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Biomedical subjects

M Egerbacher

Publications and source records attributed to M Egerbacher.

At least 19 recordsLinked to original sources
PubMed2003

Morphological changes of the endometrial epithelium in the bitch during metoestrus and anoestrus.

Although cyclic changes of the endometrium in dogs involving both stromal and glandular compartments have been described, the fate of the surface epithelium after progressive growth and secretion is still unclear. In the present study, uteri of 43 healthy bitches in metoestrus and anoestrus were examined macroscopically and histologically. Tissue biopsies were taken from three different locations (cranial and middle parts of uterine horns and bifurcation). The stage of the oestrous cycle was determined by evaluation of progesterone and oestradiol levels in plasma hormone and was also confirmed clinically. Crypts formed in the luteal phase were covered with a columnar epithelium which gradually underwent fatty degeneration. In addition, the stromal part of the crypts disappeared and finally, in early anoestrus, epithelial sheaths desquamated and shed off into the uterine lumen. The surface epithelium was replaced by new cuboidal cells proliferating and migrating from the glandular openings. These findings were confirmed by oil red O staining and immunohistochemical detection of proliferation with Ki-67 marker.

Anestrus↗
PubMed2002

Integrins and extracellular matrix proteins in the human childhood and adolescent growth plate.

Interaction of chondrocytes with the surrounding matrix significantly influences differentiation and growth. These processes involve cell surface proteins, particularly integrins. The aim of this study was to compare the expression of integrins (alpha1, alpha2, alpha3, alpha5, alpha6, alphav, beta1, beta3, and beta5 subunits) together with matching binding proteins in human childhood and adolescent growth plate cartilage using immunohistochemistry. Integrin beta1 was detected in all chondrocytes of the growth plate cartilage, beta3 only in osteoclasts of the opening zone, and beta5 in hypertrophic chondrocytes and osteoblasts. Integrin alpha1, alpha2, and alpha5 subunits were expressed by chondrocytes in the proliferative and hypertrophic zone as well as in osteoblasts and osteoclasts. Integrin av and alpha6 subunits were present in chondrocytes of all zones, alpha3 only in osteoclasts. Collagen type II and fibronectin were seen throughout the growth plate, collagen type X in the hypertrophic zone, collagen type I in the ossifying trabecules. Laminin was expressed by chondrocytes in the resting zone and more weakly in the proliferative zone, collagen VI was present in the pericellular and interterritorial matrix in all zones of the growth plate. These results differ from previous reports on the distribution of integrins in the fetal growth plate. However, there was no difference in integrin expression in children before and during puberty. Our results indicate that integrin expression is not influenced by endocrine factors during sexual maturation and suggest that the process of skeletal maturation is not regulated via altered integrin expression.

Adolescent↗
PubMed2002

Estrogen receptor-alpha and estrogen receptor-beta are present in the human growth plate in childhood and adolescence, in identical distribution.

OBJECTIVE: To localize estrogen receptor-alpha (ER-alpha) and estrogen receptor-beta (ER-beta) within the growth plate and adjacent bony tissue of children in the prepubertal and pubertal age period. METHODS: Tissue was taken during orthopedic surgery (epiphysiodesis) for correction of congenital or traumatic leg length difference in 2 prepubertal females and 2 adolescent males. Immunohistochemistry was performed on paraffin-embedded or cryostat sections by using commercially available rabbit polyclonal antibodies for ER-alpha and ER-beta. RESULTS: Both ER-alpha and ER-beta were detected within the growth plate in all sections investigated. Immunostaining was restricted to hypertrophic chondrocytes. In the bony tissue adjacent to the growth plate, osteoblasts stained positive for both ER-alpha and ER-beta, whereas osteocytes and osteoclasts were negative. Staining with ER-alpha was mainly nuclear but some cells also showed cytoplasmic signals, while ER-beta staining was predominantly cytoplasmic, only few nuclei stained positive. There was no difference in the local distribution of both ERs between tissue from prepubertal and pubertal patients. CONCLUSION: Our findings indicate that the hypertrophic chondrocyte is the main target cell for estrogen action within the growth plate. The presence of ER in prepubertal children suggests that estrogens play a role in skeletal maturation under physiological conditions also in this age-group.

Adolescent↗
PubMed2001

Immunohistochemical demonstration of Leu-7 (HNK-1), Neurone-specific Enolase (NSE) and Protein-Gene Peptide (PGP) 9.5 in the developing camel (Camelus dromedarius) heart.

