Showing papers by "University of Bern published in 1979"

Cellular calcium and cardiac cell death.

Abstract: Claude Bernard recognized over a century ago that an extracellular environment of constant chemical composition was prerequisite for life outside of the stable aquatic environment of the sea. This concept of constancy of composition extends also to the intracellular environment, which can vary only within rather narrow limits that are set by the conditions essential for cell viability. A major role for the sarcolemma, which separates the intracellular and extracellular environment, is to maintain the intracellular environment within these limits. Nevertheless, it is important to note that small variations in this intracellular composition have important implications for cell function. For example, small fluctuations of intracellular free ionized calcium (Ca2+) concentration determine both the contractile and the energetic state of the heart.

The influence of mechanical function on the development and remodeling of the tibia. An experimental study in sheep.

Abstract: Femoroacetabular impingement is recognized as a major cause of hip pain and early hip joint osteoarthritis in young adults. The dynamic conflict between the femoral neck and the acetabular rim has been shown to result in labral tears, cartilage lesions, and early osteoarthritis. To be successful, the treatment strategy should address the underlying pathomorphology at the femoral neck, the acetabulum, or both. An overview of the various pathomorphologies leading to femoroacetabular impingement and a treatment algorithm intended to preserve the native hip joint should be helpful to the orthopaedic surgeon treating patients with this condition.

Measurement of urinary 6-beta-hydroxycortisol excretion as an in vivo parameter in the clinical assessment of the microsomal enzyme-inducing capacity of antipyrine, phenobarbitone and rifampicin.

Abstract: To assess the rate of drug metabolism in man, four different in vivo measurements of microsomal enzyme activity were compared before and after the administration of three drugs known to be enzyme inducers in man: antipyrine, phenobarbitone and rifampicin. 27 healthy volunteers, divided into four different groups, were given antipyrine 1000 mg or 1200 mg, phenobarbitone 100 mg and rifampicin 600 mg or 1200 mg daily for 14 days. Before and after each drug, estimates were made of total body clearance of antipyrine, γ-glutamyl-transpeptidase in plasma and d-glucaric acid, 6-β-hydroxycortisol and 17-hydroxycorticosteroid urinary excretion in 24 h, as parameters of hepatic microsomal enzyme activity. Following treatment with antipyrine, phenobarbitone or rifampicin 600 mg daily, the total body clearance of antipyrine increased by 44–60%, and after rifampicin 1200 mg there was an increase up to 125%. d-Glucaric acid excretion in urine showed a tendency to increase to the same extent in every group investigated, and γ-glutamyl-transpeptidase increased similarly following antipyrine and phenobarbitone, although it remained unchanged following rifampicin administration. Urinary excretion of 6-β-hydroxycortisol, corrected by the 17-hydroxycorticosteroids representing the percentage proportion of 6-β-hydroxycortisol of the total amount of 17-hydroxycorticosteroids excreted, increased from 4.6–5.2% up to 9.5–28.3% depending upon the drug given. Comparing all in vivo parameters of hepatic microsomal enzyme activity by means of linear regression, a significant correlation was found between total body clearance of antipyrine and urinary excretion of 6-β-hydroxycortisol, while none of the other parameters showed any significant correlation. In addition, a better seperation of the enzyme-inducing capacity of different drugs was seen using 6-β-hydroxycortisol as a parameter of microsomal enzyme activity. Therefore, measurement of 6-β-hydroxycortisol corrected by the 17-hydroxycorticosteroid excretion, combined with estimation of the total body clearance of antipyrine, gives a valuable index, suitable for use in further studies of induction in man.

Measurements of gas exchange and momentum transfer in a circular wind-water tunnel

Abstract: Gas exchange and momentum transfer have been studied by means of a small circular wind-water tunnel. Gas transfer velocity and friction velocity first grow linearly with wind speed. At a critical wind speed, with the onset of rough waves, both increase abruptly. The experiments clearly show the enhancement of air-water exchange processes by waves. Experimental conditions were varied-nitrogen/carbon dioxide atmosphere, temperature, circulation of water unconfined/confined by a dam-and found to influence gas exchange. This, and the differing results of various authors demonstrate that gas exchange is not a function of wind speed alone, nor of friction velocity, but that further parameters, such as wave spectra, have to be considered as well. DOI: 10.1111/j.2153-3490.1979.tb00911.x

Propagation of human hepatitis A virus in a hepatoma cell line.

