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  • 1
    Electronic Resource
    Electronic Resource
    Extensive apoptotic death of rat colonic cells deprived of crypt habitat (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 177 (1998), S. 377-386 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Apoptosis in cells of different lineages is restrained by survival signals which depend upon cell-to-cell communication. The aim of this study was to determine whether colonic cells deprived of crypt ambient are doomed to die prior to their normal chronological demise. Apoptosis was studied in rat whole colonic tissue, in isolated intact crypts, and in colonic cell populations collected from the crypt axis at different stages of proliferation and differentiation. In a number of experiments, cell harvest was performed in the presence of either a tetrapeptide (YVAD-CMK) inhibitor of interleukin-1β-converting enzyme (ICE), or tyrphostin A25, a protein tyrosine kinase inhibitor, or sodium-orthovanadate, a phosphatase inhibitor. DNA fragmentation was assessed by electrophoretic and nonisotopic-labeling procedures. The ultrastructure of colonic tissue specimens and isolated cells was examined by transmission electron microscopy. Apoptosis in whole colonic tissue and in isolated crypts was confined predominantly to cells resident in the upper crypt regions. In contrast, extensive apoptotic death was observed in isolated colonic cells, irrespective of their developmental stage and positional hierarchy within the crypt continuum at harvest time. An apoptotic gradient, however, was evident. Exposure to YVAD-CMK resulted in a marked decrease in the number of apoptotic cells. Treatment with tyrphostin A25 caused a sharp rise in the apoptotic index; conversely, vanadate significantly impeded apoptosis. Cumulatively, these results indicate that disordered intercellular communication provokes unscheduled ICE-mediated apoptosis of colonocytes, and that local signals along the crypt continuum control both the reprieve from death and the timely demise of distinct colonic cell populations. Attenuation of tyrosine phosphorylation may be a contributory event in the acquisition of the apoptotic phenotype. J. Cell. Physiol. 177:377-386, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    cis-Acting DNA elements involved in oocyte-specific expression of mouse sperm receptor gene mZP3 are located close to the gene's transcription start site (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 36 (1993), S. 494-499 
    Details
    ISSN: 1040-452X
    Keywords: Luciferase gene ; 153-ZP3/LUC ; ZDT ; Transgene ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report that cis-acting DNA elements involved in oocyte-specific expression of the mouse sperm receptor gene (mZP3) are located close to the gene's transcription start site. Mice bearing a transgene that consists of only 153 nt of mZP3 5′-flanking region fused to the firefly luciferase gene (153-ZP3/LUC) expressed the reporter gene in ovary not in a wide variety of tissues; although two of three lines carrying 153-ZP3/LUC also expressed the transgene in forebrain and hypothalamus. Within the ovaries of transgenic mice, luciferase activity was restricted to growing oocytes. However, levels of luciferase activity in these oocytes were lower than those in oocytes from mice bearing transgenes that contain a larger segment of mZP3 5′-flanking region (470-6,500 nt) fused to the firefly luciferase gene. Mice bearing a trans-gene that consists of 470 nt of mZP3 5′-flanking region and mZP3 intragenic sequences (ZDT) were also analyzed. The presence of mZP3 intragenic sequences did not result in significantly increased levels of firefly luciferase activity in oocytes of mice carrying the ZDT transgene. Overall, these results suggest that as little as 153 nt of mZP3 5′-flanking region is sufficient to target expression of the firefly luciferase gene to mouse oocytes and that the mZP3 intragenic sequences probably do not contain enhancer elements. Rather, enhancer elements are probably present between  -  153 and  -  470 nt of the mZP3 5′-flanking region. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080360414
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of calcium deficiency on chondrocyte hypertrophy and type X collagen expression in chick embryonic sternum (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 198 (1993), S. 284-295 
    Details
    ISSN: 1058-8388
    Keywords: Skeletogenesis ; Endochondral ossification ; Shell-less chick embryo ; Hyaline cartilage ; Extracellular matrix ; Mineralization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Maintenance of chick embryos in long-term culture without their calcareous eggshell is a useful method for studying the relationship between calcium homeostasis and cell differentiation during skeletogenesis. Previously, we have shown that in shell-less (SL) embryos, calcium deficiency induces a cartilage-like phenotype in osteogenic tissues, such as calvaria (Jacenko and Tuan [1986] Dev. Biol. 115:215). In this investigation, we have studied the relationship between cartilage calcification and hypertrophy, and the expression of type X collagen, a specific product of hypertrophic chondrocytes. For this study, the cephalic (calcifying) and caudal (permanently cartilaginous) regions of sterna from day 