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  • Springer  (34)
  • Blackwell Publishing Ltd
  • 1
    Electronic Resource
    Electronic Resource
    Regulation of Mesolimbic Dopamine Tracts by Cyclo(Leu-GIy) (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 537 (1988), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1988.tb42138.x
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  • 2
    Electronic Resource
    Electronic Resource
    Conservation of the elastic and flexural moduli of osteopenic femoral cortical bone in experimental inflammatory arthritis in the rabbit* (2000)
    Springer
    Journal of materials science 11 (2000), S. 561-568 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Experimental inflammatory arthritis (EIA) produced by carrageenan injection provokes a rapid bone remodeling state with cortical and cancellous bone loss. The objective of this study was to determine whether changes in cortical mechanical properties and/or geometry occur in long bones, either near or remote to the site of inflammation. EIA was induced in the right tibio-femoral joint of rabbits over 56 days. The right humerus and right femur from 15 normal and 25 arthritis group animals were excized. Semi-cylindrical specimens of the medial cortical shaft were subjected to non-destructive four-point bending tests. Transverse sections at the four contact sites of the loading jig were photographed and digitized to obtain average cross-sectional area (A) and moment of inertia (I). Moment of inertia and slope of the load/deflection curve permitted calculation of modulus of elasticity (E) for each specimen. Load/time curves were also used to calculate per cent stress remaining in relaxation experiments. Per cent stress remaining, E, A, I and $$.......CONVERSION........$$ \sqrt {{\text{I/A}}} (radius of gyration) were examined for differences by bone (humerus, femur) and by treatment (N,A) using two way ANOVA. The induction of inflammatory arthritis did not significantly alter the modulus of elasticity in either the femur or humerus; however, arthritis reduced the moment of inertia from $${\text{34}}{\text{.54}} \pm {\text{2}}{\text{.88}} \times {\text{10}}^{ - {\text{12}}} {\text{m}}^{\text{4}} {\text{ to 25}}{\text{.06}} \pm {\text{1}}{\text{.80}}^{ - 12} {\text{m}}^{\text{4}} ({\text{mean}} \pm {\text{SEM,}}p 〈 0.05)$$ . This was observed in the femur (near the arthritic joint), but not in the humerus (remote from arthritic joint). Analysis of area and ratio I/A demonstrated that this geometric effect of treatment was due to reduced area without gross cross-sectional shape changes. Per cent stress remaining in the femur (but not in the humerus) was higher in the arthritis specimens than in the normal specimens $$\left( {{\text{N:}}\;{\text{80}}{\text{.86}} \pm {\text{0}}{\text{.97}}\% ;\;{\text{A:}}\;{\text{83}}{\text{.25}} \pm {\text{0}}{\text{.71}}\% ,\;{\text{p}} 〈 0.05} \right)$$ . Thus, in this arthritis model, the principal mechanical or geometric effect on cortical bone was reduction of the cross-sectional area and moment of inertia. The viscoelastic relaxation response of bone was also altered, perhaps due to loss of water or collagen degradation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008976118934
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  • 3
    Electronic Resource
    Electronic Resource
    HMDC crosslinking of bovine pericardial tissue: a potential role of the solvent environment in the design of bioprosthetic materials (1995)
    Springer
    Journal of materials science 6 (1995), S. 235-241 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The need for alternative crosslinking techniques in the processing of bioprosthetic materials is widely recognized. While glutaraldehyde remains the most commonly used crosslinking agent in biomaterial applications there is increasing concern as to its biocompatibility-principally due to its association with enhanced calcification, cytotoxicity, and undesirable changes in the mechanical properties of bioprosthetic materials. Hexamethylene diisocyanate (HMDC), like glutaraldehyde, is a bifunctional molecule which covalently bonds with amino groups of lysine residues to form covalent crosslinks. Evidence within the literature indicates HMDC-treated materials are less cytotoxic than glutaraldehyde-treated materials; however, there is limited characterization of the material properties of HMDC-treated tissue. This study uses a multi-disciplined approach to characterize the mechanical, thermal, and biochemical properties of HMDC-treated bovine pericardial tissue. Further, to facilitate stabilization of the HMDC reagent, non-aqueous solvent environments were investigated. HMDC treatment produced changes in mechanical properties, denaturation temperature, and enzymatic resistance consistent with crosslinking similar to that seen in glutaraldehyde treated tissue. The significantly lower extensibility and stiffness observed under low stresses may be attributed to the effect of the 2-propanol solvent environment during crosslinking. While the overall acceptability of HMDC as a crosslinking agent for biomaterial applications remains unclear, it appears to be an interesting alternative to glutaraldehyde with many similar features.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146862
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  • 4
    Electronic Resource
    Electronic Resource
    Crosslinking of tissue-derived biomaterials in 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) (1996)
    Springer