Abstract: Hepatitis A virus (HAV) was isolated directly from human feces and propagated serially in an HBsAg producing human hepatoma cell line. No cytopathic effect was observed in the tissue culture and no detectable amounts of HAV were present in the tissue culture supernatant fluid. However, increasing amounts of hepatitis A antigen (HAAg) were detected by radioimmunoassay in the cell extracts obtained by freezing and thawing of cells. Specificity of the HAAg determination was shown by neutralization with convalescent sera of marmosets experimentally infected with the MS-1 strain of hepatitis A and by the absence of this neutralization with preinoculation sera. HAAg was first detected after four weeks in the cell extract of infected cultures after inoculation of 10(2)--10(4) tissue culture infectious doses of HAV from second passage.

The Influence of External Real and White Noise on the LOTKA‐VOLTERRA Model

Abstract: The behaviour of a marginally stable predator‐prey system, the LOTKA‐VOLTERRA model is analyzed under the influence of parameter fluctuations. The cases of white and real noise are studied separately. It is shown that for white noise no stationary solution exists, but even for time tending to infinity explosion occurs only with zero probability. In the case of real noise the class of noise processes that permit a stationary solution is characterized by their spectral density. It turns out that this class consists of all stationary processes that do not contain the eigenfrequencies of the LOTKA‐VOLTERRA system. It is shown that for all other real noise processes a resonance phenomenon occurs and the solutions grow unboundedly. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA

Casimir effect in quantum field theory

Abstract: A new conceptual foundation for renormalizing T/sub munu/ on locally flat space-times: to obtain the so-called Casimir effect: is presented. The Casimir ground state is viewed locally as a (nonvacuum) state on Minkowski space-time and the expectation value of the normal-ordered T/sub munu/ is taken. The same ideas allow us to treat, for the first time, self-interacting fields for arbitrary mass in perturbation theory: using traditional flat-space-time renormalization theory. First-order results for zero-mass lambdaphi/sup 4/ theory agree with those recently announced by Ford. We point out the crucial role played by the simple renormalization condition that the vacuum expectation value of T/sub munu/ must vanish in Minkowski space-time, and in a critical discussion of other approaches, we clarify the question of renormalization ambiguities for T/sub munu/ in curved space-times. In an Appendix, we show how the Casimir effect arises in the C*-algebra approach to quantum field theory.

Measurement of vessel tortuosity on fundus photographs

Abstract: Quantitative measurement of vessel tortuosity and its variation on fundus photographs is a sensitive means of obtaining information about the course of an asphyctic event in newborns, virtually independent of bias produced by the photographic process. We subdivide a tortuous vessel into single arcs and measure the chord length and the arrow height (Pfeilhohe) of every arc on a projected image of the film. From these figures, a fairly accurate value for the relative length increase of the arc, as compared with the chord, can be derived by a simple approximation formula [Eq. (5)]. It is shown that neglect of the third dimension, not visible on an ordinary photograph, entails only a small error. Trained observers achieve results reproducible to about 1% in relative length variation.

The Charge Heterogeneity of Soluble Human Galactosyltransferases Isolated from Milk, Amniotic Fluid and Malignant Ascites

Abstract: UDP-galactose: N-acetylglucosamine galactosyltransferase was isolated from pooled human milk, pooled amniotic fluid and from two different individual samples of malignant ascites. The purification procedure involving two successive affinity chromatography steps on N-acetylglucosamine–agarose and α-lactalbumin–agarose yielded an enzyme preparation homogeneous by size. Under non-denaturing conditions the ascites and amniotic fluid enzymes had identical electrophoretic mobility, but they moved faster than the milk enzyme. Isoelectric analysis in the presence and absence of urea resolved the milk enzyme into at least 13 different forms, nine of which had the same isoelectric points after refocusing. All enzyme forms showed similar activity when free N-acetyl-glucosamine, ovalbumin, sialic-acid-free ovine submaxillary mucin and glucose, in the presence of α-lactalbumin, were used as acceptor substrates. Comparative isoelectric focusing of the three galactosyltransferases revealed identical patterns of the amniotic and ascites enzymes, but only partial overlap with the milk enzyme, which was less negatively charged. Neuraminidase treatment of ascites and milk galactosyltransferases produced very similar focusing patterns. The possible structural basis for this charge heterogeneity is briefly discussed.

