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Biomedical subjects

U Welsch

Publications and source records attributed to U Welsch.

At least 91 records · Page 5Linked to original sources
PubMed1990

Histochemical and biochemical observations on milk-fat-globule membranes from several mammalian species.

A specific secretory product of the lactating mammary gland are triglyceride fat globules which are enveloped by a very complex membrane, the milk fat globule membrane (MFGM). In different mammalian species (man, rhesus monkey, horse, goat, sheep, cow, grey seal, camel, alpaka) the glycoproteins of this membrane have been analyzed by gel electrophoresis, Western blotting and lectin histochemistry. A remarkable intra- and interspecific variability of these glycoproteins has been detected pointing to so far unknown physiological adaptions, which may play a role in the intestine of the new born. High molecular weight glycoproteins, with a very high degree of glycosilation have been found only in primates, horse and camel; the MFGMs of the true ruminants (cow, sheep, goat) are characterized by specific glycoproteins of a lower molecular weight range.

Animals↗
PubMed1990

Carbohydrate components of human immunodeficiency viruses type I and II.

The terminal carbohydrate residues of HIV I and II were detected by ferritin labeled lectins in electron microscopy. Different cell lines, which were infected with HIV I and II, expressed different terminal carbohydrate residues, which could also be detected on the viral envelope by electronmicroscopy. Especially N-Acetylgalactosamine residues were detected by Vicia villosa agglutinin only on Jurkat cells. This may have functional implications, since this lectin recognizes contrasuppressor T cells.

Carbohydrate Metabolism↗
PubMed1989

Lectin-binding studies of a human skin mastocytoma.

A solitary mastocytoma of the skin was investigated to assess the lectin-binding pattern of human mast cells. Of 18 Fluorescein-labelled lectins tested, nine reacted with mast cell granules. While lectins recognizing N-acetylgalactosamine or fucose residues did not stain mast cells, lectins with binding sites for N-acetylglucosamine, alpha-methyl mannopyranoside, galactose, complex carbohydrates of N-acetyl-lactosamine type and sialic acid gave a positive reaction.

Humans↗
PubMed1989

[Micromorphology of rigor mortis in human skeletal muscle].

Following our examination on rat muscle, it was investigated, whether alterations, observed in semi thin sections and by TEM could be used for forensic purposes. Investigated were extension of stiffened muscles. Samples of various muscle groups were taken at different time intervals before and after breaking the rigor muscle fibers. They were examined by light and electron microscopy. Results on the development and spontaneous disappearance of rigor mortis during the early and intermediate post mortem period are almost equivalent to those found by experiments on animals. Results concerning the breaking of rigor mortis, however, are sometimes considerably more discrete and diverge substantially. Because of artifacts, especially during the transport of the corpse, the interpretation is more difficult. The use of other techniques combined with drawing out muscle samples immediately at the place, where the corpse is found, may optimize the results.

Humans↗
PubMed1988

Histochemistry of mucosubstances in Brunner's-gland cells and duodenal goblet cells of two New World monkey species (Saimiri sciureus and Saguinus fuscicollis).

Duodenal goblet cells and Brunner's-gland cells obtained from two species of New World monkeys (Saimiri sciureus and Saguinus fuscicollis) were studied using conventional histochemical methods and by applying a panel of 17 labelled lectins. The secretions of both goblet and Brunner's-gland cells were found to contain neutral mucosubstances, while those of goblet cells also exhibit acid and sulphated carbohydrate components. Lectin binding studies allowed a more detailed analysis of the mucus glycoproteins. Marked differences between the two examined species were not detected. N-Acetyl-galactosamine, galactose, fucose and N-Acetyl-glucosamine were found to be the predominant sugar residues in Brunner's-glands glycoproteins, with mannose and glucose being only minor components.

Animals↗
PubMed1988

Structural, histochemical and biochemical observations on horse milk-fat-globule membranes and casein micelles.

Horse milk fat globules (MFGs) and casein micelles were studied using freeze fracturing, freeze etching and thin-section electron microscopy, as well as lectin histochemistry, gel electrophoresis, and Western blotting. Horse MFGs were found to be relatively small, their average volume-surface diameter being about 2.75 microns. The MFG membrane is composed of three layers: an inner proteinaceous coat occasionally having a paracrystalline substructure, a unit membrane, and a prominent filamentous glycocalyx. The last is rich in glycoconjugates, as revealed by its binding of various lectins. In addition, the glycocalyx binds cationized ferritin, which indicates the presence of negative electric charges. Gel electrophoresis revealed the presence of high-molecular-weight glycoproteins in the MFG membrane of horse milk. Such glycoproteins are also present in human MFG membranes but are absent in the bovine MFGs. The casein micelles in horse milk are relatively large, their average volume-surface diameter being about 200 nm.

