Showing papers by "University of Bern published in 1985"

Endurance training in humans: aerobic capacity and structure of skeletal muscle

Abstract: The adaptation of muscle structure, power output, and mass-specific rate of maximal O2 consumption (VO2max/Mb) with endurance training on bicycle ergometers was studied for five male and five female subjects. Biopsies of vastus lateralis muscle and VO2max determinations were made at the start and end of 6 wk of training. The power output maintained on the ergometer daily for 30 min was adjusted to achieve a heart rate exceeding 85% of the maximum for two-thirds of the training session. It is proposed that the observed preferential proliferation of subsarcolemmal vs. interfibrillar mitochondria and the increase in intracellular lipid deposits are two possible mechanisms by which muscle cells adapt to an increased use of fat as a fuel. The relative increase of VO2max/Mb (14%) with training was found to be smaller by more than twofold than the relative increase in maximal maintained power (33%) and the relative change in the volume density of total mitochondria (+40%). However, the calculated VO2 required at an efficiency of 0.25 to produce the observed mass-specific increase in maximal maintained power matched the actual increase in VO2max/Mb (8.0 and 6.5 ml O2 X min-1 X kg-1, respectively). These results indicate that despite disparate relative changes the absolute change in aerobic capacity at the local level (maintained power) can account for the increase in aerobic capacity observed at the general level (VO2max).

Evidence from polar ice cores for the increase in atmospheric CO2 in the past two centuries

Abstract: Precise and continuous measurements of atmospheric CO2 concentration were first begun in 1958 and show a clear increase from 315 parts per million by volume (p.p.m.v.)1 then to 345 p.p.m.v. now. A detailed knowledge of the CO2 increase since preindustrial time is a prerequisite for understanding several aspects of the role of CO2, such as the contribution of biomass burning to the CO2 increase and the sensitivity of climate to the CO2 concentration in the atmosphere. Estimates of the preindustrial CO2 concentration are in the range 250–290 p.p.m.v. (ref. 2), but the precise level then and the time dependence of the increase to the present levels remain obscure. The most reliable assessment of the ancient atmospheric CO2 concentration is derived from measurements of air occluded in ice cores. An ice core from Siple Station (West Antartica) that allows determination of the enclosed gas concentration with very good time resolution has recently become available. We report here measurements of this core which now allow us to trace the development of the atmospheric CO2 from a period overlapping the Mauna Loa record back over the past two centuries.

Influences of endurance training on the ultrastructural composition of the different muscle fiber types in humans

Abstract: To investigate changes in the ultrastructure of the different muscle fiber types induced by endurance training ten sedentary subjects (five women and five men) were exercised on bicycle ergometers 5 times a week for 30 min. After 6 weeks of training there were significant changes in\(\dot V_{{\text{O}}_{{\text{2max}}} } \) (+14%), in the percentage of type I (+12%) and type IIB fibers (−24%) as well as in the volume densities of mitochondria. The latter increased 35% in type I, 55% in type IIA and 35% in type IIB fibers. The relative increase in subsarcolemmal mitochondria was larger than in interfibrillar mitochondria in all fiber types. There was also a significant increase in the volume density of intracellular lipid in type II fibres. It is concluded that high intensity endurance training leads to an enhancement of the oxidative capacity in all muscle fiber types.

Polymorphic dextromethorphan metabolism: co-segregation of oxidative O-demethylation with debrisoquin hydroxylation.

Abstract: Dextromethorphan hydrobromide, 25 mg po, was given to 268 unrelated Swiss subjects to study urinary drug and metabolite profiles. Rates of O-demethylation yielding the main metabolite dextrorphan were expressed by the urinary dextromethorphan/dextrorphan metabolic ratio. We found a bimodal distribution of this parameter in our population study, which indicates that there are two phenotypes for dextromethorphan O-demethylation. The antimode at a metabolic ratio of 0.3 separated the poor metabolizer (PM; n = 23; prevalence of 9%) from extensive metabolizer (EM) phenotypes. Urinary output of dextrorphan was less than 6% of the dose in all PMs and was 50% in the 245 EMs. Pedigree analysis of 14 family studies revealed an autosomal-recessive transmission of deficient dextromethorphan O-demethylation. In these families, 37 heterozygous genotypes could be identified; however, through use of the urinary drug and metabolite analysis it was not possible to identify the heterozygous genotypes within the EM phenotype group. Co-segregation of dextromethorphan O-demethylation with debrisoquin 4-hydroxylation was also studied. Complete concordance of the two phenotypic assignments was obtained, with a Spearman rank correlation coefficient of rs = 0.78 (n = 62; P less than 0.0001) for dextromethorphan and debrisoquin metabolic ratios. Presumably the two drug oxidation polymorphisms are under the same genetic control. Thus the innocuousness and ubiquitous availability of dextromethorphan render it attractive for worldwide pharmacogenetic investigations in man.

