Adolf Mühl

Campus Vienna Biocenter (CVBC), Wien, Vienna, Austria

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Publications (59)199.66 Total impact

  • No preview · Article · Feb 2014 · Molecular Genetics and Metabolism
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    ABSTRACT: Niemann Pick disease (NP) is a rare, lysosomal storage disorder due to deficiency of the intra-lysosomal enzyme acid sphingomyelinase (ASM) resulting in intracellular accumulation of sphingomyelin. We evaluated a tandem mass spectrometry (MS/MS) method to analyze ASM activity in dried blood spots (DBS) that may be suitable for laboratory diagnosis of NP including high throughput screening of at-risk populations and potentially for newborn screening. ASM activity was measured in 3.2 mm punches from DBS. The eluate was incubated with the ASM substrate (N-Hexanoyl-D-erythro-sphingosylphosphorylcholine [C6-sphingomyelin (C(29)H(59)N(2)O(6)P)]) and an internal standard (N-butyroyl-D-erythro-sphingosine [C4-ceramide (C(22)H(43)NO(3))]). ASM product and IS were analyzed using MS/MS in multiple reaction monitoring mode for transitions m/z 370.6>264.3 (ASM internal standard) and m/z 398.6>264.3 (ASM product). ASM activities were stable for up to 2 months at or below 4℃. Position of the punch in the DBS and/or hematocrit of the DBS had a limited effect on ASM activities. Both intra- and inter-assay variability were below 10%. There was no carry-over. The median ASM activity in 2,085 newborn infants was 9.5 µmol/h/L (mean 10.6) with a SD of 5.06 µmol/h/L. Six of 2,085 (0.3%) infants were found to have ASM activities below the cut-off of 2.5 µmol/h/L. ASM activities were below the cut-off level in all 10 previously diagnosed cases with NP (range: 0.16 to 2.08 µmol/h/L). This MS/MS method for the measurement of ASM activity in DBS is robust and suitable for laboratory diagnosis of NP.
    Full-text · Article · Sep 2012 · Annals of Laboratory Medicine
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    ABSTRACT: Free asymmetric dimethylarginine (ADMA) is a competitive inhibitor of the nitric oxide synthases (NOS). Suppression of nitric oxide (NO) synthesis increases the risk of atherosclerosis. Nevertheless, in the condition of oxidative stress, NOS blockade by ADMA may exert protective effects. Protein metabolism is altered in patients with phenylketonuria (PKU) on dietary treatment and as shown recently, oxidative stress is high in PKU. Since free ADMA concentrations are determined by both protein metabolism and oxidative stress we hypothesized, that free ADMA levels may be elevated in PKU patients. Sixteen patientswith PKU on dietary treatment (mean age 10.1 ± 5.2 yrs), and 91 healthy children (mean age 11.6 ± 3.7 yrs) participated in a cross sectional study. ADMA, total homocysteine (tHcy) and blood glucose were lower and the L-arginine/ADMA ratio was higher in PKU patients compared to controls. No significant correlation was present between phenylalanine (Phe) concentrations, protein intake, and lipid profile, history of cardiovascular disease or ADMA. In contrast to our hypothesis, ADMAwas lower and the L-arginine/ADMA ratio was higher in PKU patients. Therefore, in PKU patients, the regulating function of ADMA on NO synthesis is altered and may thus contribute to oxidative stress.
    Full-text · Article · Jan 2012 · Journal of Inherited Metabolic Disease
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    ABSTRACT: Even though lysosomal storage disorders (LSDs) are considered to be orphan diseases, they pose a highly relevant cause for morbidity and mortality as their cumulative prevalence is estimated to be 1:4,000. This is especially important as treatment in form of enzyme replacement therapy, substrate reduction therapy or stem cell transplantation is amenable for some LSDs. It is plausible that an early start of treatment might improve the overall prognosis and, even more important, prevent irreversible damage of key organs. To get a more precise insight into the real frequency of some LSDs in the general population, we screened 40,024 samples from the Hungarian newborn screening (NBS) program in Szeged for Fabry disease (FD), Gaucher disease (GD), Pompe disease (PD), and Niemann-Pick A/B (NPB) disease using tandem mass spectrometry. Altogether, 663 samples (1.66%) were submitted for retesting. Genetic confirmation was carried out for 120 samples with abnormal screening results after retesting, which identified three cases of GD, three cases of FD, nine cases of PD, and two cases with NPB. In some cases, we detected up to now unknown mutations - one in NPB and seven in PD - which raise questions about the clinical consequences of a NBS in the sense of late-onset manifestations. Overall, we conclude that screening for LSDs by tandem MS/MS followed by a genetic workup in identified patients is a robust, easy, valid, and feasible technology in newborn screening programs. Furthermore, early diagnosis of LSDs gives a chance to early treatment, but needs more clinical long-term data especially regarding the consequence of private mutations.
