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A A Roscher

Publications and source records attributed to A A Roscher.

At least 19 recordsLinked to original sources
PubMed2004

Supervised machine learning techniques for the classification of metabolic disorders in newborns.

MOTIVATION: During the Bavarian newborn screening programme all newborns have been tested for about 20 inherited metabolic disorders. Owing to the amount and complexity of the generated experimental data, machine learning techniques provide a promising approach to investigate novel patterns in high-dimensional metabolic data which form the source for constructing classification rules with high discriminatory power. RESULTS: Six machine learning techniques have been investigated for their classification accuracy focusing on two metabolic disorders, phenylketo nuria (PKU) and medium-chain acyl-CoA dehydrogenase deficiency (MCADD). Logistic regression analysis led to superior classification rules (sensitivity >96.8%, specificity >99.98%) compared to all investigated algorithms. Including novel constellations of metabolites into the models, the positive predictive value could be strongly increased (PKU 71.9% versus 16.2%, MCADD 88.4% versus 54.6% compared to the established diagnostic markers). Our results clearly prove that the mined data confirm the known and indicate some novel metabolic patterns which may contribute to a better understanding of newborn metabolism.

Algorithms↗
PubMed2004

Alpha1 antitrypsin and the prevalence and severity of asthma.

In a random sample of children (aged 9-11 years; n = 5629), who were studied according to the ISAAC phase II protocol, heterozygosity of the alpha1 antitrypsin (alpha1-AT) Pi genotypes MS or MZ, or low alpha1-AT plasma levels, were not associated with an increased risk of developing asthma. Asthmatics with low levels of alpha1-AT were particularly prone to develop airway hyperresponsiveness and reduced lung function.

Asthma↗
PubMed2002

Analysis of the two common alpha-1-antitrypsin deficiency alleles PiMS and PiMZ as modifiers of Pseudomonas aeruginosa susceptibility in cystic fibrosis.

Lung disease is the direct cause of death in more than 90% of cystic fibrosis (CF) patients. Proteinase-antiproteinase imbalances are common in CF and alpha-1-antitrypsin (AAT) deficiency. We investigated the hypothesis that the AAT deficiency alleles PiS and PiZ contribute to pulmonary prognosis in CF. Two hundred and sixty-nine CF patients from Southern Germany were included in this study. The serum concentrations of AAT and C-reactive protein (CRP) were determined by nephelometry, and patients were screened by polymerase chain reaction (PCR) and restriction enzyme digest for the common AAT deficiency alleles PiS and PiZ. The onset of chronic bacterial colonization by Pseudomonas aeruginosa (Pae) was correlated with the AAT phenotypes PiMM, PiMS and PiMZ. Only three out of nine CF patients (33%) diagnosed with either PiMS or PiMZ had developed chronic Pae lung infection earlier in their lives. The remaining six patients showing a PiMS or PiMZ phenotype showed a later onset of chronic Pae lung infection. Our results indicate that PiMS and PiMZ are not associated with worse pulmonary prognosis in CF. These data need to be confirmed in studies with a much larger number of cases.

Alleles↗
PubMed2002

Lung function of school children with low levels of alpha1-antitrypsin and tobacco smoke exposure.

Exposure to environmental tobacco smoke (ETS) and other air pollutants has been associated with small decrements in lung function. The susceptibility to pollution exposure may, however, vary substantially between individuals. Children with an impaired protease-antiprotease balance may be particularly vulnerable. Therefore this study aimed to investigate the effects of ETS exposure on children with reduced levels of alpha1-antitrypsin (alpha1-AT). Random samples of school children (aged 9-11 yrs) (n=3,526) were studied according to the International Study of Asthma and Allergies in Childhood (ISAAC) phase II protocol, including parental questionnaires, pulmonary function and allergy testing. Blood samples were obtained to measure plasma levels of alpha1-AT and to genotype for pleomorphic protein inhibitor (Pi)Z and PiS alleles. Children with low levels of alpha1-AT (< or = 116 mg x dL(-1)) showed significant, albeit small decrements in baseline lung function. When exposed to ETS, pronounced decrements of pulmonary function, particularly in measures of mid- to end-expiratory flow rates, were seen in these children as compared to exposed children with normal levels of alpha1-AT. The mean levels of % predicted+/-SE in both groups were: maximum expiratory flow at 50% of vital capacity 79.4+/-7.2 versus 99.0+/-1.5, maximum expiratory flow at 25% of vital capacity 67.4+/-10.0 versus 100.3+/-2.1, maximal midexpiratory flow 73.7+/-8.6 versus 99.9+/-1.7. These findings suggest that school children with low levels of alpha1-antitrypsin are at risk of developing pronounced decrements in pulmonary function, particularly if they are exposed to environmental tobacco smoke. Parents of children with heterozygous alpha1-antitrypsin deficiency resulting in significantly reduced blood concentrations should be advised to prevent their children from being exposed to environmental tobacco smoke and dissuade them from taking up smoking.

