Hans Böhles

Effect of n–3 Polyunsaturated Fatty Acids in Asthma after Low-Dose Allergen Challenge

Background: We investigated the anti-inflammatory potential of n–3 polyunsaturated fatty acids (PUFA) on specific bronchial inflammation. Allergic asthmatics were challenged using a low-dose allergen provocation model. Methods: Our parallel double-blinded study randomly assigned 23 house dust mite-allergic asthmatics (aged 22–29 years; 13 females, 10 males) to dietary supplementation with either an n–3 PUFA-enriched fat blend (0.69 g/day) or placebo for 5 weeks. After 3 weeks, the patients were challenged daily with low doses of mite allergen for 2 weeks. Primary outcome parameters were effects on lung function (forced expiratory volume in 1 s, FEV1) and exhaled nitric oxide (eNO) as a marker of bronchial inflammation. Results: Even before the bronchial challenge, eNO was significantly lower in the n–3 PUFA group (p = 0.014). Levels of eNO increased during allergen exposure in both groups, but differences in means were significantly lower in the n–3 PUFA group (p = 0.022). During the low-dose allergen challenge, there were no differences between the groups with regard to symptoms, FEV1 or the allergen dose required to induce deterioration of lung function (PD20). Numbers of sputum eosinophils did not differ significantly, while serum eosinophils (10.1 ± 0.1.84 vs. 5.79 ± 0.69%) as well as changes in eosinophilic cationic protein (20.5 ± 9.93 vs. –1.68 ± 4.36 ng/ml) and in vitro cysteinyl leukotriene release (2,889 ± 872 vs. 1,120 ± 173 ng/ml) were significantly lower in the n–3 PUFA group (p < 0.05 each). Conclusion: Our results provide evidence that dietary supplementation with n–3 PUFA is able to reduce bronchial inflammation even after low-dose allergen challenge.

Enantioselective multidimensional gas chromatography-mass spectrometry in the analysis of urinary organic acids.

Enantioselective multidimensional gas chromatography-mass spectrometry is a valuable tool for the enantioselective analysis of compounds from complex matrices. Samples are separated initially on a precolumn and selected substances then transferred on-line to a main-column coated with suitable chiral stationary phase for enantioselective analysis with subsequent mass selective detection. In this paper the method is used as an adjunct to urinary organic acid analysis to provide information in patients with suspected inborn errors of metabolism. Lactic acid, alpha-hydroxyisocaproic acid, 3-phenyllactic acid and 3-(4-hydroxyphenyl)-lactic acid are separated in a single run. In addition, the enantioselective analysis of pyroglutamic acid is presented. D-Enantiomers of amino acids and alpha-hydroxycarboxylic acids derived from amino acids, point to a bacterial origin whereas the L-enantiomer is predominantly of endogenous origin. Therefore the enantiomeric ratio of chiral metabolites is an important parameter for the understanding of metabolic processes.

Impact of early dietary gamma‐linolenic acid supplementation on atopic eczema in infancy

Polyunsaturated fatty acids (PUFAs) are components of cell membranes and may play an immunomodulating role in the pathogenesis of atopic dermatitis (AD). The goal was to determine the impact of PUFAs on AD by dietary supplementation of infants. Based on the parents’ decision on their babies’ primary feeding, mothers and newborns were randomized to the supplementation with gamma‐linolenic acid (GLA) or placebo for up to 6 months. Breastfed infants received GLA by supplementing their mothers. Formula diet was commercial whey hydrolysate unsupplemented with PUFAs. Of 131 eligible infants, 24 developed AD within the first year of life. Of these, nine belonged to the exclusively breastfed group (n = 58), 14 to the combined‐fed group (n = 53), and one to the never breastfed group (n = 20). We could not find an influence of GLA on the development of AD. In subjects with AD, at 1 yr of age the serum‐immunoglobulin E (IgE) was the lowest in the GLA‐supplemented group A‐subjects. In the GLA‐supplemented group, GLA‐levels in breast milk were similar in atopic and non‐atopic infants. In the non‐supplemented group the GLA‐content of breast milk was 0.07% of total fatty acids in atopic infants vs. 0.17% in non‐atopic infants (p < 0.01). Dietary GLA‐supplementation could not prevent AD. Interestingly, the number of infants developing AD was the lowest in never breastfed children. In infants suffering from AD, GLA‐supplementation seemed to reduce total IgE in the first year of life.

Simultaneous enantioselective analysis of chiral urinary metabolites in patients with Zellweger syndrome.

Enantio-MDGC-MS analysis with heptakis-(2,3-di-O-methyl-6-O-tert.-butyl-dimethylsilyl)-beta-cyclodextrin as the chiral main column is a powerful tool for the separation of chiral compounds. This paper reports on the simultaneous stereodifferentiation of 2-hydroxyisocaproic acid (HICA), 3-methyladipic acid (3-MA), 2-hydroxyglutaric acid (2-HG), 3-(4-hydroxyphenyl)-lactic acid (HPLA), 2-hydroxysebacic acid (2-HS) and 3-hydroxysebacic acid (3-HS) in a single chromatographic run. These chiral urinary metabolites are useful in the diagnosis of peroxisomal diseases such as Zellweger syndrome (ZS). In this investigation, urine samples from nine patients with ZS were analysed in order to reveal the enantiomeric ratio of these chiral metabolites. The stereodifferentiation of the analysed chiral compounds may provide important information on their biochemical origin.

Enantioselective analysis of ketone bodies in patients with β-ketothiolase deficiency, medium-chain acyl coenzyme A dehydrogenase deficiency and ketonemic vomiting

Enantioselective multidimensional gas chromatography-mass spectrometry (enantio-MDGC-MS) is a valuable tool for the differentiation of enantiomers from complex matrices when present in trace amounts. The separation of chiral compounds provides further information on the diagnosis of diseases, and on normal and abnormal biochemical pathways. The formation of the normal urinary metabolite 3-hydroxy-2-methylbutanoic acid (HMBA), excreted in abnormally high amounts in beta-ketothiolase deficiency, is not absolutely clarified. Metabolic pathways involving this metabolite are isoleucine catabolism, as well as presumably beta-oxidation of fatty acids and ketogenesis. The latter two pathways are distinguishable in their enantioselectivity. Enantioselective analysis gives further information on interfering metabolic pathways and the selectivity of the enzyme(s) forming HMBA. Different ratios of the stereoisomers of HMBA in control urine samples and patients with beta-ketothiolase deficiency were detected. Analogous to HMBA urinary 3-hydroxybutanoic acid (HBA) was investigated in several diseases. The formation of HBA and HMBA is expected to result from the same or similar metabolic pathways. Differences in the enantiomeric ratio of HMBA may originate from the enantioselectivity of different enzyme systems.

Multidimensional gas chromatography-mass spectrometry for tracer studies of fatty acid metabolism via stable isotopes in cultured human trophoblast cells.

The determination of placental fatty acid metabolism using stable isotope-labeled tracers was investigated in the human placental choriocarcinoma (JAR) cell line. Stable isotope incorporation was measured by MDGC-MS. The cultured trophoblast cells incorporated and metabolized the essential fatty acids to long-chain polyunsaturated fatty acids. The described method enables the detection of a low Delta(6)-desaturase activity in this human placental cell line. The developed MDGC-MS method allows the assessment of long-chain polyunsaturated fatty acid biosynthesis in cultured cells with high sensitivity and selectivity. In this respect, tracer studies with MDGC-MS will be a powerful tool to clarify the significance of placental fatty acid metabolism.