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  • Cell & Developmental Biology  (30)
  • 1990-1994  (30)
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  • 1994  (30)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 39 (1994), S. 384-391 
    ISSN: 1040-452X
    Keywords: Transgene ; Mouse ; Embryo ; Microinjection ; PCR ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The production of transgenic animals from ungulate species is an inefficient and expensive procedure. The development of selection methods to identify the small number of transgenic preimplantation embryos produced following DNA microinjection of one-cell embryos would greatly reduce both the cost and effort of these procedures. This study has examined the fate of the ovine β-lactoglobulin-human α1-antitrypsin (AATB) minigene construct or a subfragment of this following microinjection into one-cell mouse embryos. It has examined two PCR-based methods that were designed to identify a biochemical difference between microinjected DNA constructs to select preimplantation stage embryos in which chromosomal integration of exogenous DNA has occurred. The two methods involved the modification of the AATB DNA construct either by dam-methylation or the substitution of dTTP by dUTP. The dam-sensitive DNA endonuclease Dpnl, that was used to digest nonintegrated AATB sequences at sites located between PCR oligonucleotide sequences, was found to interfere with the activity of the subsequent PCR reaction. Analyses of the fate of dUTP-DNA indicated that either repair or replication of microinjected DNA interfered with the ability to distinguish between integrated and nonintegrated DNA constructs in the mid-preimplantation stage embryo. The distribution of microinjected AATB DNA between the blastomeres of individual four and eight-cell stage embryos was also examined by the PCR reaction. Microinjected DNA was not found to be evenly distributed between all the blastomeres of individual embryos. © 1994 Wiley-Liss, Inc.
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  • 2
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The tissue distribution of P-glycoprotein (Pgp) and the structurally related cystic fibrosis transmembrane conductance regulator (CFTR) is apparently mutually exclusive, particularly in epithelia; where one protein is expressed the other is not. To study the possible function(s) of Pgp and its potential effects on CFTR expression in epithelia, HT-29 colon adenocarcinoma cells, which constitutively express CFTR, were pharmacologically adapted to express the classical multidrug resistance (MDR) phenotype (Pgp+). Concomitant with the appearance of Pgp and MDR phenotype (drug resistance, reduced drug accumulation and increased drug efflux), CFTR levels and cAMP-stimulated Cl conductances were markedly decreased compared to wild-type HT-29 (Pgp-) cells (as shown using the whole cell patch clamp technique). Removal of drug pressure led to the gradual decrease in Pgp levels and MDR phenotype, as evidenced by increased rhodamine 123 accumulation (Pgp-Rev). Concomitantly, CFTR levels and cAMP-stimulated Cl- conductances incresed. The cell responses of Pgp/Rev cells were heterogeneous with respect to both Pgp and CFTR functions. We also studied the possible contribution of Pgp to hypotonically activated (HCS) ion conductances. K+ and Cl- effluxes from Pgp- cells were markedly increased by HCS. This increase was twice as high as that induced by the cation ionophore gramicidin; it was blocked by the Cl- channel blocker DIDS (4,4′-disothiocyano-2,2′-disulfonic stilbene) and required extracellular Ca2+. In Pgp+ cells, the HCS-induced fluxes were not significantly different from those of Pgp- cells. Verapamil (10 μM), which caused 80% reversal of Pgp-associated drug extrusion, failed to inhibit the HCS-evoked Cl- efflux of Pgp+ cells. Similarly, HCS increased Cl- conductance to the same extent in Pgp-, Pgp+ and Pgp-Rev cells. Verapamil (100 μM), but not 1,9-dideoxyforskolin (50 and 100 μM), partially inhibited the HCS-evoked whole cell current (WCC) in all three lines. Since the inhibition by verapamil was not detected in the presence of the K+ channel blocker Ba2+ (3 mM), it is suggested that verapamil affects K+ and not Cl- conductance. We conclude that hypotonically activated Cl- and K+ conductances are similar in HT-29 cells irrespective of Pgp expression. Expression of high levels of Pgp in HT-29 cells confers no physiologically significant capacity for cell volume regulation. © 1994 Wiley-Liss, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 219 (1994), S. 35-46 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryos of viviparous goodeid fishes undergo a 10 to 150 × increase in dry weight during gestation. Maternal nutrients are transferred across a trophotaenial placenta comprised of the ovarian lumenal epithelium and the trophotaeniae of the embryo. Trophotaeniae are externalized projections of the embryonic hindgut. Epithelial cells of the ribbon trophotaenia (Ameca splendens) resemble