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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 4 (1968), S. 44-47 
    ISSN: 1432-0428
    Keywords: Islet of Langerhans ; spontaneous islet change ; Sprague-Dawley rat ; age and sex predisposition ; glucose tolerance ; islet regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Chez le rat de souche Sprague-Dawley (mâle) la tolérance au glucose était réduite chez le groupe âgé de 52 semaines relativement à celle des jeunes animaux bien que leurs îlots pancréatiques soient apparus histologiquement normaux. Cette diminution de la tolérance au glucose était encore plus sévère chez les rats du groupe âgé dont les îlots pancréatiques montraient certaines altérations morphologiques spontanées, que nous avons décrites précédemment (i.e. fibrose et hypertrophie). — Ces observations suggèrent que chez les rats âgés une disparité entre les demandes et les disponibilités insuliniques précède les altérations morphologiques des îlots pancréatiques. La fibröse et l'agrandissement des îlots pourraient être alors les manifestations de la défaillance du mécanisme d'ajustement compensatoire.
    Abstract: Zusammenfassung Ältere Ratten (52 Wochen alt) vom Sprague-Dawley Stamm, mit normaler Morphologie der Langerhans'schen Inseln, wiesen — im Vergleich mit gesunden jungen Ratten — eine herabgesetzte Glucosetoleranz auf. — Diese Toleranzstörung war noch ausgeprägter bei Ratten, welche eine — bereits beschriebene — Spontanveränderung der Pankreas-Inseln (Fibrose und Vergrößerung) erkennen ließen. Diese Befunde deuten darauf hin, daß bei älteren Ratten eine Diskrepanz zwischen Insulinbedarf und Verfügbarkeit besteht, welche den morphologischen Veränderungen der Langerhans'- schen Inseln vorausgeht. Fibrose und Vergrößerung können deshalb als Ausdruck eines Versagens der ausgleichenden Anpassung gewertet werden.
    Notes: Summary A decreased glucose tolerance as compared with that of healthy young rats was found in male aged rats (52 weeks) of the Sprague-Dawley strain whose pancreatic islet morphology was normal. This abnormal pattern of tolerance was further exaggerated in rats with a spontaneous islet change (fibrosis and enlargement) described by us previously. These observations suggest that in aged rats a discrepancy between insulin demand and availability preceded the morphological changes of the pancreatic islets. Thus, the islet fibrosis and enlargement may be regarded as an expression of a failing compensatory adjustment.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of solution chemistry 5 (1976), S. 833-852 
    ISSN: 1572-8927
    Keywords: Aqueous solution ; activity coefficient ; emf ; temperature dependence ; H2S ; NaHS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Values for the mean stoichiometric activity coefficient of NaHS in the system NaHS−H2S−H2O are presented from 12 to 83°C for NaHS concentrations up to 0.2m and for H2S fugacities up to 1 atm. The measurements were made potentiometrically using a novel approach employing three commercially available specific ion electrodes (Na+ glass, H+ glass, and Ag2S) combined to form two cells without liquid junction. The results are described by the equation t(°C) D B° ΔB 10 0.223 0.075 0.442 25 0.151 0.006 0.248 80 0.024 0.326 0.180 Where γ ± * is the mean activity coefficient relative to a standard state in which γ ± * →1 asm NaHS→0 and $$m_{H_2 S} \to 0$$ . As expressed by this equation, an increase in the fugacity (or activity) of H2S causes the activity coefficient of NaHS to increase at constantT, P, andm NaHS, the effect becoming more pronounced at lower temperatures. It is suggested that H2S causes the solvent molecules to adopt a quasi-clathrate structure producing partial deslvation and destabilization of Na+ and HS− ions. Hydrogen sulfide is known to form a stable clathrate compound just above 0°C when $$P_{H_2 S} = 1 atm$$ . The bisulfide ion appears to be a structure promotor based upon the value of the NaHS activity coefficient relative to those of other proton-accepting anions such as OH−, HCO in3 − , and acetate.
    Type of Medium: Electronic Resource
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