Search

Aims Although cysteamine was first used in the treatment of cystinosis in 1976 and approved by the FDA as cysteamine bitartrate (Cystagon™) in 1994, surprisingly little pharmacological data are available for this compound. Cysteamine and its related drugs are currently being evaluated for the treatment of Huntington’s and Parkinson’s disease. The aim of te study was to understand the pharmacokinetics of cysteamine bitartrate following gastrointestinal infusion. Method Cysteamine bitartrate was delivered through a naso-enteric catheter into the stomach ( n = 8), small intestine ( n = 8) and caecum ( n = 4) of normal subjects. Plasma cysteamine concentrations were determined using LC-MS/MS. Results The rate and extent of drug absorption were assessed by comparing AUC(0, ∞), Cmax and tmax, among the gastrointestinal infusion sites. Total cysteamine exposure, expressed as area under the curve (AUC(0, ∞)) was greatest when the drug was infused into the small intestine (4331.3 ± 1907.6 min × µm) followed by stomach (3901.9 ± 1591.9 min × µm) and caecum (3141.4 ± 1627.6 min × µm). Cysteamine infusion into the small intestine resulted in the most rapid rise to maximal plasma concentrations ( tmax = 21 ± 0.56 min); tmax was delayed to 50 ± 26 min and 64 ± 26 min after gastric and caecal infusion, respectively. The maximum cysteamine plasma concentration ( Cmax) was reached after infusion of the drug into the small intestine (51 ± 21 µm), which was higher than plasma Cmax concentrations after gastric (39 ± 16 µm) and caecal infusion (23 ± 15 µm). Conclusions The pharmacokinetic data generated help extend our understanding of cysteamine. [ABSTRACT FROM AUTHOR]

Abstract: In order to examine correlations which might be useful in ascertaining or confirming the diagnosis of mitochondrial disease, a retrospective analysis of urine organic acids was performed. Among 3646 analyses from randomly selected samples referred to our laboratory, there were 258 specimens from 67 patients with various known disorders of mitochondrial oxidative function, most of whom were known to have chronic and persistent elevations of blood lactic acid, and 176 samples from 21 patients with diagnosed organic acidemia. Urine lactate was not a useful discriminator; only 7.6% of results from infants with mitochondrial disease fell the 95th percentile for patients without mitochondrial disease. Most of the Krebs cycle intermediates were also not useful in discriminating patients with mitochondrial disorders. Interestingly, there was strikingly poor correlation among most of those analytes in all patient groups, but fumarate and malate were uniquely well correlated (r2=0.840). Fumarate and malate were also the most useful in distinguishing patients with mitochondrial disease and organic acidemia from the pool of unselected or undiagnosed patients, although the utility was somewhat limited. Using a cutoff value of approximately 90 mmol/mol creatinine for fumarate or malate at age <1 year, or a cutoff of approximately 25 for older patients, 25ndash;30% of mitochondrial disease patients can be distinguished with a 5% false positive rate. Further refinements to this approach may better characterize the metabolomic profile and may improve the diagnostic utility of quantitative organic acid analysis in mitochondrial disease. [Copyright &y& Elsevier]

Clinical features are reported for 37 patients with various mitochondrial disorders, treated with sodium dichloroacetate (DCA) for 3 weeks to 7 years (mean 3.25 years) at 11–50mg/kg/day (34.6±13.1) in an open-label format. DCA pharmacokinetics showed half-times approximately 86min for the first intravenous dose of 50mg/kg, 3.2h for a subsequent intravenous dose 4–6h later, and 11h after continued oral dosing of 12.5–25mg/kg twice daily. Basal blood and CSF lactate (mean values at entry 29.6 and 46.8mg/dL, respectively) decreased at 3 months (to 18.1 and 34.2, respectively) and 12 months (to 17.7 and 33.1, respectively). There was some attenuation of the blood lactate response to oral fructose but not glucose, although the baseline lactate was lower with DCA. A standardized neurologic inventory showed stabilization or improvement over one year. The subjective impression of overall disease course was worsening in 21.6%, improvement in 48.6%, and no discernable effect in 29.7%. Among 8 patients who had 17 stroke-like events in 0.25–5 years prior to study entry, there were a total of 2 events over 3–6 years of treatment. In two cases institution of DCA resulted in dramatic relief of severe headaches which had been refractory to narcotics. Given variability of symptoms and limited understanding of natural history of mitochondrial disease, it is difficult to determine the efficacy of DCA in this open-label study, but there did appear to be some cases in which there were at least temporary benefits. [Copyright &y& Elsevier]

Hereditary fructose intolerance (HFI) caused by fructose aldolase B deficiency results in hepatic dysfunction unless managed with severely restricted dietary intake of fructose and sucrose. The potential of FOS to provide a fructose load in compromised individuals has not been determined. The purpose of this study was to evaluate the safety and tolerance of FOS among subjects with established diagnoses of HFI. Five subjects with HFI (ages 14-52 yrs; 4 male, 1 female) participated in a prospective, non-randomized open challenge with FOS at 6 g/m2/d for 2 days. A female infant (5 mos) with resolved neonatal hepatitis was also studied. Diet records were maintained for the 48-hr period and analyzed for dietary fructose. Tolerance was assessed through evaluation of serum AST, ALT, GGT, glucose, bilirubin, uric acid, phosphorus, and electrolytes, upon initiation and at 12-hr intervals during the challenge. Blood chemistry values were within normal ranges and did not change appreciably during the study period, except for two patients with slight elevations of uric acid. One subject reported gastric discomfort on day 2 of the FOS challenge. These data suggest that FOS providing approximately 4.7 mg fructose/kg bw/d for 2 days is safe and well tolerated among individuals with diagnosed HFI. [Copyright &y& Elsevier]