Child↗
PubMed2001

Fish oil supplementation improves visual evoked potentials in children with phenylketonuria.

Visual evoked potentials (VEP) were measured in 36 patients with early-treated phenylketonuria (PKU; aged 1 to 11 years) and good metabolic control before and after supplementation with omega-3 long-chain polyunsaturated fatty acids (LC-PUFA) from fish oil. Patients with PKU had significantly longer P100 latencies than 22 age-matched control subjects. After 3 months of LC-PUFA supplementation, VEP latencies improved significantly in PKU patients but did not change in 12 untreated healthy children. The authors conclude that omega-3 LC-PUFA are essential substrates for nervous system function even beyond infancy.

Child↗
PubMed2001

Cloning of the human MCCA and MCCB genes and mutations therein reveal the molecular cause of 3-methylcrotonyl-CoA: carboxylase deficiency.

3-Methylcrotonyl-CoA: carboxylase (EC 6.4.1.4; MCC) deficiency is an inborn error of the leucine degradation pathway (MIM *210200) characterized by increased urinary excretion of 3-hydroxyisovaleric acid and 3-methylcrotonylglycine. The clinical phenotypes are highly variable ranging from asymptomatic to profound metabolic acidosis and death in infancy. Sequence similarity with Glycine max and Arabidopsis thaliana genes encoding the two subunits of MCC permitted us to clone the cDNAs encoding the alpha- and beta-subunits of human MCC. The 2580 bp MCCA cDNA encodes the 725 amino acid biotin-containing alpha-subunit. The MCCA gene is located on chromosome 3q26-q28 and consists of 19 exons. The 2304 bp MCCB cDNA encodes the non-biotin-containing beta-subunit of 563 amino acids. The MCCB gene is located on chromosome 5q13 and consists of 17 exons. We have sequenced both genes in four patients with isolated biotin-unresponsive deficiency of MCC. In two of them we found mutations in the MCCA gene. Compound heterozygosity for a missense mutation (S535F) and a nonsense mutation (V694X) were identified in one patient. One heterozygous mutation (S535F) was found in another patient. The remaining two patients had mutations in the MCCB gene. One consanguineous patient was homozygous for a missense mutation (R268T). In the other we identified a missense mutation in one allele (E99Q) and allelic loss of the other. Mutations were correlated with an almost total lack of enzyme activity in fibroblasts. These data provide evidence that human MCC deficiency is caused by mutations in either the MCCA or MCCB gene.

Carbon-Carbon Ligases↗
PubMed2001

Determination of amino acid tissue concentrations by microdialysis: method evaluation and relation to plasma values.

Microdialysis is an in vivo technique to monitor tissue concentrations of low molecular weight substances by means of a continuously perfused artificial capillary with a semipermeable membrane placed into the region of interest. The suitability of microdialysis to determine tissue concentrations of amino acids was evaluated in vitro by placing the catheter into Ringer buffer or into a plasma protein (50g/l) solution containing 32 different amino acids (150 micromol/l each). All amino acids tested crossed freely the microdialysis membrane with recoveries close to 100%. Microdialysis fluid was sampled from subcutaneous tissue of five newborns and amino acid content analysed. Total and non protein bound amino acids were determined in the patients plasma by acid precipitation or ultrafiltration, respectively. Mean subcutaneous tissue concentrations were lower as compared to plasma for taurine, serine, alanine, aspartate, glutamate and ornithine and higher for valine, isoleucine, leucine, methionine, phenylalanine, tyrosine and arginine, indicating net uptake or release of amino acids from subcutaneous tissue. Thus, microdialysis offers a convenient and minimal invasive way to study tissue amino acid composition and appears to be a promising analytical tool for the study of amino acid metabolism in vivo.

