Biomedical subjects

Adelbert A Roscher

Publications and source records attributed to Adelbert A Roscher.

26 records · Page 2Linked to original sources

PubMed2002

Two splice variants of human PEX19 exhibit distinct functions in peroxisomal assembly.

PEX19 has been shown to play a central role in the early steps of peroxisomal membrane synthesis. Computational database analysis of the PEX19 sequence revealed three different conserved domains: D1 (aa 1--87), D2 (aa 88--272), and D3 (aa 273--299). However, these domains have not yet been linked to specific biological functions. We elected to functionally characterize the proteins derived from two naturally occurring PEX19 splice variants: PEX19DeltaE2 lacking the N-terminal domain D1 and PEX19DeltaE8 lacking the domain D3. Both interact with peroxisomal ABC transporters (ALDP, ALDRP, PMP70) and with full-length PEX3 as shown by in vitro protein interaction studies. PEX19DeltaE8 also interacts with a PEX3 protein lacking the peroxisomal targeting region located at the N-terminus (Delta66aaPEX3), whereas PEX19DeltaE2 does not. Functional complementation studies in PEX19-deficient human fibroblasts revealed that transfection of PEX19DeltaE8-cDNA leads to restoration of both peroxisomal membranes and of functional peroxisomes, whereas transfection of PEX19DeltaE2-cDNA does not restore peroxisomal biogenesis. Human PEX19 is partly farnesylated in vitro and in vivo. The farnesylation consensus motif CLIM is located in the PEX19 domain D3. The finding that the protein derived from the splice variant lacking D3 is able to interact with several peroxisomal membrane proteins and to restore peroxisomal biogenesis challenges the previous assumption that farnesylation of PEX19 is essential for its biological functionality. The data presented demonstrate a considerable functional diversity of the proteins encoded by two PEX19 splice variants and thereby provide first experimental evidence for specific biological functions of the different predicted domains of the PEX19 protein.

Alternative Splicing↗

PubMed2002

Symptoms in carriers of adrenoleukodystrophy relate to skewed X inactivation.

Skewing of X inactivation may contribute to the manifestation of symptoms in adrenoleukodystrophy carriers. We observed highly skewed X inactivation in 32% of 22 symptomatic and asymptomatic carriers but not in 7 related and 35 unrelated controls. Skewing of X inactivation correlated with clinical neurological scores but not with the extent of very long-chain fatty acid accumulation. Transcript analysis in cultured fibroblasts revealed that skewing could occur both in favor of the mutant and the wild-type allele. Adrenoleukodystrophy carriers are more susceptible to develop skewing of X inactivation in favor of the mutant allele being associated with the manifestation of symptoms.

Adolescent↗

PubMed2002

Very high compliance in an expanded MS-MS-based newborn screening program despite written parental consent.

OBJECTIVES: In Bavaria, Germany, an expanded MS-MS-based newborn screening program was implemented in 1999. The coverage of new additional conditions and novelty of technology required introduction of written parental consent. Here we evaluated the influence of the consent procedure on compliance by systematic demographic tracking. METHODS: Comprehensive information was provided for parents, professionals, and the public. Screening notifications were matched with all birth notifications on name and date of birth. Parents of children without screening notification were contacted and counseled. RESULTS: Between August 1, 1999, and July 31, 2000, 123,284 children eligible for screening were born. Of these, 116,652 were matched successfully. Among 6,632 parents contacted, 2,516 (2%) did not respond. Three thousand thirty-four children were screened but the parents initially refused to participate in tracking. Five hundred ninety-four were screened outside the program. Four hundred eighty-eight untested newborns were identified. Three hundred twenty-five screening failures due to logistic problems were tested subsequently. Screening was definitely refused by the parents of 163 children (0.1% of target population). CONCLUSIONS: With appropriate information provided and surveillance by tracking, high compliance with newborn screening can be achieved despite a written consent requirement.

Adult↗

PubMed2002

Expanded newborn screening in Bavaria: tracking to achieve requested repeat testing.

OBJECTIVES: Expansion of newborn screening programs may increase the risk of missing cases through procedural failures. A coordinated process quality assurance procedure to track recalls was, therefore, introduced in parallel to expansion (including MS-MS and 17alpha-OHP) in Bavaria. METHODS: Using comprehensive computerized registration and automated monitoring a state-funded center coordinated all individual measures to achieve complete testing of all repeat requests-case-specific contacts to physicians, midwives, and parents. Mailing and phoning from the center were supplemented by local public health activities including home visits if needed. RESULTS: Among 243,422 children tested in 1999 and 2000 overall recall was 3.62% (8,809 children): 0.30% (726) were due to sample inadequacy, 1.35% (3,282) to early sampling (<48 h), and 1.97% (4,801) to abnormal results. Of all recalls, 80.9% were received following the initial request, 1,679 (19.1%) required special efforts. Of these, 873 were achieved following a single and 601 following repeated central activities, and 102 were achieved following local support. Sixty-three cases of parental refusal and 47 untraceable children remained. Altogether, 98.8% recalls were achieved, corresponding to 99.96% of all tested children for which definite screening results could be obtained. CONCLUSIONS: Expansion of newborn screening programs does not necessarily mean unsolvable problems in tracking of recalls if adequate logistics is established in parallel.

Germany↗

PubMed2002

Age-related reference values for serum selenium concentrations in infants and children.

