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  • Cell & Developmental Biology  (2)
  • Polymer gels  (2)
  • Bone loss  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Evolution of spinal bone loss and biochemical markers of bone remodeling after menopause in normal women (1995)
    Springer
    Calcified tissue international 57 (1995), S. 105-110 
    Details
    ISSN: 1432-0827
    Keywords: Menopause ; Bone loss ; Osteoporosis ; Bone densitometry ; Biochemical markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The main objective of this study was to describe longitudinal patterns of spinal bone loss in normal women who undergo a natural menopause. The second objective was to determine if a proportion of women suffer excessively rapid postmenopausal bone loss from the spine. If this was the case it was the aim to devise a means of predicting the women at excess risk; but if all women lost bone at similar rates, the aim was to document changing loss rates over the first 5–8 postmenopausal years. Responding women in six suburban general practices recalled for cervical smears who had their last menstrual period 9–36 months previously were invited to participate in a longitudinal study of bone loss and the biochemical markers plasma osteocalcin and urinary hydroxyproline. Sixty-four subjects agreed to participate, a response rate of 80%. In the ensuing 5 years, six received hormone replacement therapy and are not reported on. The main outcome measures were rates of spinal bone loss over 5 years, measured by dual photon absorptiometry, and radial bone loss over the first 2 years measured to quantitative computed tomography. Spinal bone loss was similar between individuals, with 94% of the variability in the data being accounted for by a statistical model that assumed parallel rates of bone loss. A less restrictive model allowing women to have different rates of spinal bone loss accounted for 12% more of the remaining variance in the data than the previous model. However, rates of radial bone loss were more dissimilar between women than rates of spinal loss. The results of the biochemical data collected serially showed that the plasma osteocalcin rose slowly to a plateau at 5 years postmenopause; in contrast, the hydroxyproline fell progressively with time over the whole period of study. These results were interpreted as being consistent with diminishing rates of bone destruction which gradually reequilibrated with bone formation as time passed after menopause.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298429
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The pellicular monolith: pore-surface functionalization and surface-phase construction in macroporous polymeric materials (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 557-562 
    Details
    ISSN: 1435-1536
    Keywords: Key words Latex ; Polymer colloid  ; Macroporous ; Polymer surface chemistry modification ; Polymer gels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We report synthesis and characterization of a macroporous polymeric material containing a covalently immobilized pore-surface phase of well-defined thickness, gel-phase porosity and organic functional group content. The pore surfaces of otherwise inert macroporous (32 μm mean pore size) ultrahigh-molecular-weight polyethylene (UHMWPE) are aminated throughout using a low-pressure flowing-discharge process to enable covalent immobilization of lightly cross-linked polymer colloid particles on all pore surfaces in the monolith. Solvent swelling and chemical derivitization of the covalently immobilized polymer colloid particles produce a pore-surface gel phase of well-defined thickness, organic amine content, and gel-phase porosity. The low degree of cross-linking in the polymer colloid particles prevents dissolution of the immobilized colloid in good solvents and enables the formation of pore-surface gel phases having high gel porosity on swelling in good solvents. The pore-surface amination introduced by the flowing discharge process varies by less than 17% through 5-mm thickness of the macroporous UHMWPE material. The properties of the pore-surface gel phase also vary by less than 17% through the cross section. The pore-surface immobilized polymer colloid particles swell by a factor of 10 in water and tetrahydrofuran after derivitization with polyethylene glycol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050424
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of the pore-surface gel phase in functionalized macroporous polymeric materials (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 1065-1071 
    Details
    ISSN: 1435-1536
