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  • LUNAR AND PLANETARY EXPLORATION  (35)
  • Life and Medical Sciences  (19)
  • 2005-2009
  • 1990-1994  (54)
  • 1
    Electronic Resource
    Electronic Resource
    Epitope mapping of monoclonal antibodies against caldesmon and their effects on the binding of caldesmon to Ca++/calmodulin and to actin or actin-tropomyosin filaments (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 20 (1991), S. 95-108 
    Details
    ISSN: 0886-1544
    Keywords: actomyosin ; smooth muscle contraction ; nonmuscle cell motility ; microinjection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of monoclonal anti-caldesmon antibodies, C2, C9, C18, C21, and C23, on the binding of caldesmon to F-actin/F-actin-tropomyosin filaments and to Ca++/calmodulin were examined in an in vitro reconstitution system. In addition, the antibody epitopes were mapped by Western blot analysis of NTCB (2-nitro-5-thiocyanobenzoic acid) and CNBr (cyanogen bromide) fragments of caldesmon. Both C9 and C18 recognize an amino terminal fragment composed of amino acid residues 19 to 153. The C23 epitope lies within a fragment ranging from residues 230 to 386. Included in this region is a 13-residue repeat sequence. Interestingly this repetitive sequence shares sequence similarity with a sequence found in nuclear lamin A, a protein which is also recognized by C23 antibody. Therefore, it is likely that the C23 epitope corresponds to this 13-residue repeat sequence. A carboxyl-terminal 10K fragment contains the epitopes for antibodies C2 and C21. Among these antibodies, only C21 drastically inhibits the binding of caldesmon to F-actin/F-actin-tropomyosin filaments and tc Ca++/calmodulin. When the molar ratio of monoclonal antibody C21 to caldesmon reached 1.0, a maximal inhibition (90%) on the binding of caldesmon to F-actin filaments was observed. However, it required double amounts of C21 antibody to exhibit a maximal inhibition of 70% on the binding of caldesmon to F-actin-tropomyosin filaments. These results suggest that the presence of tropomyosin in F-actin enhances caldesmon's binding. Furthermore, C21 antibody also effectively inhibits the caldesmon binding to Ca++/calmodolin. The kinetics of C21 inhibition on caldesmon's binding to Ca++/calmodulin is very similar to the inhibition obtained by preincubation of caldesmon with free Ca++/calmodulin. This result suggests that there is only one Ca++/calmodulin binding domain on caldesmon and this domain appears to be very close to the C21 epitope. Apparently, the Ca++/calmodulin-binding domain and the actin-binding domain are very close to each other and may interfere with each other. In an accompanying paper, we have further demonstrated that microinjection of C21 antibody into living chicken embryo fibroblasts inhibit intracellular granule movement, suggesting an in vivo interference with the functional domains [Hegmann et al., 1991: Cell Motil. Cytoskeleton 20:109-120].