Quasiconformal mappings on the Heisenberg group

Abstract: On etudie les applications conformes et quasi conformes sur le groupe de Heisenberg. La metrique invariante a gauche naturelle sur cet espace est non isotrope sous des dilatations et ne peut se decrire par une metrique de Riemann. Ceci engendre de nouveaux phenomenes

Biochemical and ultrastructural changes of skeletal muscle mitochondria after chronic electrical stimulation in rabbits.

Abstract: The purpose of the present investigation was to follow and correlate changes of structural and biochemical markers of energy metabolism during chronic electrical stimulation of tibialis anterior muscle in rabbits In the superficial portion of the muscle, 5 to 6-fold increases occurred in enzyme activities of the citric acid cycle and of fatty acid oxidation after 28 days of stimulation Enzyme activity changes in the deep, more oxidative part of the muscle were relatively smaller Consequently, levels of the citric acid cycle enzymes became similar in superficial and deep parts of the muscle after the longest stimulation periods With the exception of hexokinase, which increased in parallel with the citric acid cycle enzymes, glycolytic enzymes decreased 2 to 3-fold Muscle mass and fibre size remained unchanged, while capillary density and capillary to fiber ratio increased 2-fold The volume density of total mitochondria increased in a fashion similar to the changes of the enzymes of the citric acid cycle (7-fold in superficial and 35-fold in deep parts of the muscle) and, thus, approached values found in heart muscle Disproportionate changes in enzyme activities of ketone body utilisation and of mitochondrial glycerolphosphate oxidase indicated qualitative changes within the mitochondrial population However, the proportion of subsarcolemmal to interfibrillar mitochondria, as well as the area of inner mitochondrial membrane per unit volume of mitochondrion remained unchanged Similarly, intracellular lipid deposits remained unchanged with stimulation It is concluded that there is an excellent agreement between morphometric and biochemical measurements of tissue oxidative capacity

Sulphate and nitrate concentrations in snow from South Greenland 1895–1978

Abstract: An understanding of the phenomenon of acid rain requires the identification of the sources of the species affecting the pH of rainwater, both natural and anthropogenic, and their temporal and spatial development. The scant data concerning the historical development of the acidity in precipitation are from urban regions or their vicinity, where local effects dominate and obscure the hemispherical pattern1. The Greenland ice sheet allows us to trace the evolution of the acid rain in a remote location that is free from local effects. Sulphuric and nitric acids are the two species that dominate the acidity in precipitation2–4. We report here measurements of [SO42−] and [NO3−] in firn samples spanning the period 1895–1978. Samples, each covering 1 yr, were taken from a 70-m core drilled at Dye 3, South Greenland; [NO3−] and [SO42−] both increased by a factor of ˜2 during the period. By comparing the recent concentrations of nitrate and sulphate with those resulting from natural sources, we conclude that anthropogenic emissions of the precursors (NOx, SO2) had already surpassed natural sources in the late 1950s.

Increase of Atmospheric Methane Recorded in Antarctic Ice Core

Abstract: Air entrapped in bubbles of cold ice has essentially the same composition as that of the atmosphere at the time of bubble formation. Measurements of the methane concentration in air extracted by two different methods from ice samples from Siple Station in western Antarcitica allow the reconstruction of the history of the increase of the atmospheric methane during the past 200 years.

Structure and function of platelet membrane glycoproteins Ib and V. Effects of leukocyte elastase and other proteases on platelets response to von Willebrand factor and thrombin.

