Biomedical subjects

C Schumann

Publications and source records attributed to C Schumann.

At least 37 records · Page 2Linked to original sources

PubMed1997

Effects of lactulose and lactitol on colonic microflora and enzymatic activity.

The effects of lactulose and lactitol (2 x 10 g/d) were studied in 36 healthy volunteers in comparison to placebo. All parameters studied were affected by both treatments, lactulose in general leading to more pronounced changes compared to lactitol. Probiotic bacteria were increased, and putrefactive bacteria and potential pathogens were significantly reduced. These variations in colonic flora had the following consequences: (i) a reduced activity of pro-carcinogenic enzymes: azoreductase, 7 alpha-dehydroxylase, beta-glucuronidase, nitroreductase and urease activity; (ii) a global increase of short-chain fatty acids in faeces; (iii) an effect on pH and moisture of faeces, and (iv) also on aromatic compounds such as phenol, cresol, indole and skatol. The findings suggest that lactulose and lactitol are not comparable in their effect on the colonic microflora, its metabolism, and the consequent probiotic effects on human health. The differences found may also be of clinical relevance suggesting that neither compound is equipotent.

Adult↗

PubMed1997

Lactulose--a multifaceted substance.

Lactulose is therapeutically used in hepatic encephalopathy, constipation, and salmonellosis. This semisynthetic disaccharide is neither metabolized nor absorbed in the normal small intestines. Comparable to plant-polysaccharides lactulose is bacterially fermented in the colon to short chain fatty acids and gases. Major consequences are a drop in pH and a change in composition and metabolic activity of the colonic flora. These and other potential effects suggest complex mechanisms of action of lactulose, with the potential for additional indications in diagnosis and therapy. The use of lactulose as substrate for the H2-breath-test is well known as a means for the measurement of oroeceal transit time and as test for small intestinal bacterial overgrowth. An extension of the diagnostic potential is given by the assessment of the permeability in diffuse intestinal disease with combined disaccharide/monosaccharide test solutions, especially in Crohn's disease. Explanations for positive effects in the prophylaxis of cholesterol-gallstones, in the therapy of hypercholesterolemia and in the prevention of colorectal adenoma and carcinoma can be found in changes in lipid- and bile acid metabolism found after lactulose ingestion. Lactulose may lead to an improved glucose-tolerance in parallel to fibre and acarbose effects which involve several mechanisms of carbohydrate metabolism. Lactulose presumably reduces pathogenic bacteria in favor of the health promoting bifidusflora; also, production and absorption of endotoxines may be reduced; this suggests that lactulose may have therapeutic effects on both infectious and idiopathic inflammatory bowel diseases. Numerous studies with interesting but not as yet convincingly documented clinical relevance suggest that the many effects of lactulose may be interesting subjects for future research.

Gastrointestinal Diseases↗

PubMed1995

New photoaffinity labelled agonists of bradykinin.

Several photoaffinity labelled agonists of the peptide hormone bradykinin (BK) were synthesized by solid phase methods. Their biological activities and binding affinities were determined in both the isolated rat uterus (RUT) and guinea pig ileum (GPI). As photoreactive groups p-benzoyl-phenylalanine (Bpa) and the arylazides azidobenzoic acid (ABA) and azidosalicylic acid (ASA) were attached to the N-terminus of the BK agonists. In addition, Bpa was incorporated at different positions of the BK sequence. Three different types of BK agonists were used. Firstly, the photolabels ASA and ABA were attached to BK or to Lys-BK (kallidin). Secondly, tyrosine containing BK analogues, suitable for radioiodination, were labelled. This series is derived from the naturally occurring analogue phyllokinin [BK-Ile-Tyr(SO3H)] and from BK analogues with tyrosine at position 0 and 3. The third series includes several analogues with D-N-methyl-phenylalanine (D-NMe-Phe) at position 7, which selectively discriminate between the RUT and GPI bradykinin B2 receptors. Among the photoaffinity labelled BK agonists, the iodinatable Lys(ASA)-BK (50.8% on RUT, 73.0% on GPI), ASA-BK (26.3% on RUT), Bpa-BK-Ile-Tyr (13.6% on RUT, 14.0% on GPI) and the iodinated [D-Bpa-1, 3-I-Tyr0]-BK (15.5% on RUT, 19.0% on GPI) retained a relatively high biological activity compared with BK (100%). Thus, although BK agonists are known to allow only very restricted modifications without a strong reduction in biological activity, these compounds should be useful candidates for receptor labelling.

Affinity Labels↗

PubMed1995

Potent photoaffinity labelled and iodinated antagonists of bradykinin.

Continuing the studies on photoaffinity labelled analogues of the peptide hormone bradykinin (BK), several labelled antagonists were synthesized and characterized regarding their biological activities on rat uterus (RUT) and guinea pig ileum (GPI). The photoreactive amino acid p-benzoyl-phenylalanine (Bpa) was incorporated in potent, iodinated BK analogues at positions -2, -1, 0 and 7. The newly synthesized BK antagonists were derived from HOE 140 ([DArg0, Hyp3, Thi5, D-Tic7, Oic8]-BK) or [D-Phe7]-BK. Because the application of Bpa requires an additional group for the introduction of 125I, iodinated tyrosine was inserted at different positions as a model for radioiodination. Suitable positions for incorporation of tyrosine residues are -1, 0, 3 and 7, whereas the compound with 3-I-Tyr at position 4 had only a low biological activity. The antagonists obtained by modification of HOE 140 generally retained a high antagonistic potency. In this group [D-Bpa-2, 3-I-D-Tyr-1, D-Arg0, Hyp3, Thi5, D-Tic7, Oic8]-BK (pA2 values 8.06 on RUT and 8.15 on GPI) and [Bpa-1, D-Arg0, 3-I-Tyr3, Thi5, D-Tic7, Oic8]-BK (pA2 values 7.55 on RUT and 8.07 on GPI) belong to the most active compounds. The incorporation of D-Bpa at position 7 also resulted in potent analogues. The antagonists [3-I-Tyr-1, D-Arg0, D-Bpa7]-BK (pA2 on RUT 7.69) and [3-I-Tyr-1, D-Arg0, D-Bpa7, Oic8]-BK (pA2 on GPI 7.53) are an alternative to the N-terminal modified HOE 140 analogues. Compounds with D-Bpa7 act as pure competitive antagonists, whereas the HOE 140 derivatives show a mixed antagonism. The comparison of the results between photoaffinity labelled agonists and antagonists suggests that modifications in the series of BK antagonists were better tolerated.

Affinity Labels↗

PubMed1995

[Ventral hyperostosis of the cervical spine--a rare differential diagnosis of dysphagia].

A case of dysphagia and hoarseness due to external compression by anterior hyperostosis between the third and fourth cervical vertebra is reported. Immediate relief of the symptoms was accomplished by surgical excision of the hyperostosis through an antero-lateral approach. The pathogenesis of the symptoms with reference to literature is discussed.

Cervical Vertebrae↗

PubMed1994