Michael Leichsenring

Efficacy and outcome of expanded newborn screening for metabolic diseases - Report of 10 years from South-West Germany *

BackgroundNational newborn screening programmes based on tandem-mass spectrometry (MS/MS) and other newborn screening (NBS) technologies show a substantial variation in number and types of disorders included in the screening panel. Once established, these methods offer the opportunity to extend newborn screening panels without significant investment and cost. However, systematic evaluations of newborn screening programmes are rare, most often only describing parts of the whole process from taking blood samples to long-term evaluation of outcome.MethodsIn a prospective single screening centre observational study 373 cases with confirmed diagnosis of a metabolic disorder from a total cohort of 1,084,195 neonates screened in one newborn screening laboratory between January 1, 1999, and June 30, 2009 and subsequently treated and monitored in five specialised centres for inborn errors of metabolism were examined. Process times for taking screening samples, obtaining results, initiating diagnostic confirmation and starting treatment as well as the outcome variables metabolic decompensations, clinical status, and intellectual development at a mean age of 3.3 years were evaluated.ResultsOptimal outcome is achieved especially for the large subgroup of patients with medium-chain acyl-CoA dehydrogenase deficiency. Kaplan-Meier-analysis revealed disorder related patterns of decompensation. Urea cycle disorders, organic acid disorders, and amino acid disorders show an early high and continuous risk, medium-chain acyl-CoA dehydrogenase deficiency a continuous but much lower risk for decompensation, other fatty acid oxidation disorders an intermediate risk increasing towards the end of the first year. Clinical symptoms seem inevitable in a small subgroup of patients with very early disease onset. Later decompensation can not be completely prevented despite pre-symptomatic start of treatment. Metabolic decompensation does not necessarily result in impairment of intellectual development, but there is a definite association between the two.ConclusionsPhysical and cognitive outcome in patients with presymptomatic diagnosis of metabolic disorders included in the current German screening panel is equally good as in phenylketonuria, used as a gold standard for NBS. Extended NBS entails many different interrelated variables which need to be carefully evaluated and optimized. More reports from different parts of the world are needed to allow a comprehensive assessment of the likely benefits, harms and costs in different populations.

Measurement of 4-hydroxynonenal in small volume blood plasma samples: modification of a gas chromatographic–mass spectrometric method for clinical settings

4-Hydroxynon-2-enal (4-HNE) is one of the major aldehydic products of lipid peroxidation (LPO) and is involved in a number of pathophysiological processes. Since LPO products are useful indicators for oxidative stress in vivo, a number of detection methods for LPO products in biological tissues were developed. However, none of these methods is presently used in clinical settings. In order to introduce LPO products as biomarkers in clinical studies a suitable GC-MS method for 4-HNE detection was adapted to meet clinical requirements. As one result, the minimal sample volume could be decreased to 50 microl of plasma so that the method might even be suitable for pediatric purposes. The best internal standard (I.S.) for 4-HNE detection by GC-MS 9,9,9-D(3)-4-hydroxynon-2-enal was introduced by van Kuijk et al. [Anal. Biochem., 224 (1995) 420]. However, because of its limited availability, benzaldehyde-ring-d(5), 4-hydroxybenzaldehyde, and 2,5-dihydroxybenzaldehyde were tested to find an alternative. Out of these three, 4-hydroxybenzaldehyde was shown to serve best as I.S. To examine the applicability of the adapted method, tests on the stability of 4-HNE in samples during storage were carried out. It was shown that plasma samples need to be stored at -80 degrees C or less to avoid greater loss of 4-HNE. Samples with 4-HNE concentrations close to the physiological level were shown to be stable over 22 months at -80 degrees C. The introduction of a new and easily available I.S., reduction of the sample volume, and information about sample stability provided by this study facilitate 4-HNE determination in most clinical settings.