Abstract: Treatment of platelets with human leukocyte elastase causes a rapid loss in response to von Willebrand factor and a biphasic loss in response to thrombin, first rapid then more slowly. The rapid phase corresponds to cleavage of a 45-kDa glycopeptide from the extracellular end of membrane glycoprotein GPIb. Longer treatment removes 80-kDa and 90-kDa glycopeptides and a glycopeptide corresponding to the major part of GPV. The 45-kDa and 90-kDa species could be obtained by elastase treatment of glycocalicin, the major proteolytic cleavage product of GPIb. Polyclonal rabbit antibodies against the purified 45-kDa glycopeptide had the same effect on the action of von Willebrand factor and thrombin on platelets as cleavage of GPIb by elastase. These results indicate that both the von Willebrand factor and thrombin binding sites on GPIb are located in the same region on the outside of the molecule. Thrombin activation of platelets involves at least two receptors, one on the 45-kDa glycopeptide, which when occupied causes an increase in the speed of response of the platelets to the cleavage of the second. GPV, a candidate for the second receptor, is a hydrophobic glycoprotein that is cleaved from the platelet membrane by several proteases. Proteases that do not activate platelets but degrade the second receptor remove larger fragments from GPV than do proteases such as thrombin or trypsin which activate platelets.

Geochemistry, geochronology and petrology of Monte Mucrone: An example of EO-alpine eclogitization of Permian granitoids in the Sesia-Lanzo Zone, Western Alps, Italy

Abstract: A Permian granitoid intrusion, exposed on Monte Mucrone, Sesia-Lanzo Zone, Italy, was metamorphosed under high-pressure conditions. To elucidate the metamorphic history of this granitoid complex, investigations have been made into the chemistry of the protolith, possible mass transfer during metamorphism, phase chemistry and implications for P-T conditions, and the age of metamorphic events. The metagranitoids contain Na-pyroxene, quartz, white mica, garnet and zoisite, and vary from rocks showing a well-preserved granitic texture to strongly deformed schists and gneisses. The rocks are of granitic to granodioritic composition and originated as an I-type granite pluton. With the exception of addition of H2O, the rock series behaved isochemicaliy throughout high-pressure metamorphism and later tectonic and retrograde transformations. P,T estimates based on Na-pyroxenes, garnet-clinopyroxene and garnet-biotite pairs give minimum pressures of ∼ 14 kbar at 600°C for the peak of the eclogite metamorphism. Age determinations by RbSr and KAr methods give 129-Ma for the rejuvenation of the total rock and 114-Ma isochrons for garnet and clinopyroxene, the first eclogite phase minerals. White-mica cooling ages scatter from 90 to 60 Ma.

40Ar39Ar and K/Ar dating of the bishop and fish canyon tuffs: Calibration ages for fission-track dating standards

Abstract: Ambiguous values of the 238U spontaneous fission decay constant and complexities of absolute neutron dosimetry underline the dependency of fission-track dating upon age standards. New K/Ar and 40Ar39Ar step-heating data are presented for two putative standards: the Bishop Tuff, California and the Fish Canyon Tuff, Colorado. Measured K/Ar ages of 0.741 ± 0.014 Ma for Bishop Tuff sanidine and 27.4 ± 0.4 Ma for the Fish Canyon Tuff (mean of concordant results on biotite, sanidine, hornblende and plagioclase) show good agreement with previous results. 40Ar39Ar plateaus for Bishop Tuff sanidine (plateau age 0.734 ±0.024 Ma) and Fish Canyon Tuff biotite (plateau age 27.8 ± 0.2 Ma) suggest minimal thermal disturbance since deposition of the tuffs, supporting the underlying assumption of equality of their fission-track and argon ages.

Reversible amorphization in laser-quenched titanium alloys.

Abstract: Metastable crystalline and amorphous phases were obtained by pulsed-laser quenching of thin Au-Ti and Cr-Ti films. Subsequent furnace annealing was found to convert metastable crystalline modifications into amorphous ones for certain compositions in both systems. In ${\mathrm{Cr}}_{1\ensuremath{-}x}{\mathrm{Ti}}_{x}$ ($x\ensuremath{\sim}0.7$), a further annealing step at a higher temperature leads back to the initial metastable crystalline phase, thus making possible repeated crystalline to amorphous to crystalline transitions by simple thermal cycling. This phenomenon is unrelated to fast diffusion, but can be explained on the basis of free-energy considerations.