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970200203
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  • 2
    Electronic Resource
    Electronic Resource
    Transferrin is made and bound by photoreceptor cells (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 156 (1993), S. 280-285 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Retinal pigment epithelial cells, which form one aspect of the blood-retinal barrier, control the access of blood-borne components such as diferric transferrin to the neural retina. It has recently been shown that RPE cells remove iron from diferric transferrin in a low pH compartment and subsequently release it in a low molecular weight form that can be chelated by apo-transferrin (Hunt and Davis: J. Cell Physiol. 152:102-110, 1992). It is now shown that photoreceptor cells can bind diferric transferrin to receptors on their inner segments. Moreover, polymerase chain reaction and in situ hybridization show that cells of the neural retina, particularly photoreceptors, make apo-transferrin. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041560209
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  • 3
    Electronic Resource
    Electronic Resource
    Developmental expression of regionally specific cell surface antigens in the Xenopus gastrula (1990)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 11 (1990), S. 110-122 
    Details
    ISSN: 0192-253X
    Keywords: Embryonic cell surface ; glycoconjugates ; monoclonal antibodies ; developmental expression of glycoconjugates ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Molecular markers for specific cell lineages would be useful in studies of cellular differentiation. To isolate such markers monoclonal antibodies (MoABs) were raised against plasma membranes isolated from gastrulating Xenopus embryos. Those antibodies that recognized subsets of cells within the embryo were selected by indirect immunofluorescence. The analysis of eight such MoAbs is presented. Western blot analysis showed that all but one MoAb recognized a complex pattern of glycoconjugates associated with glycoproteins. All the antigens recognized by the MoAbs were maternal in origin and displayed similar spatial patterns of pregastrular expression. This pattern of immunoreactivity at the apical surface was inherited passively during cleavage by the resulting superficial blastomeres suggesting that ectodermal specific markers of maternal origin are pre-localized to the cortical ooplasm in mature oocytes. We suggest that these maternal components may be specific glycosyl transferases. Three different patterns of expression were observed during gastrulation as exemplified by MoAbs 1F10C1, 3A4D1, and 6F10B6. MoAb 6F10B6 was specific for both neural and non-neural epithelium. MoAb 3A4D1 was specific for non-neural epidermis. MoAb 1F10C1 appeared to recognize a protein epitope on an extracellular component expressed by the superificial and involuting epithelial cells. The pattern of expression for the 1F10C1 antigen suggests that it may play a role in facilitating the movement of the involuting cells during gastrulation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020110112
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  • 4
    Electronic Resource
    Electronic Resource
    Design and fabrication of well confined uniform magnetic field exposure systems (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 563-577 
    Details
    ISSN: 0197-8462
    Keywords: magnetic fields ; exposure system ; stray fields ; Merritt coils ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Exposure systems that provide good magnetic field uniformity, minimum stray fields, and minimal heating, vibration, and hum, as well as capability for true sham exposure in which current flows in the coils, are needed to determine rigorously the biological effects of weak magnetic fields. Designs based on acrylic polymer coil support structures and twisted pair bifilary coil windings were employed to fabricate several different systems for the exposure of laboratory animals and cell cultures to magnetic fields. These systems exhibit excellent performance characteristics in terms of exposure field uniformity, stray field containment, and exposure field cancellation in the sham exposure mode. A custom-written computer program was used to determine the best arrangement for coils with regard to field uniformity in the exposure volume and stray field containment. For in vivo exposures, modules were made up of four Merritt four-coil sets, built into a single structure and positioned to form an octapole with fields directed in the horizontal plane. For in vitro applications, two different coil configurations were selected to produce the vertical fields required. A quadrupole system, comprising modules consisting of two Merritt four-coil sets arranged side by side to limit stray fields, was built as a prototype. In the second configuration, one Merritt four-coil set was positioned inside the other to form a concentric coil set. In both in vitro systems, exposure chambers were connected to remote commercial incubators in order to reduce ambient magnetic fields in the exposure volume. An active field cancellation circuit was developed for reducing ambient AC magnetic fields in the in vitro sham exposure chamber, when necessary. These design and fabrication approaches provide systems that offer uniform field exposures and excellent stray field containment when needed and are portable, washable, and relatively inexpensive. © 1994 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250150610
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of continuous and pulsed 2450-MHz radiation on spontaneous lymphoblastoid transformation of human lymphocytes in vitro (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 13 (1992), S. 247-259 
    Details
    ISSN: 0197-8462
