glucose tetrasaccharide by HPLC; a useful marker for the investigation of patients with Pompe and other glycogen storage diseases.

  Authors: Victoria Manwaring, Helen Prunty, Katie Bainbridge, Derek Burke, Niamh Finnegan, Rebecca Franses, Amanda Lam, Ashok Vellodi, Simon Heales

  Journal of inherited metabolic disease. 08/2011; 35(2):369.

• Urine analysis of glucose tetrasaccharide by HPLC; a useful marker for the investigation of patients with Pompe and other glycogen storage diseases.

  Authors: Victoria Manwaring, Helen Prunty, Katie Bainbridge, Derek Burke, Niamh Finnegan, Rebecca Franses, Amanda Lam, Ashok Vellodi, Simon Heales

  Journal of inherited metabolic disease. 06/2011; 35(2):311-6.

  A high performance liquid chromatography method, adapted from an established urinary sugars method, has been developed for the analysis of a tetraglucose oligomer (Glc(4)) in urine. Pompe diseaseA high performance liquid chromatography method, adapted from an established urinary sugars method, has been developed for the analysis of a tetraglucose oligomer (Glc(4)) in urine. Pompe disease results from defects in the activity of lysosomal acid α-glucosidase (GAA) with patients typically excreting increased amounts of Glc(4). Rapid determination of GAA in dried blood spots is now possible. However, enzymatic analysis is unable to discriminate between patients with Pompe disease and those individuals harbouring pseudo deficiency mutations. This method was able to quantify Glc(4) levels in all patients analysed with an established diagnosis of Pompe disease, and all controls analysed had Glc(4) levels below the limit of detection for this method. Importantly the method was able to discriminate between an individual known to harbour a pseudo Pompe mutation and patients with Pompe disease, providing a useful supporting test to enzymatic analysis. Sequential measurement of urinary Glc(4) has been proposed to monitor the effects of enzyme replacement therapy (ERT). We observed a clear decrease in Glc(4) levels following commencement of treatment in three patients studied. Additionally, raised levels of Glc(4) were observed in patients with glycogen storage disease (GSD) type Ia and type III suggesting that this method may have applications in other GSDs.

• Clinical and molecular characterisation of hereditary dopamine transporter deficiency syndrome: an observational cohort and experimental study.

  Authors: Manju A Kurian, Yan Li, Juan Zhen, Esther Meyer, Nebula Hai, Hans-Jürgen Christen, Georg F Hoffmann, Philip Jardine, Arpad von Moers, Santosh R Mordekar [......] Elizabeth Wraige, Christa Dietrich, Timothy Lewis, Keith Hyland, Simon Heales, Terence Sanger, Paul Gissen, Birgit E Assmann, Maarten E A Reith, Eamonn R Maher

  Lancet neurology. 01/2011; 10(1):54-62.

  dopamine transporter deficiency syndrome is the first identified parkinsonian disorder caused by genetic alterations of the dopamine transporter. We describe a cohort of children with mutations indopamine transporter deficiency syndrome is the first identified parkinsonian disorder caused by genetic alterations of the dopamine transporter. We describe a cohort of children with mutations in the gene encoding the dopamine transporter (SLC6A3) with the aim to improve clinical and molecular characterisation, reduce diagnostic delay and misdiagnosis, and provide insights into the pathophysiological mechanisms. 11 children with a biochemical profile suggestive of dopamine transporter deficiency syndrome were enrolled from seven paediatric neurology centres in the UK, Germany, and the USA from February, 2009, and studied until June, 2010. The syndrome was characterised by detailed clinical phenotyping, biochemical and neuroradiological studies, and SLC6A3 mutation analysis. Mutant constructs of human dopamine transporter were used for in-vitro functional analysis of dopamine uptake and cocaine-analogue binding. children presented in infancy (median age 2·5 months, range 0·5-7) with either hyperkinesia (n=5), parkinsonism (n=4), or a mixed hyperkinetic and hypokinetic movement disorder (n=2). Seven children had been initially misdiagnosed with cerebral palsy. During childhood, patients developed severe parkinsonism-dystonia associated with an eye movement disorder and pyramidal tract features. All children had raised ratios of homovanillic acid to 5-hydroxyindoleacetic acid in cerebrospinal fluid, of range 5·0-13·2 (normal range 1·3-4·0). Homozygous or compound heterozygous SLC6A3 mutations were detected in all cases. Loss of function in all missense variants was recorded from in-vitro functional studies, and was supported by the findings of single photon emission CT DaTSCAN imaging in one patient, which showed complete loss of dopamine transporter activity in the basal nuclei. dopamine transporter deficiency syndrome is a newly recognised, autosomal recessive disorder related to impaired dopamine transporter function. Careful characterisation of patients with this disorder should provide novel insights into the complex role of dopamine homoeostasis in human disease, and understanding of the pathophysiology could help to drive drug development.

