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  • Life and Medical Sciences  (27)
  • Wiley-Blackwell  (27)
  • American Meteorological Society
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 29 (1991), S. 373-378 
    ISSN: 1040-452X
    Keywords: Oocyte cryopreservation ; Dilution lysis ; Cooling ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Rall and Fahy's (1985) vitrification procedure for the cryopreservation of 8-cell embryos was applied to unfertilized mouse oocytes. Unchanged, this method resulted in a mean of 24.1% of vitrified oocytes fertilizing and developing to blastocysts in vitro. Exposure of oocytes to the cryoprotectant media, but without the vitrification, resulted in 30.8% developing to blastocysts. Modifications to the durations of and media used in the dilution and equilibration steps of the procedure produced a final protocol giving a mean of 55.4% of vitrified oocytes and 72.4% of nonvitrified VS1-exposed oocytes developing to blastocysts; 85.7% of control oocytes develop to blastocysts. Osmotically induced damage was found to be the most important cause of loss of viability in these methods. Cooling of oocytes to 5-8°C during the procedure had no significant effect on their viability. No parthenogenetic activation of oocytes occurred as a result of exposure to the procedure.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 33 (1992), S. 210-214 
    ISSN: 1040-452X
    Keywords: Oocytes cryopreservation ; Vitrification ; Mouse ; Minimal cryoprotectant exposure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effects on oocyte viability of varying the duration of exposure to cryoprotectants before rapid cooling to - 196°C were examined, using the vitrification protocol of Nakagata. A very short exposure (15 sec) was found to be optimal, resulting in an overall rate of development from vitrified oocytes to hatching blastocysts of 31.8%. Very high rates of survival (77-89%) of oocytes exposed to the cryoprotectant media, but without the vitrification, together with extreme variability in results between straws in the vitrified groups, suggest that losses in viability during vitrification may result from ice damage during devitrification of the medium. (c) 1992 Wiley-Liss, Inc.
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  • 3
    ISSN: 0886-1544
    Keywords: nuclear migration ; microtubules ; F-actin ; root hairs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A prominent feature of tip growth in filamentous plant cells is that the nucleus often migrates in step with the tip as it extends. We have studied this long-recognized but unexplained relationship in root hairs of the legume Vicia hirsuta by a variety of microscopic techniques. Using rhodaminyl lysine phallotoxin, and antitubulin antibodies, root hairs are shown to contain axial bundles of F-actin and a complex microtubular system. To the basal side of the nucleus the microtubules are cortical and net axial but in the region between nucleus and tip the arrangement is more complicated. Electron microscopic thin sections demonstrate that internal bundles of microtubles exist in addition to the plasma membrane-associated kind. Computerized deblurring of through-focal series of antitubulin stained hairs clarifies the three-dimensional organization: bundles of endoplasmic microtubules progress from the nuclear region toward the apical dome where they can be seen to fountain out upon the cortex.The relationship between nucleus and tip can be uncoupled with antimicrotubule herbicides. Time lapse video microscopy shows that these agents cause the nucleus to migrate toward the base. This contrary migration can be inhibited by adding cytochalasin D, which fragments the F-actin bundles.It is concluded that microtubules connect the nucleus to the tip but that F-actin is involved in basipetal migration as is known to occur when symbiotic bacteria uncouple the nucleus from the tip.
