ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-0827
    Keywords: Amorphous mineral ; Bone ; Electron microscopy ; Ultracryotomy ; Ultramicro-incineration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The fine structure of the extracellular phase of avian medullary bone and embryonic chick femur was examined in thin sections prepared by ultracryotomy and ultramicroincineration. Since contact with solutions was completely avoided, little or no loss or dislocation of mineral constituents could occur. Amorphous bone mineral (ABM) was present in two forms: as 15–30 nm spheres and as a structure-free haze. Removal of all organic material by low temperature ashing left the ABM intact. Crystals were usually associated with the ABM. In newly ossifying regions clusters or nodules of randomly oriented crystals and ABM appeared to coalesce when they reached approximately 1 μm in diameter. In highly calcified regions crystals appeared to be oriented along collagen fibers. ABM did not appear to be associated with collagen. Unmineralized collagen was visible in osteoid after staining with dry OsO4 vapor and it appeared to be diverted around nodules. Structures which resembled matrix vesicles were present. Selected area electron diffraction patterns indicated the presence of hydroxyapatite.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-0827
    Keywords: Osteoclasts ; Plasma membrane vesicles ; Calcium transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Plasma membrane vesicles were prepared from chicken osteoclasts, and active calcium transport was demonstrated in a spectrofluorimetric assay using the fluorescent calcium concentration indicator, fura-2. Transport activity was inhibited by quercetin (10 μM), sodium vanadate (10 μM), and the anticalmodulin agents, compound 48/80 (20 and 200 μg/ml) and calmidazolium (10 and 20 μM). The transport rate (Vmax, 1.3 nmol/mg protein/min) was not altered in the presence of the protonophore, nigericin (1 μM), indicating that proton transport was not driving calcium transport. Release of accumulated calcium in the vesicles occurred with the addition of bromo-A23187 (5 μM) or ionomycin (5 μM). Increasing calcium transport occurred with increasing calcium concentration. Finally, the calmodulin content of the vesicles was demonstrated to be 54–134 U/mg protein. These results demonstrate that a calmodulin-sensitive, ATP-dependent calcium transporter is present in the osteoclast plasma membrane.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-0827
    Keywords: Matrix vesicles ; Bone ; Ultracrytomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Matrix vesicles were observed in femurs of 8-day-old chick embryos prepared by ultracryotomy. Some of the sections were subjected to ultramicroincineration. The unfixed tissues never came into contact with solutions, and thereby artifacts due to dissolution, redistribution, or rearrangement of the mineral constituents were avoided. In the osteoid, electron dense objects with the size and appearance of matrix vesicles were seen, although limiting membranes were not visible. After ultramicroincineration the vesicles were observed to contain small crystals and a less dense amorphous mineral material which may be the precursor of bone mineral. In addition, a ring of ash enclosed the crystalline and amorphous mineral and appeared to occupy the position of the vesicle membrane as seen in conventionally prepared material.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-0827
    Keywords: Autoradiography ; Calcium ; Oviduct ; Shell-gland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La localisation cellulaire du calcium de la muqueuse de l'oviducte d'oiseaux a été étudiée par autoradiographie au45Ca, à partir de tissus préparés soit par incubation dans le45Ca, soit par injection intraveneuse du45Ca. La congélation — substitution est utilisée pour retenir le calcium aisément diffusible dans le tissu. L'épithelium cylindrique de la glande de la coquille s'enrichit significativement plus en45Cain vitro, en fonction de l'augmentation du temps d'incubation, de une à dix minutes et/ou en élevant la température de 0° à 42°. Ces effets sont diminués par l'adjonction de dinitrophenol au milieu d'incubation. Les glandes tubulaires de ce tissu réagissent à peine. Généralement, après injection intravenieuse de45Ca, la glande de la coquille retient plus de radionuclide que les autres régions de l'oviducte. Lorsqu'une coquille d'œuf est en voie de calcification, l'épithelium cylindrique de cette glande contient plus de grains que les glandes tubulaires, mais, en cas d'absence de formation d'œuf, le nombre de grains est identique dans les 2 types cellulaires. Il semble que l'épithélium cylindrique de la glande de la coquille a une affinité plus grande et plus variable pour le45Ca que la glande de la coquille les glandes tutulaires ou les cellules muqueuses d'autres régions de l'oviducte. Ces résultats indiquent sans le prouver, que l'épithélium cylindrique est plus actif dans le transfert du calcium des vaisseaux sanguins vers la lumière de la glande de la coquille.
