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  • 1
    ISSN: 1432-0878
    Keywords: Key words: Gonadotropin-releasing hormone ; Hypothalamus ; Pituitary ; pars distalis ; High-performance liquid chromatography ; Immunohistochemistry ; Radioimmunoassay ; Stickleback ; Gasterosteus aculeatus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Radioimmunoassay (RIA) studies on high-performance liquid chromatography (HPLC) fractions of brain extracts of the three-spined stickleback, Gasterosteus aculeatus, provided evidence for at least two forms of gonadotropin-releasing hormone (GnRH). One form showed chromatographic and immunological properties similar to that of synthetic salmon GnRH (sGnRH). A second, unidentified form of GnRH eluted in the same position as chicken GnRH I (cGnRH-I); however, it did not cross-react in a cGnRH-I RIA. Furthermore, it cannot be excluded that chicken GnRH II (cGnRH-II) and maybe one other unidentified form are present in the stickleback. The distribution of GnRH in the brain of breeding adult male sticklebacks was studied by use of immunohistochemistry. Two antisera against sGnRH and antisera against mGnRH and cGnRH-II were applied on cryosections and visualized using the peroxidase-antiperoxidase method. Staining patterns were similar after incubations with all four antisera. Immunoreactive fibers were found in most parts of the brain. Three distinct groups of GnRH-immunoreactive perikarya were found in the nucleus olfactoretinalis, in the nucleus anterior periventricularis, and in the nucleus lateralis tuberis. Moreover, weakly stained cells occurred in a periventricular position in the midbrain. The proximal pars distalis of the pituitary, housing the gonadotropic cells, was richly innervated by GnRH-positive fibers. In the pars intermedia and in the rostral pars distalis, immunoreactive fibers were absent.
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  • 2
    ISSN: 1432-0878
    Keywords: Gonadotropin-releasing hormone ; Hypothalamus ; Pituitary ; pars distalis ; High-performance liquid chromatography ; Immunohistochemistry ; Radioimmunoassay ; Stickleback, Gasterosteus aculeatus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Radioimmunoassay (RIA) studies on highperformance liquid chromatography (HPLC) fractions of brain extracts of the three-spined stickleback, Gasterosteus aculeatus, provided evidence for at least two forms of gonadotropin-releasing hormone (GnRH). One form showed chromatographic and immunological properties similar to that of synthetic salmon GnRH (sGnRH). A second, unidentified form of GnRH eluted in the same position as chicken GnRH I (cGnRH-I); however, it did not cross-react in a cGnRH-I RIA. Furthermore, it cannot be excluded that chicken GnRH II (cGnRH-II) and maybe one other unidentified form are present in the stickleback. The distribution of GnRH in the brain of breeding adult male sticklebacks was studied by use of immunohistochemistry. Two antisera against sGnRH and antisera against mGnRH and cGnRH-II were applied on cryosections and visualized using the peroxidase-antiperoxidase method. Staining patterns were similar after incubations with all four antisera. Immunoreactive fibers were found in most parts of the brain. Three distinct groups of GnRH-immunoreactive perikarya were found in the nucleus olfactoretinalis, in the nucleus anterior periventricularis, and in the nucleus lateralis tuberis. Moreover, weakly stained cells occurred in a periventricular position in the midbrain. The proximal pars distalis of the pituitary, housing the gonadotropic cells, was richly innervated by GnRH-positive fibers. In the pars intermedia and in the rostral pars distalis, immunoreactive fibers were absent.
