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  • Chemistry  (43)
  • Atomic, Molecular and Optical Physics  (11)
  • Gonadotropin  (4)
  • Magnetism
  • 1980-1984  (58)
  • 1
    Electronic Resource
    Electronic Resource
    The brain-pituitary-gonadal axis in the rainbow trout, Salmo gairdneri: Gonadal hormones and the maturation of gonadotropic cells (1982)
    Springer
    Cell & tissue research 225 (1982), S. 45-56 
    Details
    ISSN: 1432-0878
    Keywords: Gonadotropic cells ; Maturation ; Gonadotropin ; Gonadal hormones ; Juvenile trout
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intact and castrated juvenile male rainbow trout (Salmo gairdneri) were treated with testosterone and gonadotropic hormone (GTH) to determine the maturational effects of these hormones on the GTH-cells. Electron-microscopic studies of the GTH-cells revealed that GTH and testosterone in intact animals, and testosterone in castrated fish, caused GTH-cell maturation: These cells now displayed the same appearance as GTH-cells in adult trout, including the presence of globules, a well-developed Golgi apparatus and rough endoplasmic reticulum, all of which were absent in GTH-cells of control animals. Animals with stimulated GTH-cells also had an increased GTH content of the pituitary; release of GTH could not be demonstrated. Animals treated with GTH exhibited an accelerated development of the testes, resulting in complete gametogenesis and elevated plasma testosterone levels. These results indicate that exogenous steroids as well as endogenous gonadal steroids can stimulate the full development of GTH-cells and accelerate GTH synthesis. The significance of this stimulating effect of the gonadal hormones with respect to the development of the brain-pituitary-gonadal axis and the onset of puberty is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216217
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  • 2
    Electronic Resource
    Electronic Resource
    Active-site α-helix in papain and the stability of the ion pair RS- ··· ImH+. Ab initio molecular orbital study (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 651-671 
    Details
    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: Ab initio MO calculations, using both minimal (STO-3G) and extended (Roos-Siegbahn) basis sets are reported for the systems methanethiol-imidazole, methanethiol-imidazole-formaldehyde, and methanethiol-imidazole-formamide, which, together with a point-change representation of a long α-helix, form models for the active site of papain. It is shown that the large electric field exerted by the helix in the active-site region is responsible for the presence of the essential residues Cys 25 and His 159 in the form of an ion pair RS- ··· ImH+, which is crucial for a recently proposed mechanism for the catalytic action of the enzyme. Also, an explanation is given for the anomalies in measured pK values for these residues. Detailed studies on the (sub)systems show that minimal basis sets lack the flexibility necessary for describing the type of proton transfer involved. We conclude that α-helices are essential parts of enzymes and that they play a significant role in the catalytic process.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170407
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  • 3
    Electronic Resource
    Electronic Resource
    A quantitative description of the growth of Saccharomyces cerevisiae CBS 426 on a mixed substrate of glucose and ethanol (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 22 (1980), S. 2031-2043 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Saccharomyces cerevisiae CBS 426 was grown aerobically in continuous culture with a mixture of glucose and ethanol as the carbon source. The flows of biomass, glucose, ethanol, oxygen, and carbon dioxide were measured. A model for growth with two substrates was derived. Application of this model to the above-mentioned system yielded values for YATP and P/O. The joint confidence regions for these parameters were calculated. The relevance to industrial production of bakers' yeast is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260221004
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  • 4
    Electronic Resource
    Electronic Resource
    Abriebfestigkeiten der Korrosionsschutzbeschichtungen im Stahlwasserbau (1980)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 31 (1980), S. 866-869 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Wear-resistance of anti-corrosion coatings in hydraulic steel constructionsDIN 55 928 gives rules for the protection of steel structures from corrosion by organic and metallic coatings. The durability against abrasion of such coatings is classified in part 5, table 8, columns 9-11, of this DIN. A notice to these columns gives indication of an abrasion-machine developed by the Bundesanstalt für Wasserbau in Karlsruhe.Giving the best results, this machine for testing the mechanic durability was chosen out of a number of testing systems. The result is an abrasion value (Abriebwert).This value enables us to classify the coatings in accordance with their durability.The abrasion machine, its main dimensions and its working are described.