• Endothelial, sympathetic, and cardiac function in inherited (6R)-L-erythro-5,6,7,8-tetrahydro-L-biopterin deficiency.

  Authors: Lila Mayahi, Lydia Mason, Katherine Bleasdale-Barr, Ann Donald, Iris Trender-Gerhard, Mary G Sweeney, Mary B Davis, Nicholas Wood, Christopher J Mathias, Laura Watson, Denis Pellerin, Simon Heales, John E Deanfield, Kailash Bhatia, Judith Murray-Rust, Aroon D Hingorani

  Circulation. Cardiovascular genetics. 10/2010; 3(6):513-22.

  (6R)-5,6,7,8-Tetrahydro-l-biopterin (BH4) is a cofactor for enzymes involved in catecholamine and nitric oxide generation whose synthesis is initiated by GTP cyclohydrolase I (GTPCH-1), encoded by(6R)-5,6,7,8-Tetrahydro-l-biopterin (BH4) is a cofactor for enzymes involved in catecholamine and nitric oxide generation whose synthesis is initiated by GTP cyclohydrolase I (GTPCH-1), encoded by GCH1. In the absence of a potent, specific GTPCH-1 inhibitor, natural BH4 deficiency caused by mutations in GCH1 in the rare movement disorder, DOPA-responsive dystonia (OMIM DYT5), offers the opportunity to study the role of endogenous BH4 in humans. In 16 DOPA-responsive dystonia patients with mutations predicted to affect GTPCH-1 expression or function and in age- and sex-matched control subjects, we measured plasma biopterin and nitrogen oxides by high-performance liquid chromatography and the Griess reaction, respectively, endothelial function by brachial artery flow-mediated dilation (FMD), sympathetic function by measurement of plasma norepinephrine, epinephrine, and heart rate and blood pressure in response. Cardiac function and structure were assessed by echocardiography. Plasma biopterin was lower in patients (5.76±0.53 versus 8.43±0.85 nmol/L, P=0.03), but plasma NO(2)(-)/NO(3)(-) (NOx) (median, 9.06 [interquartile range, 5.35 to 11.04] versus 8.40 [interquartile range, 5.28 to 11.44] μmol/L, P=1) and FMD were not lower (7.7±0.8% versus 7.9±0.9%, P=0.91). In patients but not control subjects, FMD was insensitive to nitric oxide synthase inhibition (FMD at baseline, 6.7±2.1%; FMD during l-NMMA infusion, 6.2±2.5, P=0.68). The heart rate at rest was higher in patients, but the heart rate and blood pressure response to sympathetic stimulation did not differ in patients and control subjects despite lower concentrations of norepinepherine (264±8 pg/mL versus 226±9 pg/mL, P=0.006) and epinephrine (33.8±5.2 pg/mL versus 17.8±4.6 pg/mL, P=0.03) in patients. There was also no difference in cardiac function and structure. Sympathetic, cardiac, and endothelial functions are preserved in patients with GCH1 mutations despite a neurological phenotype, reduced plasma biopterin, and norepinepherine and epinephrine concentrations. Lifelong endogenous BH4 deficiency may elicit developmental adaptation through mechanisms that are inaccessible during acquired BH4 deficiency in adulthood.

