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  • Life and Medical Sciences  (42)
  • PHYSICAL SCIENCES  (7)
  • 1990-1994  (48)
  • 1960-1964  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Modulation of keratin intermediate filament distribution in vivo by induced changes in cyclic AMP-dependent phosphorylation (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 291-300 
    Details
    ISSN: 0886-1544
    Keywords: PtK1 keratin filaments ; electrophoresis ; autoradiography ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Treatment of PtK1 cells with 5 mM acrylamide for 4 hr induces reversible de-phosphorylation of keratin in concert with reversible aggregation of intermediate filaments (Eckert and Yeagle, Cell Motil. Cytoskeleton 11:24-30, 1988). We have examined this phenomenon by 1) in vitro phosphorylation of isolated PtK1 keratin filaments and 2) combined treatments of PtK1 cells with both acrylamide and agents which elevate intracellular cAMP levels. PtK1 keratins were incubated in gamma-32P-ATP in the presence or absence of cAMP-dependent kinase (A-kinase) and cAMP. Levels of phosphorylation were analyzed by electrophoresis and autoradiography. Phosphorylation of keratin polypeptides (56 kD, 53 kD, 45 kD, 40 kD) occurred without added kinase, suggesting the presence of an endogenous kinase which remains with intermediate filaments in residues of Triton X-100 extracted cells. Phosphorylation levels were increased by A-kinase but not by cAMP alone, indicating the presence of cAMP-dependent phosphorylation sites in addition to sites phosphorylated by the endogenous kinase. To study the possible role of cAMP-dependent phosphorylation in acrylamide-induced aggregation of keratin filaments, we treated cells with acrylamide in the presence of 8-bromo-cAMP (brcAMP), pertussis toxin (PT), isobutylmethylxanthine (IBMX), or forskolin, which increase intracellular cAMP levels. The distribution and phosphorylation levels of keratin filaments, as well as intracellular cAMP levels, were determined for each of these treatments. In addition to aggregation and dephosphorylation of keratin filaments reported previously, treatment of cells with acrylamide alone also results in reduced levels of intracellular cAMP. 8-bromo-cAMP, IBMX, and forskolin prevent acrylamide-induced aggregation of keratin filaments and result in both normal levels of keratin phosphorylation and normal intracellular cAMP levels. PT was apparently ineffective. These observations suggest that 1) PtK1 keratins are phosphorylated by cAMP-dependent kinase and an endogenous, cAMP-independent kinase and 2) alteration of levels of cAMP-dependent phosphorylation may be involved in aggregation of keratin filaments in response to acrylamide.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970170404
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  • 2
    Electronic Resource
    Electronic Resource
    Microtubule reorganization during the cell cycle in synchronized BY-2 tobacco suspensions (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 94-106 
    Details
    ISSN: 0886-1544
    Keywords: Nicotiana tabacum ; microfilament ; nuclear envelope ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tobacco BY-2 suspension cultures were synchronized with aphidicolin in order to assess the relationship between microtubules (MTs), microfilaments (MFs), and the nuclear envelope (NE) at different stages of the cell cycle. Using immunofluorescence techniques, ordered MT arrays were found in the cortex in G1; few MTs are evident deeper in the cytoplasm or near the nucleus. However, MTs radiate from the surface of the nucleus during S and G2 as the interphase cortical array is replaced by the preprophase band. Perinuclear fluorescence is also visible at the end of cytokinesis but does not overlap with new ordered cortical arrays early in G1. When isolated nuclei are examined, associated MTs are again evident in S and G2, but not in G1. Microfilaments are colocalized with the MTs in the radiating arrays, as ascertained by dual staining of cells with rhodamine phalloidin. Propyzamide treatment leads to the loss of MTs at all stages, while cytoplasmic and perinuclear MF networks persist. Conversely, cytochalasin D disrupts MFs, including those radiating from the nucleus during S and G2, without any apparent effect on MTs. The results cast doubt on a proposed role for the NE in the generation of cortical MTs in plants. A universal role for MFs in the deployment of MTs is also in question.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180204
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  • 3
    Electronic Resource
    Electronic Resource
    Organization of cortical microfilaments in dividing root cells (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 23 (1992), S. 252-264 
    Details
    ISSN: 0886-1544