: ObjectiveTo investigate the effects of estrogen (E) and psychological stress on plasma total homocysteine levels in relation to menopausal status.: DesignDouble-blind, randomized, placebo-controlled study.: SettingThe General Clinical Research Center of a university hospital.: Patient(s)Thirty-six postmenopausal women and 26 premenopausal women. Both samples were healthy nonsmokers.: Intervention(s)Both premenopausal and postmenopausal women were subjected to a 6-minute psychological stressor. Postmenopausal women were randomized to one of three treatment arms: 2 mg of E2 or 2 mg of E2 + 5 mg of medroxyprogesterone acetate (MPA), or a placebo, all of which were given orally for 3 months. The psychological stressor was readministered after the 3-month regimen.: Main outcome measure(s)Plasma total homocysteine levels were measured before and after the psychological stressor on one occasion for premenopausal women and before and after hormone replacement or placebo for postmenopausal women.: Result(s)There were no significant differences in homocysteine levels between premenopausal (7.2 ± 1.7 μmol/L; mean ± SD) and postmenopausal women (7.9 ± 2.06; mean ± SD). There was no effect of stress or hormone replacement on homocysteine levels.: Conclusion(s)Psychological stress, menopausal status, and oral hormone replacement therapy (HRT) do not affect plasma total homocysteine levels in women with normal basal homocysteine levels. [Copyright &y& Elsevier]

Presents a study on fasting, glucose and fructose loading in mitochondrial disease. Possible impact from defects in mitochondrial function resulting in a failure of oxidative metabolism; Base of certain predictions which might be made; Details on some disorders.

The product of thiamine phosphokinase is the cofactor for many enzymes, including the dehydrogenases of pyruvate, 2-ketoglutarate and branched chain ketoacids. Its deficiency has recently been described in a small number of patients, some of whom had a Leigh syndrome phenotype. The patient who also had a Leigh phenotype was initially found to have a low concentration of biotin in plasma and massive urinary excretion of biotin. Despite treatment with biotin and thiamine, her disease was progressive. Mutations c.311delG and c.426G > C were found in the TPK1 gene. • Thiamine Phosphokinase Deficiency. • Mutation in the TPK1 gene. • Biotin Responsive Basal Ganglia Disease. • Leigh phenotype. • Leigh syndrome. [ABSTRACT FROM AUTHOR]

Background: Late-onset Pompe disease is a rare genetic neuromuscular disorder caused by lysosomal acid alpha-glucosidase (GAA) deficiency that ultimately results in mobility loss and respiratory failure. Current enzyme replacement therapy with recombinant human (rh)GAA has demonstrated efficacy in subjects with late-onset Pompe disease. However, long-term effects of rhGAA on pulmonary function have not been observed, likely related to inefficient delivery of rhGAA to skeletal muscle lysosomes and associated deficits in the central nervous system. To address this limitation, reveglucosidase alfa, a novel insulin-like growth factor 2 (IGF2)-tagged GAA analogue with improved lysosomal uptake, was developed. This study evaluated the pharmacokinetics, safety, and exploratory efficacy of reveglucosidase alfa in 22 subjects with late-onset Pompe disease who were previously untreated with rhGAA.Results: Reveglucosidase alfa plasma concentrations increased linearly with dose, and the elimination half-life was <1.2 h. Eighteen of 22 subjects completed 72 weeks of treatment. The most common adverse events were hypoglycemia (63%), dizziness, fall, headache, and nausea (55% for each). Serious adverse events included hypersensitivity (n = 1), symptomatic hypoglycemia (n = 2), presyncope (n = 1), and acute cardiac failure (n = 1). In the dose-escalation study, all treated subjects tested positive for anti-reveglucosidase alfa, anti-rhGAA, anti-IGF1, and anti-IGF2 antibodies at least once. Subjects receiving 20 mg/kg of reveglucosidase alfa demonstrated increases in predicted maximum inspiratory pressure (13.9%), predicted maximum expiratory pressure (8.0%), forced vital capacity (-0.4%), maximum voluntary ventilation (7.4 L/min), and mean absolute walking distance (22.3 m on the 6-min walk test) at 72 weeks.Conclusions: Additional studies are needed to further assess the safety and efficacy of this approach. Improvements in respiratory muscle strength, lung function, and walking endurance in subjects with LOPD may make up for the risk of hypersensitivity reactions and hypoglycemia. Reveglucosidase alfa may provide a new treatment option for patients with late-onset Pompe disease.Trial Registration: ISRCTN01435772 and ISRCTN01230801 , registered 27 October 2011. [ABSTRACT FROM AUTHOR]

Abstract: The major coenzyme Q species in humans is the decaprenyl quinoid derivative coenzyme Q10 (CoQ10), and its measurement is somewhat challenging owing to its hydrophobicity and tendency to be oxidized. There are three major methods which are suited for analysis of CoQ10: HPLC-coupled UV or electrochemical detection, and tandem mass spectrometry. The techniques are discussed, and results of these applications to determine CoQ10 concentrations in various human fluids and tissues are summarized. [Copyright &y& Elsevier]

A letter to the editor is presented in response to an article related to hepatic transplantation published in a previous issue.