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  • 3
    ISSN: 1432-136X
    Keywords: Stanniocalcin purification ; Amino acid sequencing ; Immunohistochemistry ; Intestinal Ca2+ influx ; Atlantic cod, Gadus morhua
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Chum salmon (Oncorhynchus keta) stanniocalcin was purified, partially identified and tested for bioactivity in an assay on the intestinal calcium uptake in a marine teleost (Gadus morhua). Basic ethanol extraction, ion exchange chromatography, gel filtration and reverse-phase high-performance liquid chromatography resulted in the isolation of a homogenous glycoprotein that appears as a 46-kDa product under non-reducing conditions and as a 23-kDa product under reducing conditions after sodium dodecylsulphate-polyacrylamide gel electrophoresis. The glycoprotein is likely to be a homodimer composed of two subunits of 23 kDa each. Further characterization indicates homology to Australian eel, sockeye salmon, coho salmon and rainbow trout stanniocalcin, and the glycoprotein is thus concluded to be stanniocalcin. Stanniocalcin-like immunoreactivity was demonstrated in the corpuscles of Stannius of the Atlantic cod, with a specific antiserum raised against purified chum salmon stanniocalcin. The physiological importance and the biological activity of chum salmon stanniocalcin was tested by evaluating its effect on intestinal calcium uptake by the Atlantic cod in vitro. The intestine was perfused, both vascularly and through the intestinal lumen, and the calcium mucosa-to-serosa flux was measured using 45Ca2+ as a tracer. Stanniocalcin decreased the intestinal calcium uptake in a dose-related manner by 13.5% and 22.4% at doses of 2.2 and 10.9 nM stanniocalcin, respectively. The results establish the intestine as a target organ for stanniocalcin in marine teleosts.
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  • 4
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Macroporous hydroxyapatite was implanted submucosally in the rat middle ear and studied after intratympanic injection of a Staphylococcus aureus suspension. The middle ear infection was induced 1 week after the implantation, and the effects of infection on the middle ear and the implant material were evaluated after 1, 3, 7, and 14 days by light and electron microscopy. The findings in the infected middle ear with an implant corresponded well with those described for the infected middle ear cavity without an implant. The reactions of the tissue over the implant were similar to those of the original mucosa of the middle ear.Bone was deposited on the implant and in its pores in relatively large quantities. Biodegradation, due at least partially to phagocytic activity of macrophages and multinucleated cells, was more prominent than previously found. This higher degree of biodegradation may be attributed to the use of the mucosal implantation technique, because this was the only point of divergence with respect to material or methods from earlier work reported by our group.The present results, together with those published earlier, suggest that this material has promising features for use as a bone substitute in reconstructive middle ear surgery. Definitive conclusions on biological performance and biofunctionality will, however, have to await long term clinical trials.
    Additional Material: 8 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 277-293 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The tissue/biomaterial interface reactions of four elastomers - selected as candidates for scaffolding for tympanic membrane tissue in a total alloplastic middle ear prosthesis - were studied at the electron microscopical level after implantation in the rat middle ear. Time-dependent changes in the phagocyte/polymer interface suggested degradation of porous implants made of Estane polyether urethane, polypropylene oxide, and a poly(ethylene oxide hydantoin) and poly(tetramethylene terephthalate) segmented polyether polyester copolymer (HPOE/PBT copolymer), but not of dense Silastic silicone rubber implants. Silastic was always encapsulated in fibrous tissue. Contact between fibrous tissue and HPOE/PBT copolymer or Estane was established in the third month, but fibrous tissue was never seen close to polypropylene oxide. Bone made contact only with Estane and HPOE/PBT copolymer implants. The bone/copolymer interface showed an electron-dense layer morphologically similar to that seen between bone and hydroxyapatite ceramic, suggesting that with respect to bone HPOE/PBT copolymer behaves like a bioactive implant material. The electron-dense layer was absent at the bone/Estane interface. Estane and especially HPOE/PBT copolymer seem to be suitable as alloplastic tympanic membrane because of their interface behavior with respect to fibrous tissue and bone.
    Additional Material: 7 Ill.
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  • 6
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In the present study the biological performance of macroporous and dense hydroxyapatite after implantation in the rat middle ear was evaluated during an induced Staphylococcus aureus middle ear infection. The course of the infection was similar to that in the absence of an implant. Hydroxyapatite was frequently integrated with fibrous ingrowths in the middle ear lumen, originating solely from the infection. Good epithelial covering of the implant with all types of epithelial cells of importance for middle ear defence, was found. Increase of the exudate in the pores due to the infection was relatively small, and most of the exudate was restricted to pores on the implant surface. The bony tissue in the pores was not influenced significantly by the induced infection. Degradation of hydroxyapatite was consistent with earlier results obtained in the noninfected middle ear. The results obtained so far suggest that hydroxyapatite is highly suitable for middle ear implantation.