    No preview · Article · Jan 2012
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    Full-text · Article · Nov 2011 · Clinica Chimica Acta
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    ABSTRACT: Dried blood spot (DBS) methods are currently available for identification of a range of lysosomal storage disorders (LSDs). These disorders are generally characterized by a deficiency of activity of a lysosomal enzyme and by a broad spectrum of phenotypes. Diagnosis of LSD patients is often delayed, which is of particular concern as therapeutic outcomes (e.g. enzyme replacement therapy) are generally more favorable in early disease stages. Experts in the field of LSDs diagnostics and screening programs convened and reviewed experiences with the use of DBS methods, and discuss the diagnostic challenges, possible applications and quality programs in this paper. Given the easy sampling and shipping and stability of samples, DBS has evident advantages over other laboratory methods and can be particularly helpful in the early identification of affected LSD patients through neonatal screening, high-risk population screening or family screening.
    Full-text · Article · Jul 2011 · Molecular Genetics and Metabolism
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    ABSTRACT: To evaluate the effects of creatine monohydrate (CMH) supplementation on global DNA methylation and disease-specific clinical symptoms in female patients with Rett syndrome (RTT). Double-blind, randomized, placebo-controlled crossover trial of female patients with RTT. Participants received 200 mg/kg of either CMH or placebo daily for 6 months and switched following a 4-week washout period. Primary endpoints were change in global DNA methylation and in a RTT-specific symptom score as defined by medical history and clinical evaluation with Rett Syndrome Motor and Behavioral Assessment. Secondary endpoints were changes in biochemical markers of methionine metabolism. Eighteen female patients aged 3 to 25 years with clinically diagnosed typical RTT and MECP2 mutation at clinical Stages III or IV were studied. CMH supplementation resulted in a statistically significant increase of global methylation by 0.11 (95% confidence interval 0.03-0.19, p = .009) compared with placebo. Total and subscores of Rett Syndrome Motor and Behavioral Assessment tended to improve but without statistical significance. CMH supplementation increases global DNA methylation statistically significantly. Scores were lower for creatine than for placebo reflecting clinical improvement but not reaching statistical significance. Biochemical variables of methionine-homocysteine remethylation are unaffected. Multicenter studies are urgently warranted to evaluate the long-term effects of CMH supplementation in an optimally homogenous RTT population over a prolonged period.
    Full-text · Article · Jul 2011 · Journal of developmental and behavioral pediatrics: JDBP
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    ABSTRACT: Although high levels of asymmetric dimethylarginine (ADMA) are associated with an increased risk for vasculopathy in adults, elevated ADMA concentrations also have been found in healthy young children. Patients with diabetes mellitus type 1 (DM1) are at risk for vasculopathy, and because the function of ADMA in the development of vascular symptoms is incompletely understood, we investigated ADMA concentrations in pediatric patients with DM1 compared with healthy age- and sex-matched individuals. This cross-sectional study included 85 pediatric patients with DM1 and 89 age- and sex-matched healthy controls. ADMA concentrations were significantly lower in the patients with DM1 and were inversely correlated with hemoglobin A1c concentrations. Besides its vasoprotective function, nitric oxide itself may exert oxidative stress by generating free radicals. In these circumstances, ADMA would protect the system from nitric oxide overproduction and perpetuation of oxidative stress. This theory is supported by the physiologically higher ADMA concentrations in healthy children. Thus, low ADMA concentrations in children with DM1 may be an indicator of impaired protection against oxidative stress.