‘Strangelove ocean’ before the Cambrian explosion

Abstract: The Palaeozoic and Mesozoic eras were terminated by faunal changes involving mass extinction of the old and explosive evolution of the new fauna, but the fossil record shows only a Cambrian Explosion at the end of the Precambrian. Stanley speculated that the explosion was only possible after the ubiquitous algae community had been largely eliminated1; ecological niches were thus liberated for explosive evolution. If the Cambrian Explosion were preceded by a mass mortality (or by a mass extinction), such an event should leave a record in the form of geochemical anomalies. We have undertaken a search for geochemical anomalies at the Precambrian/Cambrian contact. We report here the discovery of a sharp negative carbon-isotope shift in the carbonate of a clay immediately above a marker in the Precambrian/Cambrian boundary, the China C marker, and interpret this signal as evidence of sudden decrease in fertility before the Cambrian explosion of invertebrate evolution. The discovery suggests that the Precambrian/Cambrian boundary might be defined by an event-marker at a palaeontologically correlative horizon.

Chronic subdural hematomas: to drain or not to drain?

Abstract: A consecutive series of 21 adult patients with chronic subdural hematoma was studied in respect to postoperative resolution of subdural collections and clinical improvement after burr hole evacuation without subdural drainage. This series was compared to a previously studied series of patients with chronic subdural hematoma in whom postoperative closed system drainage had been installed. Using the identical protocol for treatment and postoperative follow-up, we obtained identical results with respect to time-related neurological improvement and persistence of subdural collections in the undrained and drained series, except that the steadily progressive clinical improvement during the early postoperative phase (24 hours) in all cases of the drained series was not universal in the undrained cases. Our study suggests that, to avoid the possibility of early postoperative clinical deterioration, burr hole craniostomy and closed system drainage is advisable. We think that subdural drainage is not necessary when the installation of the drainage system seems to be technically difficult, as it may be in cases with considerable perioperative cortical expansion.

Evidence that Prednisone-Induced Myopathy Is Reversed by Physical Training*

Abstract: Treatment with glucocorticoids causes wasting of proximal skeletal muscles. There is evidence that physical training improves muscle mass and strength in glucocorticoid-treated rats. Whether this is also true in humans is not known. The present investigation was designed to establish in what respect moderate physical training may alter muscle mass and function as assessed quantitatively by computed tomography (CT) and an isokinetic dynamometer (Cybex II). Compared with matched normal subjects (n = 12), patients (n = 12) treated with prednisone [12.6 +/- 3.3 (+/- SD) mg/day] had a 20% lower midthigh muscle area and a 36% increase in midthigh fat to muscle ratio. The mean peak torque and the total work output of the thigh muscle were lower by more than 20%. Baseline measurements of total work output or peak torque at all tested velocities increased with midthigh muscle area (r = 0.73; n = 24; P less than 0.001). Fifty days of isokinetic training in 12 patients increased the thigh muscle area, decreased the thigh fat area, and normalized the mean peak torque and total work output. The increase in peak torque was inversely correlated with the daily dose of prednisone (r = 0.60; n = 12; P less than 0.05). Thus, glucocorticoid-induced muscle wasting can be reversed by increasing physical activity in patients taking a low to moderate dose of prednisone.

Lung Cell Biology

Abstract: The sections in this article are: 1 Basic Plan of the Cell 1.1 Cell Nucleus 1.2 Cytoplasmic Membrane Systems and Granules 1.3 Mitochondria 1.4 Ground Substance and Cytoskeleton 1.5 Plasma Membrane 2 Organization of Lung Cell Population 2.1 Histogenetic Origin of Lung Cells and Tissues 2.2 Differentiation of Functional Zones 2.3 Morphometry of Lung Cell Population 3 Epithelium 3.1 Epithelium of Conducting Airways 3.2 Alveolar Epithelium 4 Vascular Endothelium 4.1 Structure of Capillary Endothelium 4.2 Structure of Arterial and Venous Endothelium 4.3 Metabolic Functions of Endothelial Cells 5 Interstitial Cells 5.1 Cells Related to Connective Tissue Fibers 5.2 Interstitial Cells With Contractile Properties 5.3 Lymphatics and Free Cells 5.4 Nerves 6 Cells of Pulmonary Defense System 6.1 Alveolar and Interstitial Macrophages 6.2 Cells of Immune Defense System 6.3 Granulocytes 7 Mesothelial Cells of Pleura