Mass spectrometry-based metabolomics is a rapidly growing field in both research and diagnosis. Generally, the methodologies and types of instruments used for clinical and other absolute quantification experiments are different from those used for biomarkers discovery and untargeted analysis, as the former requires optimal sensitivity and dynamic range, while the latter requires high resolution and high mass accuracy. We used a Q-TOF mass spectrometer with two different types of pentafluorophenyl (PFP) stationary phases, employing both positive and negative ionization, to develop and validate a hybrid quantification and discovery platform using LC-HRMS. This dual-PFP LC-MS platform quantifies over 50 clinically relevant metabolites in serum (using both MS and MS/MS acquisitions) while simultaneously collecting high resolution and high mass accuracy full scans to monitor all other co-eluting non-targeted analytes. We demonstrate that the linearity, accuracy, and precision results for the quantification of a number of metabolites, including amino acids, organic acids, acylcarnitines and purines/pyrimidines, meets or exceeds normal bioanalytical standards over their respective physiological ranges. The chromatography resolved highly polar as well as hydrophobic analytes under reverse-phase conditions, enabling analysis of a wide range of chemicals, necessary for untargeted metabolomics experiments. Though previous LC-HRMS methods have demonstrated quantification capabilities for various drug and small molecule compounds, the present study provides an HRMS quant/qual platform tailored to metabolic disease; and covers a multitude of different metabolites including compounds normally quantified by a combination of separate instrumentation. [ABSTRACT FROM AUTHOR]

Oral cysteamine therapy prevents natural disease progression in children with cystinosis, but it may cause severe gastrointestinal (GI) symptoms through gastric acid-hypersecretion. The purpose of this study was to assess the value of esomeprazole in controlling cysteamine-induced acid-hypersecretion and GI symptoms in children with cystinosis. Subjects underwent upper GI endoscopy and biopsy, serum gastrin and cysteamine measurements as well as acid secretion studies (basal, maximal and peak acid output, BAO, MAO, PAO) before and during esomeprazole therapy. A symptom score (maximum 14 points) was devised to monitor symptoms. Twelve children (mean age 5.8 years) were studied. Cysteamine ingestion resulted in mean MAO and PAO significantly higher than mean BAO, both before and during esomeprazole therapy. PAO was usually within 60 min of cysteamine ingestion. Esomeprazole therapy significantly reduced MAO ( P<0.01) and PAO ( P<0.01). The mean symptom score fell from 6.4 to 0.7 ( P<0.0001) during esomeprazole therapy. The mean final dose of esomeprazole was 1.7 mg/kg per day (range 0.7 mg/kg per day to 2.75 mg/kg per day). Plasma cysteamine levels were not affected by acid-suppression therapy. One child had multi-nucleated parietal cells. Cysteamine-induced gastric acid-hypersecretion and GI symptoms are dramatically reduced with esomeprazole therapy. Esomeprazole does not alter cysteamine absorption and is very well tolerated in children. [ABSTRACT FROM AUTHOR]

: PurposeTo evaluate total plasma homocysteine (tHcy) levels in patients diagnosed with primary open-angle glaucoma (POAG) and normal subjects.: DesignCase-control study.: MethodsThis study involved 55 POAG patients, 16 patients with secondary open-angle glaucoma or angle-closure glaucoma (non-POAG group), and 39 control healthy subjects undergoing ocular surgery. All glaucoma patients had characteristic glaucomatous optic disk damage and visual field loss. Fasting tHcy concentrations of all study participants were determined using high-performance liquid chromatography. Analysis of variance was used to compare homocysteine levels among the three diagnostic groups, and multivariate analysis was conducted to assess the associations between tHcy and diagnostic group, age, gender, smoking status, systemic hypertension, hyperlipidemia, and cardiovascular or cerebrovascular disease.: ResultsMean ± standard deviation of tHcy levels in POAG individuals, non-POAG patients and control subjects was 14.90 ± 6.45 μmol/l, 14.30 ± 4.35 μmol/l, and 14.81 ± 4.56 μmol/l, respectively (P = .93; ANOVA). No statistically significant difference was found in the proportion of patients with abnormal tHcy levels among the three diagnostic groups. In multivariate analysis, only age and positive smoking status were significantly correlated with total plasma homocysteine levels.: ConclusionNo significant difference was found in plasma homocysteine levels among POAG patients and normal control individuals. [Copyright &y& Elsevier]

Pyruvate carboxylase deficiency, complex form, presents in early infancy with lethal metabolic acidosis, resulting from ketoacidosis and lactic acidemia. Renal tubular acidosis, hyperammonemia, and citrullinemia complete the picture. In an infant with this disease, large amounts of glucose ameliorated the ketoacidosis, but worsened the lactic acidosis. Orthotopic hepatic transplantation completely reversed the ketoacidosis and the renal tubular abnormality and ameliorated the lactic acidemia. Concentrations of glutamine in cerebrospinal fluid were low and did not improve with liver transplantation. [Copyright &y& Elsevier]

Unlabelled: In eight patients with disorders of fatty acid oxidation, analysis of uric acid and creatine kinase served as indicators of the underlying disorder in episodes of acute metabolic imbalance. Six patients had deficiency of medium-chain acyl-CoA dehydrogenase, one had long-chain hydroxyacyl-CoA dehydrogenase deficiency, and one very long-chain acyl-CoA dehydrogenase deficiency. The most common presentation was with symptomatic hypoglycemia; there was one Reye-like presentation and one of rhabdomyolysis. The mechanism of the elevation of uric acid and creatine kinase appears to be the breakdown of tissue.Conclusion: it is concluded that uric acid and creatine kinase provide a useful alerting signal to the presence of a disorder of fatty acid oxidation. Maximal levels of uric acid in this series were 6.2-21.5 mg/dl and of creatine kinase 879-27,557 U/l. [ABSTRACT FROM AUTHOR]