18 and day 20 normal (NL) and SL embryos were metabolically labeled with [14C]-proline. Analysis of the biosynthetic products revealed significant differences in type X collagen expression in the cephalic region of sternal cartilage. In NL tissues, type X collagen production increased from 13.1% of total collagen at day 18 to 43.7% at day 20. In contrast, in SL embryos, type X collagen was not detectable until day 20, when it represented only 1% of total collagen. Comparison of the NL and SL embryos with respect to their serum calcium level and sternal calcium content and histology revealed a direct relationship between low systemic calcium and limited cartilage hypertrophy, undermineralization, and decreased type X collagen production in the sternal cephalic cartilage. Supplementation of CaCO3 to SL embryos increased their serum and sternal calcium, and restored cartilage hypertrophy, mineralization, and type X collagen synthesis in the cephalic portion of the sterna. These findings confirm that a critical relationship exists between calcium homeostasis, chondrocyte hypertrophy, mineralization, and type X collagen synthesis in the cephalic region of sternal cartilage. These results further demonstrate the importance of calcium in the morphogenetic events of endochondral ossification, in particular the transition from hyaline cartilage to hypertrophic cartilage, and eventually to bone. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001980406
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  • 4
    Electronic Resource
    Electronic Resource
    Electron microscopic observations on primary decidua formation in the ratThis investigation was supported by a Research Grant from the National Institutes of Health (HD 005690-03) and by the Medical Research Council of Canada. (1965)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 116 (1965), S. 217-235 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cytological changes in uterine stromal cells of the rat during induced primary decidua formation have been examined electron microscopically. Decidua forming stroma was examined at daily intervals for the five days during which the reaction reaches maximal hypertrophy and hyperplasia and was compared with pseudopregnant, non-decidual (control) endometrium. Stromal cells of control uteri resemble embryonic fibroblasts. They appear to be of two types, depending on whether they contain rough - or smooth-surfaced endoplasmic reticulum. As the decidual reaction progresses, the cells enlarge and become binucleate; cells which contain exclusively rough surface endoplasmic reticulum no longer are evident. Glycogen and fat become abundant, the former in association with smooth-surfaced membranes of the endoplasmic reticulum. Mitochondria become more numerous, smaller, and show evidence of a rearrangement in internal organization. There is a pronounced increase in a fine intracytoplasmic fibrillar component; and a spectrum of “microbodies” and lysosomes appears. At the height of the reaction, the stroma appears epithelioid. The possible functional significance of these changes is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001160111
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  • 5
    Electronic Resource
    Electronic Resource
    The histogenesis and cytology of the pancreatic islets in the rabbitA portion of a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in the Department of Pathology of the Graduate School of McGill University, 1950.This work was assisted by Grants-in-Aid from the National Research Council of Canada.Preliminary reports were given at the meeting of the American Association of Anatomists, Columbus, Ohio, 1953. (1955)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 96 (1955), S. 103-151 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1000960105
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  • 6
    Electronic Resource
    Electronic Resource
    Sequential changes in the mechanical properties of viable articular cartilage stored in vitro (1984)
    Hoboken, NJ [u.a.] : Wiley-Blackwell
    Journal of Orthopaedic Research 2 (1984), S. 55-60 
    Details
    ISSN: 0736-0266
    Keywords: Articular cartilage ; In vitro storage ; Indentation testing ; Proteoglycan degradation ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Viable articular cartilage from the medial femoral condyles of rabbits was stored in vitro in tissue culture medium with various additives and the same site of each specimen was mechanically tested sequentially throughout a 12-day storage period. Indentation testing was performed with instantaneous and sustained loads. Preservation of sustained-load carrying capacity was observed in the condyles stored with additives, indicating maintenance of an intact cartilage matrix. However, initial testing with small sustained loads (preload) showed changes not observed at higher load levels. The changes noted at small sustained initial loads may reflect alterations in cartilage surface structure and may be an early indicator of its mechanical integrity. Chondrocyte viability and proteoglycan content, as measured by 35S incorporation and hexosamine concentration, were unchanged in comparison to fresh articular cartilage.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jor.1100020109
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