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M Egerbacher

Publications and source records attributed to M Egerbacher.

30 records · Page 2Linked to original sources
PubMed1998

Confocal laser scanning microscopy of chondrocytes in vitro: cytoskeletal changes after quinolone treatment.

The use of quinolone antibiotics would be significant for chronically diseased children (e.g., cystic fibrosis) as a prophylactic long-term treatment. However, quinolones were shown to cause cartilage damage in experimental animals when administered during certain developmental stages. In the present study, the effect of quinolones on chondrocytes was studied in a cell culture model in order to avoid animal experiments, to investigate the influence of single factors, and to open up the possibility to test human tissue. Chondrocytes were obtained from hip joint cartilage of 3 to 4-weeks-old rats and cultured in control medium or quinolone-supplemented medium. It was shown that quinolones heavily disturbed adhesion of chondrocytes to the culture dish, accompanied by changes in cell shape and cytoskeletal morphology. Reduction of filamentous actin (stress fibers) and disintegration of vimentin fibers was demonstrated by immunofluorescence and evaluated by confocal laser scanning microscopy. In contrast, distribution and amount of the adhesion molecule integrin alpha 1 did not change. Results of the present study indicate that quinolones disturb the adherence mechanism of chondrocytes and lead to cytoskeleton changes.

Animals↗
PubMed1997

Expression of glial and neuronal marker proteins (S-100, glial fibrillary acidic protein, and neuron-specific enolase) by myxoid cells in the human larynx.

Areas of myxoid connective tissue were regularly found in the aryepiglottic and vestibular folds of operative resections (n = 10) or fresh postmortem specimens (n = 5) of the human larynx. Myxoid tissue was often attached to elastic cartilage (epiglottic, arytenoid, and corniculate cartilage) or spatially related to mucosal glands. This was characterized by ramified cells (myxoid cells) in an ample acidic matrix with few strands of collagen fibers. Extracellular matrix showed alcianophilia at pH 2.5 and metachromasia while tissue digestion with hyaluronidase abolished these staining reactions. Immunohistochemistry revealed reactivity of myxoid cells for S-100 alpha and S-100 beta protein, glial fibrillary acidic protein, and neuron-specific enolase. Elastic cartilage chondrocytes also stained for these markers while fibroblasts remained unstained. Reactivity for identical-neuroectodermal marker proteins of myxoid cells and chondrocytes indicated their close relationship. The presence of myxoid tissue in the larynx, as evidenced by stellate cells immunoreactive for neuroectodermal marker proteins, should be considered when using these markers in diagnostic pathology.

Chondrocytes↗
PubMed1997

Distribution of S-100 protein and its subunits in bovine exocrine glands.

The distribution of S-100 protein and its alpha- and beta-subunits in bovine exocrine glands was studied by indirect immunohistochemistry. The entire spectrum of salivary glands, glands of the respiratory tract, intestinal glands, male and female genital glands, and skin glands was examined. S-100 and its beta-subunit were identified in most serous secretory cells of mixed salivary glands, although secretory acini in some serous glands remained unreactive for these antigens. Mucous cells were constantly negative; mucoid cells were positive in the lacrimal and Harderian gland. The alpha-subunit of S-100 protein was identified in serous cells but the staining reaction was faint. Subunits of S-100 showed a characteristic distribution along the excretory duct systems of compound glands: S-100 and the beta-subunit were present in intercalated duct epithelium, while striated duct epithelium stained for S100-alpha. Therefore, it is suggested that S100-alpha is related to resorption and secretion in striated ducts, while S100-beta may govern acinar exocytosis and probably regulates proliferation and differentiation of glandular cells. Differing staining intensities for S-100 and its subunits in secretory cells of exocrine glands most probably indicate functional differences with regard to secretory activity and the cell cycle.

Animals↗
PubMed1997

Sphincters of canine hepatic sublobular veins respond to endothelin-1 and 3.