intestinal absorptive cells of suckling mammals and endocytose macromolecules. They possess an apical brush border, endocytotic complex, endosomal-lysosomal system, and apical and basal clusters of mitochondria. Cells of the rosette trophotaenia (Goodea atripinnis) lack an endocytotic apparatus, have small lysosomes, two mitochondrial clusters, and transport small molecules. Organelle-specific fluorescent probes were employed to characterize the functional organization of the two types of trophotaenial cells. In A. splendens, Lucifer Yellow, a membrane-impermeable tracer of vesicular transport, first appears in peripheral vesicles (15-45 sec), then passes into elongated tubular endosomes (1-3 min) and later appears in large central vacuoles (10-15 min). These vacuoles accumulate Acridine Orange, a classical probe for lysosomes, and have been shown to contain lysosomal enzymes. Endosomelysosome fusion was observed. In both A. splendens and G. atripinnis, Rhodamine 123 fluorescence was localized in two clusters of fine spots that corresponded to mitochondria. 4′,6-diaminido-2-phenyl-indole (DAPI) staining of nuclei established the positional relationships of cell organelles with respect to the nuclei. 3,3′-dihexyloxacarbo-cyanine iodide (DiOC6) revealed the perinuclear distribution of the endoplasmic reticulum. In order to compare in vivo fluorescence of Lucifer Yellow with previous ultrastructural observations, we employed fluorescence photoconversion and electron microscopy. © 1994 Wiley-Liss, Inc.
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  • 4
    ISSN: 0886-1544
    Keywords: cytoskeleton ; actin binding ; transgelin sequence ; gelation ; gene family ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have used degenerate oligonucleotides, derived from the amino acid sequence of transgelin peptides [Shapland et al., 1993: J. Cell Biol. 121:1065-1073], to isolate and sequence overlapping cDNA clones encoding this actin gelling protein. Primers with 5′ restriction enzyme sites directed against the N and C terminal amino acids present in these clones were then used to amplify and clone the entire transgelin coding region from reverse transcribed rat small intestine cDNA (RT-PCR). These studies have shown that transgelin is the product of a single gene which is conserved between yeast, Drosophila, molluscs, and humans. Transgelin is expressed as a single message that is regulated at the level of transcription in SV40 transformed 3T3 cells. Our data have shown that transgelin and several other proteins of unknown function, SM22α [Pearlstone et al., 1987: J. Biol. Chem. 262:5985-5991], mouse p27 [Almendral et al., 1989: Exp. Cell Res. 181:518-530], and human WS3-10 [Thweatt et al., 1992: Biochem. Biophys. Res. Commun. 187:1-7], share extensive homology. More limited regions of homology shared between transgelin and other proteins such as rat NP25 (unpublished), chicken calponins α and β [Takahashi and Nadal-Ginard, 1991: J. Biol. Chem. 266:13284-13288], and Drosophila mp20 [Ayme-Southgate et al., 1989: J. Cell Biol. 108:521-531] suggest that all of these proteins may be classified as members of a new transgelin multigene family. © 1994 Wiley-Liss, Inc.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 29 (1994), S. 354-365 
    ISSN: 0886-1544
    Keywords: exocytosis ; rat tumor mast cells ; cytoskeleton ; A23187 ; stress fibres ; tubulin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Rat basophilic leukemia (RBL-2H3) cells undergo morphological and cytoskeletal changes during antigen-induced secretion of allergic mediators. The exact role these changes play in the process of secretion is unclear. Using confocal microscopy we now show that PMA + A23187 causes extensive F-actin rearrangements during secretion of [3H] 5-HT. We also describe for the first time the association of myosin with F-actin during this secretory process. In unstimulated cells, myosin and F-actin are concentrated at the plasma membrane with no evidence of stress fibres. Upon addition of PMA or A23187, both F-actin and myosin are rearranged into membrane ruffles and discrete aggregations (foci), followed by the formation of parallel stress fibres located on the ventral membrane. This is in contrast to reports in other cell types in which PMA has been described as causing the disruption of F-actin stress fibres. The time course of secretion coincides with the formation of the foci and ruffles whilst the stress fibres form after the majority of secretion has occurred. These changes are accompanied by a 40% decrease in cell height and a two-fold increase in cell spreading and they occur in the absence of extracellular calcium but are inhibited by the protein kinase C inhibitor, Bisindolylmaleimide, which also inhibits secretion. The formation of myosin-decorated stress fibres, foci, and ruffles is not sufficient to cause secretion, as PMA alone induces these changes without any secretion. The relevance of actin and myosin rearrangements for the regulation of secretion is discussed. © 1994 Wiley-Liss, Inc.
