Biomedical subjects

Wilfried Meyer

Publications and source records attributed to Wilfried Meyer.

25 records · Page 2Linked to original sources

PubMed2003

Histochemical analysis of glycoconjugates in the ceruminous glands of the North American raccoon (Procyon lotor).

The distribution and selectivities of glycoconjugates in the ceruminous glands of the North American raccoon (Procyon lotor) were studied by light and electron microscopic histochemical methods, particularly lectin histochemistry. In the modified apocrine glands present, the apocrine secretion mode was combined with exocytosis, whereby the secretory epithelium and the luminal secretion of the ceruminous glands exhibited considerable amounts of complex carbohydrates with various terminal sugars (alpha-D-mannose, beta-D-galactose, alpha-L-fucose, alpha-N-acetyl-galactosamine, beta-N-acetyl-D-glucosamine, N-acetyl-neuraminic acid). Alpha-L-fucose and N-acetyl-neuraminic acid were distinctly prominent in secretory granules or within the free surface coat of the plasma membrane of the glandular cells, as well as in the luminal secretion. Several free sugars (alpha-D-mannose, alpha-L-fucose, beta-D-galactose, beta-N-acetyl-D-glucosamine) were also detectable in the secretion of associated sebaceous glands. The ceruminous gland secretion may control viscoelasticity and/or bacterial degradation of the glandular secretion mixture to improve the protection of the external auditory canal against physical damage or microbial contamination.

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PubMed2003

Ultracytochemical demonstration of glycoproteins in the canine knee synovium.

By various ultracytochemical methods, glycoconjugates of the synoviocytes, the intercellular matrix and the wall of the small capillaries were studied in the synovial intimal tissues of the canine knee joint. Glycoconjugates with vicinal diol groups could be visualized in certain elements of the Golgi complex, lysosomes, vacuoles, the majority of intracellular cytomembranes, the surface coat of the plasma membrane and glycogen particles in type A cells. In type B cells, less-developed Golgi complexes, and fewer lysosomes and vacuoles were present in the cytoplasm than in that of type A cells. In contrast, a large number of cytoplasmic glycogen particles and abundant vicinal diol-containing groups in the surface coat of the plasma membrane became especially obvious in the B cells. Abundant neutral and acidic glycoproteins were observed in fibrous components in the intercellular matrix. In the small capillaries, strongly positive staining intensities for neutral and acidic glycoconjugates were observed in the basement membrane and perivascular connective tissue, as well as in the surface coat of the luminal plasma membrane of the endothelial cells, although to a somewhat weaker degree. Sialic acid, particularly, was notable in the surface coat of the latter cells. In addition, glycoproteins in the type A cells were shown by lectin ultracytochemistry to contain a variety of saccharide residues such as alpha-D-mannose, alpha-D-glucose, alpha-L-fucose, N-acetyl-beta-D-glucosamine, and N-acetyl-neuraminic acid, which were also found in the plasma membrane of the B cells. The properties of the glycoconjugates found are discussed in relation to the basic functions assigned to the synovial membrane of the canine knee joint.

Animals↗

PubMed2003

Histochemistry of glycoconjugates in the nasolabial skin of the Japanese serow (Capricornis crispus, Artiodactyla, Mammalia) with special reference to glandular structures.

The histochemistry of glycoconjugates in the nasolabial skin of the Japanese serow ( Capricornis crispus ) was studied by light microscopic histochemical methods, particularly lectin histochemistry. The eccrine glands present exhibited neutral and acidic glycoconjugates with different saccharide residues (alpha-L-fucose, beta-D-galactose, beta-N-acetyl-D-glucosamine, alpha-D-galactose and N-acetyl-neuraminic acid) especially in the cells of the secretory acini, the free surface of the collecting duct cells also showed distinct positive reactions with most of the histochemical methods. The thick epidermis of the nasolabial skin contained smaller amounts of glycoproteins. The results obtained are discussed with regard to possible functions of the glandular secretions. This substance mixture may particularly improve water retention on the skin surface, and protect against physical damage as well as microbial contamination. There seem to be no basic differences of muzzle functions between wild and domesticated bovine species.

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PubMed2003

Surface properties of the skin of the pilot whale Globicephala melas.

On the skin surface of delphinids small biofoulers are challenged to high shear water flow and liquid-vapor interfaces of air-bubbles during jumping. This state of self-cleaning is supported by the even, nano-rough gel-coated epidermal surface of the skin. The present study focussed on the intercellular evolution of gel formation and the chemical composition of the gel smoothing the skin surface of the pilot whale, Globicephala melas, using X-ray photoelectron spectroscopy (XPS) in combination with cryo-scanning electron microscopy (CSM), and transmission electron microscopy (TEM). In the superficial layer of the epidermis, the stratum corneum, intercellular material was shown by electron optical methods to assemble from smaller into larger covalently cross-linked aggregates during the transit of the corneocytes towards the skin surface. XPS measurements showed that the surface of the skin and the intercellular gel included approximately the same amounts of polar groups (especially, free amines and amides) and non-polar groups, corresponding to the presence of lipid droplets dispersed within the jelly material. It was concluded from the results that the gel-coat of the skin surface is a chemically heterogeneous skin product. The advantages of chemically heterogeneous patches contributing to the ablation of traces of the biofouling process are discussed.

