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  • Life and Medical Sciences  (7)
  • Computational Chemistry and Molecular Modeling  (4)
  • 1995-1999  (4)
  • 1990-1994  (7)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 44 (1992), S. 251-261 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A quantum chemical study of the two low-lying quartet states of seven model compound I iron-porphyrin complexes with varying axial ligands has been carried out using the INDO method. The varying axial ligands included in this study are five that are models for those in the intact enzymes: imidazole and imidazolate (model peroxidase HRP and CCP), CH3CONH2 (Gln175 mutant of CCP), PhO-1 (catalase), CH3S-1 (P450), and two that have been used in biomimetics of these enzymes: Cl-1 (hemin) and PhS-1 (model P450s). The purpose of these studies was to determine the role of the axial ligands in determining (i) the relative energies of the two nearly degenerate quartet electronic states of compound I, involved either as an a1u or a2u porphyrin π cation radical and (ii) the electron and spin distributions in the a1u and a2u radical cations of compound I. For most of the model complexes, including both HRP-I and CAT-I, a moderate effect of the axial ligand on the relative energy of these two states was observed and the a1u radical cation was found to be the ground state. The energy order of these two radical cations, however, was reversed in the P450-I model complexes, indicating an association of the unique property of the Fe=O bond breaking with an a2u radical cation. The symmetry-allowed overlap between the Fe=O and 3a2u orbitals may lower the activation energy for the Fe=O bond cleavage in P450-I. However, the calculated electronic and spin properties, including the unpaired spin and net charge on the oxygen and the Fe=O bond overlap density, important determinants of the reactivity of this complex in the ligand-Fe=O region, are very similar for all complexes and in both cation states. © 1992 John Wiley & Sons, Inc.
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  • 2
    ISSN: 0730-2312
    Keywords: mechanical strain ; interleukin (IL)-α and β gene expression ; proliferation ; protein synthesis ; morphology ; keratinocyte biology ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Recent studies in our laboratory have demonstrated that mechanical strain alters many facets of keratinocyte biology including proliferation, protein synthesis, and morphology. IL-1 is known to play an important role in the autocrine regulation of these basic cellular properties under basal and stimulated conditions. However, it is not known whether IL-1 plays a role in strain-induced alteration of keratinocyte biology. Thus, the objective of this study was to test the hypothesis that cyclic strain stimulates IL-1 expression and that strain-induced changes in keratinocyte function is regulated by IL-1. To test this hypothesis, we examined the effect of cyclic strain (10% average deformation) on keratinocyte IL-1 gene expression and the effect of neutralizing antibodies of IL-1α and IL-1β on strain-induced changes in keratinocyte proliferation, morphology, and orientation. Northern blot analyses demonstrated that steady state levels of IL-1α and β mRNA were elevated by 4 h, peaked at 12 h of cyclic strain (IL-1α, 304 ± 14.2%; IL-1β, 212 ± 5.6% increase vs. static controls) and decreased gradually by 24 h. IL-1 antibodies (IL-1α, 0.01 μg/ml; IL-1β, 0.01 μg/ml) significantly blocked strain-induced keratinocyte proliferation as well as the basal rate of proliferation. In contrast, IL-1 antibodies (IL-1α, 0.01 μg/ml; IL-1β, 0.1 μg/ml) had no effect on strain-induced morphological changes such as elongation and alignment. We conclude that mechanical strain induces IL-1 mRNA expression in keratinocytes. The role of IL-1 in mediating strain-induced changes in keratinocyte biology remains to be determined but appears to be independent of morphological changes. J. Cell. Biochem. 69:95-103, 1998. © 1998 Wiley-Liss, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 71 (1998), S. 491-501 
    ISSN: 0730-2312
    Keywords: diabetic microangiopathy ; endothelium ; HMEC-1 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Diabetic microangiopathy has been implicated as a fundamental feature of the pathological complications of diabetes including retinopathy, neuropathy, and diabetic foot ulceration. However, previous studies devoted to examining the deleterious effects of elevated glucose on the endothelium have been performed largely in primary cultured cells of macrovessel origin. Difficulty in the harvesting and maintenance of microvascular endothelial cells in culture have hindered the study of this relevant population. Therefore, the objective of this study was to characterize the effect of elevated glucose on the proliferation and involved signaling pathways of an immortalized human dermal microvascular endothelial cell line (HMEC-1) that possess similar characteristics to their in vivo counterparts. Human dermal microvascular endothelial cells (HMEC-1) were grown in the presence of normal (5 mM) or high D-glucose (20 mM) for 14 days. The proliferative response of HMEC-1 was compared under these conditions as well as the cAMP and PKC pathways by in vitro assays. Elevated glucose significantly inhibited (P 〈 0.05) HMEC-1 proliferation after 7, 10, and 14 days. This effect was not mimicked by 20 mM mannitol. The antiproliferative effect was more pronounced with longer exposure (1-14 days) to elevated glucose and was irreversible 4 days after a 10-day exposure. The antiproliferative effect was partially reversed in the presence of a PKA inhibitor, Rp-cAMP (10-50 μM), and/or a PKC inhibitor, Calphostin C (10 nM). HMEC-1 exposed to elevated glucose (20 mM) for 14 days caused an increase in cyclic AMP accumulation, PKA, and PKC activity but was not associated with the activation of downstream events such as CRE and AP-1 binding activity. These data support the hypothesis that HMEC-1 is a suitable model to study the deleterious effects of elevated glucose on microvascular endothelial cells. Continued studies with HMEC-1 may prove advantageous in delineation of the molecular pathophysiology associated with diabetic microangiopathy. J. Cell. Biochem. 71:491-501, 1998. © 1998 Wiley-Liss, Inc.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 35 (1993), S. 251-256 
    ISSN: 1040-452X
    Keywords: B-50/GAP-43 ; Development ; Hippocampus ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Protein phosphorylation has been suggested to be correlated with brain development and with the molecular mechanism of behavioral effects of neuropeptides. The present study reports in vitro endogenous phosphorylation of P46, a membrane-associated protein that is changed during development of the rat hippocampus. This study indicated that the degree of endogenous phosphorylation may be correlated with the establishment of synaptic connections. Interestingly, P46 was proved to be identical to a well-known growth-associated protein B-50/GAP-43 in its identical apparent molecular weight, isoelectric point, phosphorylation dependence, and the cross immunoreaction of monoclonal anti-B-50/GAP-43 antibody and P46. Moreover, neonatal administration of neuropeptide ZNC(G)PR could facilitate the developmental progress of P46 endogenous phosphorylation. It is suggested that the changes in P46 phosphorylation could be involved in the cellular mechanism of ZNC(C)PR behavioral effects on learning. © 1993 Wiley-Liss, Inc.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 27 (1997), S. X 
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 235-240 
    ISSN: 0192-253X
    Keywords: Micronuclei ; laser tweezers ; micro-manipulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have constructed a laser optical force trap (“laser tweezers”) by coupling an Nd:YAG laser to an optical microscope with a high numerical aperture objective. The laser beam (approximately 0.1 W power) is focused to a diffraction-limited spot at the specimen plane of the objective: the wavelength chosen (1,064 nm) is not strongly absorbed by most biological materials and is thus not ablative. Because the intensity of the laser beam increases towards the center of the focal spot, small particles brought near the spot will be attracted to the center and held there. Movement of the laser beam will tend to move any trapped particles with it. The laser tweezers can permit precise, nondestructive repositioning of small structures inside a living cell, without recourse to micromanipulators. Initial work has involved the use of laser tweezers on cells of Paramecium tet-raurelia held by a rotocompressor. We have been able to trap and reposition small organelles, especially the highly refractile structures known as crystals. Using a trapped crystal as a “tool”, we have been able to push micronuclei and other structures for many micrometers to virtually any desired location in a cell. In spite of extended exposure of specific structures and of individual cells to the laser beam, no damage has been detectible. Exposed cells, which were removed from the rotocompres-sor and cultured, showed complete viabilty. The laser tweezers technique shows tremendous potential for applications to the study of many fundamental cellular and developmental phenomena in paramecia and other ciliates. For example, we intend to use this technique to investigate temporal and spatial characteristics of nuclear determining regions during sexual reorganization in Paramecium. © 1992 Wiley-Liss, Inc.