Proteasomal degradation of β‐carotene metabolite—Modified proteins

Free radical attack on β‐carotene results in the formation of high amounts of carotene breakdown products (CBPs) having biological activities. As several of the CBPs are reactive aldehydes, it has to be considered that these compounds are able to modify proteins. Therefore, the aim of the study was to investigate whether CBP‐modification of proteins is leading to damaged proteins recognized and degraded by the proteasomal system. We used the model proteins tau and ferritin to test whether CBPs will modify them and whether such modifications lead to enhanced proteasomal degradation. To modify proteins, we used crude CBPs as a mixture obtained after hypochloric acid derived BC degradation, as well as several single compounds, as apo8′‐carotenal, retinal, or β‐ionone. The majority of the CBPs found in our reaction mixture are well known metabolites as described earlier after BC degradation using different oxidants. CBPs are able to modify proteins, and in in vitro studies, we were able to demonstrate that the 20S proteasome is able to recognize and degrade CBP‐modified proteins preferentially. In testing the proteolytic response of HT22 cells toward CBPs, we could demonstrate an enhanced protein turnover, which is sensitive to lactacystin. Interestingly, the proteasomal activity is resistant to treatment with CBP. On the other hand, we were able to demonstrate that supraphysiological levels of CBPs might lead to the formation of protein‐CBP‐adducts that are able to inhibit the proteasome. Therefore, the removal of CBP‐modified proteins seems to be catalyzed by the proteasomal system and is effective, if the formation of CBPs is not overwhelming and leading to protein aggregates.

Odd-numbered long-chain fatty acids in erythrocyte phospholipids as long-term follow-up parameter in propionic acidemia.

Abstract Odd-numbered long-chain fatty acids (OLCFAs) increase in total erythrocyte lipids or plasma in patients with propionic acidemia and have been proposed as a useful parameter of metabolic control. However, up to now no parameter for long-term metabolic control has been available for this disorder. In contrast to previous investigations, we investigated OLCFAs with particular reference to differences for two phospholipid fractions of erythrocyte lipids. The phosphatidylethanolamine (PE) fraction of erythrocyte lipids has a slow turnover rate and might reflect the metabolic propionyl-CoA burden over a period of some weeks. Distinct increases in OLCFA of up to 200% in the phosphatidylcholine fraction were observed after episodes of metabolic decompensation and maximum OLCFA levels were found 3 weeks after the onset of a crisis. As a sign of poor metabolic control, OLCFA levels in PE steadily increased after recurrent episodes of decompensation, but not in clinically stable patients. However, in one patient with clinically good metabolic control, OLCFAs continually increased after the second year of life for an as yet unknown reason. In conclusion, data from this study indicate the usefulness of OLCFA analysis in the PE fraction of erythrocyte lipids, in particular with regard to the need for such a parameter for evidence-based improvement of management strategies in propionic acidemia.

Antioxidants and Lipid Peroxidation in Preterm infants fed Formula Feeds enriched in Long Chain Polyunsaturated Fatty Acids

The aim of this study was to evaluate the influence of long chain polyunsaturated fatty acids (LCP) in formula feeds on lipid peroxidation and antioxidants in premature infants. LCPs and glutathione were determined in erythrocytes, malondialdehyde (MDA) in plasma as well as alpha-and gammatocopherol in plasma, erythrocytes, plateles, monocytes, polymorphnuclear leucocytes and buccal mucosal cells.

Alpha-And Gamma-Tocopherol Status in Premature Infants Receiving Mother Milk-Tocopherol Values in Plasma and Erythrocytes During the First 6 Weeks Of Life 125

1) Background. Premature infants fed solely on mother milk are prone to develop a latent vitamin E deficiency. The aim of this study was to show developments in α- and γ-tocopherol in premature infants during the first 6 weeks of life. 2) Subjects. In 10 healthy, eutrophic premature infants with birthweight between 1280g and 1640g and gestational age between 28 and 31 weeks α- and γ-tocopherol was determined in plasma (PL) and erythrocytes (RBC) in cord blood (CD) and on days 2, 7, 14, 28 and 42 post partum. 200 μl of blood was used for each determination and HPLC with fluorescence detector was used.