The dog has been used repeatedly as a model in liver transplantation research. The microcirculation and its regulatory mechanisms play a crucial role during ischemia and reperfusion. Little is known about the role of venous sphincters in regulating blood flow in the dog liver. Hence, we performed this study to elucidate their potential role in regulating local blood flow. In 14 dogs mean systemic (MSP) and mean portal venous pressure (MPP) were measured. Light and electron microscopy (scanning and transmission) of tissue sections and vascular corrosion casts were used to elucidate the microvascular morphology. Immunocytochemistry was applied to identify smooth muscle cells and the innervation of venous sphincters. Endothelins 1 and 3 were injected to find whether the hepatic venous sphincters are sensitive to these vasoactive agents. Tufts of smooth muscle cells were found in the sublobular veins (SLV; 100 to 250 microm in diameter), that reduced the luminal diameters of veins by 34%. Nerve endings were not observed close to these venous sphincters. The MSP and MPP were 75.3+/-2.4 mmHg and 8.9+/-0.95 mmHg, respectively. Treatment with 1.0 microg/kg of endothelin-1 (ET-1) significantly increased the MSP, the MPP and the percentage of focal venous sphincter contraction by 39% (105+/-4.7 mmHg), 43% (12.8+/-1.7 mmHg) and 57% (53.5+/-4.7), respectively (P <0.01). Treatment with ET-3 caused a significant (P <0.01) decrease in the MSP, the MPP and the percentage of sphincter contraction by 19% (61.0+/-2.2 mmHg), 39% (5.8+/-2.9 mmHg) and 38% (20.9%+/-3.15). Sinusoids did not contain sphincters. Hepatic arterioles and central veins were not affected by ET-treatment. The contraction of SLV sphincters correlated with increases in MPP (r=0.81, P <0.01) and was related to the MSP (r=0.67, P <0.01). These data show that the smooth muscle sphincters in SLV of the dog liver are involved in the local regulation of blood flow and that these sphincters are stimulated by non-neurogenic mechanisms. These sphincters contract in response to ET-1 and relax in response to ET-3. Since ET-1 is released during and/or causes inflammation, e.g., during ischemia and reperfusion, its antagonists might be of benefit during transplantation reperfusion of liver.

Actins↗
PubMed1997

Myxoid tissue: its morphology, histochemistry, and relationship with other supporting tissues.

Myxoid tissue was studied in the supporting organ of the cat epiglottis ("epiglottic cartilage"). Under the light microscope, myxoid tissue was characterized by stellate cells placed into an avascular acidic extracellular matrix. This extracellular matrix was alcianophilic at pH = 2.5, reacting with the colloidal iron stain, and staining metachromatically with toluidine blue O at pH = 5.0. Treatment of sections with testicular hyaluronidase abolished these reactions. In addition, staining persisted after methylation/saponification pretreatment, indicating hyaluronic acid as the main acidic component of myxoid extracellular matrix. Under the electron microscope, myxoid extracellular matrix formed flocculent electron dense precipitates. Stellate myxoid cells were characterized by bundles of intermediate (8 nm) cytoplasmic filaments. Myxoid cells were devoid of a basal lamina, contained a few small lipid droplets, and stored some glycogen. Bundles of collagen fibrils, 80-120 nm in diameter, were seen in myxoid areas. Myxoid cells reacted to S-100 protein, glial fibrillary acidic protein, and neuron specific enolase. Moreover, in adult animals, myxoid cells stained for neurofilament protein 200. All these markers were also present in chondrocytes of elastic and fibrous cartilage, indicating a close relationship between myxoid cells and chondrocytes. This was supported by the observation of continuous transitional forms of myxoid tissue into elastic or fibrous cartilage. In 8-week-old kittens, the supporting organ of the epiglottis was found mainly to consist of myxoid tissue with only a few interspersed islets of chondrocytes. It is therefore concluded that myxoid tissue can serve as a precursor of cartilage.

Adipose Tissue↗
PubMed1997

Localization of endothelin-1 and endothelin-3 in the cochlea.

The distribution of endothelin-1 (ET-1) and endothelin-3 (ET-3) was studied by indirect immunostaining of decalcified guinea pig and rat cochleae. No species differences were observed. Perikarya and processes of spiral ganglion cells were highly reactive for both ET-1 and ET-3. The epithelial lining of the cochlear duct stained for ET-1 and ET-3, but reactivity for ET-1 was higher in the lining cells of the inner sulcus, Claudius', and Hensen's cells, while the tympanic covering layer of the basilar membrane stained stronger for ET-3 compared to ET-1. In the stria vascularis, all cell types stained for ET-3, while marginal cells were more reactive for ET-1. Spiral ligament fibroblasts were reactive for ET-1, but not for ET-3. Connective tissue cells of the spiral limbus stained for both endothelins. The region of synapses on outer hair cells reacted for ET-1 and ET-3 but sensory cells remained unstained. Endothelins are discussed to act as modulatory peptides, possibly interfering with nitric oxide, prostaglandins, and atrial natriuretic peptide in the lateral cochlear wall (lateral cochlear wall, i.e. stria vascularis and spiral ligament). The occurrence of endothelins in cochlear neurons suggest their potential role as neurotransmitters.

Animals↗
PubMed1996

Pulmonary venous sphincters in cattle.

