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  • Articles  (120)
  • Humans  (65)
  • Life and Medical Sciences  (55)
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  • Articles  (120)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 172 (1982), S. 5-22 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The siphuncle of the chambered nautilus (Nautilus macromphalus) is composed of a layer of columnar epithelial cells resting on a vascularized connective tissue base. The siphuncular epithelium taken from chambers that have not yet begun to be emptied of cameral liquid has a dense apical brush border. The great number of apical cell junctions (zonula adherens) compared to the number of nuclei suggests extensive interdigitation of these cells. The perinuclear cytoplasm of these preemptying cells is rich in rough endoplasmic reticulum. The siphuncular epithelium of both emptying and “old” siphuncle (which has already completed emptying its chamber) both show little rough endoplasmic reticulum but do contain extensive systems of mitochondria-lined infoldings of the basolateral plasma membranes. Active transport of NaCl into the extracellular space of this tubular system probably entrains the water transport involved in the chamber-emptying process. Both emptying and old siphuncular epithelium also show large basal infoldings (canaliculi) continuous with the hemocoel, which appear to be filled with hemocyanin. The apical cell junctions of emptying and old siphuncular epithelium contain septate desmosomes that may help to prevent back-flow of cameral liquid into the chambers.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 133-145 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The buccal glands of adults of the Southern Hemisphere lamprey Geotria australis consist of a pair of small, bean-shaped, hollow sacs, embedded within the basilaris muscle in the region below the eyes and to either side of the piston cartilage. Each gland, which is lined by a simple columnar epithelium and surrounded by an incomplete layer of skeletal muscle, discharges its contents into the oral cavity via a long, narrow duct. In downstream migrating young adults, the epithelial cells are low columnar, intermediate in electron density, and contain dark-staining inclusions and numerous lipid-like droplets. After saltwater acclimation, the epithelial cells become taller and the numbers of dark-staining inclusions increase whereas those of lipid-like droplets decline. By the end of the marine phase, the epithelium is more folded and now also contains dark and light cells. The ultrastructure of the epithelium shows the characteristics of both apocrine and merocrine secretion. Although intra-epithelial nerve endings were not observed, axons and occasional neurons are present in the lamina propria. Since the skeletal muscle capsule is also well innervated and contains neurons, a local feed-back mechanism may regulate the release of buccal gland fluid by monitoring the luminal pressure. Contractions of the skeletal muscle capsule and movements of the basilaris muscle during feeding would presumably assist the movement of secretion along the duct. The secretion possesses anticoagulating and haemolytic properties.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 226 (1995), S. 339-349 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mordacia mordax is one of the two anadromous parasitic lamprey species of the southern hemisphere family Mordaciidae. Its adults possess two lateral buccal glands and one central buccal gland. When the tongue-like piston is retracted, the buccal glands occupy much of the opening of the oral cavity at the rear of the buccal cavity. The glands contain numerous tube-like, ductless secretory units, which discharge directly into the buccal cavity. Their secretory epithelial cells contain numerous granules, some of which are zymogen-like, while others have a beaded, spiralled appearance. The similarity of the latter to mast cell granules suggests that they may likewise produce an anticoagulant, which would be valuable to a presumed blood feeder such as M. mordax. The mucus produced by these cells could act as a carrier for the secretions and as an adhesive for promoting retention of t he secretions on the host's surface. When the young adults is transferred to salt water, the buccal glands increase their production and discharge of secretions. Since the glands are not enclosed in musculature, their secretions are probably discharged by mechanical pressure applied by the forward movement of the head of the tooth-bearing piston into the buccal cavity. An account is given of the way in which the location, number, glandular organization, secretory granules, and type of secretion of the buccal glands of M. mordax, and thus presumably also their mode of function, differ markedly from those of members of the other lamprey family found in the southern hemisphere, and of all holarrctic lampreys. © 1995 Wiley-Liss, Inc.