    Keywords: 2450-MHz microwaves ; pulsed and continuous waves ; thermal effects ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Normal human lymphocytes were isolated from the peripheral blood of healthy donors. One-ml samples containing (106) cells in chromosome medium 1A were exposed for 5 days to conventional heating or to continuous wave (CW) or pulsed wave (PW) 2450-MHz radiation at non-heating (37°C) and various heating levels (temperature increases of 0.5, 1.0, 1.5, and 2 °C). The pulsed exposures involved 1-μs pulses at pulse repetition frequencies from 100 to 1,000 pulses per second at the same average SAR levels as the CW exposures. Actual average SARs ranged to 12.3 W/kg. Following termination of the incubation period, spontaneous lymphoblastoid transformation was determined with an image analysis system. The results were compared among each of the experimental conditions and with sham-exposed cultures. At non-heating levels, CW exposure did not affect transformation. At heating levels both conventional and CW heating enhanced transformation to the same extent and correlate with the increases in incubation temperature. PW exposure enhanced transformation at non-heating levels. This finding is significant (P 〈 .002). At heating levels PW exposure enhanced transformation to a greater extent than did conventionalor CW heating. This finding is significant at the .02 level. We conclude that PW 2450-MHz radiation acts differently on the process of lymphoblastoid transformation in vitro compared with CW 2450-MHz radiation at the same average SARs. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250130402
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  • 6
    Electronic Resource
    Electronic Resource
    Magnetic-field flux density and spectral characteristics of motor-driven personal appliances (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 439-446 
    Details
    ISSN: 0197-8462
    Keywords: magnetic field ; electric appliances ; time-weighted average exposure ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Flux density and spectral measurements were carried out on magnetic fields generated by several types of motor-driven personal appliances used near the body. Among the units tested were several for which the average flux densities, as determined at the surfaces of the appliance, exceeded 0.4 mT. Time-rates-of-change (dB/dt) for several units exceeded 1000 T/s, and several units exhibited high-frequency components in the low-MHz range. Use of such appliances, although normally of short duration, can represent exposure to magnetic fields of relatively high flux density, which may also have high-frequency components. Compared to other household and commercial sources of magnetic fields, those generated by certain motor-driven personal appliances may represent a significant contribution to time-weighted average exposure and may represent an important source of local induced currents in the body. Furthermore, high-frequency transients that represent only a minor contribution to time-weighted average exposure may generate significant instantaneous induced currents. © 1994 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250150507
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  • 7
    Electronic Resource
    Electronic Resource
    Phorbol ester-stimulated stellation in primary cultures of astrocytes from different brain regions (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 29 (1994), S. 319-327 
    Details
    ISSN: 1059-910X
    Keywords: Astrocytes ; Cell culture ; Stellation ; Protein kinase C ; Scanning confocal light microscopy ; Phorbol ester ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Stellation is the process by which astrocytes change from epithelial-like to process-bearing cells. Stellation occurs following activation of either cyclic AMP-dependent protein kinase or protein kinase C. This process occurs through tubulin-dependent rearrangement of the cytoskeleton. We have evaluated the ability of phorbol, 12-myristate, 13-acetate (PMA) to induce astrocyte stellation. Astrocytes from five brain regions (cerebellum, cerebral cortex, hippocampus, diencephalon, and brain-stem) were examined to determine if all astrocytes would exhibit similar responses to this activator of protein kinase C. Stellation was evaluated following cell fixation by either phase optics using conventional light microscop, or scanning laser confocal light microscopy of cultures prepared using immunocytochemistry for tubulin and glial fibrillary acidic protein. Both the number of cells responding to PMA and the sensitivity to PMA varied for astrocytes from each brain region. PMA-induced stellation was most robust in cerebellar and brainstem astrocytes, with greater than 70% responding. Less than 40% of hippocampal and diencephalic astrocytes responded to PMA at the maximum does (10-5 M). PMA also induced different numbers of processes or branching patterns of processes on astrocytes from different brain regions. The protein kinase C induced stellation response in astrocytes supports the hypothesis that astrocytes contribute to neural plasticity. © 1994 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070290409
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  • 8
    Electronic Resource
    Electronic Resource
    Cytogenetic, cellular, and developmental consequences of cryopreservation of immature and mature mouse and human oocytes (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 27 (1994), S. 165-193 
    Details
    ISSN: 1059-910X
    Keywords: Cryopreservation ; Mammalian oocyte ; Cytogenetics ; Fertilization ; Embryogenesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: This study examined the effects of cryopreservation on cellular organization, chromosomal complement, and developmental potential of immature and mature mouse and human oocytes. Chromosomal analyses were performed by DNA fluorescence microscopy and karyotyping on the same metaphase II-stage oocytes before and after freezing. Cellular analyses involved electron microscopy, time-lapse video recording, and fluorescent-probe microscopy of cortical granules. The findings demonstrate that while profound cytoplasmic, nuclear, and nucleolar alterations occur in the immature oocyte during cryopreservation, an apparently normal nucleus and cytoplasm is re-established progressively after thawing and culture. The resulting oocytes mature at high frequency and for the mouse, are fertilizable and capable of normal preimplantation of embryogenesis. Cryopreservation of mature mouse and human oocytes is not accompanied by a significant increase in the frequency of aneuploidy. However, cryopreserved human oocytes, while fertilizable, arrest development during the early cleavage stages and display aberrant patterns of cytokinesis. The possible etiologies of developmental failure in the human embryo that may be related to oocyte cryopreservation, as well as the potential benefits of cryopreservation of the immature oocyte, are discussed with respect to clinical and commercial applications. © 1994 Wiley-Liss, Inc.
