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  • 1
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 2 (1949), S. 85-90 
    ISSN: 0001-5520
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 310 (1983), S. 317-328 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The cross section for the3He(γ, 2p) reaction has been measured in a complete kinematics experiment in the energy rangeE γ=80–170 MeV, forθ P1=θ P2=90°. This configuration was selected in order to investigate the role of proton-proton final state interactions in the three-body breakup process. The measured proton spectra are seen to be consistent with a prediction using the Watson-Migdal formalism. The magnitude of the observed cross section clearly indicates an enhancement over phase space, presumably due to the strong proton-proton interaction in the final state. The experimental results agree, within their limited statistical accuracy, with a theoretical calculation which includes this effect.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0827
    Keywords: Phosphorus ; Intestine ; Absorption ; Rickets ; Vitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'autoradiographie en microscopie électronique est utilisée pour déterminer la distribution du phosphore dans les cellules d'absorption du duodénum pour déterminer si une différence existe entre le rat rachitique, le rat normal et le rat rachitique traité par vitamine D. Pas de différence notable n'est observée en répartition de phosphate entre les groupes, mais l'animal rachitique obsorbe du phosphore et tous les groupes présentent une répartition différente de celle du calcium. On note un marquage des microvillosités, de l'appareil terminal de jonction, des mitochondries, du noyau, des vesicules denses et claires, ainsi que de l'ergastoplasme lisse et rugueux.
    Abstract: Zusammenfassung Die elektronenmikroskopische Autoradiographie wurde verwendet, um die Verteilung von Phosphor in den absorbierenden Zellen des Duodenum zu bestimmen und um jeglichen Unterschied festzustellen, der zwischen rachitischen, normalen und Vitamin D-behandelten rachitischen Ratten bestehen könnte. Die Phosphatverteilung variierte nur wenig zwischen den verschiedenen Diät-Gruppen, hingegen konnte das rachitische Tier Phosphat absorbieren, und alle Gruppen zeigten eine Verteilung, welche von derjenigen des Calciums abwich. Die Markierung konnte auf den Microvilli, dem Terminalgeflecht, den Mitochondrien, dem Zellkern, den hellen und dichten “core vesicles” (=Vesikeln mit hellem und dichtem Kern) und dem glatten und rauhen endoplasmatischen Reticulum gesehen werden.
    Notes: Abstract Electron microscopic autoradiography was utilized to determine the distribution of phosphorus within the absorptive cells of the duodenum and to determine any difference that might exist between the rachitic, normal and vitamin-D-treated rachitic rat. No great difference was noted in phosphate distribution among the various nutrition groups, but the rachitic animal was able to absorb phosphorus and all groups demonstrated a distribution different from that of calcium. Label was seen over the microvilli, terminal web, mitochondria, nucleus, dense and light core vesicles, as well as smooth and rough endoplasmic reticulum.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0827
    Keywords: Sarcoplasmic Reticulum ; Myofilaments ; Troponin ; Pyroantimonate ; “Calcium Sink”
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'ultrastructure du muscle squelettique de lapin est étudiée après traitement au glycérol et colgoration au pyroantimonate. Des dépôts denses aux électrons sont observés dans le reticulum sarcoplasmique restant. Ils sont associés aux myofilaments. Ces granules denses sont éliminés par chélation à l'EDTA et ces granules réapparaissent aux mêmes localisations après adjonction d'ions calcium au milieu d'incubation. L'existence de sites de liaisons spécifiques inter et intramyofibrillaires est ainsi confirmée. Les sites de liaison des myofilaments sont en rapport avec la longueur du sarcomère, étant donné que la localisation des granules est différente lorsque des sarcomères plus courts sont comparés à des sarcomères plus longs. Il semble que le calcium lié aux myofilaments joue un rôle essentiel au cours de la coordination et de la phase de repos de la contraction musculaire.