    Keywords: Allium ; Tradescantia ; actin ; cell cortex ; division plane determination ; immunocytochemistry ; mitosis ; microtubules ; preprophase band ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In order to assess the possible role of microfilaments (Mfs) in events preceding plant cell division, actin was localized in root cells of Allium cepa and Tradescantia virginiana by immunofluorescence microscopy. The distribution of Mfs was compared to that of microtubules (Mts) by means of dual localizations employing both antiactin and antitubulin. Cycling interphase cells contain Mfs that extend into all regions of the cytoplasm in random fashion. Prior to the rearrangement of the cortical Mt array into the initial broad preprophase band (PPB), the number of Mfs in the cytoplasm decreases, while a new population appears in the cortex. The cortical Mfs, which usually occupy the entire cell surface, are aligned parallel to the cortical Mts. When the initial PPB appears, these Mfs still cover the cortex or are arranged as a broad band encompassing the PPB. As the PPB narrows, the Mfs are also confined to an increasingly restricted zone usually wider than the PPB.than the PPB. When the PPB reaches its narrowest, densest configuration, aligned Mfs are excluded from the band proper, while others appear in flanking regions of the cortex. From prometaphase through anaphase, cortical Mfs are largely restricted to the ends of the cell overlying the spindle poles; they also tend to become more randomly oriented. Little or no actin is present in the spindle. During telophase, the two zones of aligned cortical Mfs over the ends of the cell gradually disappear and are replaced by new interphase networks. These changes provide additional data on the possible control of PPB organization by actin, and in addition indicate that the cortex may be the origin of the actin that aggregates at the spindle poles during cytochalasin treatment. © 1992 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970230405
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of cytochalasins on actin in dividing root tip cells of Allium and Triticum: A comparative immunocytochemical study (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 107-112 
    Details
    ISSN: 0886-1544
    Keywords: cell division ; cytoskeleton ; root cell ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A collaborative effort was initiated to resolve differences in two recent papers on the effects of cytochalasins in root cells. While both studies reported similar effects on interphase cells (i.e., replacement of microfilaments by many small specks and rods), Palevitz (Cell Motil. Cytoskeleton 9:283-298, 1988) maintained that cytochalasins B and D induce actin aggregation at the poles of dividing Allium root cells at a concentration of 10 μM with rhodamine phalloidin as a reporter probe, whereas McCurdy and Gunning (Cell Motil. Cytoskeleton 15:76-87, 1990) could not find these aggregates following antiactin immunocytochemistry in Triticum roots treated with CB at 50 μM. Employing identical methods and materials in the same laboratory, we found that CD induces polar actin aggregates in dividing cells of both species. However, the aggregates in Triticum are smaller and occur less frequently than those in Allium. A similar pattern is seen with CB.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180205
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  • 5
    Electronic Resource
    Electronic Resource
    Cytoskeletal alterations in cultured cardiomyocytes following exposure to the lipid peroxidation product, 4-hydroxynonenal (1994)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 28 (1994), S. 119-134 
    Details
    ISSN: 0886-1544
    Keywords: microtubules ; vinculin ; desmin ; sarcolemmal damage ; free radicals ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Damage to the cardiac myocyte sarcolemma following any of several pathological insults such as ischemia (anoxia) alone or followed by reperfusion (reoxygenation), is most apparent as progressive sarcolemmal blebbing, an event attributed by many investigators to a disruption in the underlying cytoskeletal scaffolding. Scanning electron microscopic observation of tissue cultured rat neonatal cardiomyocytes indicates that exposure of these cells to the toxic aldehyde 4-hydroxynonenal (4-HNE), a free radical--induced, lipid peroxidation product, results in the appearance of sarcolemmal blebs, whose ultimate rupture leads to cell death. Indirect immunofluorescent localization of a number of cytoskeletal components following exposure to 4-HNE reveals damage to several, but not all, key cytoskeletal elements, most notably microtubules, vinculin-containing costameres, and intermediate filaments. The exact mechanism underlying the selective disruption of these proteins cannot be ascertained at this time. Colocalization of actin indicated that whereas elements of the cytoskeleton were disrupted by increasing length of exposure to 4-HNE, neither the striated appearance of the myofibrils nor the lateral register of neighboring myofibrils was altered. Monitoring systolic and diastolic levels of intracellular calcium ([Ca2+]i) indicated that increases in [Ca2+]i occurred after considerable cytoskeletal changes had already taken place, suggesting that damage to the cytoskeleton, at least in early phases of exposure to 4-HNE, does not involve Ca2+ -dependent proteases. However, 4-HNE-induced cytoskeletal alterations coincide with the appearance of, and therefore suggest linkage to, sarcolemmal blebs in cardiac myocytes.Although free radicals produced by reperfusion or reoxygenation of ischemic tissue have been implicated in cellular damage, these studies represent the first evidence linking cardiomyocyte sarcolemmal damage to cytoskeletal disruption produced by a free radical product. © 1994 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970280204