The development of the heart-conducting system has been controversially discussed. The common opinion that these specialized myocytes originate from mesodermal precursors has been challenged when nerve-specific antigens (Leu-7, NF, GIN2) were demonstrated in embryonic hearts of various species, suggesting a neural crest contribution to the embryonic conducting tissue. Anti-Leu-7 (HNK-1) antibodies were reported to reliably mark the conducting system in developing rat, chicken and human hearts. The present investigation was carried out on the hearts of 15 camel fetuses at 35, 45, 60, 75 and 100 cm crown-rump length (three specimens for each stage), in addition to three adult hearts. We investigated the antigenicity of cardiac structures for Leu-7, NSE (Neurone specific Enolase) and PGP (Protein Gene Peptide) 9.5. In all specimens investigated, both NSE and PGP 9.5 were expressed by cardiac nerves and conducting system components. The sinuatrial and atrioventricular nodes, the atrioventricular bundle as well as subendocardial and intramyocardial Purkinje fibers were stained. In contrast, the developing conducting system did not react with anti-Leu-7 antibody, although Leu-7 antigenicity was strongly expressed by the developing cardiac nerves. In adult camel hearts, the same pattern of immunoreactivity for the markers studied was still retained. Our results show that the expression of marker proteins for the developing conducting system is species-specific. Therefore, these markers are of little significance in discussions on the possible neurogenic nature of the heart conducting tissue.

Animals↗
PubMed2001

In vitro evidence for effects of magnesium supplementation on quinolone-treated horse and dog chondrocytes.

Quinolones and magnesium deficiency cause similar lesions in joint cartilage of young animals. Chondrocytes cultivated in the presence of quinolones and in Mg-free medium show severe alterations in cytoskeleton and decreased ability to adhere to the culture dish. We investigated whether Mg2+ supplementation can prevent quinolone-mediated effects on chondrocytes in vitro. Chondrocytes cultivated in Dulbecco's modified Eagle's medium/HAM's F-12 medium were treated with ciprofloxacin (80 and 160 microg/ml) and enrofloxacin (100 and 150 microg/ml). Mg2+ was added at a concentration of 0.0612 mg/ml (MgCl) and 0.0488 mg/ml (MgSO4) or a triple dose. In addition, cells were cultivated in Mg-free medium and accordingly treated with Mg2+ supplementation. After 5 days in culture, the number of adherent cells per milliliter was determined. The number of chondrocytes in quinolone-treated groups decreased to 12-36% that of the control group within the culture period. With Mg2+ supplementation, the number of attached cells increased to 40-70% that of control cells. The threefold dose of Mg2+ led to better results than did the single dose. Cell proliferation tested by immunohistochemical staining with Ki67 (clone MIB5) decreased from 70% in control groups to 55%, 48%, and 30% in enrofloxacin-treated groups in a concentration dependent manner (50, 100, and 150 microg/ml). Addition of Mg2+ did not increase the rate of cell proliferation. These results suggest that a great part of quinolone-induced damage is due to magnesium complex formation, as Mg2+ supplementation is able to reduce the effects in vitro. However, quinolone effects on cell proliferation seem to be an independent process that is not influenced by magnesium supplementation.

Animals↗
PubMed2001

Effects of enrofloxacin and ciprofloxacin hydrochloride on canine and equine chondrocytes in culture.

OBJECTIVE: To study chondrotoxic effects of enrofloxacin (ENR) and ciprofloxacin hydrochloride (CFX) on canine and equine articular chondrocytes in culture and to compare the effects with that of cultivation in Mg2+-free medium. SAMPLE POPULATION: Chondrocytes from articular cartilage of 4- and 6 -month old dogs and 2- to 4- year-old horses. PROCEDURE: Chondrocytes were cultivated with 10, 40, 80, and 160 microg of CFX/ml, 10, 50, 100, and 150 microg of ENR/ml, or in Mg2+-free medium. A live-to-dead test was performed to test cytotoxic effects. Morphologic changes were evaluated by electron microscopy. An attachment assay was used to test the ability of chondrocytes to adhere to collagen type-II coated-chamber slides in the presence of CFX and with Mg2+-free medium. RESULTS: Chondrocytes cultivated in quinolone-supplemented medium or Mg2+-free medium had a decreased ability to adhere to culture dishes. Cell shape and the actin and vimentin cytoskeleton changed in a concentration-dependent manner. These effects were not species-specific and developed with both quinolones. On day 1 of culture, adhesion of chondrocytes to collagen type II was reduced to 70 and 45% of control values in the CFX treatment and Mg2+-free treatment groups, respectively. On day 5 of culture, adhesion of chondrocytes was reduced to 45 and 40% of control values in the CFX treatment and Mg2+-free treatment groups, respectively. CONCLUSION AND CLINICAL RELEVANCE: In vitro, chondrotoxic effects of quinolones appear to be the result of irregular integrin signaling and subsequent cellular changes. Drug concentrations leading to morphologic changes in vitro may be achieved in articular cartilage in vivo.