• Atypical parkinsonism with apraxia and supranuclear gaze abnormalities in type 1 Gaucher disease. Expanding the spectrum: case report and literature review.

  Authors: Araceli Alonso-Canovas, Petra Katschnig, Arianna Tucci, Miryam Carecchio, Nicholas W Wood, Mark Edwards, Juan Carlos Martínez Castrillo, Derek Burke, Simon Heales, Kailash P Bhatia

  Movement disorders : official journal of the Movement Disorder Society. 07/2010; 25(10):1506-9.

• Myelin-induced microglial neurotoxicity can be controlled by microglial metabotropic glutamate receptors.

  Authors: Fleur Pinteaux-Jones, Ioanna G Sevastou, Victoria A H Fry, Simon Heales, David Baker, Jennifer M Pocock

  Journal of neurochemistry. 08/2008; 106(1):442-54.

  Microglia are present in an activated state in multiple sclerosis lesions. Incubation of primary cultured rat microglia with rat-brain derived myelin (0.1-1 microg/mL) for 24 h induced microglialMicroglia are present in an activated state in multiple sclerosis lesions. Incubation of primary cultured rat microglia with rat-brain derived myelin (0.1-1 microg/mL) for 24 h induced microglial activation; cells displayed enhanced ED1 staining, expression of inducible nitric oxide synthase, production and release of the cytokine tumour necrosis factor-alpha and glutamate release. Exposure of microglia to myelin induced the expression of neuronal caspases and ultimately neuronal death in cultured cerebellar granule cell neurons; neurotoxicity was directly because of microglial-derived soluble toxins. Co-incubation of microglia with agonists or antagonists of different metabotropic glutamate receptor (mGluR) subtypes ameliorated microglial neurotoxicity by inhibiting soluble neurotoxin production. Activation of microglial mGluR2 exacerbated myelin-evoked neurotoxicity whilst activation of mGluR3 was protective as was activation of group III mGluRs. These data show that myelin-induced microglial neurotoxicity can be prevented by regulation of mGluRs and suggest these receptors on microglia may be promising targets for therapeutic intervention in multiple sclerosis.

• Pyridoxal 5'-phosphate values in cerebrospinal fluid: reference values and diagnosis of PNPO deficiency in paediatric patients.

  Authors: Aida Ormazabal, Marcus Oppenheim, Mercedes Serrano, Angels García-Cazorla, Jaume Campistol, Antonia Ribes, Angeles Ruiz, Juan Moreno, Keith Hyland, Peter Clayton, Simon Heales, Rafael Artuch

  Molecular genetics and metabolism. 06/2008; 94(2):173-7.

  Our aim was to establish reference values for cerebrospinal fluid (CSF) pyridoxal 5'-phosphate (PLP) in a paediatric population for the diagnosis of pyridox(am)ine 5'-phosphate oxidase (PNPO)Our aim was to establish reference values for cerebrospinal fluid (CSF) pyridoxal 5'-phosphate (PLP) in a paediatric population for the diagnosis of pyridox(am)ine 5'-phosphate oxidase (PNPO) deficiency. For reference values, CSF samples from 113 paediatric controls (age range: 1 day-18 years) from Barcelona and London were analysed. Cerebrospinal fluid PLP and biogenic amine concentrations were analysed by HPLC with fluorescence and electrochemical detection. Pyridoxal 5'-phosphate concentrations in 4 patients with PNPO deficiency were determined. A negative correlation between CSF PLP values and age of controls was observed in both populations (r=-0.503; p<0.0001 and r=-0.542; p=0.002). Reference values were stratified into 4 (Barcelona) and 3 age groups (London). For the newborn period, CSF PLP reference intervals were 32-78 and 44-89 nmol/L for the Barcelona and London centers, respectively). No correlation was observed in the different age groups between PLP values and biogenic amines metabolites. PLP values in neonates with PNPO deficiency were clearly decreased (PLP=3.6, 12.0, 14.0 and 18.0 nmol/L) compared with our reference ranges. In conclusion, reference values for CSF PLP should be stratified according to age. No association was observed between PLP values and biogenic amines metabolites. In our 4 cases with PNPO deficiency, CSF PLP values were clearly below the reference values.

