Showing papers by "University of Bern published in 1970"

The influence of pyrophosphate, condensed phosphates, phosphonates and other phosphate compounds on the dissolution of hydroxyapatite in vitro and on bone resorption induced by parathyroid hormone in tissue culture and in thyroparathyroidectomised rats.

Abstract: Earlier studies have shown that inorganic pyrophosphate (PPi) inhibits the dissolution of hydroxyapatite crystalsin vitro and it has been suggested that PPi might be a physiological regulator of bone resorption. In this study PP1 and other phosphate compounds have been tested for their ability to inhibit bone resorption induced by parathyroid hormone in mouse calvaria and to inhibit the rise in plasma calcium induced by parathyroid hormone in thyroparathyroidectomised rats on a low calcium diet. Orthophosphate, pyrophosphate, polyphosphate and two polymeric phosphate inhibitors of phosphatases did not inhibit the resorption of calvaria or the rise in plasma calcium. In contrast, several phosphonates containing P-C-P bonds retarded the dissolution of hydroxyapatite crystalsin vitro, and, at concentrations down to 1.6×10−6M, inhibited bone resorption in tissue culture. Some diphosphonates also inhibited the rise in plasma calcium in thyroparathyroidectomised rats. One reason for the difference between the effects of compounds containing P-O-P and P-C-P bonds may be related to the greater resistance of the latter to chemical and enzymic hydrolysis. Phosphonates may provide a model for the effect of endogenous PP1 in bone, and might be of use in elucidating provide a model for the effect of endogenous PP1 in bone, and might be of use in elucidating mechanisms of bone formation and resorption and in the therapy of diseases that involve increased resorption of bone.

The Inhibitory Effect of Phosphonates on the Formation of Calcium Phosphate Crystals in vitro and on Aortic and Kidney Calcification in vivo

Abstract: 1. Various phosphonates, which are compounds containing C-P bonds, have been studied to see whether they are able to inhibit, in a manner similar to that of pyrophosphate and the condensed phosphates, the crystallization of calcium phosphate in vitro and the pathological calcification of the aorta and the kidneys of rats given large amounts of vitamin D3. 2. Six of the ten compounds studied markedly increased the minimum product, [Ca] × [P], required to induce the precipitation of calcium phosphate in vitro under physiological conditions of pH, ionic strength and temperature. Inhibition was observed at concentrations as low as 10-7—106M. 3. Most of the diphosphonates, particularly those possessing P-C-P bonds, showed some ability to inhibit the calcification of the aortas and kidneys of rats treated with large amounts of vitamin D3. The most effective inhibitors were methylene diphosphonate (MDP), ethane-1-hydroxy-1: I-diphosphonate (EHDP) and diehloromethylene diphosphonate (Cl2MDP). 4. The phosphonates that possess P-C-P bonds thus appear to have effects on the deposition of calcium phosphate in vitro and in vivo similar to those of inorganic pyrophosphate and the condensed phosphates, which possess P-O-P bonds. These phosphonates differ from the condensed phosphates in that they inhibit kidney calcification as well as aortic calcification and are active by mouth as well as parenterally. The wider spectrum of activity of the phosphonates in vivo may be due to the fact that they are more resistant to chemical and enzymic breakdown. 5. Phosphonates might be used therapeutically in man against diseases in which calcium salts deposit in soft tissues.

On acceleration and motion of ions in corona and solar wind

Abstract: Assuming a stationary, radial, spherically symmetric solar wind and a radial magnetic field direction in the vicinity of the sun, an equation of motion for ions heavier than protons in the solar wind is derived. The general properties of this equation are discussed and the results of numerical integrations are given. These results are based on the assumption of maxwellian velocity distribution functions for electrons, protons and ions, but the effects of first order deviations from such distributions are also presented and discussed. It is shown that dynamical friction, i.e. momentum transfer from protons to heavier ions accounts for the observed fact that heavier ions - if accelerated at all - normally reach the same velocity as the protons in the solar wind. Because of the non-linear relation between dynamical friction and proton-ion velocity difference a minimum proton flux is required to carry a certain ion species in the solar wind. Formulae comparing the minimum fluxes for different ions are given. It is shown that elements up to and beyond iron will be carried along in the solar wind as long as helium is carried along. Substantial isotopic fractionation is possible, in particular in the case of helium. The effects of ion motion and escape on abundances in the corona and in the outer convective zone of the sun are discussed.