Animals↗

PubMed2002

Effect of hypercholesterolemia on expression and function of vascular soluble guanylyl cyclase.

BACKGROUND: Vasorelaxation to endothelial NO is mediated by activation of soluble guanylyl cyclase (sGC) and impaired by hypercholesterolemia in animals and humans. We investigated whether hypercholesterolemia impacts expression and function of sGC. METHODS AND RESULTS: White New Zealand rabbits (n=10 per group) received a standard diet for 16 weeks (SD16) (n=20) or 32 weeks (SD32) and a cholesterol diet (7.5 g/kg) for 16 weeks (CD16) (n=20) or 32 weeks (CD32), respectively. Another group received cholesterol diet for 16 weeks followed by standard diet for 16 weeks (CD/SD). Aortic expression of the alpha1-subunit of sGC (sGC-alpha1) and beta1-subunit of sGC (sGC-beta1) was assessed by Western blot. Function was measured by aortic relaxation to S-Nitroso-N-acetyl-D, L-penicillamine (SNAP) and sGC activity in aortic cytosols. Hypercholesterolemia induced an upregulation of sGC-beta1 in CD16 (3.5+/-0.4-fold, P<0.001 versus SD16) and CD32 (4.0+/-0.4-fold, P<0.001 versus SD32). A similar increase was found for sGC-alpha1. In striking contrast, basal and NO-stimulated sGC activities in aortic cytosols of CD16 were only slightly enhanced (1.4-fold, P<0.05). Furthermore, the vasodilator potency of SNAP (EC50 in -logM) was 10-fold lower in CD16 (6.76a+/-0.09) than in SD16 (7.66+/-0.14, P<0.01). The increase of sGC expression was completely reversible, as indicated by comparable sGC-beta1 amounts in SD32 and CD/SD (1.2+/-0.1-fold, P>0.05). Immunohistochemical analysis suggests that a great portion of the overexpressed sGC is located in intimal lesions. Additional experiments showed that increased vascular superoxide production induced by 6-anilino-5,8-quinolinedione (LY85385) reduces sGC-activity but increases sGC-expression. CONCLUSIONS: These results suggest that hypercholesterolemia induces a reversible overexpression of a dysfunctional vascular sGC, which may contribute to the pathogenesis of atherosclerosis.

Aminoquinolines↗

PubMed2002

The architecture of growing compact bone in the dog: visualization by 3D-reconstruction of histological sections.

The three-dimensional architecture of growing canine compact bone was investigated by generating a composite virtual model including both cellular and extracellular elements. Serial trichrome-stained histological sections were prepared from samples of the diaphysis of the humerus of six week old Beagle puppies. Identical fields of vision were recorded in consecutive sections, preprocessed in Adobe Photoshop 5.5, and then transferred into the program AVS/Express for 3D-reconstruction and visualization. Based on two different but integrated reconstruction techniques a hybrid model was created, depicting shape and orientation of bony trabeculae as well as the distribution of osteoblasts. This virtual model could be explored and navigated in with real time interactivity, and thus disclosed the specific architectural characteristics of immature compact bone. In young puppies, bone tissue of the corpus humeri forms a labyrinth of communicating osseous walls which are covered with a multitude of osteoblasts. These results are discussed in relation to findings in adult dogs.

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PubMedDate not supplied

[Skin layer thickness at the ear of the domesticated pig , with special reference to the use of the ear integument for human dermatological research].

Based on a shrinkage-free methodical approach (special plastic resin embedding, frozen section technique) and histological routine staining, the thickness of the different skin layers was measured from 15 regions of the outer and the inner side of the porcine auricle. Mean thickness values were for the str. corneum: 19 microns outside/20 microns inside, vital epidermis without ridges: 52 microns outside/56 microns inside, dermis: 1175 microns outside/1112 microns inside, hypodermis: 1024 microns outside/741 microns inside, perichondrium: 295 microns outside/220 microns inside. When both sides of the auricle were compared, it became obvious that the outer side generally had a thicker dermis (1140-1290 microns) and hypodermis (780-1150 microns), whereas the inner side had a thicker vital epidermis (50-60 microns) and deeper epidermal ridges (145-165 microns). The results are discussed with regard to corresponding findings from the human skin, and one region of the outer side of the porcine auricle is recommended as suitable for human dermatological research.

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