• Erratum.

  Authors: Alison Wood-Kaczmar, Sonia Gandhi, Zhi Yao, Andrey Y Abramov, Erik A Miljan, Gregory Keen, Lee Stanyer, Iain Hargreaves, Kristina Klupsch, Emma Deas, Julian Downward, Louise Mansfield, Parmjit Jat, Joanne Taylor, Simon Heales, Michael R Duchen, David Latchman, Sarah J Tabrizi, Nicholas W Wood

  PLoS ONE. 02/2008; 3(8).

  [This corrects the article on p. e2455 in vol. 3, PMID: 18560593.].

• PINK1 is necessary for long term survival and mitochondrial function in human dopaminergic neurons.

  Authors: Alison Wood-Kaczmar, Sonia Gandhi, Zhi Yao, Andrey S Y Abramov, Erik A Miljan, Gregory Keen, Lee Stanyer, Iain Hargreaves, Kristina Klupsch, Emma Deas, Julian Downward, Louise Mansfield, Parmjit Jat, Joanne Taylor, Simon Heales, Michael R Duchen, David Latchman, Sarah J Tabrizi, Nicholas W Wood

  PLoS ONE. 02/2008; 3(6):e2455.

  Parkinson's disease (PD) is a common age-related neurodegenerative disease and it is critical to develop models which recapitulate the pathogenic process including the effect of the ageing process.Parkinson's disease (PD) is a common age-related neurodegenerative disease and it is critical to develop models which recapitulate the pathogenic process including the effect of the ageing process. Although the pathogenesis of sporadic PD is unknown, the identification of the mendelian genetic factor PINK1 has provided new mechanistic insights. In order to investigate the role of PINK1 in Parkinson's disease, we studied PINK1 loss of function in human and primary mouse neurons. Using RNAi, we created stable PINK1 knockdown in human dopaminergic neurons differentiated from foetal ventral mesencephalon stem cells, as well as in an immortalised human neuroblastoma cell line. We sought to validate our findings in primary neurons derived from a transgenic PINK1 knockout mouse. For the first time we demonstrate an age dependent neurodegenerative phenotype in human and mouse neurons. PINK1 deficiency leads to reduced long-term viability in human neurons, which die via the mitochondrial apoptosis pathway. Human neurons lacking PINK1 demonstrate features of marked oxidative stress with widespread mitochondrial dysfunction and abnormal mitochondrial morphology. We report that PINK1 plays a neuroprotective role in the mitochondria of mammalian neurons, especially against stress such as staurosporine. In addition we provide evidence that cellular compensatory mechanisms such as mitochondrial biogenesis and upregulation of lysosomal degradation pathways occur in PINK1 deficiency. The phenotypic effects of PINK1 loss-of-function described here in mammalian neurons provides mechanistic insight into the age-related degeneration of nigral dopaminergic neurons seen in PD.

• (6R)-5,6,7,8-tetrahydro-L-biopterin and its stereoisomer prevent ischemia reperfusion injury in human forearm.

  Authors: Lila Mayahi, Simon Heales, David Owen, Juan P Casas, Joanne Harris, Raymond J MacAllister, Aroon D Hingorani

  Arteriosclerosis, thrombosis, and vascular biology. 07/2007; 27(6):1334-9.

