Effect of alkali cations on the interaction between detergents and erythrocyte membranes

Resumen Los distintos cationes alcalinos monovalentes (145 mM) y divalentes (100 mM) modifican marcadamente el grado de hemólisis de eritrocitos humanos provocado por Triton X-100 y por desoxicolato de Na (DOC). La serie de actividad con cationes monovalentes en hemólisis por Triton es K>Rb=Cs>NaLi, y por DOC es Li>Rb=Cs>K>Na. Por el contrario, el grado de solubilización de membranas eritrocitarias producido por Triton o DOC es independiente de los distintos cationes alcalinos.     

Glutamate and GABA levels and glutamate decarboxylase activity in brain regions of rats after prolonged treatment with alkali cations

Resume L'administration chronique des cations des métaux alcalins (Na⁺, Rb⁺, Cs⁺) à les rats a provoqué la croissance des niveaux de glutamate et GABA dans certaines régions du cerveau. On n'a remarqué aucun changement en activité GAD de ces régions.     

Ptolemy's maps of earth and the heavens: A new interpretation

Communicated by A. Aaboe     

Realism on the rocks: Novel success and James Hutton's theory of the earth

In this paper, I introduce a new historical case study into the scientific realism debate. During the late-eighteenth century, the Scottish natural philosopher James Hutton made two important successful novel predictions. The first concerned granitic veins intruding from granite masses into strata. The second concerned what geologists now term “angular unconformities”: older sections of strata overlain by younger sections, the two resting at different angles, the former typically more inclined than the latter. These predictions, I argue, are potentially problematic for selective scientific realism in that constituents of Hutton's theory that would not be considered even approximately true today played various roles in generating them. The aim here is not to provide a full philosophical analysis but to introduce the case into the debate by detailing the history and showing why, at least prima facie, it presents a problem for selective realism. First, I explicate Hutton's theory. I then give an account of Hutton's predictions and their confirmations. Next, I explain why these predictions are relevant to the realism debate. Finally, I consider which constituents of Hutton's theory are, according to current beliefs, true (or approximately true), which are not (even approximately) true, and which were responsible for these successes.     

Effects of monovalent cations on the responses of motoneurones to different groups of amino acid excitants in frog and rat spinal cord

Summary Classification of excitatory amino acids into different groups, of possible value for transmitter identification, can be made on the basis of the differential effects of altered external [Na⁺] and [K⁺] on motoneurone depolarization in frog and immature rat spinal cord.Acknowledgments. We thank Mr D. J. Oakes for skilled technical assistance. This work was supported from the Medical Research Council.     

Contraction of frog stomach muscle and heart in non-ionic solutions

Zusammenfassung Herz und Magenmuskulatur des Frosches verlieren in halb-isotoner Rohrzuckerlösung innert 1 h alles Natrium. Trotzdem bleibt die spontane Kontraktilität erhalten. Natrium ist also für die Erregbarkeit dieser Muskeln nicht Voraussetzung.     

Electrometric studies on the reaction between thorium and alkali tungstate

Zusammenfassung Es wurde die Reaktion zwischen Th⁴⁺ und WO₄ ^2–-Ionen durch amperometrische, pH und konduktometrische Titrationen zwischen Th(NO₃)₄ und Na₂WO₄ untersucht. Elektrometrisch konnte bewiesen werden, dass sich zwischen pH 4.50–5.75 normales Thoriumtungstat ThO₂ · 2WO₃ bildet.     

Contraction of frog stomach muscle and frog heart in electrolyte-free solutions

Zusammenfassung Der Verlust der Reizbarkeit bei Froschherz- und Magenmuskulatur auf verschiedenen Temperaturstufen verläuft parallel mit einem Adenosintriphosphat-Verlust, was andeutet, dass das Nichtfunktionieren in natriumfreier Lösung von einem Adenosintriphosphat-Verlust abhängig ist.     

The interaction of organic cations with the mitochondrial membrane

Summary Weak and strong organic bases behave in an opposite manner in respect to several mitochondrial functions. The former induce a catalytic exchange with K⁺ in valinomycon-treated, respiratory-inhibited mitochondria, and act as uncouplers in respiring mitochondria. The latter induce a stoicheometric exchange with K⁺ and are actively taken up by respiring mitochondria.     

Hubris to humility: Tonal volume and the fundamentality of psychophysical quantities

Psychophysics measures the attributes of perceptual experience. The question of whether some of these attributes should be interpreted as more fundamental, or “real,” than others has been answered differently throughout its history. The operationism of Stevens and Boring answers “no,” reacting to the perceived vacuity of earlier debates about fundamentality. The subsequent rise of multidimensional scaling (MDS) implicitly answers “yes” in its insistence that psychophysical data be represented in spaces of low dimensionality. I argue the return of fundamentality follows from a trend toward increasing epistemic humility. Operationism exhibited a kind of hubris in the constitutive role it assigned to the experimenter's presuppositions that is abandoned by the algorithmic methods of MDS. This broad epistemic trend is illustrated by following the trajectory of research on a particular candidate attribute: tonal volume.     

“Eratosthenes' measurement of the earth reconsidered”

Communicated by C. Wilson     

Contraction of the large conductance coronary artery produced by acetylcholine in the mini pig

Summary In the mini pig, acetylcholine reduced the coronary blood flow and constricted the large coronary artery. These effects were abolished by atropine, but not by phentolamine, suggesting that cholinergic mechanisms may be involved in coronary artery vasoconstriction.     

The interaction of organic cations with the mitochondrial membrane.

Weak and strong organic bases behave in an opposite manner in respect to several mitochondrial functions. The former induce a catalytic exchange with K+ in valinomycon-treated, respiratory-inhibited mitochondria, and act as uncouplers in respiring mitochondria. The latter induce a stoicheometric exchange with K+ and are actively taken up by respiring mitochondria.     

Maxwell's color statistics: From reduction of visible errors to reduction to invisible molecules

This paper presents a cross-disciplinary and multi-disciplinary account of Maxwell's introduction of statistical models of molecules for the composition of gases. The account focuses on Maxwell's deployment of statistical models of data in his contemporaneous color researches as established in Cambridge mathematical physics, especially by Maxwell's seniors and mentors. The paper also argues that the cross-disciplinary, or cross-domain, transfer of resources from the natural and social sciences took place in both directions and relied on the complex intra-disciplinary, or intra-domain, dynamics of Maxwell's researches in natural sciences, in color theory, physical astronomy, electromagnetism and dynamical theory of gases, as well as involving a variety of types of communicating and mediating media, from material objects to concepts, techniques and institutions.     

Low temperature-induced contracture of depolarized smooth muscle and the effects of calcium and multivalent cations

Summary Lowering of temperature caused tension development in the smooth muscle of the guinea-pig vas deferens, which was dependent on extracellular Ca. Mn²⁺ and La³⁺ reversed the effect and induced phasic contraction on rewarming.Part of the results were presented at the 14th Int. Congress of Physiological Science, Budapest 1980.     

The physical state of alkali ions in a Halobacterium: Some NMR results

Summary Nuclear magnetic relaxation measurements of the ions Na⁺, Rb⁺ and Cs⁺ in a Halobacterium sp. are described. The results support a theoretical model which involves the binding of intracellular alkali ions.We wish to thank the European Molecular Biology Organization (EMBO) and the Nederlandse Stichting voor Zuiver Wetenschappelijk Onderzoek (ZWO) for the financial support that made our stay in Groningen possible.