Animals↗
PubMed1988

Lectinhistochemical observations on the bronchial glands and the goblet cells of the airway epithelium of marine diving mammals.

Carbohydrate components were investigated in the bronchial glands and goblet cells of two species of seals with different diving habits (Weddell seal, Crabeater seal). Bouin-fixed tissue was incubated with various fluorescein-iso-thiocyanate-conjugated lectins (WGA, RCA I, PNA, PHA I, HPA, GSA I, DBA, Con A, LFA, SBA, UEA I), additionally PAS- and HID-reactions as well as Alcian Blue stains were applied. The two species differ in respect of their carbohydrate histochemistry, e.g., the PAS reaction gives only a faint stain at the apical membrane in the bronchial glands of the Weddell seal, whereas in the Crabeater seal several cells give a positive reaction in the entire cytoplasm; or RCA I has only few binding sites at the apical membranes of the bronchial glandular cells of the Weddell seal whereas many cells of Crabeater bronchial glands react strongly positive. It is concluded that the secretory products of the bronchial glands of the long- and deep-diving Weddell seal are relatively poor in mucins, which is in contrast to other mammals studied so far.

Animals↗
PubMed1988

Glycoprotein filament removal from human milk fat globules by heat treatment.

Freeze-etch electron microscopy was applied to milk fat globules to observe surface details. A remarkable array of filaments, approximately 0.5 micron in length, was seen on human, but not bovine, globules. Heating human globules removed the filaments that were identified as high molecular weight glycoproteins by freeze-etch and gel electrophoretic analysis of the heating medium. Extraction of these globule glycoproteins was slight at 60 degrees C for one minute but substantial and tending to plateau at 80 degrees C for one minute. Such heat-induced alterations of the milk fat globule surface provide an alternative or additional explanation to milk lipase inactivation as the cause of reduced milk fat absorption from heated milk by the preterm infant.

Animals↗
PubMed1987

Fine structure of the ganglion of Cephalodiscus gracilis (Pterobranchia, Hemichordata).

The ganglion of Cephalodiscus gracilis M'Intosh 1882 is entirely intraepithelial and located in the dorsal epidermis immediately behind the tentacular apparatus that is formed by the mesosome (collar). A characteristic feature of the ganglion is a well-developed neuropile in which different types of nerve fibres can be discerned, many of which contain small granules with electron-dense contents. There are no glia-like cells in association with these fibres. Only slender basal processes of epidermal epithelial cells traverse the neuropile. In the depth of the epithelium the neuropile borders the epidermal basal lamina; apically it is covered by a layer of cell bodies, the majority of which belong to what appear to be ordinary ciliated epidermal cells. Besides these epidermal cells the perikarya of two additional types of cells, which are considered to be neurons, can be discerned. One type is characterised by many rough endoplasmic reticulum cisterns and mitochondria, the other by abundant small, electron-dense granules. The nuclei of these cells are comparatively pale and contain a prominent nucleolus. The neuron cell bodies do not form a distinct layer; but they are loosely distributed somewhat deeper than those of the ordinary epidermal cells. They probably send off an apical process to the epidermal surface and a basally directed one into the neuropile. The ganglion has been compared to the nervous systems in cnidarians, some spiralians, and especially other hemichordates, echinoderms, and chordates; it is found to be of primitive rather than degenerate nature. Furthermore, the possible functional significance of its close connection to the food-capturing tentacular apparatus is discussed.

Animals↗
PubMed1987

Histological, histochemical, and fine structural observations on the spleen of seals.