Phosphate transport by rat renal brush border membrane vesicles: influence of dietary phosphate, thyroparathyroidectomy, and 1,25-dihydroxyvitamin d3

Abstract: In the present work we have investigated whether the changes in the renal handling of inorganic phosphate (Pi) induced by 1) dietary Pi, 2) removal of parathyroid glands and 3) 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], are associated with alterations in the Na-dependent Pi uptake by brush border membrane vesicles (BBMV) isolated from renal cortex. Shamoperated (SHAM) or thyroparathyroidectomized (TPTX) rats treated or not with 26 pmol/day of 1,25 (OH)2D3i.p. were fed low (0.2%) or high (1.2%)P diet for 7 days. The results showed that in SHAM, TPTX and TPTX+1,25 (OH)2D3 the Pi uptake by BBMV was greater after low than high Pi diet. It was greater in TPTX than in SHAM counterparts fed either diets. In TPTX fed low or high Pi diet 1,25 (OH)2D3 decreased the Pi uptake to the level observed in SHAM. A striking parallelism was found between variations in Pi uptake by BBMV and in the tubular Pi reabsorption of the whole kidney. The Na-dependent glucose, the mannitol uptake by BBMV, and the alkaline phosphatase activity in cortical homogenates and BBMV were not affected by the various treatments. Thus, dietary Pi, chronic TPTX and 1,25 (OH)2D3 appear to specifically affect the Na-dependent Pi transport system bound to the brush border membranes of renal cortical tubules. The alterations observed at this membrane level could account, at least in part, for the changes induced by these three factors on the overall tubular reabsorption of Pi.

CNS-active phenylpropylamines ofCatha edulis FORSK. (Celastraceae) of Kenyan origin

Abstract: The phenylpropylamine fraction ofCatha edulis FORSK. grown in Kenya has been investigated. The major components have been found to be (S)-(−)-α-aminopropiophenone (1), (+)-norpseudoephedrine (2) and(−)-norephedrine (3). Quantitative ratios of1, 2, 3 in tissues of different age are discussed.

The effect of different inorganic nitrogen sources and plant age on the composition of bleeding sap of phaseolus vulgaris

Abstract: Summary The composition of the bleeding sap N of Phaseolus vulgaris varied with the inorganic nitrogen source fed to the plant but was not changed by a fourfold difference in external nitrate concentration. Highest sap N concentration and fastest growth were observed in ammonium nitrate grown plants. With nitrate grown plants 60 % of the total sap N was inorganic nitrate-N and 40 % organic-N whereas with ammonium nitrate grown plants nitrate contributed 30 % to the total N and organic-N 70 %. Virtually all of the N in the sap of ammonium grown plants was organic-N. Allantoic acid was the major individual reduced N compound in the bleeding sap of plants fed with nitrate, ammonium or ammonium nitrate. During the development of the plant from seedling to mature plant with ripened pods, the concentration of N in the bleeding sap of nitrate grown plants decreased sharply initially and then gradually during pod formation; it increased again when the pods had ripened. Nitrate reductase activity of leaf extracts was correlated with nitrate content of bleeding sap and was not much affected by increases in reduced N compounds in the sap.

Threshold Fluctuations, Interpolations and Spatial Resolution in Perimetry

Abstract: The detrimental effect of threshold fluctuations upon detectability of sensitivity loss is emphasized. The only remedy seems to consist in the application of averaging methods, thereby attenuating threshold noise with computer methods. Two scanning methods directed at a rapid and accurate detection of scotomata are considered. In the first, the scanning points are distributed as a rectangular grid. In the second, the points are aligned along meridians. The average detectability of the first method is rated superior and is therefore preferred. Furthermore, particular consideration is given to the role of interpolation procedures played in perimetry.