  OBJECTIVE: 6R-5,6,7,8-tetrahydro-L-biopterin (6R-BH4) is a cofactor for endothelial nitric oxide synthase but also has antioxidant properties. Its stereo-isomer 6S-5,6,7,8-tetrahydro-L-biopterinOBJECTIVE: 6R-5,6,7,8-tetrahydro-L-biopterin (6R-BH4) is a cofactor for endothelial nitric oxide synthase but also has antioxidant properties. Its stereo-isomer 6S-5,6,7,8-tetrahydro-L-biopterin (6S-BH4) and structurally similar pterin 6R,S-5,6,7,8-tetrahydro-D-neopterin (NH4) are also antioxidants but have no cofactor function. When endothelial nitric oxide synthase is 6R-BH4-deplete, it synthesizes superoxide rather than nitric oxide. Reduced nitric oxide bioavailability by interaction with reactive oxygen species is implicated in endothelial dysfunction (ED). 6R-BH4 corrects ED in animal models of ischemia reperfusion injury (IRI) and in patients with cardiovascular risks. It is uncertain whether the effect of exogenous 6R-BH4 on ED is through its cofactor or antioxidant action. METHODS AND RESULTS: In healthy volunteers, forearm blood flow was measured by venous occlusion plethysmography during intra-arterial infusion of the endothelium-dependent vasodilator acetylcholine, or the endothelium-independent vasodilator glyceryl trinitrate, before and after IRI. IRI reduced plasma total antioxidant status (P=0.03) and impaired vasodilatation to acetylcholine (P=0.01), but not to glyceryl trinitrate (P=0.3). Intra-arterial infusion of 6R-BH4, 6S-BH4 and NH4 at approximately equimolar concentrations prevented IRI. CONCLUSION: IRI causes ED associated with increased oxidative stress that is prevented by 6R-BH4, 6S-BH4, and NH4, an effect mediated perhaps by an antioxidant rather than cofactor function. Regardless of mechanism, 6R-BH4, 6S-BH4, or NH4 may reduce tissue injury during clinical IRI syndromes.

• Depletion of reduced glutathione precedes inactivation of mitochondrial enzymes following limbic status epilepticus in the rat hippocampus.

  Authors: Hannah Sleven, Julie E Gibbs, Simon Heales, Maria Thom, Hannah R Cock

  Neurochemistry international. 01/2006; 48(2):75-82.

  The time course and critical determinants of mitochondrial dysfunction and oxidative stress following limbic status epilepticus (SE) were investigated in hippocampal sub-regions of an electricalThe time course and critical determinants of mitochondrial dysfunction and oxidative stress following limbic status epilepticus (SE) were investigated in hippocampal sub-regions of an electrical stimulation model in rats, at time points 4-44h after status. Mitochondrial and cytosolic enzyme activities were measured spectrophotometrically, and reduced glutathione (GSH) concentrations by HPLC, and compared to results from sham controls. The earliest change in any sub-region was a fall in GSH, appearing as early as 4h in CA3 (-13%, p<0.05), and persisting at all time points. This was followed by a transient fall in complex I activity (CA3, 16h, -13%, p<0.05), and later changes in aconitase (CA1,-18% and CA3, -22% at 44h, p<0.05). The activity of the cytosolic enzyme glyceraldehyde-3-phosphate-dehydrogenase was unaffected at all time points. It is known that GSH levels are dependent both on redox status, and on the availability of the precursor cysteine, in turn dependent on the cysteine/glutamate antiporter, for which extracellular glutamate concentrations are rate limiting. Both mechanisms are likely to contribute indirectly to GSH depletion following seizures. That a relative deficiency in GSH precedes later changes in the activities of complex I and aconitase in vulnerable hippocampal sub-regions, occurring within a clinically relevant therapeutic time window, suggests that strategies to boost GSH levels and/or otherwise reduce oxidative stress following seizures, deserve further study, both in terms of preventing the biochemical consequences of SE and the neuronal dysfunction and clinical consequences.