We report that recessive inheritance of a post-GPI attachment to proteins 2 (PGAP2) gene variant results in the hyperphosphatasia with neurologic deficit (HPMRS) phenotype described by Mabry et al., in 1970. HPMRS, or Mabry syndrome, is now known to be one of 21 inherited glycosylphosphatidylinositol (GPI) deficiencies (IGDs), or GPI biosynthesis defects (GPIBDs). Bi-allelic mutations in at least six genes result in HPMRS phenotypes. Disruption of four phosphatidylinositol glycan (PIG) biosynthesis genes, PIGV , PIGO , PIGW and PIGY , expressed in the endoplasmic reticulum, result in HPMRS 1, 2, 5 and 6; disruption of the PGAP2 and PGAP3 genes, necessary for stabilizing the association of GPI anchored proteins (AP) with the Golgi membrane, result in HPMRS 3 and 4. We used exome sequencing to identify a novel homozygous missense PGAP2 variant NM_014489.3:c.881C > T, p.Thr294Met in two index patients and targeted sequencing to identify this variant in an unrelated patient. Rescue assays were conducted in two PGAP2 deficient cell lines, PGAP2 KO cells generated by CRISPR/Cas9 and PGAP2 deficient CHO cells, in order to examine the pathogenicity of the PGAP2 variant. First, we used the CHO rescue assay to establish that the wild type PGAP2 isoform 1, translated from transcript 1, is less active than the wild type PGAP2 isoform 8, translated from transcript 12 (alternatively spliced to omit exon 3). As a result, in our variant rescue assays, we used the more active NM_001256240.2:c.698C > T, p.Thr233Met isoform 8 instead of NM_014489.3:c.881C > T, p.Thr294Met isoform 1. Flow cytometric analysis showed that restoration of cell surface CD59 and CD55 with variant PGAP2 isoform 8, driven by the weak (pTA FLAG) promoter, was less efficient than wild type isoform 8. Therefore, we conclude that recessive inheritance of c.881C > T PGAP2 , expressed as the hypomorphic PGAP2 c.698C > T, p.Thr233Met isoform 8, results in prototypical Mabry phenotype, HPMRS3 (GPIBD 8 [MIM: 614207]). This study highlights the need for long-term follow up of individuals with rare diseases in order to ensure that they benefit from innovations in diagnosis and treatment. [ABSTRACT FROM AUTHOR]

The incidence of type 2 diabetes is increasing more rapidly in adolescents than in any other age group. We identified and compared metabolite signatures in obese children with type 2 diabetes (T2D), obese children without diabetes (OB), and healthy, age- and gender-matched normal weight controls (NW) by measuring 273 analytes in fasting plasma and 24-hour urine samples from 90 subjects by targeted LC-MS/MS. Diabetic subjects were within 2 years of diagnosis in an attempt to capture early-stage disease prior to declining renal function. We found 22 urine metabolites that were uniquely associated with T2D when compared to OB and NW groups. The metabolites most significantly elevated in T2D youth included members of the betaine pathway, nucleic acid metabolism, and branched-chain amino acids (BCAAs) and their catabolites. Notably, the metabolite pattern in OB and T2D groups differed between urine and plasma, suggesting that urinary BCAAs and their intermediates behaved as a more specific biomarker for T2D, while plasma BCAAs associated with the obese, insulin resistant state independent of diabetes status. Correlative analysis of metabolites in the T2D signature indicated that betaine metabolites, BCAAs, and aromatic amino acids were associated with hyperglycemia, but BCAA acylglycine derivatives and nucleic acid metabolites were linked to insulin resistance. Of major interest, we found that urine levels of succinylaminoimidazole carboxamide riboside (SAICA-riboside) were increased in diabetic youth, identifying urine SAICA-riboside as a potential biomarker for T2D. [ABSTRACT FROM AUTHOR]

We report a rare presentation of mitochondrial disorder in a child with recurrent carpopedal spasms due to hypocalcemia and hypomagnesemia, secondary to renal proximal tubulopathy and possible hypoparathyroidism. At least two mutant mitochondrial DNA species were identified, and abnormal mitochondria were found in the muscle and renal biopsy specimens. The case illustrates the spectrum and diversity of mitochondrial presentations, arising because of heteroplasmy of mutations and the type of organs affected. [ABSTRACT FROM AUTHOR]

The acetyltransferase, E1a-binding protein (p300), is proposed to regulate various aspects of skeletal muscle development, metabolism, and mitochondrial function, via its interaction with numerous transcriptional regulators and other proteins. Remarkably, however, the contribution of p300 to skeletal muscle function and metabolism, in vivo, is poorly understood. To address this, we used Cre-LoxP methodology to generate mice with skeletal muscle-specific knockout of E1a-binding protein (mKO). mKO mice were indistinguishable from their wild-type/floxed littermates, with no differences in lean mass, skeletal muscle structure, fiber type, respirometry flux, or metabolites of fatty acid and amino acid metabolism. Ex vivo muscle function in extensor digitorum longus and soleus muscles, including peak stress and time to fatigue, as well as in vivo running capacity were also comparable. Moreover, expected adaptations to a 20 d voluntary wheel running regime were not compromised in mKO mice. Taken together, these findings demonstrate that p300 is not required for the normal development or functioning of adult skeletal muscle, nor is it required for endurance exercise-mediated mitochondrial adaptations. [ABSTRACT FROM AUTHOR]