Amino Acids↗
PubMed2001

Mothers with congenital adrenal hyperplasia and their children: outcome of pregnancy, birth and childhood.

OBJECTIVES: Fertility rates in women with congenital adrenal hyperplasia (CAH) are reported to be poor, but few data are available. We assessed rates and course of pregnancy, mode of delivery and long-term outcome of offspring from women with CAH. DESIGN: A large cohort of women with CAH due to 21-hydroxylase deficiency had initially been diagnosed and followed at one centre. Those women who had given birth were contacted. Information was gathered from hospital records, direct patient contact, structured questionnaire and the Documentation of Pregnancy and Preventive Care Booklets. RESULTS: Between 1978 and 1998, 18 women with CAH (one salt wasting, 12 simple virilizing, five nonclassical) had given birth to 31 children (18 females, 13 males). Delivery was by Caesarean section in 16 out of the 31 children. None of the female newborns was masculinized. Twenty-nine children were born at term, five children were small for gestational age (SGA). Postnatal development was basically normal in all children; 18 are now older than 10 years, seven are between 5 and 10 years old, six are less than 5 years old. CONCLUSIONS: Fertility is reduced in females with CAH, especially those with the severe or salt wasting phenotype. In those women with CAH who do conceive, course and outcome of pregnancy is mostly uneventful, although the rate of SGA offspring may be increased. Psychomotor and somatic long-term development of the children was within normal limits.

Adrenal Hyperplasia, Congenital↗
PubMed2001

Polymorphisms in the bradykinin B2 receptor gene and childhood asthma.

Bradykinin has been suggested as one of the key mediators of bronchial asthma. Polymorphisms with a potential functional relevance have been described in the B2 bradykinin receptor gene. Study of these polymorphisms in 77 children with asthma and 73 controls revealed no association. However, when comparing the asthmatics according to their age at onset (before and after age 4), the exon 1 allele BE1-2G was significantly associated with late-onset asthma (p<0.05). Since BE1-2G has previously been shown to lead to a higher transcription rate of the B2 receptor, this result warrants further investigation of the role of bradykinin in conferring susceptibility to pediatric asthma.

Adolescent↗
PubMed2001

Hepatic carnitine palmitoyltransferase I deficiency: acylcarnitine profiles in blood spots are highly specific.

BACKGROUND: In carnitine palmitoyltransferase I (CPT-I) deficiency (MIM 255120), free carnitine can be increased with no pathologic acylcarnitine species detectable. As inclusion of CPT-I deficiency in high-risk and newborn screening could prevent potentially life-threatening complications, we tested whether CPT-I deficiency might be diagnosed by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). METHODS: A 3.2-mm spot of whole blood dried on filter paper was extracted with 150 microL of methanol. After derivatization of carnitine and acylcarnitines to their butyl esters, the samples were analyzed by ESI-MS/MS with 37.5 pmol of L-[(2)H(3)]carnitine and 7.5 pmol of L-[(2)H(3)]palmitoylcarnitine as internal standards. RESULTS: In all dried-blood specimens from each of three patients with CPT-I deficiency, we found an invariably increased ratio of free carnitine to the sum of palmitoylcarnitine and stearoylcarnitine [C0/(C16 + C18)]. The ratio in patients was between 175 and 2000, or 5- to 60-fold higher than the ratio for the 99.9th centile of the normal newborn population in Bavaria (n = 177 842). No overlap with the values of children that were known to be supplemented with carnitine was detected [C0/(C16 + C18), 34 +/- 30; mean +/- SD; n = 27]. CONCLUSIONS: ESI-MS/MS provides a highly specific acylcarnitine profile from dried-blood samples. The ratio of free carnitine to the sum of palmitoylcarnitine and stearoylcarnitine [C0/(C16 + C18)] is highly specific for CPT-I deficiency and may allow presymptomatic diagnosis.