    Notes: In der Tabelle 8 des Teils 5 der DIN 55 928 - Korrosionsschutz von Stahlbauten durch Beschichtungen und Überzüge - wird in Spalte 9-11 die mechanische Beanspruchung der Beschichtungen klassifiziert und in einer Bemerkung dazu auf ein Prüfgerät hingewiesen, das bei der Bundesanstalt für Wasserbau in Karlsruhe entwickelt wurde.Das Prüfgerät ist das Ergebnis einer längeren Entwicklung; es ermöglicht die Angabe eines „Abriebwertes“ als Abstufung der Belastbarkeit von Beschichtungssystemen.Die Entwicklung des Prüfgerätes wird dargelegt und das Prüfgerät sowie der Prüfvorgang beschrieben.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19800311105
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  • 5
    Electronic Resource
    Electronic Resource
    Schwingungsrißkorrosion an plasmanitriertem stahlAuszugsweise vorgestellt auf der Hauptversammlung der Deutschen Gesellschaft für Metallkunde 1982 in Villach (1982)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 33 (1982), S. 647-653 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Corrosion fatigue of plasmanitrided steelThe effect of plasma-nitriding of steel 34 CrAlMo 5 on corrosion fatigue has been investigated in cyclic torsion. The tests were conducted in air, tap water and artifical sea water. Crack initiation and propagation have been studied by means of metallographic and fractographic methods to identify the fatigue mechanisms.Main results may be summarized as follows: The fatigue strength increases by about 40% due to plasma-nitriding over that of nonnitrided steel when tested in air. Even in corrosion environment plasma-nitriding improves remarkably the fatigue strength. The torsional fatigue strength of plasmanitrided specimen is not affected by the presence of tap water. In artifical sea water the distinct fatigue limit disappears. However, the fatigue life of the plasmanitrided specimen increases by factor of 10 compared with that of non-nitrided specimen. The reasons for this improvement were discussed by considering the mechanical and metallurgical aspects of the problems.
    Notes: Das Schwingungsrißkorrosionsverhalten von plasmanitriertem Stahl 34 CrAlMo 5 wurde in Torsionswechselversuchen an Luft, in Leitungswasser und in künstlichem Meerwasser untersucht. Rißbildung und Rißausbreitung wurden mittels metallographischer und fraktographischer Untersuchungsmethoden analysiert. Die Ergebnisse lassen sich folgendermaßen zusammenfassen: Durch das Plasmanitrieren wird an Luft eine Steigerung der Dauerfestigkeit um 40% gegenüber dem unbehandelten Zustand erreicht. Auch bei Einwirkung eines korrosiven Mediums bewirkt die Plasmanitrierschicht eine wesentliche Verbesserung des Dauerschwingverhaltens. Die Torsionswechselfestigkeit des plasmanitrierten Werkstoffes wird von einer Leitungswasserumgebung nicht beeinträchtigt. Im künstlichen Meerwasser existiert sowohl im unbehandelten als auch im plasmanitrierten Werkstoffzustand keine Dauerfestigkeit. Die Lebensdauer des plasmanitrierten Werkstoffes ist jedoch um eine Zehnerpotenz größer als die des unbehandelten Werkstoffes. Für die dargestellten Versuchsergebnisse werden verschiedene Deutungsmöglichkeiten diskutiert.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19820331202
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  • 6
    Electronic Resource
    Electronic Resource
    Fine structure and function of isolated gonadotropic cells as revealed from pituitaries of immature rainbow trout, Salmo gairdneri, by means of a new enzymatic dispersion technique (1982)
    Springer
    Cell & tissue research 226 (1982), S. 641-653 
    Details
    ISSN: 1432-0878
    Keywords: Juvenile Trout ; Dispersion ; Pituitary cells ; Gonadotropin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A procedure has been developed for dissociating pituitary glands of juvenile rainbow trout, Salmo gairdneri, producing a preparation of single dispersed pituitary cells in which morphological and functional integrity is preserved. The pituitaries are dispersed by sequential treatment with 0.1% collagenase, 0.04% ethylene-diamine-tetra-acetic acid (EDTA) and 0.125% dispase. The cell yield is 0.3–0.35 × 106 cells per pituitary with a cell viability percentage of 95±1 % and single cell percentage of 87±4%. The isolated cells are kept in a suspension system and the gonadotropic cells are identified by the double antibody immuno-enzyme-cytochemical technique using anti-carp β-gonadotropin as first antibody. Secretory activity is estimated by measuring the gonadotropin content in cells and culture media by radioimmunoassay. Isolated cells show an autonomy of gonadotropin secretion. 17α-Methyltestosterone both in vivo and in vitro stimulates the production of gonadotropin in the cells and seems to inhibit its release from the cells. It is concluded that this in vitro system can be used as a model for studying the control of gonadotropic cells in juvenile rainbow trout.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214791
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  • 7
    Electronic Resource
    Electronic Resource
    Accumulation of glycoprotein gonadotropin in the pituitary of juvenile rainbow trout in response to androgens and C21-steroids, including 11-steroids (1984)
    Springer
    Cell & tissue research 235 (1984), S. 635-642 
    Details
    ISSN: 1432-0878