    Keywords: Key words Macroporous ; Polymer colloid ; Polymer surface chemistry modification ; Polymer gels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Covalently immobilized pore-surface gel phases were prepared in a functionalized macroporous ultra-high-molecular-weight polyethylene by covalent coupling of lightly cross-linked polymer colloid particles [50% styrene, 49.8% (chloromethyl)stryrene, 0.2% divinylbenzene] to the interstitial pore surfaces. Swelling the covalently coupled colloid particles in a good solvent followed by chemical derivitization resulted in an immobilized pore-surface gel phase rich in primary amine groups. The macromolecular reactivity and molecular size-exclusion characteristics of the aminated pore-surface gel phase were then determined using monofunctional, amine-reactive, poly (ethylene glycol)s (PEG). Pegylated pore-surface gel phases that ranged from 71% (10,000 molecular weight PEG) to 56% (40,000 molecular weight PEG) PEG by weight resulted from reaction of the aminated gel phase with the PEG probe molecules. The number of PEG molecules reacting with the aminated pore-surface gel phase depends only on the Flory radius (or radius of gyration) of the PEG molecule to the negative 2.49th power i.e., 1/R f 2.49, corresponding to a M−1.48 dependence. The immobilized and pegylated polymer colloid particles swell by a factor of 16–25 times the diameter of the original polymer colloid particles in water, thereby demonstrating that pegylation occurred though a substantial fraction of the volume of the immobilized colloid particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050491
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  • 4
    Electronic Resource
    Electronic Resource
    A Golgi study of the opossum ventral basal complex (1983)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 177 (1983), S. 277-299 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of neurons in the ventral basal complex (VBC) of the adult opossum (Didelphis virginiana) is described from thick coronal brain sections, using Golgi-, horseradish peroxidase (HRP)-, and Nissl-staining methods. Soma cross-sectional area, dendritic field shape, and the number of appendages (spines) in a defined major branch zone (MBZ) are quantified and statistically analyzed. Results indicate that neurons in opossum VBC have relatively large cell bodies, dendrites which branch in a tufted pattern, and numerous dendritic appendages. These neurons are designated as relay cells because of (1) their tufted dendritic branch patterns, considered characteristic of thalamic relay cells (Ramon-Moliner, '62), and (2) the similarity of their soma sizes with HRP-labeled somata after somatosensory cortical injections. Neurons with traditionally described interneuron morphology do not appear to be present in the VBC of this animal, and, in this respect, the neuronal morphology of opossum VBC is similar to that in rat (McAllister and Wells, '81).Based on statistical analysis of the structural features observed, the presumed relay cells in opossum VBC do not show significant differences in morphology, and consequently are not subdivided into classes. Opossum VBC neurons are recognized as forming a single category in which broad and continuous variations in morphology are indicated. Recognition of a singular class of relay cell is consistent with descriptions for rat and cat VBC (Scheibel and Scheibel, '66), but at variance with a previous report for the primate Galago VBC (Pearson and Haines, '80) subdividing thalamic relay cells into Types I, II, and intermediate categories.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051770306
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Permeability of human venous endothelial cell monolayers perfused in microcarrier cultures: Effects of flow rate, thrombin, and cytochalasin D (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 149 (1991), S. 88-99 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have applied a multiple isotope dilution technique to examine junctional permeability of human umbilical vein endothelial cells (HUVEC) in vitro. Primary cultures were grown to confluence on porous Cytodex-3 microcarrier beads, packed into 0.3 ml columns (3 × 106 cells) and perfused at varying flow rates (0.3-1.2 ml/min) with HEPES-buffered Tyrodes solution containing unlabeled cyanocobalamin, insulin, and albumin. Columns were challenged periodically with mixtures of radioactive tracers of different molecular size. Permeability to 22Na+, [57Co]cyanocobalamin (1.3 kD), [125l]insulin (6 kD) or [125l]albumin (66 kD) was assessed relative to [131l]lgG (160 kD, impermeant reference tracer) by comparing column elution profiles. Although the single passage extraction of [125l]albumin by beads alone approximated 40%, the presence of confluent HUVEC rendered these beads effectively impermeable to albumin. High junctional extractions were measured for cyanocobalamin (0.79 ± 0.02, n = 28) and insulin (0.51 ± 0.05, n = 14) in cultures perfused at 0.3-0.4 ml/min, and tracer extraction decreased as perfusion rates increased. Permeability coefficients for cyanocobalamin (9.66 × 10-5 cm/s) and insulin (4.18 × 10-5 cm/s) increased significantly during perfusion with thrombin (10 U/ml) or cytochalasin D (1 μg/ml), whereas permeability to albumin (0.39 × 10-5 cm/s) remained unchanges. Morphological studies, using the glycocalyx stain ruthenium red, revealed that thrombin or cytochalasin D increased the penetration of the stain into junctions between endothelial cells.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041490112
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    Paper (German National Licenses)
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