    Abstract: Zusammenfassung Die celluläre Verteilung von Calcium in der Eileitermucosa von Hühnern wurde anhand von45Ca-Autoradiographien in Gewebe studiert, welches entweder durch Inkubation mit45Ca oder durch intravenöse Injektion von45Ca präpariert wurde. Gefriersubstitution wurde verwendet, um leicht diffundierbares Calcium im Gewebe zurückzuhalten.In vitro nahm das Cylinderepithel der Schalendrüse auffallend mehr45Ca auf, wenn die Inkubationszeit von einer auf zehn Minuten verlängert wurde und/oder wenn die Temperatur von 0° auf 42° erhöht wurde. Diese Wirkungen wurden durch die Zugabe von Dinitrophenol zum Inkubations-medium vermindert. Die Tubulärdrüsen dieses Gewebes reagierten kaum. Im allgemeinen schlossen die Schalendrüsen nach intravenöser Injektion von45Ca mehr Radionuklid ein als andere Teile des Eileiters. Wenn eine Eierschale calcifizierte, zeigte das Cylinderepithel der Schalendrüse bei der Autoradiographie eine höhere Anzahl von Silberkörnern als die Tubulärdrüsen, aber wenn keine Schale gebildet wurde, war sie bei beiden Zelltypen ähnlich. Die Resultate zeigen, daß das Cylinderepithel der Schalendrüse, eine größere und unterschiedlichere Affinität für45Ca hat als Schalendrüse Tubulärdrüsen oder Schleimhautzellen aus anderen Gebieten des Eileiters. Die Befunde deuten darauf hin, aber beweisen es nicht, daß das Cylinderepithel beim Transport von Calcium aus den Blutgefäßen in die Schalendrüse das aktivste ist.
    Notes: Abstract The cellular location of calcium in the mucosa of the avian oviduct has been studied by45Ca autoradiography in tissue prepared either by incubation with45Ca or by intravenous injection of45Ca. Freeze-substitution was used to retain easily diffusible calcium in the tissue.In vitro, columnar epithelium of the shell gland acquired significantly more45Ca as the length of incubation time was increased from one to ten minutes and/or when the temperature was raised from 0° to 42°. These effects were diminished by the addition of dinitrophenol to the incubation medium. The tubular glands of this tissue responded minimally. Genrally, after intravenous injection of45Ca, the shell gland sequestered, more radionuclide than the other regions of the oviduct. When an egg shell was being calcified, the columnar epithelium of the shell gland revealed a higher grain count than the tubular glands, but when a shell was not forming, grain counts were similar over the two types of cells. The results show that the columnar epithelium of the shell gland has a greater and more variable affinity for45Ca than have the shell gland tubular glands or mucosal cells from other regions of the oviduct. The data suggest, but do not prove, that the columnar epithelium is the most active in translocation of calcium from the blood vessels to the lumen of the shell gland.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1432-0878
    Keywords: Osteoclasts ; H+-ATPase ; Ultracytochemistry ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of Mg+ +-ATPase in osteoclasts along the endosteal surface of the chick tibia was investigated by neutral and alkaline pH cytochemical methods at the electron-microscopic level. Reaction product was observed in mitochondria, cytoplasmic vesicles, and ruffled-border membrane. Levamisole, ouabain, and vanadate did not affect the enzymatic activity. Para-chloromercuribenzoic acid (PCMB) prevented staining of mitochondria, ruffled border, and most cytoplasmic vesicles. Tri-n-butyltin decreased the amount of reaction product in cytoplasmic vesicles and ruffled-border membrane, but did not inhibit reaction product formation within mitochondria. Duramycin, which is a potent inhibitor for proton-pump ATPase, blocked reaction-product formation along the ruffled-border membrane, in mitochondria, and in cytoplasmic vesicles at alkaline pH, but not at neutral pH. It is concluded that the alkaline pH method for Mg+ +-ATPase appears to demonstrate sites of proton-pump ATPase activity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1432-0878
    Keywords: Na+,K+-ATPase ; Sodium pump ; H+-ATPase ; Osteoclasts ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cytochemical methods for the demonstration of p-nitrophenylphosphatase (p-NPPase) at the electron-microscopic level were applied to avian osteoclasts to elucidate some of the functional differences among ruffled border, other membrane systems, and cellular organelles. The localization of p-NPPase activity occurred in mitochondria, in lysosomes, and on the cytoplasmic side of the ruffled-border membrane. Enzymatic activity in the ruffled-border membrane was sensitive to ouabain and was partially dependent on potassium. Thus, Na+,K+-ATPase, the proposed sodium pump, appears to be present in the osteoclast ruffled border. The activity in ruffled border occurred only when osteoclasts were attached to bone. Following calcitonin treatment many osteoclasts were detached from the bone surface and lacked reaction product along the ruffled border membrane. The lysosomal p-NPPase activity was not sensitive to ouabain and was distinct from that of other lysosomal phosphatases. The p-NPPase activity in mitochondria was not inhibited by ouabain but was sensitive to duramycin. The mitochondrial p-NPPase may, therefore, represent the mitochondrial proton pump.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0730-2312