Über Oxidhydroxide des vierwertigen Mangans mit Schichtengitter. 1. Mitteilung. Natriummangan (II, III)manganat(IV)

Abstract: The preparation of Na4Mn14O27, 9H2O (hitherto named manganomanganite or δ-MnO2) by oxidation of a fresh Mn(OH)2 suspension in aqueous NaOH by molecular oxygen, and its probable structure are described. It is a double layer manganate (IV) structure resembling other manganates such as chalcophanite. Orthorhombic unit cell parameters are, a0 = 8,54, b0 = 15,39, c0 = 14,26 A. In diluted nitric acid topotactical transition to manganese (III) manganate (IV), Mn7O13.5H2O (unit cell: a0 = 2,84, c0 = 7,27 A; primitively hexagonal), and by prolonged digestion to nsutite, γ-MnO2, occurs.

The solar-wind composition experiment

Abstract: The Apollo 16 SWC experiment is a continuation of the earlier experiments; however, an essential change was introduced in the solar wind particle collection technique. Platinum surfaces were incorporated in the collector foil, and use was made of a layer technique for distinguishing particles of different energies and different directions of arrival. The improvements and the expanded scope of the Apollo 16 experiment, relative to the earlier SWC experiments, can be summarized as follows: elimination of possible residual dust contamination by treating the platinum foil sections with dilute hydrofluoric acid before analysis; increased accuracy of solar wind argon abundance; determination of solar wind albedo; and search for helium in the energy range above approximately 40 KeV/nucleon.

Über Oxidhydroxide des vierwertigen Mangans mit Schichtengitter 2. Mitteilung: Mangan (III)-manganat (IV)

Abstract: The preparation and probable structure of managanese (III)-manganate (IV) Mn7O13, 5H2O (a0 = 2,84, c0 = 7,27 A) and manganous (II)-manganate (IV) Mn7O12, 6H2O are described. Both consist of platelets. Digesting in diluted HNO3 leads to γ-MnO2 (nsutite). Manganese (III)-manganate (IV) is much less stable than the sodiummanganese (II, III)-manganate-(IV) described earlier and looses water easily when heated or in vacuo. Water loss results in breaking down of the double layer lattice, and the product is only two-dimensionally ordered, producing only prism reflections on the X ray diagramm. Heating results in a continuous transition to the two-dimensionally ordered phase, then to a finely divided and very disordered γ-MnO2, and eventually to a finely divided and disordered β-MnO2 (pyrolusite). The transition is topotactical so far, but further heating produces δ-Mn2O3 without obvious topotactical relations to the earlier products. The so-called ‘δ-MnO2’ (birnessite) appears to be a family of finely divided and very disordered varieties of such manganates (IV) with part of the Mn3+ substituted by Mn4+. Since such products usually contain remarkable amounts of alkali ions, they are rather varieties of the earlier described sodiummanganese (II, III)-manganate (IV). A provisional explanation of the streaking in the electron diffractions of these manganate (IV). A provisional explanation of the streaking in the electron diffractions of these manganates (IV) is given. With respect to these results the so-called ‘δ-MnO2’ can no longer be attributed to the true manganese dioxides.

The step from diagenesis to metamorphism in pelitic rocks during alpine orogenesis

Abstract: Summary Pelitic rocks were followed from unmetamorphosed clays and marls of Upper Triassic and Lower Liassic to anchimetamorphosed phyllites of the Alpine border region in Switzerland. Phengite and Al-rich chlorite formed from mixed-layer illite/montmorillonite; pyrophyllite from kaolinite. For the formation of paragonite, the following sequence is proposed: irregular mixed-layer illite/montmorillonite regular mixed-layer mica/montmorillonite mixed-layer paragonite/phengite paragonite. Besides the formation of new minerals in the transition zone (anchizone) between diagenesis and greenschist facies, other changes with increasing metamorphic grade are: the crystallinity of illite (in the sense of Kubler, 1967) increases, the intensity ratio 002/001 of the illite basal reflexions increases, 1Md illite changes to 2M1 phengite; the slates change colour from red to pink; the mean density increases; and textural changes due to reactions between clastic quartz and clay cement occur.

