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Biomedical subjects

H Rohde

Publications and source records attributed to H Rohde.

At least 55 records · Page 3Linked to original sources
PubMed1985

Sample taking problems in measuring actual histamine levels of human gastroduodenal mucosa: specific and general relevance in clinical trials on peptic ulcer pathogenesis and selective proximal vagotomy.

Changes in histamine storage in the oxyntic mucosa of duodenal ulcer patients and their reversal by vagotomy and the histamine H2-antagonist cimetidine supported the hypothesis that histamine could be a causal factor in peptic ulcer pathogenesis. The specificity of these findings was impaired by problems in biopsy taking, however, and in the preparative steps before measuring the actual histamine contents in all parts of the gastric mucosa and in the duodenum. A prospective trial was carried out in 190 patients to identify these sources of bias and to overcome them by appropriate study designs. Usually a direct correlation was found between weight of biopsy and mucosal histamine content. This problem was solved by selecting a biopsy forceps producing smaller variations in sample size, by limiting the time of cold ischaemia to four to five minutes only and by taking three biopsy specimens for each single histamine value. The actual histamine content of mucosal biopsies remained constant for about four to five minutes only. The 'disappearance' rate was faster in control subjects than in duodenal ulcer patients. Hence by variation of the cold ischaemia time any artefacts of differences between mucosal histamine levels in controls and duodenal ulcer patients could be produced. Using the optimised sample taking procedure mucosal histamine contents of several gastric regions and the duodenal bulb were measured in 24 patients with duodenal ulcer, after selective proximal vagotomy without drainage and in control subjects without any stomach disease (randomised controlled trial). The histamine content was lower in all parts of the upper gastrointestinal tract in duodenal ulcer patients than in controls and was raised again in all regions after selective proximal vagotomy. As the most likely hypothesis it is suggested that vagal reflexes with afferent fibres coming from the oxyntic mucosa stimulate histamine release in duodenal ulcer patients by efferent peptidergic neurones to all parts of the stomach and the duodenum where the ulcer lesion is situated.

Adult↗
PubMed1983

Immunochemical properties of the aminopropeptide of procollagen type III.

The precursor-specific aminopropeptide of bovine type III procollagen is a strong immunogen in rabbits, guinea pigs and mice and induces antibodies which do not cross-react with type I procollagen. The antibody response is regulated by immune response genes associated with the major histocompatibility complex. Major antigenic determinants were found in the compact, non-collagenous domain (fragment Col 1) located at the N terminus of the aminopropeptide and were destroyed by reduction of disulfide bonds. Minor antigenic determinants independent of disulfide bonds also exist in fragment Col 1 and could be localized on a distinct tryptic peptide. Fragment Col 1 showed a lower affinity for antibody when compared with the intact aminopropeptide which causes a non-parallel shift in radioimmuno-inhibition profiles. Monovalent antibody fragments showed an average tenfold reduction in affinity constant and failed to distinguish between aminopropeptide and fragment Col 1. This indicates that the stronger binding of bivalent antibody by the triple-stranded aminopropeptide is due to multiple interactions with both antibody binding sites which are lost for a single-stranded antigen (Col 1) or with monovalent antibody fragments.

Animals↗
PubMed1983

Serum and urine analysis of the aminoterminal procollagen peptide type III by radioimmunoassay with antibody Fab fragments.

A radioimmunoassay based on antibody Fab fragments was developed for the aminoterminal peptide Col 1-3 of bovine type III procollagen. This assay does not distinguish the intact aminopropeptide Col 1-3 from its globular fragment Col 1. Parallel inhibition profiles were observed with human serum and urine allowing the simultaneous quantitative determination of intact and fragmented antigens in these samples. Most of the material has a size similar to that of fragment Col 1 indicating that the aminopropeptide is degraded under physiologic conditions. The concentration of aminopeptide in normal sera was in the range 15-63 ng/ml. Daily excretion was found to be in the range 30-110 micrograms. More than 50% of patients with alcoholic hepatitis and liver cirrhosis showed elevated serum levels of aminopropeptide by the Fab assay. Elevated concentrations were detected more frequently with an antibody radioimmunoassay which measures mainly the intact form of the aminopropeptide. It is suggested that analysis of patients material by both assays could improve their diagnostic application.

Adolescent↗
PubMed1982

Low rate of procollagen conversion in dermatosparactic sheep fibroblasts is paralleled by increased synthesis of type I and type III collagens.

Dermatosparaxis is a genetic defect found in humans and animals, which affects the conversion of procollagen to collagen and aminopropeptides . Under cell culture conditions a reduction of the release of aminopropeptides is paralleled by an increased synthesis of collagens type I and III. This fact provides further evidence for a regulatory involvement of aminopropeptides in the biosynthesis of collagen.

Animals↗
PubMed1982

Assay and identification of histamine in human gastric aspirate by a fluorometric--fluoroenzymatic technique. Its application in patients with chronic duodenal ulcer.