    No preview · Article · Nov 2010 · The Journal of pediatrics
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    ABSTRACT: Gaucher disease (GD) is due to deficiency of acid-β-glucosidase (ABG) and comprises a clinical spectrum with variable age of onset and severity. We evaluated a tandem mass spectrometry (MS/MS) method to measure ABG activity for high through-put screening. ABG activity was measured in 3.2 mm punches from dry blood spots (DBS). Each punch was incubated for 21 h with the substrate D-Glucosyl-β1-1'-N-dodecanoyl-D-erythro-sphingosine [C12-glucocerebroside (C(36)H(69)NO(8))] and internal standard N-myristoyl-D-erythro-sphingosine [C14-ceramide (C(32)H(63)NO(3))]. The product and internal standard were quantified using MS/MS. ABG activities in anonymized newborn screening samples from NY State were (mean) 22.0 μmol/h/L±(SD) 13.8 μmol/h/L (n=2088, median 19.9 μmol/h/L, 95%CI 22.59-21.41 μmol/h/L). The enzymatic activity in DBS from 10 treatment naïve adult Gaucher patients was less than 4.2 μmol/h/L. ABG activity was stable for 3 months at room temperature a 20% activity reduction was observed. Inter- and intra-run imprecisions were 8% and 13.7%, respectively. The limit of detection was 0.75 μmol/h/L and limit of quantification was 1.25 μmol/h/L. The measurement of ABG activities in DBS using MS/MS is suitable for high-throughput analysis of at-risk individuals and potentially for newborn screening for GD.
    No preview · Article · Nov 2010 · Clinica chimica acta; international journal of clinical chemistry
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    ABSTRACT: Biotinidase deficiency (BD) is an autosomal recessive disorder of biotin metabolism that causes incomplete recycling of free biotin. The resulting depletion of intracellular biotin leads to impaired activities of biotin-dependent carboxylases. The ensuing clinical phenotype includes progressive neurologic deterioration with epileptic seizures, muscular hypotonia as well as skin eczema. BD may be readily diagnosed by analysing enzyme activity in dried blood spots during newborn screening but typically requires molecular confirmation. More than 100 different mutations in the biotinidase gene have been reported to date. To simplify molecular testing we have developed a rapid and accurate denaturing high pressure liquid chromatography (dHPLC) method of the promoter, 3'UTR, all exons including exon/intron boundaries as a first line screen followed by direct sequencing of the respective PCR products. To validate this method we used DNA from 23 different, newly diagnosed patients with biochemically proven BD from Austria, India, Morocco and Spain. A total of 11 mutations, missense 7, frameshift 3 and 1 nonsense, were screened. Six mutations were novel to this study. All mutations revealed distinct dHPLC pattern thus enabling their accurate detection. This study revealed that dHPLC method is robust, automated, economical and above all highly sensitive for the molecular analysis of biotinidase gene and should be used as a pre-analytical tool followed by sequencing of aberrant heteroduplex forming amplicons.
    Full-text · Article · May 2010 · Molecular Genetics and Metabolism
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    ABSTRACT: Fabry disease (FD) is an X-linked lysosomal storage disorder caused by the deficiency of alpha-galactosidase A (GLA). We evaluated a tandem mass spectrometry method to measure GLA activity. One 3.2mm punch from a dried blood spot sample (DBS) was incubated with substrate and internal standard in the reaction buffer for 22 h. The resulting product was quantified against internal standard using MS/MS. The median GLA activity of male newborn DBS (N=5025) was 9.85 + or - 6.4 micromol/h/l (CI 95% is 9.67-10.02 micromol/h/l); The median GLA activity of female newborns (N=4677) was 10.2 + or - 6.3 micromol/h/l (CI 95% is 10.02-10.38 micromol/h/l). The difference between the two subgroups is within assay analytical variation. The GLA activities in the DBS samples from 9 juvenile and adult males with previously identified FD were below 1.64 micromol/h/l. The GLA activities from 32 juvenile and adult females with confirmed FD were below 4.73 micromol/h/l. In 5 (16%) females GLA activities were above the 0.5th percentile of lower limit of CI 95% at 3.18 micromol/h/l. The MS/MS method for Fabry disease newborn screening is robust and can be readily multiplexed with other lysosomal disorders such as Pompe, Gaucher, Niemann-Pick, and Krabbe diseases.