    Journal of materials science 7 (1996), S. 531-541 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: In contrast to bifunctional reagents such as glutaraldehyde or polyfunctional reagents such as polyepoxides, carbodiimides belong to the class of zero-length crosslinkers which modify amino acid side-groups to permit crosslink formation, but do not remain as part of that linkage. The authors have compared the effects of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and glutaraldehyde (the de facto industrial standard crosslinker) on the hydrothermal, biochemical, and uniaxial mechanical properties of bovine pericardium. EDC crosslinking was optimized for maximum increase in collagen denaturation temperature using variables of pH, concentration, and ratio of EDC to N-hydroxysuccinimide (NHS): a reagent for formation of activated esters. EDC and glutaraldehyde crosslinked materials were subjected to hydrothermal denaturation tests, biochemical degradation by enzymes (collagenase, trypsin) and CNBr, amino acid analysis for unreacted lysine, and to high strain rate mechanical tests including: large deformation stress-strain studies (0.1 to 10 Hz), stress relaxation experiments (loading time 0.1 s) and small deformation forced vibration (1 and 10 Hz). A protocol for EDC crosslinking was developed which used 1.15% EDC (2:1 EDC:NHS) at pH 5.5 for 24 h. The increase in denaturation temperature for EDC (from 69.7±1.2°C to 86.0±0.3°C) was equivalent to that produced by glutaraldehyde (85.3±0.4°C). Both treatments equivalently increased resistance to collagenase and CNBr degradation; however, after denaturation, the EDC-treated tissue was slightly more resistant to collagenase, and markedly more resistant to trypsin. EDC-treated materials were more extensible and more elastic than glutaraldehyde-treated materials. Despite the differences in crosslinking mechanism, EDC and glutaraldehyde-treated materials are very similar. Subtle but intriguing differences in biochemical structure remain to be investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122176
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  • 5
    Electronic Resource
    Electronic Resource
    Ametropic efficiency of visual pathway neurons (1972)
    Springer
    Cellular and molecular life sciences 28 (1972), S. 1053-1054 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Bestimmung der Auswirkung von artefiziellen Refraktionsanomalien auf die Aktivität von Neuren in primären Sehzentren.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01918667
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  • 6
    Electronic Resource
    Electronic Resource
    Visual cortical cells: How critical is focus? (1973)
    Springer
    Cellular and molecular life sciences 29 (1973), S. 1496-1497 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Nachweis, dass rezeptive Kortexfelder der Kaninchen (70% der visuellen Zellen) auf Lichtstimuli bzw. Schärfe-Unschärfe-Änderung mit Amplitudenabfall reagieren.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01943877
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  • 7
    Electronic Resource
    Electronic Resource
    Phosphorylation dependence of the initiation of productive transcription of Balbiani ring 2 genes in living cells (1996)
    Springer
    Chromosoma 104 (1996), S. 422-433 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Using polytene chromosomes of salivary gland cells of Chironomus tentans, phosphorylation state-sensitive antibodies and the transcription and protein kinase inhibitor 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB), we have visualized the chromosomal distribution of RNA polymerase II (pol II) with hypophosphorylated (pol IIA) and hyperphosphorylated (pol II0) carboxyl-terminal repeat domain (CTD). DRB blocks labeling of the CTD with 32Pi within minutes of its addition, and nuclear pol II0 is gradually converted to IIA; this conversion parallels the reduction in transcription of protein-coding genes. DRB also alters the chromosomal distribution of II0: there is a time-dependent clearance from chromosomes of phosphoCTD (PCTD) after addition of DRB, which coincides in time with the completion and release of preinitiated transcripts. Furthermore, the staining of smaller transcription units is abolished before that of larger ones. The staining pattern of chromosomes with anti-CTD antibodies is not detectably influenced by the DRB treatment, indicating that hypophosphorylated pol IIA is unaffected by the transcription inhibitor. Microinjection of synthetic heptapeptide repeats, anti-CTD and anti-PCTD antibodies into salivary gland nuclei hampered the transcription of BR2 genes, indicating the requirement for CTD and PCTD in transcription in living cells. The results demonstrate that in vivo the protein kinase effector DRB shows parallel effects on an early step in gene transcription and the process of pol II hyperphosphorylation. Our observations are consistent with the proposal that the initiation of productive RNA synthesis is CTD-phosphorylation dependent and also with the idea that the gradual dephosphorylation of transcribing pol II0 is coupled to the completion of nascent pol II gene transcripts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00352266
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  • 8
    Electronic Resource
    Electronic Resource
    Phosphorylation dependence of the initiation of productive transcription of balbiani ring 2 genes in living cells (1996)
    Springer