Background The hepatic urea cycle is the main metabolic pathway for detoxification of ammonia. Inborn errors of urea cycle function present with severe hyperammonemia and a high case fatality rate. Long-term prognosis depends on the residual activity of the defective enzyme. A reliable method to estimate urea cycle activity in-vivo does not exist yet. The aim of this study was to evaluate a practical method to quantify 13 C-urea production as a marker for urea cycle function in healthy subjects, patients with confirmed urea cycle defect (UCD) and asymptomatic carriers of UCD mutations. Methods 13 C-labeled sodium acetate was applied orally in a single dose to 47 subjects (10 healthy subjects, 28 symptomatic patients, 9 asymptomatic carriers). Results The oral 13 C-ureagenesis assay is a safe method. While healthy subjects and asymptomatic carriers did not differ with regards to kinetic variables for urea cycle flux, symptomatic patients had lower 13 C-plasma urea levels. Although the 13 C-ureagenesis assay revealed no significant differences between individual urea cycle enzyme defects, it reflected the heterogeneity between different clinical subgroups, including male neonatal onset ornithine carbamoyltransferase deficiency. Applying the 13 C-urea area under the curve can differentiate between severe from more mildly affected neonates. Late onset patients differ significantly from neonates, carriers and healthy subjects. Conclusion This study evaluated the oral 13 C-ureagenesis assay as a sensitive in-vivo measure for ureagenesis capacity. The assay has the potential to become a reliable tool to differentiate UCD patient subgroups, follow changes in ureagenesis capacity and could be helpful in monitoring novel therapies of UCD. [ABSTRACT FROM AUTHOR]

The drug nitisinone (NTBC) is used to treat tyrosinemia type I, and more recently has been also used for the treatment of another disorder of tyrosine metabolism, alkaptonuria. While studying the dose effects of NTBC treatment on alkaptonuria, untargeted metabolomics revealed perturbations in a completely separate pathway, that of tryptophan metabolism. Significant elevations in several indolic compounds associated with the indolepyruvate pathway of tryptophan metabolism were present in NTBC-treated patient sera and correlated with elevations of an intermediate of tyrosine metabolism. Indolic compounds of this pathway have long been associated with commensal bacterial and plant metabolism. These exogenous sources of indoles have been more recently implicated in affecting mammalian cell function and disease. We studied the correlation of these indolic compounds in other disorders of tyrosine metabolism including tyrosinemia types I and II as well as transient tyrosinemia, and demonstrated that 4-hydroxyphenylpyruvate (4-HPP) was directly responsible for the promotion of this pathway. We then investigated the regulation of the indolepyruvate pathway and the role of 4-HPP further in both mammalian cells and intestinal microbial cultures. We demonstrated that several of the indolic products, including indolepyruvate and indolelactate, were in fact generated by human cell metabolism, while the downstream indole metabolite, indolecarboxaldehyde, was produced exclusively by microbial cultures of human gut flora. This study describes a symbiotic perturbation in host and microbiome tryptophan metabolism in response to elevations related to defects of tyrosine metabolism and concomitant drug treatment. [ABSTRACT FROM AUTHOR]

Abstract: Very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) is a fatty acid oxidation disorder with widely varying presentations that has presented a significant challenge to newborn screening (NBS). The Western States Regional Genetics Services Collaborative developed a workgroup to study infants with NBS positive for VLCADD. We performed retrospective analysis of newborns with elevated C14:1-acylcarnitine on NBS in California, Oregon, Washington, and Hawai'i including available confirmatory testing and clinical information. Overall, from 2,802,504 children screened, there were 242 cases screen-positive for VLCADD. There were 34 symptomatic true positive cases, 18 asymptomatic true positives, 112 false positives, 55 heterozygotes, 11 lost to follow-up, and 12 other disorders. One in 11,581 newborns had an abnormal NBS for suspected VLCADD. Comparison of analytes and analyte ratios from the NBS demonstrated statistically significant differences between true positive and false positive groups for C14:1, C14, C14:1/C2, and C14:1/C16. The positive predictive value for all true positive cases was 94%, 54%, and 23% when C14:1 was ≥2.0μM, ≥1.0μM, and ≥0.7μM, respectively. Sequential post-analytical analysis could reduce the referral rate in 25.8% of cases. This study is the largest reported follow-up of infants with NBS screen-positive results for suspected VLCADD and demonstrates the necessity of developing comprehensive and consistent long-term follow-up NBS systems. Application of clinical information revealed differences between symptomatic and asymptomatic children with VLCADD. Comparison of NBS analytes and analyte ratios may be valuable in developing more effective diagnostic algorithms. [Copyright &y& Elsevier]