• Pulmonary hypertension in a GTP-cyclohydrolase 1-deficient mouse.

  Authors: Manasi Nandi, Alyson Miller, Raymond Stidwill, Thomas S Jacques, Amanda A J Lam, Sheila Haworth, Simon Heales, Patrick Vallance

  Circulation. 05/2005; 111(16):2086-90.

  BACKGROUND: GTP-cyclohydrolase 1 (GTP-CH1) catalyzes the first step for the de novo production of tetrahydrobiopterin (BH4), a cofactor for nitric oxide synthase (NOS). The hyperphenylalaninemicBACKGROUND: GTP-cyclohydrolase 1 (GTP-CH1) catalyzes the first step for the de novo production of tetrahydrobiopterin (BH4), a cofactor for nitric oxide synthase (NOS). The hyperphenylalaninemic mutant mouse (hph-1) displays a 90% reduction in GTP-CH1 activity. Reduced BH4 decreases NOS activity and may lead to endothelial dysfunction, and there is increasing evidence that a dysfunction of the NOS pathway may be implicated in pulmonary hypertension. The aim of the study was to investigate whether reduced BH4 in the hph-1 mouse results in a pulmonary hypertensive phenotype. METHODS AND RESULTS: Morphological characterization of the heart, lung, and kidney and measurements of systemic and right ventricular blood pressures were performed in both hph-1 and wild-type mice. BH4 and NO(x) levels were also measured. Hph-1 mice had significantly lower NO(x) and BH4 levels, consistent with previous findings. Both morphological and in vivo data were indicative of a pulmonary but not systemic hypertensive phenotype. We observed increased right ventricle-left ventricle plus septum ratios attributable only to an increase in right ventricular mass, increased smooth muscle medial area in pulmonary resistance vessels, and significantly higher right ventricular pressures in vivo. There were no significant differences between left ventricular masses and systemic pressures, and there was no observed evidence of systemic hypertension in kidney sections between wild-type and hph-1. CONCLUSIONS: This study demonstrates that mice deficient in GTP-CH1/BH4 display a pulmonary hypertensive but not systemic hypertensive phenotype.

• L-Dopa-responsive Parkinson's syndrome in association with phenylketonuria: In vivo dopamine transporter and D2 receptor findings.

  Authors: Andrew H Evans, Durval C Costa, Sveto Gacinovic, Regina Katzenschlager, John D O'Sullivan, Simon Heales, Phillip Lee, Andrew J Lees

  Movement disorders : official journal of the Movement Disorder Society. 11/2004; 19(10):1232-6.

  Reports of parkinsonism in phenylketonuria are exceedingly rare. We report on a patient who had received a delayed diagnosis of phenylketonuria as an infant and subsequently developedReports of parkinsonism in phenylketonuria are exceedingly rare. We report on a patient who had received a delayed diagnosis of phenylketonuria as an infant and subsequently developed levodopa-responsive parkinsonism at the age of 33. Single-photon emission computed tomography (SPECT) using (123)I-FP-CIT ([(123))I]-2 beta-carbomethoxy-3beta-(-4-iodophenyl)-N-(3-fluoropropyl)-nortropane) used to measure dopamine transporter levels on two occasions, 7 and 9 years after the onset of neurological symptoms, were normal. Iodine-123-iodo-lisuride SPECT (IBZM) imaging, however, showed reduced caudate over putamen binding. This combination of imaging findings indicates a possible upregulation of postsynaptic D2 receptors in the context of intact presynaptic dopamine nerve terminal density.

• Association between mitochondrial dysfunction and severity and outcome of septic shock.

  Authors: David Brealey, Michael Brand, Iain Hargreaves, Simon Heales, John Land, Ryszard Smolenski, Nathan A Davies, Chris E Cooper, Mervyn Singer

  Lancet. 08/2002; 360(9328):219-23.