Histamine assays can be unreliable in individual subjects or samples even though the particular method is in general working very well. Therefore the specificity and accuracy of histamine determination in the gastric aspirate of individual duodenal ulcer patients was thoroughly examined and shown to be satisfactory. Pitfalls of the fluorometric assay were investigated. A native (non-histamine) fluorescence in gastric aspirate which occurs before the addition of OPT was not removed by the original Shore procedure. In the combined assay (Dowex 50 + butanol extraction) this fluorescence no longer interferes with the assay. For the identification of histamine in a single gastric aspirate of an individual duodenal ulcer patient, the reversed blank (3 M HCl added to the reaction mixture before OPT instead after OPT), excitation and fluorescence spectra, the heating test with spectra recorded and the HMT test were found to be reliable. The formaldehyde test and the heating test without recording the spectra were useless since they gave false negative results. Since the HMT test was regarded as a reference method it was thoroughly investigated both by theoretical considerations (enzyme kinetics) and by a series of measurements in a single patient as well as in a group of nine subjects. Samples from the period of peak acid output in response to pentagastrin showed an average histamine concentration of about 8 ng/ml and a histamine output of 1.5 microgram/30 min.

Adult↗
PubMed1982

Laminin.

Explore the source record for details and available documents.

Animals↗
PubMed1981

[Transparent adhesive tape as postoperative dressing. Randomized, clinical study for comparison with a conventional dressing technic].

To evaluate the effect of a thin, transparent, adhesive and elastic polyurethane drape permeable only to gas and water vapor molecules but not to bacteria in comparison to a conventional drape for postoperative dressings, a randomized trial was conducted in 90 male and female patients. 44 patients had the transparent adhesive drape and 46 a conventional dressing. Both groups were reasonably well matched according to age, sex, height, weight and type of operation. There was no difference in healing of skin wounds. But reddening around the stitches was seen more often in patients with the conventional dressing than in those with the polyurethane drape (p less than 0.05). Surprisingly, most of the patients with the transparent drape (42 of 44) accepted it. The transparent adhesive drape was found to be much less expensive than the conventional dressing.

Adult↗
PubMed1981

[Structural and functional alterations of the mucosa of a jejunal segment, interposed isoperistaltically after total gastrectomy according to Longmire-Gütgeman (author's transl)].

Six patients had total gastrectomy because of carcinoma followed by jejunum isoperistaltic interposition according to Longmire. A jejunal biopsy was taken in every case during operation and three and six months later endoscopically for morphometric and functional evaluation of small bowel mucosa. Three months after the operation a rise of L-phenylalanin in vitro uptake, an increase in villus height, surface area and a deepening of the crypts with raised mitotic activity of the crypt cells was found. The ratio of villus height to crypt depth was increased, although not significantly. On the other hand the activity of sucrase was initially decreased. Six months postoperatively all parameters had become normal besides the disaccharidases. These changes may be due to adaptive mucosal hyperplasia after small bowel resection or to luminal mucosal damage followed by compensatory hyperregeneration. Finally a humoral stimulus for mucosal hyperplasia as a postoperative effect is discussed.

Biopsy↗
PubMed1980

Basal lamina glycoproteins are produced by neuroblastoma cells.

Murine neuroblastoma cells have been widely used as a model system for neuronal cells as they can be induced to differentiate in culture by various stimuli, such as dibutyryl cyclic AMP (dbcAMP), prostaglandin, and serum starvation. The cells respond with assembly of microtubules, leading to neurite outgrowth, with increased activity of neuronal-specific enzymes, tyrosine hydroxylase, choline acetyltransferase and acetylcholine-esterase, and synthesis of neurotransmitters. The differentiated cells lose tumorigenicity. Cell-to-substratum adhesion is evidently crucial for neurone extension in vitro. Neurite outgrowth is induced by treatments that increase cell-to-substratum adhesion in some neuronal cell cultures. We have now identified the major high molecular weight proteins synthesized and secreted by murine C1300 neuroblastoma cells as fibronectin, laminin and type IV procollagen, of which the latter two were also found to be deposited in pericellular matrix form.

Animals↗
PubMed1980

Characterization of pepsin fragments of laminin in a tumor basement membrane. Evidence for the existence of related proteins.

Laminin was extracted with neutral buffer from a tumor basement membrane and subjected to extensive degradation by pepsin. The treatment released two homogenous fragments P1 (Mr = 290,000) and P2 (Mr = 45,000) in addition to a mixture of smaller peptides. Fragments P1 and P2 together contained more than 90% of the disulfide bonds and accounted for about one third of the mass of laminin. Both peptides differed in amino acid composition, immunological properties and a complex chain structure demonstrating the existence of two disulfide-bonded domains in the molecule. Part of the laminin in the tumor matrix could only be solubilized by pepsin treatment and several fragments were purified. The major fragment P1i closely resembled P1 of soluble laminin in its chemical and immunological properties. Minor fragments Pa, Pb, Pc and Pd (Mr = 44,000-74,000) were only related to P1 or P2 in amino acid composition, chain pattern and antigenicity. The data were interpreted as indicating that proteins similar but not identical to laminin exist in the basement membrane and account for the minor peptide variants.

Amino Acids↗
PubMed1980

[Effect of planned treatment policy in patients with upper gastrointestinal bleeding using endoscopic neodymium-YAG laser therapy (author's transl)].

In a prospective trial with and without laser therapy the outcome on 105 patients was evaluated according to a defined protocol and terminology. Only patients with actively bleeding lesions during early endoscopy had laser therapy. Patients showing evidence of recent bleeding or no bleeding had none. Defects of the laser equipment or impossibility of reaching a bleeding lesion prevented its use in some patients (control group). There was no difference concerning rate of recurrent bleeding or mortality. Controlled trials with defined groups of patients are urgently needed.

Adolescent↗