    Keywords: Gonadotropin ; Gonadotropic cells ; Pituitary ; Steroid hormones ; Teleosts (trout)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Effects of steroids on the accumulation of glycoprotein gonadotropin (GTH) in pituitaries of juvenile trout were investigated by means of scanning cytophotometry applied to immunocytochemical preparations, and with the use of a radioimmunoassay. Effects on other aspects of GTH-cell activity were analyzed by measuring the size of the gonadotrops and their nuclei. Progesterone added to aquarium water and methyltestosterone incorporated into the food showed a pronounced stimulatory effect on the accumulation of GTH. To a lesser extent, treatment with cortisol, cortisone, and desoxycorticosterone acetate administered to aquarium water, and 11β-hydroxy-androstenedione added to the food resulted in an increase of the hypophysial content of GTH. Steroids stimulating the accumulation of GTH in the pituitary also exhibited a positive effect on GTH-cell activity as indicated by an increase in the size of gonadotropic cells. Progesterone incorporated into the food did not influence the GTH-content and the GTH-cell activity. It is suggested that the route of administration of an exogenous steroid is essential for its effect on GTH cells in trout. Comparison of GTH values reveals an excellent correlation between the data from the radioimmunoassay and those from the corresponding densitometric measurements. No correlation was observed between values of morphometrically determined GTH-cell activity and the densitometric values reflecting hypophysial GTH content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226962
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of 17α-methyltestosterone, estradiol-17β and synthetic LHRH on production of gonadotropic hormone in pituitaries of rainbow trout (organ culture) (1983)
    Springer
    Cell & tissue research 232 (1983), S. 157-176 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary, juvenile trout ; Gonadotropin ; Steroids ; LHRH ; Organ culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pituitary glands from 6-month-old sexually immature female rainbow trout, Salmo gairdneri, were kept in organ culture for 48 or 72 h. Certain groups of pituitaries were cultivated for 48 h on either control medium or medium with 17α-methyltestosterone (MT), or with estradiol-17β (E2) in concentrations of 8.5 × 10-7 M. Other groups of pituitaries were cultivated for 72 h on control medium, or for 48 h on either control medium or MT-medium or E2-medium, and subsequently for 24 h on medium with synthetic LHRH in concentrations of 8.5 × 10-7 M and 8.5 × 10-10 M. Gonadotropic (GTH) cells are identified by Alcian Blue-Periodic Acid Schiff-Orange G staining and the double-antibody immunoenzyme-cytochemical technique using anti-carp βGTH as the first antibody. A quantitative histological procedure was used to study the nuclear size of the GTH cells in response to the different hormones. Secretory activity was estimated by measuring the gonadotropin (GTH) content in extracts of pituitaries, plasma, and the culture media every 24 h by radioimmunoassay. Cultivation on MT- or E2-enriched medium results in an increase of the total amount of GTH in the pituitary and medium, an accumulation of GTH in GTH-cells (approximately 20 percentage points) and an increase in their nuclear size, indicating a stimulation of GTH synthesis. However, autonomous GTH-release is not affected by these steroids. Subsequent cultivation of the pituitaries for 24 h with LHRH causes stimulation of GTH synthesis (approximately 20 percentage points). Preincubation with steroids increases the GTH synthesis capacity of LHRH only when used in a concentration of 8.5 × 10-10 M. Moreover, 8.5 × 10-7 M LHRH causes a stimulation of GTH-release. Preincubation of the pituitaries with steroids increases the responsiveness of GTHcells to LHRH. It is concluded that GTH-production in pituitaries of immature female rainbow trout can be directly influenced by gonadal steroids and by a hypophysiotropic substance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222381
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  • 9
    Electronic Resource
    Electronic Resource
    Electronic states near dislocations in transition metals: An application of quantum chemistry in technology (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 575-582 
    Details
    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: This paper outlines a model for calculating the localized states of a 〈 100 〈 edge dislocation in α-Fe. The model used for the calculations is based on the multiple-scattering model (SCF-X α-SW). The purpose of this research is twofold: (1) To determine changes in electronic structure of the lattice near the core region of defects in α-Fe. (2) The variations of hydrostatic pressure about an edge dislocation produce a rearrangement of the conduction electrons. The question is what electrical interaction might be expected between a dislocation and a charged solute atom. The calculations show that the electrons tend to flow away from the compression side toward the dilated regions. The electrical contribution to the binding energy of a solute atom and a dislocation in α-Fe is of the order of 0.01 Ry/electronic unit charge of the atom.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180229
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  • 10
    Electronic Resource
    Electronic Resource
    Calculation of periodic molecular systems with perturbed periodicity within the PCILO framework. I. Method (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 21 (1982), S. 711-716 
    Details
    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 method within the PCILO framework for the study of periodic molecular systems involving impurities is described regarding a one-dimensional chain. The calculation of the whole system is reduced to the calculation of subsystem pairs only. By use of the first-neighbor approximation only one or two subsystem pairs must be considered for subsystems with identical or differing surroundings, respectively. The procedure described yields the ground state energies and charge distributions of the subsystems.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560210405
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