Biomarkers↗
PubMed2000

Defective peroxisome membrane synthesis due to mutations in human PEX3 causes Zellweger syndrome, complementation group G.

Zellweger cerebro-hepato-renal syndrome is a severe congenital disorder associated with defective peroxisomal biogenesis. At least 23 PEX genes have been reported to be essential for peroxisome biogenesis in various species, indicating the complexity of peroxisomal assembly. Cells from patients with peroxisomal biogenesis disorders have previously been shown to segregate into >/=12 complementation groups. Two patients assigned to complementation group G who had not been linked previously to a specific gene defect were confirmed as displaying a cellular phenotype characterized by a lack of even residual peroxisomal membrane structures. Here we demonstrate that this complementation group is associated with mutations in the PEX3 gene, encoding an integral peroxisomal membrane protein. Homozygous PEX3 mutations, each leading to C-terminal truncation of PEX3, were identified in the two patients, who both suffered from a severe Zellweger syndrome phenotype. One of the mutations involved a single-nucleotide insertion in exon 7, whereas the other was a single-nucleotide substitution eight nucleotides from the normal splice site in the 3' acceptor site of intron 10. Expression of wild-type PEX3 in the mutant cell lines restored peroxisomal biogenesis, whereas transfection of mutated PEX3 cDNA did not. This confirmed that the causative gene had been identified. The observation of peroxisomal formation in the absence of morphologically recognizable peroxisomal membranes challenges the theory that peroxisomes arise exclusively by growth and division from preexisting peroxisomes and establishes PEX3 as a key factor in early human peroxisome synthesis.

Amino Acid Sequence↗
PubMed2000

Human adrenoleukodystrophy protein and related peroxisomal ABC transporters interact with the peroxisomal assembly protein PEX19p.

Four ABC half transporters (ALDP, ALDRP, PMP70, and PMP69) have been identified in the mammalian peroxisomal membrane but no function has been unambiguously assigned to any of them. To date X-linked adrenoleukodystrophy (X-ALD) is the only human disease known to result from a defect of one of these ABC transporters, ALDP. Using the yeast two-hybrid system and in vitro GST pull-down assays, we identified the peroxin PEX19p as a novel interactor of ALDP, ALDRP, and PMP70. The cytosolic farnesylated protein PEX19p was previously shown to be involved in an early step of the peroxisomal biogenesis. The PEX19p interaction occurs in an internal N-terminal region of ALDP which we verified to be important for proper peroxisomal targeting of this protein. Farnesylated wild-type PEX19p and a farnesylation-deficient mutant PEX19p did not differ in their ability to bind to ALDP. Our data provide evidence that PEX19p is a cytosolic acceptor protein for the peroxisomal ABC transporters ALDP, PMP70, and ALDRP and might be involved in the intracellular sorting and trafficking of these proteins to the peroxisomal membrane.

ATP Binding Cassette Transporter, Subfamily D↗
PubMed2000

The human PEX3 gene encoding a peroxisomal assembly protein: genomic organization, positional mapping, and mutation analysis in candidate phenotypes.

In yeasts, the peroxin Pex3p was identified as a peroxisomal integral membrane protein that presumably plays a role in the early steps of peroxisomal assembly. In humans, defects of peroxins cause peroxisomal biogenesis disorders such as Zellweger syndrome. We previously reported data on the human PEX3 cDNA and its protein, which in addition to the peroxisomal targeting sequence contains a putative endoplasmic reticulum targeting signal. Here we report the genomic organization, sequencing of the putative promoter region, chromosomal localization, and physical mapping of the human PEX3 gene. The gene is composed of 12 exons and 11 introns spanning a region of approximately 40 kb. The highly conserved putative promoter region is very GC rich, lacks typical TATA and CCAAT boxes, and contains potential Sp1, AP1, and AP2 binding sites. The gene was localized to chromosome 6q23-24 and D6S279 was identified to be the closest positional marker. As yeast mutants deficient in PEX3 have been shown to lack peroxisomes as well as any peroxisomal remnant structures, human PEX3 is a candidate gene for peroxisomal assembly disorders. Mutation analysis of the human PEX3 gene was therefore performed in fibroblasts from patients suffering from peroxisome biogenesis disorders. Complementation groups 1, 4, 7, 8, and 9 according to the numbering system of Kennedy Krieger Institute were analyzed but no difference to the wild-type sequence was detected. PEX3 mutations were therefore excluded as the molecular basis of the peroxisomal defect in these complementation groups.