Cysteamine is approved for the treatment of cystinosis and is being evaluated for Huntington's disease and non-alcoholic fatty liver disease. Little is known about the bioavailability and biodistribution of the drug. The aim was to determine plasma, cerebrospinal fluid ( CSF), and tissue (liver, kidney, muscle) cysteamine levels following intraduodenal delivery of the drug in rats pretreated and naïve to cysteamine and to estimate the hepatic first-pass effect on cysteamine. Healthy male rats ( n = 66) underwent intraduodenal and portal ( PV) or jugular ( JVC) venous catheterization. Half were pretreated with cysteamine, and half were naïve. Following intraduodenal cysteamine (20 mg/kg), serial blood samples were collected from the PV or the JVC. Animals were sacrificed at specific time points, and CSF and tissue were collected. Cysteamine levels were determined in plasma, CSF, and tissue. The Cmax was achieved in 5-10 min from PV and 5-22.5 min from JVC. The PV- Cmax ( P = 0.08), PV- AUC0- t ( P = 0.16), JVC- Cmax ( P = 0.02) and JVC- AUC0- t ( P = 0.03) were higher in naive than in pretreated animals. Plasma cysteamine levels returned to baseline in ≤120 min. The hepatic first-pass effect was estimated at 40%. Peak tissue and CSF cysteamine levels occurred ≤22.5 min, but returned to baseline levels ≤180 min. There was no difference in CSF and tissue cysteamine levels between naïve and pretreated groups, although cysteamine was more rapidly cleared in the pretreated group. Cysteamine is rapidly absorbed from the small intestine, undergoes significant hepatic first-pass metabolism, crosses the blood brain barrier, and is almost undetectable in plasma, CSF, and body tissues 2 h after ingestion. Sustained-release cysteamine may provide prolonged tissue exposure. [ABSTRACT FROM AUTHOR]

Abstract: We collected data on 48 patients from 38 families with guanidinoacetate methyltransferase (GAMT) deficiency. Global developmental delay/intellectual disability (DD/ID) with speech/language delay and behavioral problems as the most affected domains was present in 44 participants, with additional epilepsy present in 35 and movement disorder in 13. Treatment regimens included various combinations/dosages of creatine-monohydrate, l-ornithine, sodium benzoate and protein/arginine restricted diets. The median age at treatment initiation was 25.5 and 39months in patients with mild and moderate DD/ID, respectively, and 11years in patients with severe DD/ID. Increase of cerebral creatine and decrease of plasma/CSF guanidinoacetate levels were achieved by supplementation with creatine-monohydrate combined with high dosages of l-ornithine and/or an arginine-restricted diet (250mg/kg/d l-arginine). Therapy was associated with improvement or stabilization of symptoms in all of the symptomatic cases. The 4 patients treated younger than 9months had normal or almost normal developmental outcomes. One with inconsistent compliance had a borderline IQ at age 8.6years. An observational GAMT database will be essential to identify the best treatment to reduce plasma guanidinoacetate levels and improve long-term outcomes. [Copyright &y& Elsevier]

Abstract: Background: Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is an autosomal recessive inborn error of mitochondrial fatty acid oxidation with highly variable biochemical, genetic, and clinical characteristics. SCADD has been associated with accumulation of butyryl-CoA byproducts, including butyrylcarnitine (C4), butyrylglycine, ethylmalonic acid (EMA), and methylsuccinic acid (MS) in body fluid and tissues. Differences in genotype frequencies have been shown between patients diagnosed clinically versus those diagnosed by newborn screening. Moreover, while patients diagnosed clinically have a variable clinical presentation including developmental delay, ketotic hypoglycemia, epilepsy and behavioral disorders, studies suggest patients diagnosed by newborn screening are largely asymptomatic. Scant information is published about the biochemical, genetic and clinical outcome of SCADD patients diagnosed by newborn screening. Methods: We collected California newborn screening, follow-up biochemical levels, and ACADS mutation data from September, 2005 through April, 2010. We retrospectively reviewed available data on SCADD cases diagnosed by newborn screening for clinical outcomes. Results: During the study period, 2,632,058 newborns were screened and 76 confirmed SCADD cases were identified. No correlations between initial C4 value and follow-up biochemical markers (C4, EMA or MS levels) were found in the 76 cases studied. We found significant correlation between urine EMA versus MS, and correlation between follow-up C4 versus urine EMA. Of 22 cases where ACADS gene sequencing was performed: 7 had two or more deleterious mutations; 8 were compound heterozygotes for a deleterious mutation and common variant; 7 were homozygous for the common variant c.625G>A; and 1 was heterozygous for c.625G>A. Significant increases in mean urine EMA and MS levels were noted in patients with two or more deleterious mutations versus mutation heterozygotes or common polymorphism homozygotes. Clinical outcome data was available in 31 patients with follow-up extending from 0.5 to 60months. None developed epilepsy or behavioral disorders, and three patients had isolated speech delay. Hypoglycemia occurred in two patients, both in the neonatal period. The first patient had concomitant meconium aspiration; the other presented with central apnea, poor feeding, and hypotonia. The latter, a c.625G>A homozygote, has had persistent elevations in both short- and medium-chain acylcarnitines; diagnostic workup in this case is extensive and ongoing. Conclusions: This study examines the largest series to date of SCADD patients identified by newborn screening. Our results suggest that confirmatory tests may be useful to differentiate patients with common variants from those with deleterious mutations. This study also provides evidence to suggest that, even when associated with deleterious mutations, SCADD diagnosed by newborn screening presents largely as a benign condition. [Copyright &y& Elsevier]