  BACKGROUND: Sepsis-induced multiple organ failure is the major cause of mortality and morbidity in critically ill patients. However, the precise mechanisms by which this dysfunction is caused remainBACKGROUND: Sepsis-induced multiple organ failure is the major cause of mortality and morbidity in critically ill patients. However, the precise mechanisms by which this dysfunction is caused remain to be elucidated. We and others have shown raised tissue oxygen tensions in septic animals and human beings, suggesting reduced ability of the organs to use oxygen. Because ATP production by mitochondrial oxidative phosphorylation accounts for more than 90% of total oxygen consumption, we postulated that mitochondrial dysfunction results in organ failure, possibly due to nitric oxide, which is known to inhibit mitochondrial respiration in vitro and is produced in excess in sepsis. METHODS: We did skeletal muscle biopsies on 28 critically ill septic patients within 24 h of admission to intensive care, and on nine control patients undergoing elective hip surgery. The biopsy samples were analysed for respiratory-chain activity (complexes I-IV), ATP concentration, reduced glutathione (an intracellular antioxidant) concentration, and nitrite/nitrate concentrations (a marker of nitric oxide production). FINDINGS: Skeletal muscle ATP concentrations were significantly lower in the 12 patients with sepsis who subsequently died than in the 16 septic patients who survived (p=0.0003) and in controls (p=0.05). Complex I activity had a significant inverse correlation with norepinephrine requirements (a proxy for shock severity, p=0.0003) and nitrite/nitrate concentrations (p=0.0004), and a significant positive correlation with concentrations of reduced glutathione (p=0.006) and ATP (p=0.03). INTERPRETATION: In septic patients, we found an association between nitric oxide overproduction, antioxidant depletion, mitochondrial dysfunction, and decreased ATP concentrations that relate to organ failure and eventual outcome. These data implicate bioenergetic failure as an important pathophysiological mechanism underlying multiorgan dysfunction.

• Selective decrease in central nervous system serotonin turnover in children with dopa-nonresponsive dystonia.

  Authors: Birgit Assmann, Martin Köhler, Georg F Hoffmann, Simon Heales, Robert Surtees

  Pediatric research. 07/2002; 52(1):91-4.

  Childhood dystonia that does not respond to treatment with levodopa (dopa-nonresponsive dystonia, DND) has an unclear pathogenesis and is notoriously difficult to treat. To test the hypothesis thatChildhood dystonia that does not respond to treatment with levodopa (dopa-nonresponsive dystonia, DND) has an unclear pathogenesis and is notoriously difficult to treat. To test the hypothesis that there may be abnormalities in serotonin turnover in DND we measured cerebrospinal fluid (CSF) concentrations of homovanillic (HVA) and 5-hydroxyindoleacetic (HIAA) acids, metabolites of dopamine and serotonin, respectively, in 18 children with dystonia not responsive to levodopa. These were combined with a reference population of 85 children with neurologic or metabolic disease known not to affect dopamine or serotonin metabolism. Because of the known natural age-related decrement in HVA and HIAA concentrations, the results were analyzed using multiple regression using age and DND as predictors of CSF HIAA and HVA concentrations. DND was a highly significant predictor of CSF HIAA concentration (p < 0.001) but not of CSF HVA concentration (p = 0.59). After fitting a regression model, the geometric mean ratio of CSF HIAA in DND compared with the reference range was 0.53 whereas that for CSF HVA was 0.95. We also analyzed CSF HIAA/HVA ratios. After fitting a regression model, we found no dependence on age, and the mean of CSF HIAA/HVA in DND was 0.28 whereas that for the reference range was 0.49 (p < 0.001). We conclude that a significant number of children with DND have reduced CNS serotonin turnover. Treatment with drugs that increase serotonin concentration in the synaptic cleft should be considered in this group of patients.