Chapter 8 Genetical Methods for Schizosaccharomyces pombe

Abstract: Publisher Summary This chapter discusses genetical methods for Schizosaccharomyces pombe . The normal life cycle of Schizosaccharomyces pombe is that of a haplontic organism, the diplophase being confined to the zygote, which is formed by pair-wise copulation of two haploid vegetative cells. The zygote immediately reduces to form four haploid ascospores that germinate into haploid vegetative cells again. In S. pombe Lindner str. liquefaciens (Osterwalder), a strain obtained from the Yeast Division of the “Centraalbureau voor Schimmelcultures” in Delft in 1947 and used since then in the genetic work with S. pombe, three types of mating behaviours are known, two types being heterothallic and representing two opposite mating types, positive (+) and negative ( – ), and the third being homothallic. In mass matings of heterothallic strains, as well as in single cultures of homothallic strains, copulation and sporulation are observed on any solid medium, one of the best sporulation media being malt agar that is routinely used for this purpose in genetic work with S . pombe. Although vegetative reproduction normally occurs in the haplophase, haploid strains regularly contain rare diploid cells arising presumably by endomitosis.

Mechanisms for the Oxidation of Fe3O4

Abstract: WE have published results1 of a study of the kinetics of the oxidation of a sample of Fe3O4 consisting of submicron crystals almost perfectly cubic and almost uniform in size2. In agreement with Egger and W. F.3 and W. F.4,5, it was found that the reaction was single phase topotactic (Fe3O4→Fe3−xO4→γ-Fe2O3). The mechanism proposed was based on the diffusion of iron cations, the coefficient of which was found to depend on the Fe2+/total iron ratio. When a model of this mechanism was simulated on a computer, an accurate prediction was obtained of the kinetic behaviour over all composition ranges.

Microwave self-modulation of a diode laser coupled to an external cavity

Abstract: An external cavity coupled to a conventional Fabry-Perot GaAs diode laser operating continuously has been found to cause modulation of the light output at a frequency within the range 05 to several GHz The modulation depth is close to 100 percent and the linewidth can be made as narrow as 180 kHz The modulation is thought to be stimulated by the intensity noise fluctuations, which peak at the well-known spiking frequency f r The oscillations are strongly enhanced by a frequency locking action of the external cavity, being efficient when the external cavity round-trip time 2L/c , or a multiple thereof, corresponds to the inverse of the spiking frequency Since the latter is dependent on both pump current and temperature, the system can simply be tuned by adjusting the pump current For a fixed resonator length, the narrow-band oscillations occur in a small current range, in which an increase in frequency with increasing current at a rate of 400 kHz/mA is observed A small-signal analysis based on simple rate equations shows the influence of the external cavity on the intrinsic resonance frequency f r It demonstrates that self-modulation can only occur for small values of the coupling coefficient e between the laser diode and the external cavity

Die konvexe Hülle von n rotationssymmetrisch verteilten Punkten

Abstract: The number of edges A n , the length l n and the surface F n of the convex hull of n independent, identically distributed random points in the plane are considered under the assumption of rotational symmetry. The asymptotic behaviour of the expectations E(A n ), E(l n ) and E(F n ) is studied according to the behaviour of the function Pr( $$Pr{\text{(}}\overline {OP} > x{\text{) as }}x \to {\text{1}}$$ as x → 1 (distributions on the unit disc) or x→∞ (distributions on the whole plane).

An automatic sampling stage microscope for stereology.

Abstract: SUMMARY A new instrument is described which permits automatic sampling of microscopic fields on sections. For this purpose a motor-driven high-precision specimen stage was fitted to a microscope. The motors are controlled by an electronic unit to permit the following modes of operation: (a) continuous operation by a four-position joy-stick switch for easy and rapid scanning of the preparation; (b) single-step operation, where the specimen is displaced in either the x- or the y-direction by a preselected distance adjustable between 15 μm and 20 mm; (c) automatically repeated step operation, where the steps occur at intervals pre-selectable between 0·5 and 34 sec; (d) scanning operation, where the specimen continuously moves along the x-axis and is shifted to the next line at a preselected distance when the end of the sweep is reached. The details of principle and operation are presented together with a few typical examples of application.

Trapped solar wind noble gases, kr81/kr exposure ages and k/ar ages in apollo 11 lunar material.

Abstract: Grain size and etching experiments show that the fine lunar material contains large amounts of trapped solar wind particles. Elemental and isotopic compositions of the noble gases in solar material and in the terrestrial atmosphere are significantly different, except for the Ar(36)/ Ar(38) and the Kr isotope ratios. Exposure ages of two rocks and of the fine material are between 380 and 510 x 10(6) years. Feldspar concentrates give K/Ar ages of 3220 and 3300 x 10(6) years, significantly higher than the unseparated rock.