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  • 6
    ISSN: 0886-1544
    Keywords: kinesin ; brain mitochondria ; motility ; membrane-associated ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Kinesin, a mechanochemical enzyme that translocates membranous organelles, was initially identified and purified from soluble extracts from vertebrate brains. However, immunocytochemical and morphological approaches have demonstrated that kinesin could be associated to intracellular membranous organelles. We used an antibody raised against the head portion of the Drosophila kinesin heavy chain to reveal the presence of this protein in membranous organelles from rat brain. By using differential centrifugation and immunoblotting we observed a 116 kDa protein that crossreacts with this antibody in microsomes, synaptic vesicles, and mitochondria. This protein could be extracted from mitochondria with low salt concentrations or ATP. The 116 kDa solubilized protein has been identified as conventional kinesin based on limited sequence analysis. We also show that a polyclonal antibody raised against mitochondria-associated kinesin recognizes soluble bovine brain kinesin. The soluble and mitochondrial membrane-associated kinesins show a different isoform pattern. These results are consistent with the idea that kinesin exists as multiple isoforms that might be differentially distributed within the cell. In addition digitonin fractionation of mitochondria combined with KI extraction revealed that kinesin is a peripheral protein, preferentially located in a cholesterol-free outer membrane domain; this domain has the features of contact points between the mitochondrial outer and inner membranes. The significance of these observations on the functional regulation of the mitochondria-associated kinesin is discussed. © 1994 Wiley-Liss, Inc.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 56 (1994), S. 283-294 
    ISSN: 0730-2312
    Keywords: differentiation ; lineage ; osteogenesis ; chondrogenesis ; bone marrow ; osteoporosis ; fracture repair ; bioactive factors ; monoclonal antibodies ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Bone formation in the embryo, and during adult fracture repair and remodeling, involves the progreny of a small number of cells called mesenchymal stem cells (MSCs). These cells continuously replicate themselves, while a portion become committed to mesenchymal cell lineages such as bone, cartilage, tendon, legament and muscle. The differentiation of these cells, within each lineage, is a complex multistep pathway involving discrete cellular trasitions much like that which occurs during hematopoiesys. Progression from one stage to the next depends on the presence of specific bioactive factors, nutrients, and other environmental cues whose exquisitely controlled contributions orchestrate the entire differentiation phgenomenon. As understanding of the cellular and molecular events of osteogenic differentiation of MSCs provides the foundation for the emergence of a new therapeutic technilogy for cell therapy. The isolation and in vitro mitotic expansion of autologous human MSCs will support the development of novel protocols for the treatment of many clinically challenging conditions. For example, local bone defects can be repaired through site-directed delivery of MSCs in an appropriate carrier vehicle. Generalized conditions, such as osteoporosis, may be treatable by systemic administration of culture-expanded autologous MSCs or through biopharmaceutical regimens based on the discovery of critical regulatory molecules in the differentiation process. With this in mind, we can begin to explore therapeutic options that have never before been available.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 56 (1994), S. 449-454 
    ISSN: 0730-2312