ATP-Binding Cassette Transporters↗
PubMed2000

Carrier assessment in families with lowe oculocerebrorenal syndrome: novel mutations in the OCRL1 gene and correlation of direct DNA diagnosis with ocular examination.

Lowe oculocerebrorenal syndrome (OCRL) (MIM 309000) is a rare X-linked multisystem disorder characterized by congenital cataracts, muscular hypotonia, areflexia, mental retardation, maladaptive behavior, renal tubular dysfunction, vitamin-D-resistant rickets, and scoliosis. The underlying gene OCRL1 is located on chromosome Xq25-q26 and contains 24 exons. It encodes a 105-kDa phosphatidylinositol 4,5-bisphosphate (PtdIns[4,5]P(2)) 5-phosphatase that is localized to the Golgi complex. To confirm the clinical diagnosis and to assess the carrier state of female relatives for genetic counseling we examined 6 independent patients and their families (a total of 23 individuals) using an improved mutation screening strategy for the OCRL1 gene by sequencing of large PCR amplicons. Four novel and two known mutations were identified: three premature terminations caused by either frameshift mutations (1899insT in exon 17 and 2104-2105delGT in exon 18) or a nonsense mutation (1399C > T in exon 12), two missense mutations (1676G > A and 1754C > T in exon 15), and a 6-bp deletion (1609-1614delAAGTAT in exon 14). An ophthalmological examination was performed in all patients and 14 female relatives. All genotypically proven carrier females showed characteristic lenticular opacities, while all proven noncarriers were lacking this phenotypic finding. The results confirm that ophthalmological evaluation is an apparently reliable first-line method to ascertain the carrier state in Lowe oculocerebrorenal syndrome. The high expressivity of lenticular symptoms in OCRL1 gene carriers is consistent with the hypothesis that (PtdIns[4,5]P(2)) 5-phosphatase activity has low functional reserve capacity for maintaining a balanced homeostasis of lenticular metabolism.

Adolescent↗
PubMed2000

The biochemical metabolite screen in the Munich ENU Mouse Mutagenesis Project: determination of amino acids and acylcarnitines by tandem mass spectrometry.

BACKGROUND: Gene mutations often result in altered protein expression and, in turn, lead to changes in metabolite levels in one or more distinct biochemical pathways. Traditional analytical methods for metabolite determination are usually time consuming, expensive, and, thus, not suitable for high throughput analysis. However, recent developments in electrospray-tandem-mass-spectrometry allow comprehensive metabolite scanning from very small amounts of blood with high speed, cost effectiveness, and accuracy. METHODS: A blood spot from a filter paper equivalent to 3 microl of blood was punched out and transferred to a 96-well microtiter plate. After addition of a set of 14 stable isotope-labeled internal standards, amino acids and acylcarnitines were extracted with methanol. The dried residue was derivatized with butanolic hydrochloric acid and subjected to MSMS analysis. RESULTS: Acyl-carnitines were all determined by a precursor ion scan of 85 Da. Neutral loss scanning of 102 Da was suitable for the quantitation of threonine, serine, proline, histidine, alanine, aspartic acid, glutamic acid, methionine, tyrosine, phenylalanine, isoleucine/leucine and valine. Glycine was detected by a loss of a 56-Da fragment, whereas a 119-Da loss was suitable for the measurement of citrulline, ornithine, arginine, and lysine. Specific problems encountered: owing to their identical molecular weight, isoleucine and leucine could not be quantitated separately, and, owing to their instability, glutamine and asparagine were found to be decarboxylated to their respective acids. Determination was linear over the concentration range tested (20 to 1000 micromol/L), and intraassay and interassay coefficients of variation were in the range of 10-15%. CONCLUSION: ESI-MSMS proved to be a highly sensitive, linear, and sufficiently precise method for the quantitative determination of amino acids and acylcarnitines in mouse blood, allowing large-scale screening applications when speed and cost effectiveness are mandatory.

