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Differential in vivo and in vitro intestinal permeability to lactulose and mannitol in animals and humans: a hypothesis Bijlsma, P.B.; Peeters, R.A.; Groot, J.A.; Dekker, P.R.; van den Meer, R.; Taminiau, J.A.J.M. Published in: Gastroenterology DOI:10.1016/0016-5085(95) Link to publication Citation for published version (APA): Bijlsma, P. B., Peeters, R. A., Groot, J. A., Dekker, P. R., van den Meer, R., & Taminiau, J. A. J. M. (1995). Differential in vivo and in vitro intestinal permeability to lactulose and mannitol in animals and humans: a hypothesis. Gastroenterology, 108, 687-696. https://doi.org/10.1016/0016-5085(95)90440-9 General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Background/Aims: Clinical interpretation of urinary recovery ratios of lactulose and mannitol is hampered by incomplete understanding of the mechanisms of transmucosal passage. The aim of this study was to compare in vivo and in vitro probe permeability. Methods: Stripped sheets of small intestine from rodents and human biopsy specimens were mounted in Ussing chambers, and mucosa-to-serosa fluxes of lactulose and mannitol were determined. Urinary recovery of orally applied probes was measured in rodents, cats, and humans. Results: In vitro lactulose/mannitol flux ratios were close to 0.8 in all species. Urinary recovery ratios differed between rodents and cats or humans; low ratios in cats and humans were due to high mannitol recovery. Conclusions: Interspecies variation in urinary recovery of mannitol is caused by differences specific for the intact small intestines in vivo. Because hyperosmolality of villus tips in vivo varies, being highest in humans and cats as a result of vascular countercurrent multiplication, it is hypothesized that the high urinary recovery of mannitol in these species is caused by solvent drag through pores that allow the passage of mannitol but not of lactulose. Therefore, the lactulose/ mannitol ratio is primarily a standard for the normal functioning of villus epithelial cells in metabolite absorption and for normal villus blood flow.T he urinary recovery ratio of orally ingested lactulose and mannitol is frequently used as a noninvasive tool in the diagnosis of intestinal disorders. An increased ratio is usually considered to be indicative of changes in small...

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Whey protein concentrate was hydrolyzed using the technical food-grade enzyme Corolase 7092 in order to abolish the allergenicity of whey proteins. The immunological properties of the hydrolysates were tested in vitro with a human-immunoglobulin E (human-IgE) enzyme-linked immunosorbent assay (ELISA) using sera obtained from children allergic to milk proteins and in vivo with a mouse-rat heterologous passive cutaneous anaphylactic test and an anaphylactic shock test in mice. The protein efficiency ratio, determined in young growing rats, was compared to that of casein. Ultrafiltration of the hydrolysates appeared to be necessary to obtain a hypo-allergenic product. The minimal molecular mass to elicit immunogenicity and allergenicity of whey protein hydrolysates appeared to be between 3,000 and 5,000 Da, so the molecular weight cut-off value of the filters required must be in this range. Although there was no evidence that extensively hydrolyzed whey protein is nutritionally inferior to casein, the slightly bitter taste might reduce food intake.

A cDNA clone for the human skeletal-muscle fatty-acid-binding protein (FABP) was isolated by screening of a human adult muscle lambda gt11 expression library with an anti-(muscle FABP) serum. The identify of the clone was confirmed by transcription/translation in vitro in plasmid pSP6.5, followed by immunoprecipitation. The nucleotide sequence of the 551 bp cDNA insert showed an open reading frame of 399 nucleotides, coding for a protein of 133 amino acid residues with a calculated molecular mass of 14858 Da and a pI of 4.94. Only one cysteine residue was found, at position 125. Peptide sequence analyses of human skeletal-muscle and heart FABP, after carbamoylmethylation and lysyl endopeptidase digestion followed by automatic Edman degradation, showed that both proteins are identical. No evidence was found for the existence of isoproteins in muscle. The chromosomal localization of the human muscle FABP gene was determined by analysing 31 human x rodent somatic-cell hybrid lines. The human muscle FABP gene could be assigned to chromosome 1pter-q31.

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The coding part of the cDNA encoding human muscle fatty-acid-binding protein (FABP) was ligated in the pET8c vector and expressed under the control of the lacUV5 promoter. After induction with isopropyl beta-D-thiogalactopyranoside, almost 12% of the cytoplasmic proteins consisted of FABP. The protein could be isolated after sonication of the bacterial pellet followed by (NH4)2SO4 precipitations, anion-exchange chromatography and gel filtration. The muscle FABP produced in Escherichia coli has an isoelectric point of 5.3 and is recognized by anti-(human muscle FABP) antiserum after Western blotting. The purified FABP has a preference for binding to palmitic acid and C18-C22 (poly)unsaturated fatty acids, and no affinity to palmitoyl-CoA or other hydrophobic ligands tested. The dissociation constant for oleic acid is 0.58 microM, with a binding stoichiometry of 0.72 mol of fatty acid/mol of protein. The physicochemical and binding characteristics of the protein were in complete agreement with those of FABP isolated from human skeletal muscle.