    Additional Material: 9 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 423-439 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The biocompatibility of two silicone rubbers, Silastic and Dow Corning Elastomer, and of a polyether and a polyester urethane, a polyether polyester copolymer, and polypropylene oxide was assessed in vitro. These elastomers were selected for assessment as a possible alloplastic tympanic membrane. For these studies use was made of rat middle ear mucosa explants and serially cultured epithelium. The quantitative results were based on epithelial growth curves, the morphological picture was based on the findings in epithelium, and the aging of a biomaterial was simulated. Epithelium morphology was investigated by scanning and transmission electron microscopy and x-ray microanalysis. Quantitative results showed that on Dow Corning Elastomer and polypropylene oxide, cell proliferation was significantly lower compared to normal growth curves. The morphological findings were negative for polypropylene oxide, and did not discriminate between the other biomaterials under study. The simulation results indicated better biocompatibility for the polyurethanes and the polyether polyester copolymer compared with that of polypropylene oxide and both silicone rubbers. Under the simulation conditions, cells exposed to Silastic showed siliconcontaining inclusions. These in vitro results suggest that the biocompatibility of the polyurethanes and the polyether polyester copolymer is better than that of both silicone rubbers and polypropylene oxide.
    Additional Material: 9 Ill.
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  • 8
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The biocompatibility of dense Silastic implants and porous implants made of Estane 5714 F1 polyether urethane, polypropylene oxide, and an HPOE/PBT segmented polyether polyester copolymer was evaluated during an induced Staphylococcus aureus middle ear infection.The middle ear response to infection seemed not to be affected by the presence of implants made of either of the polymers. Light microscopical morphometry and transmission electron microscopy showed degradation of the porous implants under study, but not of Silastic implants, which were invariably surrounded by a fibrous capsule. This finding, combined with the degree of porous implant degradation, the composition of the tissues surrounding the implants, and the tissue/biomaterial interface reactions are consistent with the results obtained in the noninfected middle ear. Round-cell infiltrates however, were predominantly associated with implants made of polypropylene oxide and HPOE/PBT copolymer; while the presence of (phagocytosed) microbial debris was associated with copolymer.The present findings indicate that with respect to implant behavior in infected surroundings Estane is the best porous material, whereas the behavior of Silastic implants did not deviate from that in noninfected ears.
    Additional Material: 9 Ill.
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  • 9
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Epithelial reactions to Silastic, Estane polyether urethane, polypropylene oxide, and a poly(ethylene oxide hydantoin) and poly(tetramethylene terephthalate) segmented polyether polyester copolymer were investigated after implantation in tympanic membranes and submucosa of noninfected and Staphylococcus aureus-infected rat middle ears. Porous implants made of Estane and polypropylene oxide were completely covered by tympanic-membrane connective tissue, epidermis, and epithelium in 2 weeks and those made of copolymer in between 2 and 4 weeks postoperatively. Silastic implants, which were dense, were not enveloped by tympanic-membrane tissue but rejected. Starting in the 6th postoperative month the proliferative activity and structure of both the tympanic membrane epithelium and epidermis became normal except for the presence of iron-containing secretory epithelium near polypropylene oxide. After initial swelling caused by the surgical trauma, neither the proliferative activity nor the composition of the epithelium covering submucosal implants was affected by the presence of any of the biomaterials. Infection of middle ears bearing implants induced epithelial reactions similar to those associated with infected middle ears without an implant.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 30 (1996), S. 139-143 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In this in vivo study, low-molecular-weight as-polymerized PLLA powder was placed in the medullary cavity of a porcine femur in order to study the tissue reaction on predegradated PLLA. An attempt was made to simulate the long-term degradation of a large PLLA implant. This phase can be characterized by the release of PLLA particles and acid compounds from a heterogeneously degrading PLLA implant into the surrounding tissues. The clinical consequences and tissue response were studied. The clinical recovery of the experimental animals was favorable. No signs of clinical inflammation could be detected during the eight-week follow-up period. Histological analysis of the bone/PLLA interface showed signs of a mild inflammatory tissue response. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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