We used exome sequencing to identify the genetic basis of combined malonic and methylmalonic aciduria (CMAMMA). We sequenced the exome of an individual with CMAMMA and followed up with sequencing of eight additional affected individuals (cases). This included one individual who was identified and diagnosed by searching an exome database. We identify mutations in ACSF3, encoding a putative methylmalonyl-CoA and malonyl-CoA synthetase as a cause of CMAMMA. We also examined a canine model of CMAMMA, which showed pathogenic mutations in a predicted ACSF3 ortholog. ACSF3 mutant alleles occur with a minor allele frequency of 0.0058 in ?1,000 control individuals, predicting a CMAMMA population incidence of ?1:30,000. ACSF3 deficiency is the first human disorder identified as caused by mutations in a gene encoding a member of the acyl-CoA synthetase family, a diverse group of evolutionarily conserved proteins, and may emerge as one of the more common human metabolic disorders. [ABSTRACT FROM AUTHOR]

Abstract: Methylcrotonylglycinuria (MCG) is an inborn error of leucine catabolism and has a recessive pattern of inheritance that results from the deficiency of 3-methylcrotonyl-CoA carboxylase (MCC). The clinical phenotypes are highly variable ranging from neonatal onset with severe neurological involvement to asymptomatic adults. Here we identified two novel MCCA (exon 3: c.137G>A; p.46G>E), (IVS7-1G>A splice site mutation), and four novel MCCB (exon 11: c.1065A>T; p.355L>F), (exon 15: c.1430A>G; p.477Q>R), (exon 16: c.1549G>A; p.517G>R), (exon 16: c.1559A>C; p.520Y>S) mutant alleles from five MCC-deficient patients. [ABSTRACT FROM AUTHOR]

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Cysteamine bitartrate is taken lifelong, every 6 h and for the treatment of cystinosis. Recent studies using cysteamine for for other diseases such as neurodegenerative disorders adopt the same dosing regimen for cysteamine. Regular cysteamine bitartrate (Cystagon) may cause upper gastrointestinal symptoms in some patients. WHAT THIS STUDY ADDS • This is the only study that provides pharmacokinetic data for cysteamine delivered in an enteric-release preparation in normal subjects. EC-cysteamine is very well tolerated and does not cause increased gastrin concentrations, even at relatively high doses. • EC-cysteamine at the higher dose results in better drug uptake as measured by Cmax and AUC and is more likely to be effective. AIMS Cysteamine bitartrate (Cystagon®) is the approved treatment for cystinosis. Poor compliance and patient outcome may occur because the drug needs to be taken every 6 h and in some patients causes gastrointestinal symptoms due to hypergastrinaemia. A formulation of cysteamine requiring twice daily ingestion would improve the quality of life for these patients. This study compares the pharmacokinetics and gastrin production following cysteamine bitartrate non-enteric-coated and cysteamine bitartrate enteric-coated in normal healthy subjects. METHODS Enteric-coated cysteamine was prepared. Following single doses of cysteamine bitartrate non-enteric-coated 450 mg and cysteamine bitartrate enteric-coated 450 mg and 900 mg, serial plasma cysteamine and gastrin concentrations were measured. Two subjects also received cysteamine bitartrate non-enteric-coated 900 mg. Gastrointestinal (GI) symptoms were recorded. RESULTS Six healthy adults (mean age 20.7 years, range 18–24 years; mean weight 59.3 kg) received drug. All post-dose gastrin concentrations were within the normal range (<100 pg ml–1). The tmax following cysteamine bitartrate non-enteric-coated (mean and SD is 75 ± 19 min) was shorter than cysteamine bitartrate enteric-coated (220 ± 74 min) ( P= 0.001), but only the Cmax and AUC estimates following 900 mg cysteamine bitartrate enteric-coated were significantly greater than any of the other preparations or doses ( P < 0.05). One patient had GI symptoms following both 900 mg cysteamine bitartrate non-enteric-coated and cysteamine bitartrate enteric-coated. CONCLUSION Although patient numbers were low, single high doses of cysteamine bitartrate enteric-coated were better tolerated than similar doses of cysteamine bitartrate non-enteric-coated in the healthy subjects and all had normal gastrin concentrations. The delayed tmax following cysteamine bitartrate enteric-coated suggested that the cysteamine was released enterically. [ABSTRACT FROM AUTHOR]

Abstract: We investigated in a patient with holocarboxylase synthetase deficiency, the relation between the biochemical and genetic factors of the mutant protein with the pharmacokinetic factors of successful biotin treatment. A girl exhibited abnormal skin at birth, and developed in the first days of life neonatal respiratory distress syndrome and metabolic abnormalities diagnostic of multiple carboxylase deficiency. Enzyme assays showed low carboxylase activities. Fibroblast analysis showed poor incorporation of biotin into the carboxylases, and low transfer of biotin by the holocarboxylase synthetase enzyme. Kinetic studies identified an increased Km but a preserved Vmax. Mutation analysis showed the child to be a compound heterozygote for a new nonsense mutation Q379X and for a novel missense mutation Y663H. This mutation affects a conserved amino acid, which is located the most 3′ of all recorded missense mutations thus far described, and extends the region of functional biotin interaction. Treatment with biotin 100mg/day gradually improved the biochemical abnormalities in blood and in cerebrospinal fluid (CSF), corrected the carboxylase enzyme activities, and provided clinical stability and a normal neurodevelopmental outcome. Plasma concentrations of biotin were increased to more than 500nM, thus exceeding the increased Km of the mutant enzyme. At these pharmacological concentrations, the CSF biotin concentration was half the concentration in blood. Measuring these pharmacokinetic variables can aid in optimizing treatment, as individual tailoring of dosing to the needs of the mutation may be required. [Copyright &y& Elsevier]