    Keywords: bFGF ; extracellular matrix ; in situ hybridization ; RT-PCR ; immunocytochemistry ; cell proliferation ; Western blotting ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Basic fibroblast growth factor (bFGF) is a permissive mitogen for cultured chondrocytes and has been localized in the specific zones of the epiphyseal growth plate. In this study, we demonstrate that bFGF present in cartilage originates from within the cellular constituents of this tissue. Utilizing reverse transcription coupled to the polymerase chain reaction (PCR), bFGF mRNA was found in extracts of cartilage tissue. Immunocytochemical studies revealed that bFGF was present intracellularly in freshly isolated proliferative chondrocytes and in the extracellular matrix (ECM) after 24 h of culture. Western blot analysis of protein extracts from isolated proliferative chondrocytes identified a bFGF immunoreactive species with a molecular weight of approximately 18 kDa. In situ hybridization confirmed the presence of bFGF mRNA in freshly isolated proliferative chondrocytes. The bFGF in the ECM seemed to be sequestered and not available for biological activity, since these cells still required exogenous bFGF for cell proliferation. This sequestered bFGF could be released to stimulate cell proliferation when cultures were treated with plasmin, a proteolytic enzyme. These data support the hypothesis that bFGF is synthesized by chondrocytes and functions as an autocrine/paracrine mitogen via its deposition into the ECM with subsequent release from the ECM of cartilage being a critical step in biological activity. In addition, the study provides further evidence that locally produced bFGF plays an important role in normal growth and development of cartilage tissue. © 1996 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 0730-2312
    Keywords: calcium-regulating hormones ; bone cells ; acridine orange ; signal transduction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Osteoclasts, isolated from the endosteum of 2.5- to 3-week-old chickens, were treated with acridine orange, a hydrogen ion concentration-sensitive fluorescent dye, in order to monitor changes in acid production. The adenylate cyclase inhibitor, alloxan, blocked parathyroid hormone (PTH)-stimulated acid production. Dibutyryl cyclic adenosine monophosphate, a membrane-permeant form of cyclic adenosine monophosphate, mimicked the PTH effect. Bisindolylmaleimide, a specific inhibitor of protein kinase C (PKC), blocked the initial stimulation (15, 30, and 60 min) of acid production by PTH but had no effect on long-term stimulation (120 min). Confocal microscopy of osteoclasts stained with fluorescein-conjugated bisindolylmaleimide revealed a shift in location of PKC from the cytoplasm to the plasma membrane region after treatment with parathyroid hormone. The results of these studies support the hypothesis that PTH regulation of acid production in osteoclasts involves both adenylate cyclase and PKC as effectors. J. Cell. Biochem. 65:565-573. © 1997 Wiley-Liss Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 0730-2312
    Keywords: osteoclast ; spectrin ; membrane skeleton ; bone ; bone resorption ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The presence of spectrin was demonstrated in chick osteoclasts by Western blotting and light and electron microscopic immunolocalization. Additionally, screening of a chick osteoclast cDNA library revealed the presence of α-spectrin. Light microscope level immunocytochemical staining of osteoclasts in situ revealed spectrin staining throughout the cytoplasm with heavier staining found at the marrow-facing cell margin and around the nuclei. Confocal microscopy of isolated osteoclasts plated onto a glass substrate showed that spectrin encircled the organelle-rich cell center. Nuclei and cytoplasmic inclusions were also stained and the plasma membrane was stained in a nonuniform, patchy distribution corresponding to regions of apparent membrane ruffling. Ultracytochemical localization showed spectrin to be found at the plasma membrane and distributed throughout the cytoplasm with especially intense staining of the nuclear membrane and filaments within the nuclear compartment. J. Cell. Biochem. 71:204-215, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...