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  • 4
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 203 (1990), S. 87-96 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology, cell types, and innervation of the several small papillae (x̄ = 17) and two larger papillae, which together form a ring just outside the fimbriae surrounding the suctorial disc of adult Geotria australis, have been studied using various histological stains, including silver impregnation, and scanning and transmission electron microscopy. The epithelium of all papillae consists almost entirely of mucigenic cells. The multivillous and oligovillous cells, which are found elsewhere in the lamprey epidermis, were not observed, and Merkel and polyvillous cells are rare. Free nerve endings are common, however, in the basal layers of the epidermis. Unlike the small papillae, the two large papillae contain a core of skeletal muscle and a prominent layer of dermal collagen. In the submucosa of these large papillae, the nerves form a dense, compact layer that contains many large and probably sensory axons. It is suggested that the oral disc papillae of adult G. australis are encapsulated mechanosensory structures that play a role in enabling the animal to locate and attach to a suitable point on host fishes or other surfaces.
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  • 6
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Conjugates of the single-chain ribosome-inactivating protein gelonin with ligands that bind to cell surface molecules vary greatly in their cytotoxicity. Conjugates that are not endocytosed after binding to cells exhibit low cytotoxicity similar to that of free gelonin, while conjugates that are endocytosed demonstrate enhanced cytotoxicity relative to free gelonin. However, the number of internalized gelonin molecules needed to intoxicate cells to the same degree has been found to be similar for all conjugates and for free gelonin. The intracellular concentration of gelonin has to be between 2,000-10,000 molecules/cell to achieve a surviving fraction of 0.37. Our studies revealed the presence of three distinct categories of cell surface molecules, those that are efficient in mediating endocytosis of im-munotoxins, those that are only moderately efficient, and those that seem not to cause internalization of bound immunotoxins.
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  • 7
    ISSN: 0730-2312
    Keywords: glycoprotein trafficking variant ; mouse mammary tumor virus ; heterokaryons ; glucocorticoid receptor deficient variant ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The biological control of posttranslational maturation and compartmentalization reactions that operate upon proteins during transport to their final cellular desti- nations is crucial for normal cellular function. Using the expression of mouse mammary tumor virus (MMTV) glycoproteins as sensitive probes in the viral- infected rat hepatoma cell line M1.54, we have discovered and documented a novel glucocorticoid-regulated trafficking pathway that controls the cell surface localization of MMTV glycoproteins. One complement-selected derivative of M1.54 cells, CR4, failed to compartmentalize cell surface MMTV glycoproteins in the presence of dexamethasone. To test genetically if this glycoprotein trafficking pathway is mediated by cellular or viral gene products, CR4 cells were fused with uninfected Fu5 rat hepatoma cells. Indirect immunofluorescence of CR4 × Fu5 heterokaryons revealed that Fu5 complemented the defect in CR4 only after exposure to 1 μM dexamethasone. The glucocorticoid inhibition of Fu5 proliferation was exploited to recover the receptor-deficient uninfected derivative EDR3 that expressed a 100-fold lower level of [3H]dexamethasone binding activity. Analysis of CR4 × EDR3 cell fusions by indirect immunofluorescence revealed that EDR3 cells complemented CR4 in a dexamethasone-dependent manner, suggesting that EDR3 supplied a functional trafficking component while CR4 provided a functional glucocorticoid receptor to the heterokaryons. Taken together, our results demonstrate that cellular-encoded glucocorticoid-inducible components mediate the regulated trafficking of cell surface MMTV glycoproteins.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 31 (1995), S. 408-419 
    ISSN: 1059-910X
    Keywords: Neuronal mosaic ; Coupling ; Network ; Dopamine ; Nitric oxide ; Connexin ; Development ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The vertebrate retina is a highly laminated assemblage of specialized neuronal types, many of which are coupled by gap junctions. With one interesting exception, gap junctions are not directly responsible for the ‘vertical’ transmission of visual information from photoreceptors through bipolar and ganglion cells to the brain. Instead, they mediate ‘lateral’ connections, coupling neurons of a single type or subtype into an extended, regular array or mosaic in the plane of the retina. Such mosaics have been studied by several microscopic techniques, but new evidence for their coupled nature has recently been obtained by intracellular injection of biotinylated tracers, which can pass through gap junctional assemblies that do not pass Lucifer Yellow. This evidence adds momentum to an existing paradigm shift towards a population-based view of the retina, which can now be envisaged both as an array of semi-autonomous vertical processing modules, each extending right through the retina, and as a multi-layered stack of interacting planar mosaics, bearing some resemblance to a set of interleaved neural networks. Junctional conductance across mosaics of horizontal cells is known to be controlled dynamically with a circadian rhythm, and other dynamically-regulated conductance changes are also likely to make important contributions to signal processing. The retina is an excellent system in which to study such changes because many aspects of its structure and function are already well understood. In this review, we summarize the microscopic appearance, coupling properties and functions of gap junctions for each cell type of the neural retina, the regulatory properties that could be provided by selective expression of different connexin proteins, and the evidence for gap junctional coupling in retinal development. © 1995 Wiley-Liss, Inc.