BACKGROUND: The pulmonary veins of rats have regular focal narrowing by tufts of smooth muscle (sphincters) that can contract in response to a variety of stimuli, but these structures are not well studied in other species, and there is little information about their innervation and control. METHODS: The pulmonary veins of 21 cattle were cast with methacrylate, and the casts were studied by scanning electron microscopy, or the fixed tissue was studied by light microscopy with immunocytochemistry and transmission electron microscopy. RESULTS: Constrictions occurred in series along the course of veins (9.6/500 microns), giving the cast veins a string-of-pearl look, with narrowing of 33-81% of the outer diameter. No resin appeared beyond the most narrowed veins. The percentage of contraction did not correlate with the diameter of the veins. With immunohistochemistry using antibodies to S-100, protein gene peptide 9.5, neuron-specific enolase, neurofilament 200, and glial fibrillary acidic protein and with transmission electron microscopy, we could identify no neuronal elements associated with the venous smooth muscle tufts. Bronchial smooth muscle bundles in the same sections stained positively. CONCLUSIONS: The veins of cattle are unlike the rat because the focal venous smooth muscle protrudes deeply into the venous lumen and may completely obstruct perfusion. If the focal venous muscle has no innervation (this study) and can constrict without blood flow (as shown previously), then the venous constriction and, hence, local blood flow regulation must be controlled by local mediators.

Animals↗
PubMed1995

Morphology, histochemistry, and differentiation of the cat's epiglottic cartilage: a supporting organ composed of elastic cartilage, fibrous cartilage, myxoid tissue, and fat tissue.

BACKGROUND: In carnivores, the supporting organ of the epiglottis is usually called "epiglottic cartilage" (EC) although it is composed of elastic cartilage and unilocular fat storing cells. We studied the cat's EC in order to decide whether these fat storing cells are true adipocytes or fat storing (dedifferentiated) chondrocytes. METHODS: ECs were studied in cat embryos at gestation days 40 and 60, in newborn, postnatal, and adult cats. We used classical staining methods, immunohistochemistry, and transmission electron microscopy to identify the different kinds of tissues contributing to the EC and to follow their differentiation. RESULTS: The cat's EC was defined by a layer of coarse collagen fibers representing a tunica albuginea. This tunica covered irregularly formed and irregularly sized areas of elastic cartilage, fibrous cartilage, myxoid tissue, and lobules of unilocular fat cells. All these tissue showed regular morphology. Adipocytes were provided with continuous basal laminae and fat lobules were well supplied with capillaries. Alcianophilia of ground substance was observed in all tissue components but was strongest in elastic cartilage. Most islets of elastic cartilage adhered to the tunica albuginea of the EC at one surface and were connected to the opposite surface by coarse strands of connective tissue traversing the organ. Intercalated areas of fibrous cartilage contained fuchsinophilic collagen bundles. Myxoid tissue was characterized by stellate cells in alcianophilic ground substance with intermingled fuchsinophilic bundles. All kinds of supporting tissues combined with each other without clear demarcation. Immunohistochemistry revealed strong reactivity for S-100 of chondrocytes, myxoid cells, and fat cells. Chondrocytes and myxoid cells also stained for glial fibrillary acidic protein, neurofilament protein 200, and neuron specific enolase. During development, condensation of mesenchymal cells indicated the blastema of the EC at gestation day 40. At day 60, delicate collagen fibrils indicated the future tunica albuginea, faint alcianophilia was noted in the ground substance, and multilocular fat cells were scattered throughout the blastema. At birth, alcianophilia was moderate and multilocular fat cells were numerous. Three weeks after birth, single and grouped unilocular fat cells were seen, alcianophilia of ground substance was prominent, and former blastema cells presented as ramified myxoid cells. Eight weeks after birth, the EC primarily consisted of myxoid tissue, but the first islets of cartilage were seen in the center of myxoid areas. Unilocular fat cells already formed lobules. CONCLUSIONS: These results show that in the cat EC a) differentiation of adipocytes precedes differentiation of all the other tissue components, and b) differentiation of myxoid tissue precedes differentiation of cartilage. It is concluded that myxoid tissue may serve as a precursor of fibrous and elastic cartilage.

Adipocytes↗
PubMedDate not supplied

Development of pancreas.

Pancreatic development is reviewed in man, mammals, and birds. Anatomical differences and differing topography of pancreatic excretory ducts are described in a series of mammalian species. Species differences are discussed with respect to their embryological significance. The developmental potency of the hepatopancreatic ring is stressed. Cytodifferentiation of exocrine and endocrine cells is considered.

Animals↗
PubMedDate not supplied

Morphology of the pancreatic duct system in mammals.

The morphology of pancreatic excretory duct segments was reviewed in mammals. The fine structure of the epithelial lining was described in intercalated ducts, intra- and extralobular ducts, and in major pancreatic ducts. Morphological characteristics of the various cell types comprising to the duct epithelium were detailed. Principal cells in the epithelial linings of interlobular and major pancreatic ducts ("Wirsungiocytes") were discussed with respect to their appearance as either clear or dark variety. In addition, the capacity of both these cell types in elaborating mucoid glycoprotein, secretions was considered and intra- and extraepithelial mucoid glands of major pancreatic ducts (ductular glands, accessory glands) was described. Finally, the wall composition of the various excretory duct segments was described. The presence of smooth muscle cells, myofibroblasts, and a peculiar periductal vascular plexus in major interlobular ducts and in main pancreatic ducts was emphasized.

Animals↗