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 422-437 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A procedure is reported for the prediction of dense crystal structures of C-, H-, N-, O-, and F-containing organic compounds in the primitive triclinic, monoclinic, and orthorhombic space groups with Z ≤ 4. The crystal environments of molecules in 242 crystal structures have been analyzed to determine the common coordination sphere pattens. This led to the development of the MOLPAK (MOLecular PAcKing) program, which uses a rigid-body molecular structure probe to build packing arrangements (possible crystal structures) in the various space groups. A MOLPAK search, which involves the investigation of all unique orientations of a central molecule and the construction of the appropriate coordination patterns about the central molecule, provides a 3-D map of minimum unit cell volume as a function of the orientation of the central molecule. MOLPAK uses a repulsion-only potential and a preset threshold to place molecules in contact with each other. The 5-10 smallest volume packing arrangements from a search are subjected to a lattice energy minimization refinement with the WMIN program to yield possible crystal structures. The results are described from the analyses of several known compounds starting with the crystal molecular structures as the MOLPAK search probes in the P1, P21, P21/c, and P212121 space groups. In addition, several examples are given in which the search probes were created by AM1 geometry optimization of preliminary molecular models. More extensive data are given in supplementary tables. © 1993 John Wiley & Sons, Inc.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 13 (1992), S. 187-198 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: In this article we report a newly developed direct CI program and its preliminary applications. This program is based mainly on the relationship between direct and exchange type loops and the rederivation of the external loop shapes.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 159 (1994), S. 51-59 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The transforming growth factor-β (TGF-β) family of proteins exert diverse and potent effects on proliferation, differentiation, and extracellular matrix synthesis. However, relatively little is known about the stability or processing of endogenous TGF-β activity in vitro or in vivo. Our previous work indicated that (1) TGF-β1 has strong heparin-binding properties that were not previously recognized because of neutralization by iodination, and (2) heparin, and certain other polyanions, could block the binding of TGF-β1 to α2-macroglobulin (α2-M). The present studies investigated the influence of heparin-like molecules on the stability of the TGF-β1 signal in the pericellular environment. The results indicate that heparin and fucoidan, a naturally occurring sulfated L-fucose polymer, suppress the formation of an initial non-covalent interaction between 125I-TGF-β1 and activated α2-M. Electrophoresis of 125I-TGF-β1 showed that fucoidan protects TGF-β1 from proteolytic degradation by plasmin and trypsin. While plasmin caused little, if any, activation of latent TGF-β derived from vascular smooth muscle cells (SMC), plasmin degraded acid-activated TGF-β, and purified TGF-β1, and this degradation was inhibited by fucoidan. In vitro, heparin and fucoidan tripled the half-life of 125I-TGF-β1 and doubled the amount of cell-associated 125I-TGF-β1. Consistent with this protective effect, heparin- and fucoidan-treated SMC demonstrated elevated levels of active, but not latent, TGF-β activity. © 1994 wiley-Liss, Inc.
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  • 10
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previous studies indicated that a major factor in heparin's ability to suppress the proliferation of vascular smooth muscle cells is an interaction with transforming growth factor-β1 (TGF-β1). Heparin appeared to bind directly to TGF-β1 and to prevent the association of TGF-β1 with α2-macroglobulin (α2-M). The present studies indicate that 20-70% of iodinated TGF-β1 binds to heparin-Sepharose and the retained fraction is eluted with ∼0.37 M NaCI. Native, unlabelled platelet TGF-β1, however, is completely retained by heparin-Sepharose and eluted with 0.9-1.2 M NaCI. Using synthetic peptides, the regions of TGF-β1 that might be involved in the binding of heparin and other polyanions were examined. Sequence analysis of TGF-β1 indicated three regions with a high concentration of basic residues. Two of these regions had the basic residues arranged in a pattern homologous to reported consensus heparin-binding regions of other proteins. The third constituted a structurally novel pattern of basic residues. Synthetic peptides homologous to these three regions, but not to other regions of TGF-β1, were found to bind to heparin-Sepharose and were eluted with 0.15 M-0.30 M NaCI. Only two of these regions were capable of blocking the binding of heparin to 125I-TGF-β. Immobilization of these peptides, followed by affinity purification of heparin, indicated that one peptide was capable of isolating subspecies of heparin with high and low affinity for authentic TGF-β1. The ability of TGF-β1 to bind to heparin or related proteoglycans under physiological conditions may be useful in understanding the biology of this pluripotent growth and metabolic signal. Conversely, a subspecies of heparin molecules with high affinity for TGF-β1 may be a factor in some of the diverse biological actions of heparin. © 1992 Wiley-Liss, Inc.
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