Showing papers by "University of Bern published in 1980"

Correlation of 18 O in precipitation with temperature and altitude

Abstract: The 18O/16O ratio in precipitation is correlated to climatic parameters, especially temperature. However, the meteorological processes determining the stable isotope composition of precipitation are complex and only partly understood, so that a quantitative interpretation of ancient isotope ratios in precipitation, as recorded in polar ice1 or in carbonate sediments from lakes2, has not yet been possible. For several years we have measured 18O/16O ratios on monthly precipitation samples from Switzerland and here summarize these data.

Regulatory genes controlling mitosis in the fission yeast schizosaccharomyces pombe

Abstract: Fifty-two wee mutants that undergo mitosis and cell division at a reduced size compared with wild type have been genetically analyzed. The mutants define two genes, wee1 and cdc2 , which control the timing of mitosis. Fifty-one of the mutants map at the wee1 locus, which is unlinked to any known cdc gene. One of the wee1 alleles has been shown to be nonsense suppressible. The 52nd wee mutant maps within cdc2 . Previously, only temperature-sensitive mutants that become blocked at mitosis have been found at the cdc2 locus. The simplest interpretation of these observations is that wee1 + codes for a negative element or inhibitor, and cdc2 + codes for a positive element or activator in the mitotic control. The gene dosage of wee1 + plays some role in determining the timing of mitosis, but the gene dosage of cdc2 + has little effect. However, some aspect of the cdc2 gene product activity is important for determining when mitosis takes place. The possible roles of wee1 and cdc2 in the mitotic control are discussed, with particular reference to the part they may play in the monitoring of cell size and cell growth rate, both of which influence the timing of mitosis.

The optimal efficiency and the economic degrees of coupling of oxidative phosphorylation.

Abstract: A phenomenological theory considering the output characteristics of oxidative phosphorylation has been worked out by adopting the formalism of linear nonequilibrium thermodynamics. The linearity of oxidative phosphorylation in the range of the output forces of practical interest has been experimentally verified. The efficiency of oxidative phosphorylation is zero if either a load with a zero conductance (open-circuited situation) or a load with an infinite conductance (short-circuited situation) is attached to oxidative phosphorylation. In between these extreme conductances there exists a finite load conductance permitting oxidative phosphorylation to operate with optimal efficiency. The necessary and sufficient condition for optimal efficiency was found to be L33/L11=√1−q2 where L11 is the phenomenological conductance of phosphorylation, L33 the phenomenological conductance of the load and q the degree of coupling of oxidative phosphorylation driven by respiration. This condition was called conductance matching. Under the condition of conductance matching, four output functions of oxidative phosphorylation of practical interest were optimized. A maximal net rate of oxidative phosphorylation occurs at a degree of coupling qf= 0.78. A maximal output power of oxidative phosphorylation, i.e. net rate times established phosphate potential, results at qp= 0.91. The maximization of the function net rate times efficiency yielded an economic degree of coupling qecp= 0.95 for maximal ATP flow. Finally, maximization of the function output power times efficiency led to a degree of coupling qecp= 0.97. This last function simultaneously maximizes net rate of ATP production, developed phosphate potential and efficiency and reflects therefore the most economic solution to the output problem under the condition of conductance matching. In isolated rat livers perfused in a metabolic resting state, the condition of conductance matching is fulfilled. In addition, the degree of coupling of oxidative phosphorylation under these conditions corresponds to the economic degree of coupling qecp.

Localization of Individual Lysine-Binding Regions in Human Plasminogen and Investigations on Their Complex-Forming Properties

Abstract: After partial digestion of human plasminogen with elastase, followed by chymotryptic cleavage of one of the fragments produced, two polypeptides with molecular weights of approximately 10000 and with lysine-binding sites still intact were isolated by means of affinity chromatography and gel filtration. One fragment, which was completely sequenced (88 residues), was identified as the fourth kringle, whereas the other, according to partial sequence analysis represented the first kringle. Equilibrium, dialysis against 6-aminohexanoic acid yielded for the first kringle one high-affinity binding site (Ka= 60 mM−1) and for the fourth kringle one single low-affinity binding site (Ka= 28 mM−1). Moreover, interactions were detected between the first kringle and the N-terminal CNBr fragment of plasminogen and also fibrin. In these cases an additional lysine- binding site, though of low affinity, appears to be involved. Thus, the first kringle seems to play important roles, structurally by contributing to the maintenance of a compact structure of plasminogen through an intramolecular interaction with its N-terminal polypeptide region, and functionally by increasing the fibrin affinity of Lys-plasminogen (plasminogen lacking the first 76 residues) and plasmin.