Abstract: 3-MCC deficiency is among the most common inborn errors of metabolism identified on expanded newborn screening (1:36,000 births). However, evidence-based guidelines for diagnosis and management of this disorder are lacking. Using the traditional Delphi method, a panel of 15 experts in inborn errors of metabolism was convened to develop consensus-based clinical practice guidelines for the diagnosis and management of 3-MCC screen-positive infants and their mothers. The Oxford Centre for Evidence-based Medicine system was used to grade the literature review and create recommendations graded from A (evidence level of randomized clinical trials) to D (expert opinion). Panelists reviewed the initial evaluation of the screen-positive infant–mother dyad, diagnostic guidelines, and management of diagnosed patients. Grade D consensus recommendations were made in each of these three areas. The panel did not reach consensus on all issues. This consensus protocol is intended to assist clinicians in the diagnosis and management of screen-positive newborns for 3-MCC deficiency and to encourage the development of evidence-based guidelines. [Copyright &y& Elsevier]

The ‘classical’ organic anion secretory pathway of the renal proximal tubule is critical for the renal excretion of the prototypic organic anion, para-aminohippurate, as well as of a large number of commonly prescribed drugs among other significant substrates. Organic anion transporter 1 (OAT1), originally identified as NKT (Lopez-Nieto, C. E., You, G., Bush, K. T., Barros, E. J. G., Beier, D. R., and Nigam, S. K. (1997) J. Biol. Chem. 272, 6471–6478), has physiological properties consistent with a role in this pathway. However, several other transporters (e.g. OAT2, OAT3, and MRP1) have also been proposed as important PAH transporters on the basis of in vitro studies; therefore, the relative contribution of OAT1 has remained unclear. We have now generated a colony of OAT1 knockout mice, permitting elucidation of the role of OAT1 in the context of these other potentially functionally redundant transporters. We find that the knock-out mice manifest a profound loss of organic anion transport (e.g. para-aminohippurate) both ex vivo (in isolated renal slices) as well as in vivo (as indicated by loss of renal secretion). In the case of the organic anion, furosemide, loss of renal secretion in the knock-out results in impaired diuretic responsiveness to this drug. These results indicate a critical role for OAT1 in the functioning of the classical pathway. In addition, we have determined the levels of ∼60 endogenous organic anions in the plasma and urine of wild-type and knock-out mice. This has led to identification of several compounds with significantly higher plasma concentrations and/or lower urinary concentrations in knock-out mice, suggesting the involvement of OAT1 in their renal secretion. We have also demonstrated in xenopus oocytes that some of these compounds interact with OAT1 in vitro. Thus, these latter compounds might represent physiological substrates of OAT1. [ABSTRACT FROM AUTHOR]

Objective. Carnitine is thought to be a conditionally essential biological cofactor for premature infants. A preliminary study suggested that carnitine could significantly reduce apnea of prematurity. The objective of this study was to evaluate critically the role of carnitine in idiopathic apnea of prematurity and to determine whether the use of carnitine would facilitate discontinuation of mechanical ventilatory support, shorten the duration of ventilatory support, and reduce the amount of time that such infants are exposed to both mechanical ventilation and oxygen. We also wanted to determine the effects of supplemental carnitine on weight gain, time to regain birth weight, time to achieve full enteral feedings, and length of hospital stay. Methods. A prospective, randomized, blinded trial was conducted on 44 preterm infants who were from the same neonatal intensive care unit and who were ≤32 weeks' gestational age with a postnatal age <48 hours and a birth weight <1500 g and required total parenteral nutrition (TPN). Infants were randomized to receive carnitine supplementation or placebo without crossover. Carnitine-supplemented infants received 30 mg/kg/d carnitine in their TPN until the they were tolerating 120 mL/kg/d enteral feedings, and then they received 30 mg/kg/d oral carnitine. The placebo group received TPN without supplemental carnitine; when they tolerated 120 mL/kg/d enteral feedings, they received an oral placebo. The 2 groups continued on their respective supplemental carnitine or placebo until 34 weeks' adjusted age, at which time the study period was completed. Twelve-hour cardiorespiratorygrams to record heart rate, respiratory impedance, and oxygen saturation, and a nasal thermistor to detect expiratory airflow were performed every 4 days on 3 occasions and at 30 and 34 weeks' adjusted age. Plasma carnitine levels were measured at day 14. Results. There were no significant differences between the 2 groups in the occurrence of... [ABSTRACT FROM AUTHOR]

Abstract: Guanidinoacetate methyltransferase (GAMT) deficiency is a good candidate disorder for newborn screening because early treatment appears to improve outcomes. We report elevation of guanidinoacetate in archived newborn dried blood spots for 3 cases (2 families) of GAMT deficiency compared with an unaffected carrier and controls. We also report a new case of a patient treated from birth with normal developmental outcome at the age of 42months. [Copyright &y& Elsevier]

Abstract: We describe a 45-year-old patient who was diagnosed with propionic acidemia in infancy, who experienced an unstable first two years of life but who eventually had a good developmental outcome. She developed severe renal failure requiring renal transplantation in her forties and premature ovarian failure. Renal failure and premature ovarian failure have not previously been associated with propionic acidemia. We hypothesize that propionic acidemia may have contributed to these complications, and discuss several possible mechanisms for this, emphasizing mainly the electron transport chain/mitochondrial energy deficiency hypothesis. [Copyright &y& Elsevier]

A letter to the editor is presented in response to the article "Time Before Isolating Cystinotic Leukocytes Affects Reliability of Cystine Determination," by Meredith C. Fidler and colleagues in the April 25, 2009 issue.