Electron microscopic studies on specific organelles of endothelial cells in the frog (Rana temporaria)

Abstract: Endothelzellen der Wirbeltiere enthalten spezifische Organellen, deren Funktion unbekannt ist. Diese Organellen werden beim Frosch (Rana temporaria) nach unterschiedlichen Fixierungen elektronenmikroskopisch untersucht. Die Organellen sind walzenformig mit mannigfachen Abweichungen, bis zu 2μ lang und 0,1 bis 0,5μ dick. Ihre oft unterbrochene Ausenmembran ist dicker als zytoplasmatische Membranen. Das Innere der Organellen besteht aus Tubuli, die in eine elektronendichte Matrix eingebettet sind. Die Dichte dieser Matrix zeigt deutliche Abstufungen. Die Tubuli sind moglicherweise aus einer spiralformigen Molekulkette aufgebaut. Das Verteilungsmuster der Organellen wird mit stereologischen Methoden untersucht. Die groste Volumendichte weisen die Aortae thoracicae mit 8% auf. Die Volumendichte der Organellen im Zytoplasma der Endothelzellen scheint mehr von der Entfernung der betreffenden Gefasstrecke zum Herzen abzuhangen als von der Gefasgrose. Es werden Verbindungen der Organellen zu zytoplasmatischen Membransystemen aufgezeigt. Auf Besonderheiten des Endothels, darunter Aggregationen von Ribosomen, wird hingewiesen.

Helly Type Theorems Derived from Basic Singular Homology

Abstract: (1970). Helly Type Theorems Derived from Basic Singular Homology. The American Mathematical Monthly: Vol. 77, No. 4, pp. 375-380.

A method for ultrastructural study of lesions found in conventional histological sections

Abstract: Histological sections of paraffin-embedded formalin-fixed postmortem specimens have been prepared for electronmicroscopic study by a modified method of “open-face” embedding. Lesions or other features are located and photographed by the light microscope. Their locations are then marked, coverglasses removed, sections rehydrated, postfixed in OsO4, dehydrated and the study foci embedded in epoxy resin, separated from the slide, sectioned and stained for electronmicroscopy. Thus, the morphological features of disease processes may be recorded through a much greater range of magnification than hitherto available.

Palaeohistory of the Spruce in Switzerland

Abstract: Pollen and carbon dating suggest that the Post-Glacial spread of the spruce (Picea) in Switzerland has been influenced by human activity. This is different from the situation in the eastern Alps.

Push‐pull‐Cyclobutadiene

Abstract: Two push-pull-cyclobutadienes 10b and 10c are prepared by reaction of two eq of the corresponding acetylenes having electrondonating and electronaccepting groups (4) with one eq of HBF4 to cyclic cyanine salts, followed by elimination of HBF4 with KOC(CH3)3 These cyclobutadienes, stable in cristalline form at room temperature respectively for a short time (10b RCH3) or for several days (10c ROCH3), are extremely reactive in solution towards various nucleophiles and electrophiles Cleavage of the nascent cyclobutenes leads to butadienes The cyclobutadienes 10 dimerise thermally to cyclooctatetraenes 18

Characterization of ICR-170-induced mutations in Schzosaccharomyces pombe

Abstract: 67 ICR-170-induced ad -6 mutants and 50 ICR-170-induced ad -7 mutants in Schizsaccharomyces pombe were characterized by means of ( i ) physiological tests (temperature sensitivity and osmotic remediability); ( ii ) sensitivity to the action of nonsense suppressors; ( iii ) determination of the complementation pattern; and ( iv ) tests for specific revertibility by N -methyl- N ′-nitro- N -nitrosoguanidine (MNNG) and ICR-170. The ICR-170-induced mutants were compared with 18 nitrous acid-induced complementing ad -6 mutants. Using absence of ( i ) nonpolarized complementation behaviour, ( ii ) temperature sensitivity and/or osnotic remediability, ( iii ) suppressor sensitivity and ( iv ) MNNG-revertibility on the one hand, and high ICR-170 revertibility on the other hand as criteria for frame-shift mutations, it is concluded that at least 19% of the ICR-170-induced ad -6 mutants and 32% of the ICR-170-induced ad -7 mutants are of the frame-shift type.

Verbessertes Gerät zur Gleichgewichts-Dialyse

Abstract: Zur Bestimmung der Bindungsparameter von Wechselwirkungen zwischen niedermolekularen Liganden und Biopolymeren wird ein Gleichgewichts-Dialysegerat beschrieben. Der Gleichgewichtszustand wird nach einer Dialysierzeit von 2–4 h bei 20° C erreicht.