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  • 1980-1984  (4)
  • Life and Medical Sciences  (4)
  • Choline acetyltransferase
  • Physical Chemistry
  • 1
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The intraarterial cushions present in the rat at the points of branching of the main uterine artery have been studied by means of scanning electron microscopy. Such studies confirmed the three-dimensional concept of these structures gained from previous light microscopic serial section reconstructions as incomplete, raised, asymmetric ridges which encompass the branch orifice. The examination of methacrylate corrosion casts of the uterine vasculature with the scanning electron microscope provided a means for evaluating the relative protrusion or retraction of the cushion structures within the vessel lumen, and thus for assessing their role in regulating uterine blood flow in various physiologic states. Cushions were studied in this manner at the stages of the estrous cycle, in castrated animals, and in animals receiving pharmacologic doses of an alpha adrenergic agonist, phenylephrine. Evaluation of the relative depth of the impression left upon the vascular casts by cushions permitted the following conclusions. The cushions protruded maximally (and thus impeded flow most effectively) in castrated animals and in animals treated with the vasoconstrictor, phenylephrine. In contrast, the cushions protruded less in animals in proestrus and estrus. These data suggest that the cushions do respond, either actively, by virtue of the contractile state of the smooth muscle within the cushion, or passively, as a function of overall vessel geometry, to alpha adrenergic stimulation. The contrast in cushion protrusion between the castrated state, and proestrus and estrus, suggests that ovarian hormones exert an influence over the functional morphology of the cushions in a manner which promotes maximal uterine perfusion during those periods of the estrous cycle which are documented as periods of uterine hyperemia. These studies thus provide evidence for the dynamic role of intraarterial cushions in the regulation of uterine blood flow.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 198 (1980), S. 461-474 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Light and electron microscopic studies of the spermatic granuloma of the rat vas deferens which arises post-vasectomy were undertaken to determine if such granulomata exhibit the morphological features typical of granulomata described in other systems. Vasectomy was performed utilizing a technique of division and fulguration, and tissues for study were fixed in situ by means of vascular perfusion at 2, 4, or 12 weeks post-operatively. Invariably, a spermatic granuloma formed at the testicular end of the sectioned vas by 2 weeks post-vasectomy. At the time periods studied, the granulomata exhibited a cellular wall of variable thickness and complexity surrounding a central mass of sperm. This wall consistently was divisible into (1) a loosely arranged interface region populated by neutrophils and other spermiophagic cells, and (2) a more peripheral, compactly arranged region populated primarily by macrophages and epithelioid cells. Multinucleate giant cells were especially prominent in the later stages studied. Peripheral to the wall, but without an intervening basal lamina, lay a loosely organized, highly vascular connective tissue region containing only sparse collagen and few fibrocytes. Here, too, macrophages, epithelioid cells, lymphocytes, and plasma cells were noted in abundance. A well-developed capsule composed of fibrocytes, collagenous bundles, and smooth muscle cells surrounded the granuloma. Such features conform to those descriptions in the literature of chronic granulomatous inflammation.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 170 (1984), S. 483-490 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The classical macrophage is one of the most important cells involved in presenting antigen to helper T cells, because of its ability to regulate its expression of Ia molecules and to encounter and process particulate and soluble antigens. We have summarized in this report studies examining the handling by macrophages of two different antigens, the bacteria Listeria monocytogenes and the protein hen egg white lysozyme (HEL). The purpose was to identify potential sources of immunogenic peptides. Presentation of Listeria required an intracellular processing stage sensitive to lysosomotropic drugs. The Listeria required internalization and processing, after which immunogenic molecules were recognized by T cells on the macrophage surface. Metabolic studies showed that Listeria-derived peptides were released by macrophages that had phagocytosized the bacteria. The release of these peptides was a temperature-dependent process, unaffected by inhibiting lysosomal catabolism by treatment with chloroquine. Listeria-derived peptides were also detected on the surface of the macrophage. These peptides behaved like integral membrane proteins, some of which persisted for at least 24 hr at the macrophage surface. When tested for immunogenicity, the released peptides were very weakly immunogenic. The membrane-associated peptides alone could not stimulate Listeria-specific T cells, but could be reprocessed by additional macrophages and subsequently stimulate the T cells. A defined antigen system using HEL-specific T-cell hybridomas was used to examine the processing of HEL. Presentation of HEL required a choloroquine-sensitive intracellular processing stage. In examining two T-cell hybridomas, a differential requirement for antigen processing was determined. The immunogenicity of released HEL from HEL-pulsed macrophages was also tested, and no “processed” antigen was detected capable of directly stimulating T cells; however, native HEL was released from the macrophage and could be processed and presented by other macrophages.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 115 (1983), S. 283-290 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Synchronous populations of HeLa S3 cells suffer synergistic killing during S phase in the presence of 0.5-5 mM hydroxyurea together with 5-10 mM caffeine. Both the rate and the extent of killing are greater than expected for independent action of the two drugs. Only simultaneous treatment is effective. The dependence of the synergistic killing on cell age resembles the age dependence for killing by hydroxyurea alone (〉3 mM), but not that by high concentrations of caffeine. In addition, rapid killing occurs if caffeine is added to cultures that have been incubated in the presence of hydroxyurea from early G1 and are blocked at the beginning of S, although such cells are killed only slowly on continued incubation in ≥ 10 mM hydroxyurea alone. Furthermore, cells that are incubated with the two drugs from early G1 begin to undergo synergistic killing at about 12 h after mitotic collection, but they do not commence DNA replication for another 2-3 h if the drugs are removed. It is concluded that cells that have reached a point in the cycle identical with or close to the end of G1 are sensitive to the combination whether or not they are able to synthesize DNA, and whether or not they are sensitive to hydroxyurea alone. A tentative model is proposed: hydroxyurea is postulated to kill cells by interacting with sites of replication in DNA, and the synergism is attributed to the extra replication points that caffeine is known to induce.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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