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  • 4
    ISSN: 0886-1544
    Keywords: actin-bundling protein ; phosphorylation ; macrophage fractions ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The actin-bundling protein fimbrin is homologous to l-plastin, a 65kD phosphoprotein expressed in leukocytes and transformed cells [de Arruda et al., J. Cell Biol. 111, 1069-1080]. Because fimbrin is present in cell adhesion sites, we studied the phosphorylation state of fimbrin and its distribution in macrophages sequentially extracted with Triton-X-100 (soluble fraction), Tween 40-deoxy-cholate (cytoskeletal fraction), and SDS (insoluble cytoskeletal fraction). The approximate distribution of fimbrin and actin among these fractions was found to be: 65% fimbrin/55% actin in the soluble fraction, 30% fimbrin/20% actin in the cytoskeletal fraction, and 5% fimbrin/25% actin in the insoluble cytoskeletal fraction. PMA did not alter this distribution. Fluorescence microscopy of acetone-extracted macrophages showed that actin is concentrated in podosomes at the substratum interface and is diffusely distributed throughout the remainder of the cell. Fimbrin colocalizes with actin in podosomes and also exhibits a punctate distribution in the cytoplasm that overlaps with actin. In Tween 40/DOC-extracted cells, podosomes remain, and fimbrin also exhibits a punctate distribution along actin filaments. Metabolic 32PO4 labeling revealed that fimbrin is constitutively phosphorylated and that phosphorylated fimbrin is concentrated in the insoluble cytoskeletal fraction. PMA increased the relative levels of fimbrin phosphorylation twofold but did not alter the pattern of fimbrin fluorescence or the distribution of phosphorylated fimbrin. Limited trypsin digestion and phosphoamino acid analysis demonstrated that phosphorylation occurs specifically on serine residues within the 10kD headpiece domain of fimbrin. Phosphorylation of the headpiece domain could regulate the actin binding and bundling properties of fimbrin, or it could regulate the interaction of fimbrin with other proteins. © 1993 Wiley-Liss, Inc.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 115 (1964), S. 319-354 
    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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  • 6
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytotoxic effect of high, as well as low, oxygen tension of proliferation and metabolism of Low line cells in culture is reversible even after several days of exposure provided the cells are returned to 95% air + 5% CO2 environment. This suggests that the activity of certain mechanisms within the cells may have been altered or in other ways inhibited by the abnormal environments but are quite rapidly regenerated once the adverse condition is removed. The cells tolerate a low O2 exposure for at least 20 days while continuous exposure to high O2 atmosphere results in degeneration and death after 7-10 days. Both glucose utilization and lactic acid production are elevated in cultures exposed to either low or high O2 tensions, although they are markedly higher in the latter condition. When cell so exposed are returned to an air + 5% CO2 atmosphere, rate of glucose uptake and lactic acid formation soon approaches that found in control cultures.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 129 (1986), S. 193-198 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationship between total glutathione (GSH) content and cell growth was examined in 3T3 fibroblasts. The intracellular GSH level of actively growing cultures gradually decreases as these cells become quiescent by either serum deprivation or high cell density. Upon mitogenic stimulation of sparse, quiescent (G0/G1) cultures with serum, there is a rapid 2.3-fold elevation in intracellular GSH levels which, is maximal by 1 h and returns to baseline by 2 h. This is followed by a more gradual increase in GSH content as cells enter the S phase. In addition, the elevation in GSH content is required for maximum induction of DNA synthesis. Treatments that prevent the early increase in intracellular GSH levels do not affect protein synthesis but result in a reversible dose-dependent decrease in the percent of cells capable of entering S phase. These results indicate that GSH may be important in the regulation of cellular proliferation.