BACKGROUND: Children are at particular risk for selenium deficiency, which has potentially serious medical implications. Reliable age-specific reference values for serum selenium concentrations in children are sparse, but are essential for the identification of selenium deficiency and decisions regarding selenium supplementation. METHODS: Using electrothermal atomic absorption spectrometry, we analyzed serum selenium concentrations from 1010 apparently healthy children (age range, 1 day to 18 years) and from 60 patients on a protein-restricted diet because of inborn errors of metabolism. Reference intervals were defined according to recommended guidelines. RESULTS: Medians for serum selenium concentrations showed a statistically significant age dependency: a decrease from the age <1 month (0.64 micromol/L) to 4 months (0.44 micromol/L); an increase to 0.62 micromol/L in the 4-12 months age group; constant values in children between 1 and 5 years of age (0.90 micromol/L); and an additional slight increase to reach a plateau between 5 and 18 years (0.99 micromol/L). Of 43 children older than 1 year and on a protein-restricted diet, 87% showed serum selenium concentrations below the 2.5 percentile. CONCLUSIONS: Because of nutritional changes, serum selenium concentrations are significantly higher in older children than in infants under 1 year of age. The application of age-adjusted reference values may provide more specific criteria for selenium supplementation. Long-term protein restriction in children is reflected by a failure to achieve higher serum selenium concentrations with increasing age.

Adolescent↗

PubMed2002

Multiplex minisequencing of the 21-hydroxylase gene as a rapid strategy to confirm congenital adrenal hyperplasia.

BACKGROUND: Congenital adrenal hyperplasia (CAH) is a frequent autosomal recessive disease, with a wide range of clinical manifestations, most commonly attributable to mutations in the 21-hydroxylase gene (CYP21). Large gene deletions, large gene conversions, a small 8-basepair deletion, and eight point mutations in CYP21 account for approximately 95% of all enzyme deficiencies. We developed a new strategy for a rapid CYP21 analysis. METHODS: DNA samples from 40 CAH patients previously genotyped by direct DNA sequencing were reanalyzed by allele-specific amplification of the functional CYP21 gene followed by a multiplex minisequencing reaction using 13 primers. In addition, a second PCR that amplified a part of exon 3 was used to demonstrate the presence or absence of at least one functional gene. RESULTS: The assay detected the P453S mutation and nine of the most common mutations (P30L, intron 2 splice, Delta 8bp, I172N, exon 6 cluster, V281L, F306+t, Q318X, and R356W) caused by microconversions from the CYP21P pseudogene. The concordance was 100% for detecting these mutations, including gene deletions and large gene conversions. The 40 patient DNA samples were analyzed in 1.5 working days by one technician (actual hands-on time, 3.5 h). The material cost for analyzing one sample was approximately 10.00 Euros (US $9.00). CONCLUSIONS: This novel mutation screening strategy rapidly detects 90-95% of all mutations associated with CAH and appears applicable as a tool for confirmation of increased 17-hydroxyprogesterone found in neonatal CAH screening.

Adrenal Hyperplasia, Congenital↗

PubMed2001

Mutations in the proenteropeptidase gene are the molecular cause of congenital enteropeptidase deficiency.

Enteropeptidase (enterokinase [E.C.3.4.21.9]) is a serine protease of the intestinal brush border in the proximal small intestine. It activates the pancreatic proenzyme trypsinogen, which, in turn, releases active digestive enzymes from their inactive pancreatic precursors. Congenital enteropeptidase deficiency is a rare recessively inherited disorder leading, in affected infants, to severe failure to thrive. The genomic structure of the proenteropeptidase gene (25 exons, total gene size 88 kb) was characterized in order to perform DNA sequencing in three clinically and biochemically proved patients with congenital enteropeptidase deficiency who were from two families. We found compound heterozygosity for nonsense mutations (S712X/R857X) in two affected siblings and found compound heterozygosity for a nonsense mutation (Q261X) and a frameshift mutation (FsQ902) in the third patient. In accordance with the biochemical findings, all four defective alleles identified are predicted null alleles leading to a gene product not containing the active site of the enzyme. These data provide first evidence that proenteropeptidase-gene mutations are the primary cause of congenital enteropeptidase deficiency.

Alleles↗

PubMedDate not supplied

Effect of amino acid infusion on human postoperative colon protein synthesis in situ.

BACKGROUND: Amino acids are an integral part of parenteral nutrition because of their anabolic action helping to conserve body protein after surgical stress. At the gastrointestinal tract, an adequate supply of amino acids may be particularly important because of the gut's high rate of protein turnover, cell division, and proliferation. However, no information is available about the effects of amino acids on human intestinal protein metabolism after surgery. METHODS: Studies were performed in postabsorptive patients 8-10 days after major abdominal surgery. Mass spectrometry techniques (capillary gas chromatography/combustion isotope ratio mass spectrometry) were used to directly determine the incorporation rate of 1-[13C]-leucine into colon mucosal protein. All subjects had a colostomy, which allowed easy access to the colon mucosa, and consecutive sampling from the same tissue was performed during continuous isotope infusion (0.16 micromol/kg min). Isotopic enrichments were determined at baseline and after a 4-hour infusion of amino acids or after infusion of saline (control group). RESULTS: Compared with baseline, infusion of amino acids reduced fractional colon protein synthesis significantly by -29.2 +/- 8.3%. This decrease was also significantly different from the corresponding (insignificant) change during saline infusion (+19.4 +/- 26.9%, p < .05 vs amino acid group). CONCLUSIONS: After surgery, an amino acid infusion acutely reduces postoperative colon protein synthesis. This effect possibly may be attributed to interactions of specific amino acids (glutamine) with an altered intestinal immune system and enterocyte activity.

Amino Acids↗