• Determination of quinonoid dihydrobiopterin by high-performance liquid chromatography and electrochemical detection

  Authors: Simon Heales, Keith Hyland

  Journal of Chromatography B: Biomedical Sciences and Applications.

  Sodium bisulphite is shown to react with quinonoid dihydrobiopterin to form a stable adduct. Sodium bisulphite does not react with tetrahydrobiopterin. Quinonoid dihydrobiopterin reacts withSodium bisulphite is shown to react with quinonoid dihydrobiopterin to form a stable adduct. Sodium bisulphite does not react with tetrahydrobiopterin. Quinonoid dihydrobiopterin reacts with dithioerythritol to form tetrahydrobiopterin, whereas the quinonoid dihydrobiopterin bisulphite adduct does not. Using these properties we have developed an indirect method for the quantitative measurement of quinonoid dihydrobiopterin. The method requires division of a sample into two. Dithioerythritol is added to one half (a). This converts quinonoid dihydrobiopterin to tetrahydrobiopterin and prevents the oxidation of tetrahydrobiopterin. Measurement of the tetrahydrobiopterin content of this sample by electrochemistry following high-performance liquid chromatographic separation (with dithioerythritol present in the mobile phase to prevent autoxidation of the tetrahydrobiopterin on column), therefore provides a total value of the tetrahydrobiopterin plus quinonoid dihydrobiopterin present within the original sample. Sodium bisulphite is added to the other portion of the sample (b), followed immediately by dithioerythritol which prevents autoxidation of the remaining tetrahydrobiopterin. The bisulphite reacts with the quinonoid dihydrobiopterin present and the quinonoid dihydrobiopterin-bisulphite adduct is no longer detected by electrochemistry at the retention time of tetrahydrobiopterin. Using reversed-phase high-performance liquid chromatography and redox electrochemical detection, measurement of tetrahydrobiopterin in the absence (a) and presence (b) of bisulphite enables the concentration of quinonoid dihydrobiopterin to be calculated by subtraction (a-b). This method is shown to be quantitative and preliminary experiments demonstrate that it can be adapted for biological samples.

• Correction: PINK1 Is Necessary for Long Term Survival and Mitochondrial Function in Human Dopaminergic Neurons

  Authors: Alison Wood-Kaczmar, Sonia Gandhi, Zhi Yao, Andrey Y Abramov, Erik A Miljan, Gregory Keen, Lee Stanyer, Iain Hargreaves, Kristina Klupsch, Emma Deas, Julian Downward, Louise Mansfield, Parmjit Jat, Joanne Taylor, Simon Heales, Michael R Duchen, David Latchman, Sarah J Tabrizi, Nicholas W Wood

• Rapid neonatal weight gain in rats results in a renal ubiquinone (CoQ) deficiency associated with premature death.

  Authors: Piran Shelley, Jane Tarry-Adkins, Malgorzata Martin-Gronert, Lucilla Poston, Simon Heales, John Clark, Susan Ozanne, Josie McConnell

  Mechanisms of ageing and development. 128(11-12):681-7.

  We have recently reported that maternal dietary imbalance during pregnancy and lactation can reduce the lifespan of offspring. Rats that were growth restricted in utero by maternal proteinWe have recently reported that maternal dietary imbalance during pregnancy and lactation can reduce the lifespan of offspring. Rats that were growth restricted in utero by maternal protein restriction and underwent rapid weight gain when suckled by control fed dams died earlier than animals whose mothers were fed a control diet throughout pregnancy and lactation. We demonstrate here that mitochondrial abnormalities and DNA damage occur in the kidney of offspring who die prematurely. We have established by direct measurement and by in vitro supplementation that mitochondrial abnormalities occur because of a functional deficit of the mitochondrial cofactor coenzyme Q9 (CoQ9). These data provide molecular insight into the association between maternal nutrition and determination of offspring lifespan, and identify, a potential dietary intervention to prevent detrimental consequences of imbalanced maternal nutrition.