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  • 6
    Electronic Resource
    Electronic Resource
    Oncogene amplification correlates with dense lymphocyte infiltration in human breast cancers: A role for hematopoietic growth factor release by tumor cells? (1990)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 44 (1990), S. 189-198 
    Details
    ISSN: 0730-2312
    Keywords: breast cancer ; dense immune cell infiltrate ; c-erbB2 ; int-2 ; c-myc ; CSF-1 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: One hundred six primary breast cancer samples were analysed for c-erbB2, int-2, and c-myc gene amplification. Surgically confirmed nodal involvement was observed in 42%. Level of gene amplification was studied by Southern and/or slot blottechniques. Amplified c-erbB2 gene sequences were present in 21.5% of all samples. Int-2 was amplified in 13.1% and c-myc was amplified in 10.3%. In a non-parametric test (Kruskal-Wallis) a strong negative association was found between high levels of c-erbB2 amplification and absence of estrogen receptor (ER) (P = .0009) or progesterone receptor (PR) (P = .011) expression. No correlations were found between all or high levels of amplification of each oncogene separately or combined with T, N, grade, multifocality of tumor, or associated carcinoma in situ. There was a trend approaching statistical significance for patients with c-erbB2 amplifications to have positive lymph nodes at surgery (P = 0.09). A somewhat surprising finding however was a very strong association between oncogene amplification and dense lymphocyte infiltration of the tumor (P = .05). This correlation is even stronger when only high levels of amplification are considered, either for each oncogene separately (P = .0048) or in combination (P = .007). We propose that malignant cell cytokine production may help explain this observation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240440307
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  • 7
    Electronic Resource
    Electronic Resource
    Neutral metalloendopeptidase associated with the smooth muscle cells of pregnant rat uterus (1991)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 45 (1991), S. 401-411 
    Details
    ISSN: 0730-2312
    Keywords: neutral endopeptidase ; uterus contractions ; oxytocin ; kidney enkephalinase ; uterus enzyme ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The pregnant rat uterus contains a membrane-bound metalloendopeptidase that is biochemically and immunologically similar to kidney enkephalinase (E.C.3.4.24.11). The uterus enzyme readily cleaved specific neutral endopeptidase substrates and oxytocin as well as the synthetic elastase substrate, Suc(Ala)3-pNA, yet did not digest native elastin. Using specific inhibitors, the uterus endopeptidase was identified as a metallopeptidase and not a serine protease, having an absolute requirement for zinc and perhaps calcium for maximal activity. The uterus endopeptidase cross-reacted with polyclonal antiserum to kidney microvillar endopeptidase and a monoclonal antibody to common acute lymphocytic leukemia antigen. Immunohistochemical localization of the enzyme in a 17 day pregnant uterus indicated that the enzyme was localized on the smooth muscle bundles of the myometrium and the endometrial epithelium. Total enzyme activity was 25 times higher in the late-term pregnant uterus (17th day of pregnancy) than in the nonpregnant uterus. Enzyme levels dropped rapidly prior to parturition and within 4 days after delivery the enzyme activity had returned to control levels. Inhibition of NEP in uterine strips with phosphoramidon resulted in a marked potentiation of oxytocin-induced contractions. Our results suggest that the uterine endopeptidase may have an important role in regulating uterine smooth muscle cell contraction during the latter stages of pregnancy through its action on oxytocin and perhaps other biologically active peptides.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240450414
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  • 8
    Electronic Resource
    Electronic Resource
    Protein-Tyrosine phosphatases and the regulation of insulin action (1992)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 48 (1992), S. 33-42 
    Details
    ISSN: 0730-2312