    No preview · Article · Mar 2010 · Clinica chimica acta; international journal of clinical chemistry

  • No preview · Article · Mar 2010 · Clinica chimica acta; international journal of clinical chemistry
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    ABSTRACT: Twenty-three patients with late onset argininosuccinate lyase deficiency (ASLD) were identified during a 27-year period of newborn screening in Austria (1:95,600, 95% CI=1:68,036-1:162,531). One additional patient was identified outside the newborn screening with neonatal hyperammonemia. Long-term outcome data were available in 17 patients (median age 13 years) ascertained by newborn screening. Patients were treated with protein restricted diet and oral arginine supplementation during infancy and childhood. IQ was average/above average in 11 (65%), low average in 5 (29%), and in the mild intellectual disability range in 1 (6%) patients. Four patients had an abnormal EEG without evidence of clinical seizures and three had abnormal liver function tests and/or evidence of hepatic steatosis. Plasma citrulline levels were elevated in four patients. Plasma ammonia levels were within normal range prior and after a protein load in all patients. Seven different mutations were identified in the 16 alleles investigated. Four mutations were novel (p.E189G, p.R168C, p.R126P, and p.D423H). All mutations were associated with low argininosuccinate lyase activities (0-15%) in red blood cells. Newborn screening might be beneficial in the prevention of chronic neurologic and intellectual sequelae in late onset ASLD, but a proportion of benign variants might have contributed to the overall favorable outcome as well.
    No preview · Article · Feb 2010 · Molecular Genetics and Metabolism
  • O.A. Bodamer · A. Dajnoki · C. Hung · G. Fekete · A. Mühl
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    ABSTRACT: Lysosomal storage disorders are a heterogeneous group of more than 50 disorders of lysosomal metabolism, that are characterised through a progressive clinical course and multi-organ involvement. Enzyme replacement therapy is available for some disorders where the defective enzyme is replaced through an intravenous infusion of the respective, recombinant enzyme. Early diagnosis, preferably when the patient is still oligosymptomatic and prompt initation of enzyme replacement therapy may have the potential to reduce long-term morbidity and mortality. Newborn screening for lysosomal storage disorders may use tandem mass spectrometry, immune capture or flurometric techniques respectively, although our group has the largest experience with the use of tandem mass spectrometry for enzyme analysis in lysosomal storage disorders. In fact we have been able to adapt and validate the tandem mass spectrometry technique for detection of POMPE and FABRY diseases in newborn infants. However, prior to implementation of newborn screening programmes for lysosomal storage disorders national and international guidelines for confirmatory testing and follow up management of affected infants have to be agreed upon.
    No preview · Article · Aug 2009 · Padiatrische Praxis
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    ABSTRACT: Transcobalamin II deficiency (# MIM 275350) is a rare, recessively inherited disorder of cobalamin transport that leads to intracellular cobalamin depletion with secondary impairment of methionine synthetase and methyl-malonyl CoA mutase activities. Affected individuals may suffer from long-term neurological sequelae if therapy with intramuscular hydroxocobalamin is not initiated promptly. We report two sisters with complete absence of transcobalamin due to homozygosity for a novel mutation (c.insC110) in the TCN2 gene that leads to a premature stop codon and non-functional protein. The older sister, now 4.5 years old, presented at 6 weeks of age with pancytopenia, protein losing enteropathy and a rapidly declining clinical course. Prompt therapy with 1mg hydroxocobalamin/day led to full recovery within days. Her now 1.5 year old sister was diagnosed shortly after birth and was started on hydroxocobalamin prior to onset of clinical symptoms. Interestingly, urinary methylmalonic acid excretion was increased significantly during the first days of life suggesting that functional cobalamin deficiency is present also during fetal life, although not giving rise to clinical symptoms until well after birth.
    No preview · Article · Jul 2009 · Molecular Genetics and Metabolism
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    Full-text · Article · Apr 2009 · Neurology
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    ABSTRACT: High urinary creatine to creatinine ratio (U-CrCrtR) is a potential diagnostic marker of X-linked creatine transporter (SLC6A8) deficiency. We developed a tandem mass-spectrometry method to simultaneously determine urinary creatine and creatinine in 975 individuals (0-18 years). U-CrCrtR increased up to 8 years and decreased thereafter. U-CrCrtR was 2.29 and 2.12 (99th percentile: 1.87) in two males with subsequently confirmed SLC6A8 mutations. The frequency of SLC6A8 deficiency was 2.3% in 157 males at risk.