    Keywords: antioxidantss ; diethylnitrosamine ; liver tumors ; methylxanthines ; modulation of carcinogenesis ; modifiers of matabolism ; oesophageal tumors ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A series of 16 experiments, using a total of 2,000 BD6 rats, was designed in order to assess the ability of 8 individual agents or their combinations to modulate the liver and oesophageal carcinogenesis induced by multiple doses of diethylnitrosamine (DEN). Of the antioxidants tested, sodium selenite, ascorbic acid, and butylated hydroxytoluence generally exhibited protective effects on both types of tumors. In contrast, retinoic acid behaved as a promoter of DEN hepatocarcinogenesis, but this effect could be eliminated by its combination with either selenite or butylated hydroxytoluene. Caffeine and theophyline, when individually assayed, were devoid of significant protective effects, and the later methylxanthine stimulated oesophageal tumorigenesis when administered afer exposure to the carcinogen. Caffeine tended to decrease tje multiplicityof tumors and potentiated the inhibitory effect of selenite in the liver. Irrespective of combination with caffeine, treatment with phwnobarbital before each DEN injection tended to reduce the multiplicity of both liver and oesophageal tumors. On the other hand, the metabolic inhibitoe diethyldithiocarbamate, given after each DEN injection, dramatically enhancedd the incidence and multiplicity of oesophageal tumors. Thus, on the whole, modulation of DEN carcinogenesis varied depending on test agents, their conbinations, dosages, treatment schedules, and target organ.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 56 (1994), S. 162-167 
    ISSN: 0730-2312
    Keywords: bioactive glass ; in vitro synthesis of bone tissue ; osteoblast ; bone tissue ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Using in vitro synthesifzed bone tissue with cells aspirated fpom the patient's marrow is an appealing idea to avoid the profound limitations of biological of biologiaal and synthetic grafts. Procedures to synthesize bone tiqsue on vitro primapily relied on seeding various subqtpates with cellq that have osteogenia capacity in culture. It should be noted that in an in vitro system, msteoppogenitor cells, as well as bone themselves an papidiy change their phenotype, hence the substrate needs to promote the expression or the bone cell Phenotype. Furthermore, it needs to provide a template for bone deposition while gradually resorbing once bone tissue has been laid down. This paper presents initial evidence that optimally combines the requirements of the ideal template for in vitro synthesis of bone tissue. When made in popous dorm, and conditioned to detelop a bone-like surface prior to being seeded with pluripoteltial cells capable of expressing the osteoblastic phenotype, these templates lead to expeditious and a undalt in vitro synthesis of extracellular matrix with most important characteristics of bone tissue.
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  • 10
    ISSN: 1059-910X
    Keywords: Sinus afferent pathway ; SP interneurons ; Double immunocytochemistry ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The ultrastructure of substance P-containing nerve terminals synapsing on catecholamine neurons in the rat commissural subnucleus of the nucleus tractus solitarii (NTScom) was studied using a double immunocytochemical labeling technique. Although there were numerous tyrosine hydroxylase-immunoreactive (TH-I) somata present, substance P immunoreactive (SP-I) cell bodies were only occasionally found in the NTScom. At the light microscopic level, many SP-I terminals were seen closely associated with TH-I dendrites and somata. At the electron microscopic level, SP-I terminals synapsing on TH-I structures were also readily encountered. SP-I terminals contained small, clear, and predominantly spherical vesicles (32 ± 4 nm diameter), as well as large dense-cored vesicles approximately 100 nm in diameter. Postsynaptic TH-I dendritic profiles of various calibers and somata were encountered. These postsynaptic TH-I structures often showed postsynaptic densities. The morphological features of the SP-TH synapses in the present study, that is, the size of synaptic vesicles and the presence of postsynaptic densities, are quite different from those of central carotid sinus afferent synapses reported in our previous study [Chen et al. (1992), J. Neurocytol., 21:137-147]. Therefore, most of the SP terminals of the SP-TH synapses in the NTScom appear not to originate from the carotid sinus afferents. SP-I second-order neurons of the carotid sinus afferent pathway [Chen et al. (1991), J. Auton. Nerv. Syst., 33:97-98] may be one of the possible sources of such terminals. © 1994 Wiley-Liss, Inc.
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