Thigh Muscle Mass and Function in Patients Treated With Glucocorticoids

Abstract: Treatment with glucocorticoids causes wasting of proximal skeletal muscles. There is evidence that physical training improves muscle mass and strength in glucocorticoid-treated rats. Whether this is also true in humans is unknown. The present investigation was designed to establish in what respect moderate physical training may alter muscle mass and function as assessed quantitatively by computed tomography (CT) and with an isokinetic dynamometer (Cybex II). Compared with matched controls, both female (n = 17) and male (n = 22) patients treated with prednisone (15.4 +/- 6.6 mg die-1) had a lower mid-thigh muscle area of 20 and 45% and an increased mid-thigh fat/muscle ratio of 25 and 100%, respectively. The mean peak torque and the total work output of the thigh muscle were lower by 20-30% (n = 14). Fifty days of isokinetic training in six patients increased the thigh muscle area, decreased the thigh fat area and normalized the mean peak torque and total work output. Thus, glucocorticoid-induced muscle wasting can be reversed by increasing physical activity.

The behavior of intra-daily exchange rates

Abstract: The behavior of exchange rates is examined as they evolve continuously over time. The data consist of Swiss franc/U.S. dollar rates for nine days during the years 1978–1980 as quoted by a major Swiss dealer operating on the interbank market. Since this market is highly organized, the observations are market prices at the same time. The distributions of relative changes in exchange rates measured over one minute are highly leptokurtic. The normal distribution is rather rapidly approached when the measurement interval is lengthened from one up to ten minutes. Time series analysis reveals that the natural logarithms of exchange rates are adequately described by a random walk, the same stochastic process as has been found for daily, weekly, monthly and quarterly observations. For short time intervals, significant autocorrelations sometimes occur at the first few lags, which are, however, not stable enough over time to form a basis for reliable forecasts.

Effect of solution conditions on the proportion and morphology of goethite formed from ferrihydrite

Abstract: In alkaline media and at 70°C dilute suspensions of ferrihydrite transformed to goethite between pH 112 and 14 and to a mixture of goethite and hematite above and below this pH range Increasing the temperature of the transformation or the concentration of the suspension reduced the pH range in which goethite alone formed The morphology of goethite was chiefly a function of the pH of the system Acicular crystals formed at all pHs and exclusively above pH 122 Epitaxial twinned crystals predominated at pHs below 11, and twins free from hematite formed at higher pHs Increasing the suspension concentration, ionic strength, or temperature extended the pH range over which twinned crystals formed Electron micrographs showed that twins formed mainly during the initial stage of the transformation, whereas acicular crystals formed over a longer period Thus, the twins appeared to nucleate in the ferrihydrite; nucleation of acicular particles took place in solution

Malleability of skeletal muscle in overcoming limitations: structural elements

Abstract: The quantitative structural composition of skeletal muscle tissue shows a wide range of variability among different species of animals and in any one species among muscles with a different function. Moreover, experimental manipulations such as exercise training or chronic electrical stimulation can dramatically change the ultrastructural appearance of the muscles involved. Both in endurance exercise and in chronic electrical stimulation the volume density of mitochondria can be increased greatly (by more than three-fold in the stimulation experiments). This happens without an apparent change of the internal architecture of the mitochondria, since the surface density of the inner mitochondrial membranes remains constant. In situations where both the mitochondrial volume and the maximal rate of oxygen consumption of the muscle tissue are known, these two variables are found to be linearly related. It can be calculated that the ‘maximal’ oxygen consumption of a unit volume of mitochondria in muscle is close to 5 ml O2 min-1 cm-3 under comparable conditions in man, mouse and a series of African mammals. It is hypothesized that there is a constant volume of oxygen metabolized per unit volume of mitochondria and unit time under limiting conditions in working skeletal muscle tissue. Given the efficiency of muscular energy conversion, this would allow an estimate of the potential for aerobic power production of a muscle from measurement of its volume density of mitochondria.