Language mixing in young bilinguals.

Abstract: The speech of four two-year-old children growing up bilingually in a German-speaking community was studied for periods varying between five and nine months. An analysis of their language mixing revealed an initially higher rate of mixing which diminished with a growth in language development as measured in MLU. The data suggest that the children were at various stages in a gradual process of language differentiation thus providing support for the one-system theory of bilingual acquisition. An examination of the distribution of lexical substitutions by part of speech revealed that nouns were most frequently substituted by all children; however, more function words were substituted than content words overall.

Trends in analytical chemistry

Abstract: ING AND INDEXING

Infrared study of the adsorption of hydroxycarboxylic acids onα-FeOOH and amorphous Fe (III)hydroxide

Abstract: The adsorption of lactic acid, meso-tartaric acid,l-tartaric acid and citric acid onα-FeOOH and amorphous Fe(III)hydroxide was investigated by i.r. spectroscopy. The results indicate that adsorption is based on partial replacement of the surface hydroxyl groups by carboxylate groups. For meso-tartaric acid onα-FeOOH and for lactic acid andl-tartaric acid on amorphous Fe(III)hydroxide deprotonated alcoholic hydroxyl groups participate in the surface complex formation. A tentative model for the adsorption on the (100) face ofα-FeOOH is presented.

On the estimation of particle number.

Abstract: Two methods are proposed for estimating the number of separated particles within a solid structure per unit volume of structure, Nv. Apart from being arranged with independence of any size parameter, no special assumptions upon the size, shape and orientation of the particles are made. The first method is based on the identity NV = (NA)u . microunits-1, where (NA)u is the mean number of particle sections per unit area of a plane probe Tu which is uniform random within the structure and perpendicular to a given direction u, whereas microunits is the mean particle caliper length along u. The second method uses NV - AA . v-1, where AA is the mean areal fraction of the particles per unit area of section, whereas v is the mean particle volume. The estimation of (NA)u, microunits and v requires the examination of parallel serial sections above and below Tu. Particle model reconstructions are not needed, however. Previous approaches to the problem are discussed.

The Thermodynamic‐Buffer Enzymes

Abstract: Oxidative phosphorylation operates at optimal efficiency if and only if the condition of conductance matching L33/L11=√1−q2 is fulfilled. In this relation L11 is the phenomenological conductance of phosphorylation, L33 the phenomenological conductance of the load, i.e. the irreversible ATP-utilizing processes in the cell, and q the degree of coupling of oxidative phosphorylation driven by respiration. Since during short time intervals L11 and q are constant whereas L33 fluctuates in the cell, oxidative phosphorylation would only rarely operate at optimal efficiency due to violation of conductance matching. This paper demonstrates that the reversible ATP-utilizing reaction catalyzed by adenylate kinase can effectively compensate deviations from conductance matching in the presence of a fluctuating L33 and hence allows oxidative phosphorylation to operate at optimal efficiency in the cell. Since the adenylate kinase reaction was found to buffer a thermodynamic potential, i.e. the phosphate potential, this finding was generalized to the concept of thermodynamic buffering. The thermodynamic buffering ability of the adenylate kinase reaction was demonstrated by experiments with incubated rat-liver mitochondria. Considerations of changes introduced in the entropy production by the adenylate kinase reaction allowed to establish the theoretical framework for thermodynamic buffering. The ability of thermodynamic buffering to compensate deviations from conductance matching in the presence of fluctuating loads was demonstrated by computer simulations. The possibility of other reversible ATP-utilizing reactions, like the ones catalyzed by creatine kinase and arginine kinase, to contribute to thermodynamic buffering is discussed. Finally, the comparison of the theoretically calculated steady-state cytosolic adenine nucleotide concentrations with experimental data from perfused livers demonstrated that in livers from fed rats conductance matching is fulfilled on a time average and that the degree of coupling corresponded to qecp= 0.97 permitting the most economic maintenance of a maximal output power of oxidative phosphorylation. For the case of livers from starved rats this analysis suggested that the degree of coupling corresponded to qecf= 0.95, permitting the most economic maintenance of a maximal net rate of ATP synthesis at optimal efficiency of oxidative phosphorylation.

Human brain aldehyde reductases: relationship to succinic semialdehyde reductase and aldose reductase.

