D Claus

Clustering of increased small intestinal permeability in families with Crohn's disease

BACKGROUND & AIMS Small intestinal permeability is increased in a proportion of patients with Crohns disease (CD) and a subset of their healthy relatives. A primary permeability defect was postulated in the pathogenesis of the disease. The aim of this study was to identify a possible genetic pattern in the distribution of CD and/or abnormal permeability. METHODS Differential urinary excretion of lactulose and mannitol (L/ M) in complete CD families was determined. Controls included healthy families and families with ulcerative colitis. Pedigrees were used to compare the distribution of CD and/or increased permeability. RESULTS The L/M was significantly increased in patients with CD. Seventeen of 67 first-degree relatives (25%) had a ratio greater than the upper limit (P95 = 0.0170). Permeability results of CD families showed a highly significant familial aggregation. The lack of a genetic pattern in relation with CD and occurrence of disturbed permeability especially within generation, points toward a shared environmental factor. Five of 14 healthy spouses (36%) of patients with CD had also an increased permeability, and prevalence of increased permeability was not higher in families with known familial occurrence (P = 0.85). CONCLUSIONS This large family study confirms an increased permeability in a subset of healthy relatives of patients with CD. However, the absence of a typical family pattern and the high prevalence in spouses is in favor of a common nongenetic factor or a subclinical disease manifestation.

Influence of dietary protein supplements on the formation of bacterial metabolites in the colon.

BACKGROUND: To evaluate the influence of increased dietary protein intake on bacterial colonic metabolism in healthy volunteers. METHODS: Short chain fatty acids, ammonia, and volatile organic compounds in faecal samples, and phenols in the urine of five volunteers were measured after one week of basal nutrient intake and and after one week of a diet supplemented with a protein rich food (Fortimel; Nutricia, Zoetermeer, The Netherlands). Paired t tests and factor analysis were used for statistical analysis. RESULTS: Total energy and resistant carbohydrate intake remained unchanged in each study period. The percentage energy intake delivered as dietary protein, increased significantly (from 15.4% to 23.8%; p = 0.007) during supplement intake. A significant increase in faecal ammonia (p = 0.002), faecal valeric acid (p = 0.02), and urinary p-cresol (p = 0.04) was noted during supplementary protein intake. A total of 120 different volatile compounds were isolated from the faecal samples of which 10 increased significantly during dietary protein supplementation. The change in volatile pattern, especially for S containing metabolites, was clearly shown by a factor analysis model which made a distinction between the two dietary regimens for all volunteers. CONCLUSION: An increase in dietary protein leads to altered products formation by colonic metabolism, mainly reflected by an increase in faecal ammonia, faecal volatile S substances, and urinary p-cresol.

Evidence for impaired assimilation and increased colonic fermentation of protein, related to gastric acid suppression therapy

Although the role of gastric digestion (by acid‐dependent pepsins) in overall protein assimilation has never thoroughly been studied, it is generally considered to be limited. Protein that escapes assimilation in the small intestine is intensely fermented by the colonic flora. Phenol and p‐cresol are specific bacterial metabolites of tyrosine.

Screening method for the determination of volatiles in biomedical samples by means of an off-line closed-loop trapping system and high-resolution gas chromatography-ion trap detection

A method is described for the analysis of volatile organic compounds in biological matrices (faeces and urine). The technique is based on off-line preconcentration by means of a closed-loop trapping system followed by high-resolution gas chromatography-ion trap detection (HRGC-ITD) for separation and identification of the compounds. The technique has been validated for pattern recognition in faecal and urine samples from healthy volunteers. It is considered a very promising tool in metabolic research.

Determination of Deuterated Phenylalanine and Tyrosine in Egg Protein by GCQ

In order to study protein digestibility by means of noninvasive tracer techniques (stable isotopes), a representative oral tracer, i.e. a stable isotope labeled protein, is needed. Therefore, egg white containing L-[ring-2H5]phenylalanine and L-[ring-2H4]tyrosine was prepared. The aim of this study was to measure the isotopic enrichment of the labeled amino acids in the egg white. The use of a standard GC-MS, based on ion trap technology was found to be a reliable technique. The enrichment of L-[ring-2H5]phenylalanine and L-[ring-2H4]tyrosine, expressed in Molar Percent (MP) amounted to 23.2 MP and 2.8 MP respectively.