    Chromosoma 104 (1996), S. 422-433 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Using polytene chromosomes of salivary gland cells of Chironomus tentans, phosphorylation state-sensitive antibodies and the transcription and protein kinase inhibitor 5,6-dichloro-1-β-d-ribofuranosyl-benzimidazole (DRB), we have visualized the chromosomal distribution of RNA polymerase II (pol II) with hypophosphorylated (pol IIA) and hyperphosphorylated (pol IIO) carboxyl-terminal repeat domain (CTD). DRB blocks labeling of the CTD with 32Pi within minutes of its addition, and nuclear pol IIO is gradually converted to IIA; this conversion parallels the reduction in transcription of protein-coding genes. DRB also alters the chromosomal distribution of IIO: there is a time-dependent clearance from chromosomes of phosphoCTD (PCTD) after addition of DRB, which coincides in time with the completion and release of preinitiated transcripts. Furthermore, the staining of smaller transcription units is abolished before that of larger ones. The staining pattern of chromosomes with anti-CTD antibodies is not detectably influenced by the DRB treatment, indicating that hypophosphorylated pol IIA is unaffected by the transcription inhibitor. Microinjection of synthetic heptapeptide repeats, anti-CTD and anti-PCTD antibodies into salivary gland nuclei hampered the transcription of BR2 genes, indicating the requirement for CTD and PCTD in transcription in living cells. The results demonstrate that in vivo the protein kinase effector DRB shows parallel effects on an early step in gene transcription and the process of pol II hyperphosphorylation. Our observations are consistent with the proposal that the initiation of productive RNA synthesis is CTD-phosphorylation dependent and also with the idea that the gradual dephosphorylation of transcribing pol IIO is coupled to the completion of nascent pol II gene transcripts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00352266
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  • 9
    Electronic Resource
    Electronic Resource
    A rationale for coastal wetland restoration through spoil bank management in Louisiana, USA (1994)
    Springer
    Environmental management 18 (1994), S. 271-282 
    Details
    ISSN: 1432-1009
    Keywords: Wetland ; Restoration ; Dredging ; Spoil ; Louisiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The rationale and outline of an implementation plan for restoring coastal wetlands in Louisiana is presented. The rationale for the plan is based on reversing the consequences of documented cause-and-effect relationships between wetland loss and hydrologic change. The main feature is to modify the extensive interlocking network of dredged spoil deposits, or spoil banks, by reestablishing a more natural water flow at moderate flow velocity (〈5 cm/sec). Guidelines for site selection from thousands of potential sites are proposed. Examples of suitable sites are given for intermediate marshes. These sites exhibit rapid deterioration following partial or complete hydrologic impoundment, implying a strong hydrologic, rather than sedimentological, cause of wetland deterioration. We used an exploratory hydrologic model to guide determination of the amount of spoil bank to be removed. The results from an economic model indicated a very effective cost-benefit ratio. Both models and practical experience with other types of restoration plans, in Louisiana and elsewhere, exhibit an economy of scale, wherein larger projects are more cost effective than smaller projects. However, in contrast to these other projects, spoil bank management may be 100 to 1000 times more cost effective and useful in wetland tracts 〈1000 ha in size. Modest spoil bank management at numerous small wetland sites appears to offer substantial positive attributes compared to alternative and more intensive management at a few larger wetland sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02393768
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  • 10
    Electronic Resource
    Electronic Resource
    Fuzzy Rule Based Prediction System of Surface Damage in the Laser Cleaning Process (2000)
    Springer
    The international journal of advanced manufacturing technology 16 (2000), S. 649-655 
    Details
    ISSN: 1433-3015
    Keywords: Keywords: Acoustic wave; Fuzzy rule based expert system; Laser cleaning; Prediction of surface damage; Process control algorithm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: During laser cleaning, surface damage on the substrate could easily occur by overexposure to a laser pulse of high fluence. Successful cleaning without surface damage can be achieved by skilled operators with long experience and good technique. This paper presents a fuzzy rule based expert system to predict surface damage during laser cleaning in the same way as a human expert. In this work, a fuzzy rule base was used to embed the acoustic information, which gives an indication of both progress in cleaning and the result. This is achieved by a wide-band microphone. An inference process was conducted to predict whether and how much surface damage would be induced on the substrate. Tests of the performance of the fuzzy system showed that the prediction of surface damage is well correlated with the actual results, independent of initial surface conditions. Based on the prediction of surface damage, the process control algorithm of laser cleaning has been developed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001700070035
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