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  • 9
    ISSN: 0730-2312
    Keywords: Cytochrome P-450 ; N-acetyltransferase ; 32P-postlabelling ; H-ras mutations ; larynx ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Metabolic activation, DNA adducts, and H-ras mutations were examined in human laryngeal tissue (n = 16) from both smoker and non/ex-smoker patients with laryngeal cancer. DNA adducts detected by 32P-postlabelling were evident only in smokers (n = 13); in fact, smoking cessation for as little as 10 months resulted in no DNA adducts detected (n = 3). Total DNA adduct levels in these samples were significantly correlated with levels of cytochromes P-4502C and 1A1 in laryngeal microsomes. Moreover, the P-4501A1 levels represent the highest yet found in human tissues. In contrast, laryngeal microsomes did not have detectable P-4501A2 activity, while laryngeal cytosols showed appreciable N-acetyltransferase activity for p-aminobenzoic acid (NAT1) but not sulfamethazine (NAT2).DNA was extracted from laryngeal specimens and amplified by PCR. Nylon filter dot or slot blots were hybridized with 32P-labelled probes for codons 12, 13, and 61 of the H-ras gene. Sixty percent of specimens demonstrated mutations in either codon 12, 13, or 61; a single common and specific mutation was a Gln → Glu transversion in codon 61. This mutation appeared in 5 laryngeal specimens, all from smokers.These results implicate cigarette smoke components, bioactivated by CYP1A1 and/or CYP2C, in DNA adduct formation. These results also demonstrate a probable smoking-related H-ras Gln → Glu transversion in codon 61.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 29 (1994), S. 151-154 
    ISSN: 1059-910X
    Keywords: Catecholamines ; Human ; Mouse ; MPTP ; Antiparkinsonian medication ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Parkinson's disease has been described as a multisystem disorder that includes alterations in the function of the autonomic nervous system. The activity of the adrenal medulla in this disease has not been thoroughly investigated. Previous reports are reviewed that demonstrate that the adrenal medullae of parkinsonian patients are compromised, having a decreased content of all catecholamines and several neuropeptides. An animal model was used to investigate whether the observations made in human patients were related to extended treatment with antiparkinsonian medications or were a natural concomitant of the disease. Administration of L-dopa and/or carbidopa to C57BL mice for 4-16 weeks had no significant effect on the level of any of the adrenal medullary catecholamines. Treatment with MPTP 4-16 weeks prior to sacrifice did not deplete adrenal medullary catecholamines in these animals, thus not fully mimicking Parkinson's disease in this animal model. The only significant effect was an interaction between group (MPTP or control) and treatment with antiparkinsonian medications; L-dopa, in the absence and presence of carbidopa, had opposite effects in the two groups. Based primarily on the lack of effect of antiparkinsonian medications on adrenal medullary catecholamines, it was concluded that the adrenal medullary depletion observed in human patients was a peripheral concomitant of Parkinson's disease. © 1994 Wiley-Liss, Inc.
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