    Additional Material: 118 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070270209
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  • 9
    Electronic Resource
    Electronic Resource
    Management of polyamine pools and the regulation of ornithine decarboxylase (1990)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 44 (1990), S. 199-205 
    Details
    ISSN: 0730-2312
    Keywords: polyamine synthesis ; polyamine transport ; ornithine decarboxylase control ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The management of polyamine synthesis and polyamine pools differs fundamentally from that of most other small molecular-weight endproducts. The polyamines are vital to growth and important cellular functions, but they are toxic in excess. I argue here that their multivalent cationic character, leading to binding to cell constituents, precludes fluent feedback inhibition of synthesis. This has led to the development of elaborate alternative regulatory mechanisms controlling ornithine decarboxylase, the key initial enzyme of the pathway. Poorly regulated polyamine synthesis and the toxicity of polyamines impose upon cells a need to control uptake and to dispose of excess polyamines. Recent data on polyamine transport suggest unorthodox mechanisms of accomplishing these functions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240440402
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  • 10
    Electronic Resource
    Electronic Resource
    Identification of a role of the vitronectin receptor and protein kinase C in the induction of endothelial cell vascular formation (1993)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 51 (1993), S. 206-218 
    Details
    ISSN: 0730-2312
    Keywords: angiogenesis ; basement membrane ; integrins ; phosphorylation ; cord formation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: When cultured on a basement membrane substratum, endothelial cells undergo a rapid series of morphological and functional changes which result in the formation of histotypic tube-like structures, a process which mimics in vivo angiogenesis. Since this process is probably dependent on several cell adhesion and cell signaling phenomena, we examined the roles of integrins and protein kinase C in endothelial cell cord formation. Polyclonal antisera directed against the entire vitronectin (αvβ3) and fibronectin (α5β1) receptors inhibited cord formation. Subunit-specific monoclonal antibodies to αv, β3, and β1 integrin subunits inhibited cord formation, while monoclonal antibodies to α3 did not, which implicated the vitronectin receptor, and not the fibronectin receptor, in vascular formation. Protein kinase C inhibitors inhibited cord formation, while phorbol 12-myristate 13-acetate (PMA) caused endothelial cells to form longer cords. Since the vitronectin receptor has been shown to be phosphorylated in an in vitro system by protein kinase C, the possible functional link between the vitronectin receptor and protein kinase C during cellular morphogenesis was examined. The vitronectin receptor was more highly phosphorylated in cord-forming endothelial cells on basement membrane than in monolayer cells on vitronectin. Furthermore, this phosphorylation was inhibited by protein kinase C inhibitors, and PMA was required to induce vitronectin receptor phosphorylation in endothelial cells cultured on vitronectin. Colocalization studies were also performed using antisera to the vitronectin receptor and antibodies to protein kinase C. Although no strict colocalization was found, protein kinase C was localized in the cytoskeleton of endothelial cells initially plated on basement membrane or on vitronectin, and it translocated to the plasma membrane of C-shaped cord-forming cells on basement membrane. Thus, both the vitronectin receptor and protein kinase C play a role in in vitro cord formation. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240510213
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