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 115 (1983), S. 137-142 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Somatomedin is secreted by multiple types of cultured cells including human fibroblasts. Since the control of somatomedin (Sm) production by fibroblasts may be an important regulatory step in cell division, we undertook studies to define the variables in tissue culture experimental design that may have significant effects on the secretion of Sm. Cell density was an important parameter in determining basal Sm production rates. Cultures plated at 2.5 × 104 cells/well produced 0.38 ± 0.06 U/ml/105 cells whereas an increase in culture density to 6.2 × 104 cells/well was associated with a decrease in Sm production per cell to 0.23 ± 0.04 U/ml/105 cells (P 〈 .01). Cultures stimulated by platelet-derived growth factor (PDGF) showed a similar reduction in Sm production with increasing cell density. Epidermal growth factor was stimulatory (5.4-fold increase) in low-density cultures but had no effect when high-density cultures were used. If the experiments were initiated between 2 and 4 days after the last media change there were no significant differences in basal or PDGF-stimulated Sm concentrations. Between days 5 and 9 however, there was a progressive increase in the basal Sm production rate. The duration of incubation was an important variable since Sm production increased during the first 12 h in noncycling cells and showed an accelerated increase between 4 and 8 h in cycling cells. Cells between the eighth and 12th passage had similar basal Sm production (0.22 ± 0.04 U/ml/105 cells) rates; cells between the 19th and 20th passages had significantly higher basal Sm production rates (0.41 ± 0.05 U/ml/105 cells) (P 〈 .01). These results suggest that several variables, particularly cell density and passage number, are critical variables when quantitating the effect of hormones and growth factors on Sm production by cultured fibroblasts.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 23 (1983), S. 81-94 
    ISSN: 0730-2312
    Keywords: Rous sarcoma virus ; env gene mutants ; membrane anchor region ; deletion mutant ; signal peptide ; cleavage site mutants ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The env gene of Rous sarcoma virus codes for two glycoproteins which are located on the surface of infectious virions. Subcloning of these coding sequences in the place of the late region of SV40 DNA has allowed the expression of a normally glycosylated, functionally active glycoprotein complex on the surface of monkey cells. Through the use of site-directed mutagenesis, the role of specific amino acids in the signal peptide, signal peptidase cleavage site, and membrane anchor region have been investigated. Amino-terminal mutations have shown that deletion of the signal peptidase cleavage site along with one or two amino acids of the hydrophobic signal peptide results in the synthesis of an unglycosylated. uncleaved, and presumably cytoplasmically located precursor. Nevertheless, changing the signal peptidase cleavage site from ala/asp to ala/asn does not block the translocation of the glycoprotein across the membrane or the action of the peptidase. At the other end of the molecule, carboxy-terminal mutations have shown that the deletion of the hydrophobic membrane anchor region is not sufficient for the secretion of the truncated glycoprotein. Interpretations of these results based on recent models for protein transport and secretion are discussed.
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  • 10
    ISSN: 0730-2312
    Keywords: carcinogenesis ; chemoprevention ; intermediate end point ; biomarkers ; differentiation ; growth factors ; lung cancer ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The need for validate intermediate end point markers to facilitate lung cancer chemointervention research is competing. Three major classes of lung markers are relevant for this application. Since lung cancer includes four distinct hitologies, markers that map degrees of histologic differentiation are important. Many of the markers for squamous differentiation overlap with the candidates for application in the study of head and neck cancer. Production of tissue-specific cell product especially for surfactant or CEA is of interest, because the gene structure is known and many differentiation-related polymorphisms exist. This strategy would be useful for adenomatous type of tissue. A second type of marker is the broad group of differentiation markers. The carbohydrates or blood group-like antigens comprise a representative example. Carbohydrate structures are expressed in a specific sequence during fetal processes, and this sequence appears to reverse with the development of a cancer. Retrodifferentiation of specific differentiation markers is the basis of a major effort to effect earlier lung cancer detection using sputum immunocytochemistry. The final class includes markers which affects either positive or negative aspects of growths. Candidates in this area include growth factors or their receptors or genes that regulate growth. If the intermediate end point marker reflects tumor biology and is in that casual path of tumor progression, serial observation of that parameter should indicate the success of the intervention. In all three of these examples the clinical material to be analyzed could be sputum specimens bonrchial biopsies or resected lung tissue. Systematic analysis of these markers in context of intervention trials required to validate their utility. Long term clinical follow up will demonstrate the degree of concordance between biomarkers and more traditional clinical trial end points and will establish if such tools can play a role in catalyzing the rate of prevention research. © 1992 Wiley-Liss, Inc.
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