Animals↗
PubMed2000

Ciprofloxacin causes cytoskeletal changes and detachment of human and rat chondrocytes in vitro.

Quinolones cause damage of articular cartilage in different species by forming chelate complexes with divalent cations and inducing magnesium deficiency. Cations are important for regular function of integrins, a group of transmembrane proteins which connect extracellular matrix proteins with the intracellular cytoskeleton. We have shown that cultivation of rat chondrocytes in ciprofloxacin (CFX)-supplemented and Mg(2+)-free medium led to pronounced changes in the cytoskeleton and decreased adhesion of cells to the culture dish. In order to test whether or not these effects are species-specific, we extended our studies on human chondrocytes. Human chondrocytes cultivated in CFX-supplemented medium (10, 40, 80 and 160 microg/ml) or Mg(2+)-free medium showed decreased ability to adhere to growth support, cell shape changes, and alterations in actin and vimentin cytoskeleton in a concentration dependent manner. Attachment of human chondrocytes to collagen type II coated cover slips was reduced to 90% in CFX group and 75% in Mg(2+)-free group on day 1. This effect even increased after 4 days of culture in the respective medium (32% in CFX and 58% in Mg(2+)-free group). We concluded that Mg(2+) deficiency is exerted via integrins, resulting in decreased ability to attach to extracellular matrix proteins and cytoskeletal changes. These effects are not species-specific. The attachment assay proves to be an easy to use experimental set-up to test ciprofloxacin and other quinolones for their chondrotoxic effects.

Animals↗
PubMed2000

Bones in the heart skeleton of the otter (Lutra lutra).

In most mammalian species the cardiac skeleton is composed of coarse collagen fibres, fibrocartilage, and pieces of hyaline cartilage. Bone, the os cordis, is a regular constituent of the ruminant heart. The cardiac skeleton of the otter (Lutra lutra) has not previously been described. The skeleton in 30 otter hearts was studied by x-ray analysis and light microscopy. Serial sections were cut parallel to the atrioventricular plane and histochemical staining methods were performed to identify connective tissue fibres, glycosaminoglycans, mineral deposits, and bone. Age and sex of the animals under investigation were considered. The otter heart skeleton was composed of coarse collagen fibres with intercalated pieces of fibrous and/or hyaline cartilage, calcified cartilage, and lamellar bone with red or white marrow. Pieces of hyaline cartilage were not clearly defined: a perichondrial layer was missing and coarse connective tissue continuously transformed into fibrous and hyaline cartilage. In both sexes the amount of cartilage and bone were found to increase with age. Our results establish the presence of bony material in the heart skeleton of the otter, a small mammalian species. This finding indicates that differentiation of bone is not exclusively related to the size of the organ. Increasing amounts of calcified cartilage and bone correlated with increasing age.

Aging↗
PubMed1999

Integrins mediate the effects of quinolones and magnesium deficiency on cultured rat chondrocytes.

Chondrocyte-matrix interaction is mediated by a series of adhesion molecules. Both alpha and beta integrin subunits are involved and govern crucial functions of cell adhesion and signal transduction. These molecules modulate proliferation and differentiation, thus establishing cartilage integrity. We studied the influence of magnesium deficiency and quinolone antibiotics (which form chelate complexes with divalent cations) on chondrocytes in vitro in order to assess the role of Mg2+ ions in integrin function and to establish cellular changes mediated via integrin signal transduction. Mg2(+)-free medium and quinolone supplementation was found to decrease chondrocyte attachment to collagen type II-coated coverslips. Adhesion and growth of chondrocytes were reduced in the respective medium. Organisation of cytoskeletal fibers (vimentin) was changed and formation of stress fibers (f-actin) was disturbed. Additionally, rates of cell proliferation declined. These results indicate that quinolone-magnesium complex formation is important for chondrotoxicity of these substances. Cell-matrix detachment and morphological alterations described in vitro may explain the lesions observed in articular cartilage after quinolone administration in vivo. The attachment assay described could serve as a simple test to establish the susceptibility of chondrocytes of different species to different quinolones in use or new ones to be introduced.

Animals↗
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↗