    Abstract: Zusammenfassung Die Ultrastruktur des Skelettmuskels von Kaninchen wurde durch Einlegen in Glycerin und Färbung mit Pyroantimonat untersucht. Es wurden im residualen Sarkoplasma-Reticulum elektronendichte Ablagerungen beobachtet und mit Myofilamenten in Zusammenhang gebracht. Diese dichten Granula verschwanden durch Chelation mit EGTA, und neue Granula erschienen an denselben Stellen, wenn dem Inkubationsmedium Calciumionen beigegeben wurden. Auf diese Weise wurde das Auftreten spezifischer inter- und intramyofibrillärer Bindungsstellen bestätigt. Es wurde festgestellt, daß die Myofilament-Bindungsstellen von der Länge der Sarkomeren abhingen, denn die Verteilung der Granula war verschieden, wenn kürzere Sarkomeren mit längeren verglichen wurden. Es wird vorgeschlagen, daß das an Myofilamente gebundene Calcium eine wesentliche Rolle in der Kontraktion, der Verbinding und der Relaxation spielt.
    Notes: Abstract The ultrastructure of rabbit skeletal muscle was studied following glycerolation and staining with pyroantimonate. Electron-dense deposits were observed within the residual sarcoplasmic reticulum and associated with myofilaments. These dense granules were removed by chelation with EGTA and granules reappeared at these same sites upon the addition of calcium ions to the incubation medium. Specific inter- and intra-myofibrillar binding sites were thus confirmed. Myofilament binding sites were found to be a function of sarcomere length, since the granule distribution was different when shorter sarcomeres were compared to longer sarcomeres. It is proposed that calcium bound to myofilaments plays an essential role in contraction coupling and relaxation.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 3 (1969), S. 184-193 
    ISSN: 1432-0827
    Keywords: Mitochondria ; Calcification ; Calcium ; Chondrocytes ; Growth plate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des cultures d'épiphyse prélevées sur des rats et des souris ont été étudiées sous le microscope électronique. Un profile de granules mitochondriques de densité électronique a été trouvé. Les chondrocytes dans la zone proliférative avaint peu de granules, alors que ceux des zones successives ont montré une augmentation progressive de leur nombre et densité jusqu'à ce que la zone de calcification provisoire ait été atteinte. Cette zone a montré une distribution périphérique de mitochondries et une réduction du nombre et de la densité des granules mitochondriques. Du calcium isotopique 47 a été utilisé autoradiographiquement pour déterminer la location de calcium dans ces cellules. Des grains ont été trouvés sur les membranes R.E. et sur la plupart des mitochondries. La preuve d'un profile de ces granules et de leur rapport spatial avec la face de minéralisation indique une action éventuelle de mitochondries dès le début de la calcification de la matrice.
    Abstract: Zusammenfassung Epiphysekulturen von Ratten und Mäusen wurden unter dem Elektronenmikroskop untersucht. Ein Profil von mitochondrischen Körnchen mit elektronischer Dichte wurde gefunden. Chondrozyten in der Proliferationszone wiesen wenig Körnchen auf, während die der nachfolgenden Zonen allmählich an Zahl und Dichte zunahmen, bis die Zone der provisorischen Verkalkung erreicht wurde. Diese Zone zeigte eine periphere Verteilung der Mitochondrien und eine Abnahme in Zahl und Dichte der mitochondrischen Körnchen. Isotopes Kalzium 47 wurde autoradiographisch verwendet, um die Lage des Kalziums in diesen Zellen zu bestimmen. Körnchen wurden auf den E.R.-Membranen und auf einem Großteil der Mitochondrien gefunden. Der Nachweis eines Profils dieser Körnchen und ihres räumlichen Verhältnisses zur Mineralisierungsfläche weist auf einen möglich Einfluß der Mitochondrien mit Beginn der Matrixverkalkung hin.