    Keywords: protein-tyrosine phosphatases ; phosphoprotein phosphatases ; protein phosphorylation ; insulin receptor ; insulin resistance ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Protein-tyrosine phosphatases (PTPases) play an important role in the regulation of insulin action by dephosphorylating the active (autophosphorylated) form of the insulin receptor and attenuating its tyrosine kinase activity. PTPases can also modulate post-receptor signalling by catalyzing the dephosphorylation of cellular substrates of the insulin receptor kinase. Dramatic advances have recently been made in our understanding of PTPases as an extensive family of transmembrane and intracellular proteins that are involved in a number of pathways of cellular signal transduction. Identification of the PTPase(s) which act on various components of the insulin action cascade will not only enhance our understanding of insulin signalling but will also clarify the potential involvement of PTPases in the pathophysiology of insulin-resistant disease states. This brief review provides a summary of reversible tyrosine phosphorlyation events in insulin action and available data on candidate PTPases in liver and skeletal muscle that may be involved in the regulation of insulin action.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240480107
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of oocyte maturation medium on in vitro development of in vitro fertilized bovine embryos (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 31 (1992), S. 72-77 
    Details
    ISSN: 1040-452X
    Keywords: Oocyte maturation ; Bovine ; Cattle ; Culture media ; Embryo IVF ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The objective of this study was to examine the effects of different culture media used for maturation of bovine oocytes on in vitro embryo development following in vitro fertilization. Oocytes were aspirated from 2-5 mm follicles of ovaries collected at a local abattoir. The oocyte-cumulus complexes (OCCs) were cultured for 23-25 h in one of seven commercially available media supplemented with 6 mg/ml bovine serum albumin (BSA), 0.25 mM pyruvate, 10 μg/ml luteinizing hormone (LH), 0.5 μg/ml follicle-stimulating hormone (FSH), and 1 μg/ml estradiol. After maturation for 23-25 h, all eggs were subjected to the same in vitro fertilization protocol using modified TALP medium and subsequently cultured in the same serum-free embryo culture medium (HECM-1/BSA) for 8 days, after which embryo development was assessed. Five media (SFRE, MEMα, TCM199, MEMα/+, RPMI:MEMα) better supported normal oocyte maturation as determined by embryo development to the two-cell (76-82%), morula/blastocyst (25-32%), and blastocyst (12-19%) stages. Oocytes that were matured in Waymouth's medium MB 752/1 or Ham's F-12 had a significantly reduced incidence of cleavage to the two-cell stage (52% and 37%, respectively), which was not attributed to failure of fertilization. Of the eggs that did cleave to the two-cell stage in these two media, 27% and 9% developed to morulae/blastocysts but only 6% and 3%, respectively, developed into blastocysts. This study demonstrates that (1) the culture medium used for bovine oocyte maturation can markedly affect subsequent embryo development at several stages, including blastocysts, and (2) bovine oocytes can be matured and fertilized and develop to blastocysts in serum-free medium.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080310113
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  • 10
    Electronic Resource
    Electronic Resource
    Golden hamster embryonic genome activation occurs at the two-cell stage: Correlation with major developmental changes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 32 (1992), S. 229-235 
    Details
    ISSN: 1040-452X
    Keywords: Preimplantation embryo ; Development ; Transcription ; UDP/UTP incorporation ; Hamster 2-cell embryo ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The earliest time of onset of embryonic genome activation in golden hamsters was investigated. The inhibition of transcription by α-amanitin (11 μg/ml) in cultured embryos resulted in a total arrest of development of early 2-cell embryos (26 hr post-egg activation); under similar conditions, immediate cleavage divisions of 1-, late 2-, 4-, and 8-cell embryos were not affected. Electrophoretic analysis of [35S]methionine-labeled embryonic proteins showed that α-amanitin treatment apparently inhibited transcription-dependent protein synthesis in early 2-cell and, to some extent, in late 2-cell when compared to 4-cell embryos. Analysis of total RNA synthesis, using [α32P]-UTP or [32P]-orthophosphate, showed that there was a high proportion of radioactivity associated with the macromolecular fraction (RNA) at the early and late 2-cell stages and at the 4-cell stage compared to that at the 1-cell stage. These results indicate that the de novo synthesis of RNA, encoded by the embryonic genome, occurs at the 2-cell stage and that the second and subsequent cleavage divisions of hamster preimplantation embryos are dependent on new transcriptional activity. This initial activity of the embryonic genome in hamsters is coincident with several characteristic features of in vitro development such as a block to development, synthesis of major proteins, change in energy substrate preference, phosphate-inhibition of development and a requirement for amino acids.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080320307
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