Spleens of three species of Antarctic seals with different diving habits (Weddell seal, crabeater seal, and fur seal) have been studied with histological, histochemical, and electron microscopic methods. The spleens can be classified as nonsinusoidal, with capsule and trabeculae rich in innervated smooth muscle cells. The trabecular system is particularly well developed in the deep- and long-diving Weddell seal. As in other mammals the pulp can be divided into white and red pulp. In the white pulp, periarteriolar lymphatic sheaths and secondary lymphatic nodules occur; both are surrounded by a marginal zone rich in macrophages and eosinophils. The nodules can be observed frequently, which is in accordance with abundance of plasma cells in the red pulp. Well-developed white pulp and numerous plasma cells and eosinophils obviously reflect a high load of nematodes, which have mainly been found in lung and stomach. Additionally, in the red pulp morphological evidence for the following functions has been found: destruction of erythrocytes, erythropoiesis, and thrombopoiesis. In respect to blood flow through the red pulp, we interpret our observations in the following way: terminal branches of arterioles open into the space between the fibroblastic reticulum cells; blood draining from here is collected into pulp veins, which are mainly found near the trabeculae. Thus, the seals have an open vascular compartment in their spleens, as also occurs in the cat. The red pulp is innervated by numerous nerve fibers that seem to include both cholinergic and adrenergic ones. The target cells of these fibers seem to be the fibroblastic reticulum cells, whose state of contraction may influence the direction of blood flow through the red pulp.

Animals↗
PubMed1984

Freeze-fracture study of the turtle lung. 2. Rod-shaped particles in the plasma membrane of a mitochondria-rich pneumocyte in Pseudemys (Chrysemys) scripta.

In thin sections of the lung of the fresh-water turtle Pseudemys (Chrysemys) scripta some pneumocytes can be distinguished from the remaining pulmonary epithelial cells by a larger amount of mitochondria. In these cells the typical features of type-I and type-II cells are absent. Freeze-fracture replicas reveal rod-shaped particles in the apical plasma membrane of a small population of pneumocytes, which by cytological criteria seem to be identical with the mitochondria-rich cells observed in thin sections. It is assumed that these cells represent a distinct type of pneumocytes in the turtle lung and that they are a member of the group of mitochondria-rich cells present in some ion-transporting epithelia. The function of these cells in this location remains to be determined.

Animals↗
PubMed1984

Internalization of ferritin-concanavalin A by the lactating mammary cell in vivo.

Ferritin-concanavalin A (Fer-Con A) was used to label the apical plasma membrane of the lactating cell to determine whether membrane internalization takes place. Rat glands were infused in vivo via the teat with 0.2 mg of Fer-Con A in 0.2 ml tris buffer (pH 7.0) containing 0.1% trypan blue, the latter acting as a marker of the infusate. Tissues were obtained from separate animals 5, 10 and 60 min postinfusion. Fer-Con A was seen in alveolar lumina bound to the outer surfaces of apical plasma membrane, microvilli and milk fat globules. It was observed within lactating cells on the inner membrane surfaces of endocytotic vesicles, Golgi cisternae, and secretory vesicles containing casein micelles, and in multivesicular bodies and lysosomes. Internalization of the ferritin-lectin conjugate into casein-containing secretory vesicles was detectable in the 5-min postinfusion tissue. Lysosomes were the only structures in control tissue that contained particles bearing some resemblance to Fer-Con A. The data provide evidence that apical plasma membrane is internalized and distributed to a number of intracellular compartments.

Animals↗
PubMed1984

Intramammary infusion technique for genetic engineering of the mammary gland.

The mammary gland is an appropriate substrate for genetic engineering because of its capacity to synthesize and secrete molecules of biological importance. An approach to mass production of such molecules involves transfer of genes into the lactating cell by infusion via the teat and duct system. We describe an infusion technique with the rat, a useful animal in which to develop such technology. By dye maker, trypan blue, and the ultrastructural marker, ferritin-concanavalin A, infusions by this route can permeate the entire gland and deliver molecules to apical membranes of lactating cells.

Animals↗
PubMed1983

Freeze-fracture study of the turtle lung. 1. Intercellular junctions in the air-blood barrier of Pseudemys scripta.

The air-blood barrier in the lung of the turtle Pseudemys scripta was studied by means of freeze-fracture replicas in an attempt to give a detailed account on the structural organization of the intercellular junctions. Between the pneumocytes, zonulae occludentes containing 4-19 strands in the apico-basal direction are present; they are considered to be physiologically very tight. In the endothelium, fasciae occludentes, i.e., discontinuous occluding junctions can be found, composed of up to 4 strands. These junctions are regarded to be very leaky. The findings are discussed in relation to recent physiological results, suggesting that in comparison with 'dry' mammalian lungs, the turtle lung is a rather wet lung based on its much larger transcapillary fluid filtration into the interstitium. In addition, small maculae communicantes are demonstrated between the pneumocytes; they possibly serve for metabolic coupling.

Animals↗