    Notes: Abstract Rat and mice epiphyseal growth plates were studied with the electron microscope. A gradient of mitochondrial electron-dense granules was found. Chondrocytes in the proliferative zone had few granules, while those of the succeeding zones showed a gradual increase in number and density until the zone of provisional calcification was reached. This zone showed a peripheral distribution of mitochondria and a decrease in the number and density of mitochondrial granules. Isotopic47calcium was used autoradiographically to determine the location of calcium in these cells. Grains were found over the endoplasmic reticulum membranes and over most mitochondria. The demonstration of a gradient of these granules and their spatial relation to the mineralization front suggests a possible involvement of mitochondria in the onset of matrix calcification.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 26 (1978), S. 181-190 
    ISSN: 1432-0827
    Keywords: Cellular calcium ; Electron microscopy ; Osteoblasts ; Chondrocytes ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The calcium distribution in cartilage and bone cells during beginning ossification of fetal mouse long bones was studied after fixation with 2% K-pyroantimonate in 1% osmium. In the developing periosteum, the future osteoblasts showed a sparse cation-antimonate precipitate over the cytoplasm. In young osteoblasts the precipitate was accumulated on the mitochondrial membranes and the plasmalemma. Both organelles were sharply outlined by precipitate in the mature osteoblasts at the onset of mineralization. X-Ray microprobe analysis of these organelles demonstrated the presence of both Sb and Ca. In the extracellular compartment, a collagen-associated precipitate with 50 to 60 nm periodicity appeared during osteoblastic differentiation. During the initial phase of matrix mineralization, a random gross precipitate appeared in the matrix and seemed to be accumulated by osmiophilic matrix vesicles while the collagen fibrils lost their precipitate. Subsequently, during the confluent phase of matrix mineralization, the precipitate rapidly disappeared from the cells, leaving them devoid of precipitate once they were surrounded by mineralized matrix. Similar changes were found in the chondrocytes of the growth plate, but cartilage collagen, unlike osteoid collagen, did not bind precipitate. The results indicate that both osteoblasts and calcifying cartilage cells bind calcium prior to matrix mineralization. Bone collagen has strong pyroantimonate binding capacity, but it is not directly involved with initial stages of matrix mineralization, which starts in close association with matrix vesicles.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 24 (1977), S. 1-10 
    ISSN: 1432-0827
    Keywords: Microfilaments ; Cytochalasin B-Endosteal osteoblasts ; Microvilli ; Filopodia ; Blebs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The lining osteoblasts of the rat tibial endosteum were treated for various times (between 1 and 60 min) and increasing doses (3.87–38.7 μg/ml) with the macrolide fungal metabolite cytochalasin B (CB). Dimethylsulfoxide (DMSO) served as the vehicle for CB and was administered to control tissues. An in vitro incubation system and scanning electron microscopy (SEM) were used to evaluate the effects of CB. The drug initiated cell rounding (contraction), nuclear protrusion, bleb formation, and the subsequent clustering of blebs and microvilli into aggregates. All CB-induced aberrations of the surface structure were readily reversible when tissues were washed with CB-free media. DMSO had no significant effect on cell surface morphology. The reversible structural changes brought about by CB are explained in terms of alterations of the subplasmalemmal cortical microfilament system of osteoblasts. The potential use of CB in evaluating the bone cell cytoskeleton and its relationship to the physiology of the cellular functional membrane (endosteum) of bone is discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 4 (1970), S. 37-38 
    ISSN: 1432-0827
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0827
    Keywords: Absorption ; Calcium ; Vitamin D ; Rickets ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La mise en évidence intracellulaire du calcium au niveau du revêtement muqueux de l'intestin grêle de rats normaux, rachitiques et traités à la vitamine D2 est réalisée à l'aide de l'auto radiographie au45Ca, de la micro-incinération et de la microscopie électronique. De petits granules denses aux électrons et le marquage autoradiographique sont visibles surtout dans les microvillosités et les mitochondries. Les granules sont rares dans les mitochondries des rats rachitiques, alors que les mitochondries du rat normal en sont toujours pourvues. Les mitochondries des rats, traités à la vitamine D2, contiennent de nombreux granules denses. Ces granules subsistent après micro-incinération. Un rapport inverse est noté dans le nombre des granules présents dans les mitochondries et les microvillosités. Les granules sont limités aux microvillosités chez les animaux rachitiques, et ils augmentent significativement dans les mitochondries après traitement à la vitamine D2. Cette étude indique qu'une quantité importante de calcium est absorbée à travers la membrane cellulaire et ce calcium se lie aux microvillosités. La vitamine D semble nécessaire pour mobiliser le calcium lié aux microvillosités. Ce calcium pénètre dans les mitochondries et traverse la cellule pour aller vers les vaisseaux sanguins adjacents.