Abstract: Human brain contains multiple forms of aldehyde-reducing enzymes. One major form (AR3), as previously shown, has properties that indicate its identity with NADPH-dependent aldehyde reductase isolated from brain and other organs of various species; i.e., low molecular weight, use of NADPH as the preferred cofactor, and sensitivity to inhibition by barbiturates. A second form of aldehyde reductase ("SSA reductase") specifically reduces succinic semialdehyde (SSA) to produce gamma-hydroxybutyrate. This enzyme form has a higher molecular weight than AR3, and uses NADH as well as NADPH as cofactor. SSA reductase was not inhibited by pyrazole, oxalate, or barbiturates, and the only effective inhibitor found was the flavonoid quercetine. Although AR3 can also reduce SSA, the relative specificity of SSA reductase may enhance its in vivo role. A third form of human brain aldehyde reductase, AR2, appears to be comparable to aldose reductases characterized in several species, on the basis of its activity pattern with various sugar aldehydes and its response to characteristic inhibitors and activators, as well as kinetic parameters. This enzyme is also the most active in reducing the aldehyde derivatives of biogenic amines. These studies suggest that the various forms of human brain aldehyde reductases may have specific physiological functions.

Use of dermestid beetles for cleaning bones.

Abstract: Various parts of the skeleton of normal and osteoporotic rats were compared with respect to their dry weight, ash weight, and calcium content when the bones were cleaned byDermestes maculatus beetles or manually. Both techniques gave similar results. This was also true when whole body calcium measured by neutron activation and total skeletal calcium from bones cleaned by the beetles were compared. Thus dermestid beetles are useful as a technique to clean bones, especially for the parts of the skeleton which are difficult to dissect by hand.

Diagnostic value of orotic acid excretion in heritable disorders of the urea cycle and in hyperammonemia due to organic acidurias

Abstract: Orotic acid excretion in urine is increased in ornithine transcarbamylase deficiency, citrullinemia and argininemia; it is barely increased in argininosuccinic aciduria and normal in carbamylphosphate synthetase deficiency and in hyperammonemia due to organic aciduria. The determination of orotic acid excretion is useful in differentiating the causes of hyperammonemia and reduces the need for enzymatic assays on tissue biopsies for decisions on therapy. The data indicate that orotic acid does not merely reflect ammonia concentration in plasma, but depends on carbamylphosphate concentration. Arginine could play a key role in the regulation of ammonia detoxication.

Linear spin-zero quantum fields in external gravitational and scalar fields. II. Generally covariant perturbation theory

Abstract: The quantum theory of both linear, and interacting fields on curved space-times is discussed. It is argued that generic curved space-time situations force the adoption of the algebraic approach to quantum field theory: and a suitable formalism is presented for handling an arbitrary quasi-free state in an arbitrary globally hyperbolic space-time. For the interacting case, these quasi-free states are taken as suitable starting points, in terms of which expectation values of field operator products may be calculated to arbitrary order in perturbation theory. The formal treatment of interacting fields in perturbation theory is reduced to a treatment of “free” quantum fields interacting with external sources. Central to the approach is the so-called two-current operator, which characterises the effect of external sources in terms of purely algebraic (i.e. representation free) properties of the source-free theory. The paper ends with a set of “Feynman rules” which seems particularly appropriate to curved space-times in that it takes care of those aspects of the problem which are specific to curved space-times (and independent of interaction). Heuristically, the scheme calculates “in-in” rather than “in-out” matrix elements. Renormalization problems are discussed but not treated.

Hypothalamic lesions in rats with long-term streptozotocin-induced diabetes mellitus. A semiquantitative light- and electron-microscopic study.

Abstract: Sixteen male Wistar rats, 1 year after injection of streptozotocin or vehicle, were fixed by whole-body perfusion, the brains were removed and processed for light and electron microscopy Study of semithin sections from the hypothalamic area revealed changes in the arcuate nucleus and median eminence The lesions, in comparison with controls, were subjected to a blind semiquantitative evaluation The following changes were observed by light microscopy in diabetic rats: accumulation of glycogen (P<001), degeneration of neurons (P<005), hypotrophy of tanycytes (P<001), and axonal changes Electron microscopy of diabetic rats revealed that glycogen was increased in neuronal bodies and processes (axons, synapses), also in tanycytes, and glia cells In neurons were seen: dilated and fragmented endoplasmic reticulum, degranulated ergastoplasm, loss of organelles, increased number of microtubuli, myelin figures, irregulatities in the form of nuclei, and appearance of chromatin The tanycytes in diabetic animals were reduced in volume, had an increased nuclear cytoplasmic ratio, a reduced number of organelles, short basal processes, and almost complete loss of the apical processes These changes demonstrate the existance, under experimental conditions, of an encephalopathy pathogenetically related to streptozotocin-induced diabetes

Plasma concentrations of mebendazole during treatment of echinococcosis: preliminary results.