    No preview · Article · Feb 2009 · Molecular Genetics and Metabolism

  • No preview · Article · Dec 2008 · Clinical Therapeutics
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    ABSTRACT: Lysosomal storage disorders (LSDs) comprise more than 40 genetic diseases that result in the accumulation of products that would normally be degraded by lysosomal enzymes. A tandem mass spectrometry (MS/MS)-based method is available for newborn screening for 5 LSDs, and many laboratories are initiating pilot studies to evaluate the incorporation of this method into their screening panels. We developed and evaluated dried blood spot (DBS) QC materials for LSDs and used the MS/MS method to investigate their suitability for LSD QC monitoring. We incubated 3.2-mm punches from DBS controls for 20-24 h with assay cocktails containing substrate and internal standard. Using MS/MS, we quantified the resulting product and internal standard. Samples were run in triplicate for 3 consecutive days, and results were reported as product-to-internal standard ratios and enzyme activity units (micromol/L/h). Enzyme activity interday imprecision (CV) for the high, medium, and low series were 3.4%-14.3% for galactocerebroside alpha-galactosidase, 6.8%-24.6% for acid alpha-galactosidase A, 7.36%-22.1% for acid sphingomyelinase, 6.2%-26.2% for acid alpha-glucocerebrosidase, and 7.0%-24.8% for lysosomal acid alpha-glucosidase (n = 9). In addition, DBS stored at -20 degrees and 4 degrees C showed minimal enzyme activity loss over a 187-d period. DBS stored at 37 degrees and 45 degrees C had lower activity values over the 187-day evaluation time. Suitable QC materials for newborn screening of LSDs were developed for laboratories performing DBS LSD screening. Good material linearity was observed, with goodness-of-fit values of 0.953 and higher. The QC materials may be used by screening laboratories that perform LSD analysis by MS and/or more conventional fluorescence-based screening methods.
    No preview · Article · Dec 2008 · Clinical Chemistry
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    ABSTRACT: The aim of this study was to establish a stand-alone, perfused, rotary cell culture system using small human hepatocytes (SH) for bioartificial liver (BAL) support. SH were grown on cytodex 3 microcarriers (beads) to a maximum density of 1.2 +/- 0.3 x 10(7) cells per mL within 12 days. Size of aggregates formed by up to 15 beads was regulated by rotation speed. Cell function was proven by treatment with ammonia and galactose, and metabolism was analyzed. Treatment strategy was comprised of two phases, namely growth phase and treatment phase. Cells were grown for 6 days and subsequently incubated with ammonia or galactose for 2 days, followed by a 2-day regeneration period and another 2-day treatment phase. Consumption of glucose, release of lactate dehydrogenase, formation of lactate, and production of urea and albumin were determined regularly. Mean galactose consumption was 50 microg per 106 cells per hour, ammonia-induced urea formation was 3.6 microg per 106 cells per hour, and albumin production was 110 ng per 106 cells per hour. All metabolic parameters followed a logarithmic trend and were found to be very stable in the second half of the culture period when cells were treated with ammonia or galactose. Dissolved oxygen (%DO), pH, and temperature were monitored in-stream at intervals of 7 min, and the values were logged. Viability and morphology of cells were monitored via confocal microscopy. Viability was around 95% in controls and 90% during treatment. Promising results were obtained in support of our ongoing efforts to establish a fully autonomous BAL support device utilizing SH as a bridge to transplantation.
    No preview · Article · Nov 2008 · Tissue Engineering Part A

Publication Stats

1k Citations
199.66 Total Impact Points


  • 2012
    • Campus Vienna Biocenter (CVBC)
      Wien, Vienna, Austria
  • 2000-2011
    • Medical University of Vienna
      • • Department of Paediatrics and Adolescent Medicine
      • • Department of Obstetrics and Gynecology
      Wien, Vienna, Austria
  • 2010
    • IST Austria
      Klosterneuberg, Lower Austria, Austria
  • 2005-2010
    • University of Iowa Children's Hospital
      Iowa City, Iowa, United States
  • 1995-2009
    • University of Vienna
      • Department of Medicinal Chemistry
      Wien, Vienna, Austria
  • 2008
    • University of Szeged
      • Faculty of Medicine
      Algyő, Csongrád, Hungary
  • 2001-2007
    • Vienna General Hospital
      Wien, Vienna, Austria
  • 1996
    • Children´s Hospital Association
      Overland Park, Kansas, United States