Amino Acids↗
PubMed2000

Carnitine-acylcarnitine translocase deficiency: metabolic consequences of an impaired mitochondrial carnitine cycle.

We describe a patient with carnitine-acylcarnitine translocase deficiency (MIM 212138), who presented with neonatal generalized seizures, heart failure, and coma. Laboratory evaluation revealed hypoglycemia, hyperammonemia, lactic acidemia, hyperuricemia, and mild dicarboxylic aciduria. The fact that total plasma carnitine (7.1 micromol/l [20-30]) and free carnitine (1.9 micromol/l [12-18]) were low together with a high acylcarnitine/free carnitine ratio of 2.7 [0.4-1.0] prompted acylcarnitine analysis. This revealed the presence of large amounts of long-chain derivatives including C(16:0), C(16:1), C(18:1), C(18:2). Based on these findings carnitine-acylcarnitine translocase deficiency was suspected which was confirmed by enzyme studies in fibroblasts. The underlying complex metabolic consequences of this defect are reviewed. Prenatal diagnosis was performed in a subsequent pregnancy and a defect ruled out by measurement of carnitine-acylcarnitine translocase activity in cultured chorionic villi cells. As the clinical recognition of a life-threatening fatty acid oxidation disorder may be difficult, defects in this pathway should be considered in any child with coma, an episode of a Reye-like syndrome, and cardiomyopathy. Since routine laboratory tests often do not provide clues about potential disorders and profiles of urinary organic acids may not be characteristic, we recommend to measure free carnitine and acylcarnitines in plasma in any child with hyperammonemia, hypo/hyperketotic hypoglycemia or lactic acidemia for prompt treatment, proper genetic counseling, and potential prenatal diagnosis.

Ammonia↗
PubMed2000

[Model project for updating neonatal screening in Bavaria: concept and initial results].

The newborn screening programme in Bavaria was confronted with several problems. Number of disorders and process quality no longer complied with screening guidelines. Mixed financing, distributed between the state (PKU, galactosaemia) and health insurances (hypothyroidism) had promoted an increasing dissipation of the system. Notified participation rates had dropped to < 80%. Increasing need for a second screening due to early discharge was an additional challenge. To overcome these problems, and considering the availability of improved screening methodology (tandem mass spectrometry) the programme was reorganised. The project, which started on Jan 1, 1999, is based on a cooperation model between laboratory (logistics, analysis), universities (treatment, scientific evaluation), and public health services (coordination, tracking). Time of blood sampling was predated to the third day of life. Screening was extended to biotinidase deficiency, congenital adrenal hyperplasia (CAH) and by introduction of tandem mass spectrometry for screening of many other disorders (besides PKU). Insurances now finance complete laboratory analysis which was transferred to the private sector. To enable all newborn to participate, the names of screened children are matched against birth lists by public health services on a regional basis. Recalls and conspicuous results are consistently followed up until disorders are either excluded or confirmed. Two clinical hotlines were established in the children's hospitals of the universities in Munich (Southern Bavaria) and in Erlangen (Northern Bavaria). Written consent is required for participation in the programme. Participation in the new programme could be continually increased; coverage is > 95% since April. In several cases screening was made up for not tested children by contacting their parents. Omitted screening was mostly due to misunderstandings regarding testing responsibility or lost samples. Altogether 52 cases of disorder were found in the 87,000 newborn screened until August 1999. Hence, the detection rate of children affected by inborn errors of metabolism was about twice as high than before changes. Among the newly screened diseases CAH was detected most often (11 cases). In 22 cases diagnosis was based on the use of tandem mass spectrometry. Among these (besides PKU, 9 cases) MCAD deficiency (6 cases) was detected most frequently. Whereas recall rates of most disorders were < 0.1%, screening for CAH still revealed a high recall rate, particularly in premature births. Second screening due to early discharge (< 48 h) was required in 1.3%. About 20% of pending recalls required contacting birth hospitals, doctors, midwives or parents. So far all affected children could be brought to treatment in time.

Female↗