Abstract: High oral doses of mebendazole are used experimentally for the treatment of human alveolar and cystic echinococcosis. In order to assess bioavailability of this drug 1.5 g doses were given to 3 volunteers. Measurable plasma concentrations of 17 to 134 nmol/l were found only if mebendazole was given together with a fatty meal. In a patient with cholestasis plasma concentrations were higher than in the 3 normal subjects. In patients on long term treatment the increase in plasma concentration after administration of a 1 g dose varied between 0 and 500 nmol/l. It is concluded that systemic availability of mebendazole is enhanced by concomitant food intake. In view of the large intra- and interindividual variation in plasma concentration, monitoring plasma levels during long term therapy appears advisable.

Comparison of Dietary Habits and Dental Health of Subjects with Hereditary Fructose Intolerance and Control Subjects

Abstract: The diets, oral hygiene, and caries experience were examined in 17 persons who have to avoid sweets, most fruits, and other foods containing sucrose. These records were compared with those of a control group to determine the sucrose intake, the nutrient value of diets, and the oral hygiene status of both groups.

Neutrino Experiment to Test the Nature of Muon-Number Conservation

Abstract: This paper reports on a search for nu-bar/sub e/ from ..mu../sup +/ ..-->.. e/sup +/nu-bar/sub e/..nu../sub ..mu../, allowed by multiplicative but not additive muon conservation, and for ..nu../sub e/ from ..mu../sup +/ ..-->.. e/sup +/..nu../sub e/nu-bar/sub ..mu../, allowed by both. Neutrinos from the Clinton P. Anderson Meson Physics Facility have been used, together with a six-ton Cherenkov counter filled with H/sub 2/O (D/sub 2/O) to look for ..nu../sub p/p ..-->.. ne/sup +/(..nu../sub e/d ..-->.. ppe/sup -/). The branching ratio (..mu../sup +/ ..-->.. e/sup +/..nu../sub e/..nu../sub ..mu../)/..mu../sup +/ ..-->.. all) =-0.001 +- 0.040 is in excellent agreement with the additive law. The cross section .. ppe/sup -/) >= (0.52 +- 0.18) x 10/sup -4/ cm/sup 2/ agrees with theory.

Cold hardiness of some Alpine Collembola

Abstract: . 1 Individual supercooling points ranged from -2 to -44°C for six species of springtails, five species from the Swiss Alps and one from lowland Britain. Individuals of Isotomurus alticola (Carl) and Isotoma viridis Bourlet without gut contents had substantially lower supercooling points than those containing food material. 2 Juveniles were more cold resistant than adults in both I.alticola and Isotoma hiemalis Schott, both with respect to supercooling point and to their survival at prolonged subzero temperatures. 3 Temperature and acclimation time affected the degree of supercooling of four of the Alpine species especially I.hiemalis. 4 Duration of culture period had no consistent influence on the supercooling potential of all the species. 5 Tests for glycerol in the body fluids of the five Alpine springtails were negative, but the presence of a sugar, probably glucose, together with a five carbon polyhydric alcohol was indicated by chromatography.

Incidence of berry aneurysms of the unpaired pericallosal artery : angiographic study

Abstract: The highest incidence of aneurysms at bifurcations of different configuration among all cerebral arteries occurs at the bifurcation of large unpaired pericallosal arteries. A berry aneurysm was present in seven (41%) of 17 unpaired pericallosal arteries in our material.

Increased serum low-density lipoprotein cholesterol in men treated short-term with the diuretic chlorthalidone

Abstract: The effect of the diuretic chlorthalidone (100 mg/day for 6 weeks) on serum lipoproteins was evaluated in 37 subjects. In 19 men with essential hypertension (aged 41 ± 3 yr), 8 normal men (26 ± 3 yr), or all of these men considered together, chlorthalidone significantly increased serum low density lipoprotein-cholesterol (LDL-C) by 20% (p < 0.05 to <0.01). There was also a tendency for increased LDL-C in seven postmenopausal women (+ 15%) but not in three premenopausal women with essential hypertension. High density lipoprotein-cholesterol was not significantly changed in hypertensive women or normal men and decreased slightly (p < 0.05) in hypertensive men. Apolipoproteins A-I, A-II, and B were not changed significantly in women or men. Diuretic-induced lipoprotein alterations were not associated with altered plasma volume and unrelated to variations in serum potassium, glucose, insulin levels, blood pressure, and body weight. Short-term diuretic therapy with chlorthalidone may increase serum LDL-C in young or middle-aged men with normal or high blood pressure.