    Abstract: Zusammenfassung Die intrazelluläre Lokalisation von Calcium in der Mucosa des Dünndarms von normalen, rachitischen und Vitamin D2-behandelten Ratten wurde anhand von45Ca-Autoradiographie, Microveraschung und Elektronenmikroskopie untersucht. Kleine elektronenundurchlässige Granula und autoradiographische Markierung wurden vorerst innerhalb der Microvilli und Mitochondrien festgestellt. Es fanden sich spärlich Granula in den Mitochondrien rachitischer Ratten, während sie in denjenigen von normalen Ratten regelmäßig vorlagen. Die Mitochondrien der Vitamin D2-behandelten Ratten enthielten zahlreiche elektronenundurchlässige Granula. Diese Granula waren auch nach Mikroveraschung noch vorhanden. Die Anzahl der Granula in den Mitochondrien und in den Microvilli standen in einem umgekehrten Verhältnis zueinander. Die Granula waren bei rachitischen Tieren auf die Microvillus-Region beschränkt und stiegen in den Mitochondrien nach Vitamin D2-Behandlung signifikant an. Diese Untersuchung zeigt, daß eine große Calciummenge durch die Zellmembran absorbiert und dann innerhalb des Microvillus gebunden wird. Es scheint, daß Vitamin D für die Freisetzung dieses gebundenen Calciums aus den Microvilli notwendig ist. Das freigesetzte Calcium tritt in die Mitochondrien ein oder wandert durch die Zelle zu den anliegenden Blutgefäßen.
    Notes: Abstract The intracellular localization of calcium in the mucosal lining of the small intestine of normal, rachitic, and Vitamin D2 treated rats was studied using45Ca-autoradiography, microincineration, and electron microscopy. Small, electron-dense granules and autoradiographic label were seen primarily within microvilli and mitochondria. The granules were sparse in mitochondria from rachitic rats while normal rat mitochondria demonstrated them regularly. The mitochondria of Vitamin-D2-treated rats contained numerous electron dense granules. These granules remained following microincineration. An inverse relation in the amount of granules appearing in the mitochondria and in the microvillus was found. Granules were limited to the microvillus region in the rachitic animals and increased significantly in the mitochondria following treatment with Vitamin D2. This study indicates that a large amount of calcium is absorbed across the cell membrane and is then bound within the microvillus. Vitamin D is apparently necessary for mobilizing this bound calcium from the microvilli. The mobilized calcium enters the mitochondria or passes through the cell to the adjacent blood vessels.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cancer chemotherapy and pharmacology 31 (1993), S. 467-474 
    ISSN: 1432-0843
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Light-activated merocyanine 540 (pMC540) has been shown in our earlier studies to be effective against certain types of tumor cells and viruses, including human immunodeficiency virus (HIV-1). To test the potential extracorporeal and systemic use of pMC540, its toxicity was investigated in DBA/2 mice, pigs, and dogs. The lethal dose in DBA/2 mice after an i.p. injection was 370 mg/kg, and the 50% lethal dose (LD50) was 320 mg/kg; however, following i.v. administration, the lethal dose and the LD50 dose were 240 and 160 mg/kg, respectively. Tritium-labeled MC540 was used to study the biodistribution of pMC540 in DBA/2 mice. Almost 70% of the injected radioactivity was excreted within 6 h of injection. After 1 week, the pMC540 was almost completely cleared, with only 1.89% of the activity remaining, and had a plasma half life of 23 h. Pigs injected with an accumulated dose of 10 mg/kg and followed for a period of 30 days did not show adverse signs of toxicity as monitored by SMAC-28 analysis, CBC profile, and blood-coagulation studies. A dog injected with a single dose of 20 mg/kg showed induction of the hepatic enzymes glutamic oxaloacetic transminase (AST) and glutamic pyruvic transaminase (AST); however, serum levels of gamma-glutamyl transpeptidase (GGT) remained unchanged. The data presented herein may serve to identify certain drug-dose limitations in the systemic use of pMC540.
    Type of Medium: Electronic Resource
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