Showing papers by "University of Bern published in 1981"
TL;DR: Researchers report here studies on single channel currents recorded from heart muscle cells, in which they have found a channel, abundant in cardiac membrane, which does not seem to belong in any of the familiar categories.
Abstract: Present concepts of excitable membrane function are based primarily on knowledge of two classes of channels: those activated by neurotransmitters1 and those activated by membrane potential2. Recent evidence suggests that these notions may have to be modified to include other channel types, such as special ion channels activated by membrane potential but regulated by ligands3–5. We report here studies on single channel currents recorded from heart muscle cells, in which we have found a channel, abundant in cardiac membrane, which does not seem to belong in any of the familiar categories. This channel shows little selectivity between cations, but excludes anions. It is activated by intracellular Ca ions but is not appreciably affected by membrane potential.
662 citations
TL;DR: In this article, the authors suggest the replacement of the term glauconite, which has been interchangeably used to designate a morphological form and a specific mineral, by Glaucony (facies).
Abstract: The glauconitic facies is widespread on present-day continental shelves from 50° S to 65° N and at water depths between 50 and 500 m, and is in particularly great abundance on the upper slope and outer shelf between 200 and 300 m. It is also common in many ancient rocks of post-late Precambrian age.
It occurs as sand- to pebble-sized, essentially green particles (granular facies) but also as a surface coating on particles and hardgrounds and as a diffuse impregnation (film and diffuse facies). We suggest the replacement of the term ‘glauconite’, which has been interchangeably used to designate a morphological form and a specific mineral, by glaucony (facies) and glauconitic smectite and glauconitic mica as end members of the glauconitic mineral family.
The widely accepted model of Burst and Hower for glauconitization requires a degraded, micaceous (2: 1 layer lattice structure) parent clay mineral. However, detailed analysis of numerous samples of Recent glaucony reveals that such a parent substrate is exceptional. The model therefore requires modification. Generally the parent material is carbonate particles, argillaceous (kaolinitic) faecal pellets, infillings of foraminiferal tests, various mineral grains and rock fragments, that pass gradually into the commonly occurring green grains.
We show that the process of glauconitization is achieved by de novo authigenic growth of automorphous crystallites in the pores of the substrate, accompanied by progressive alteration and replacement of the substrate. It is this two-fold evolution that causes the ‘verdissement’of granular substrates, macrofossils and hardgrounds. The authigenic mineral is an iron-rich and potassium-poor glauconitic smectite. While new smectites are growing into the remaining pore space the earlier smectites are modified by incorporation of potassium, producing decreasingly expandable minerals with a non-expandable glauconitic mica as the end member. This mineralogical diversity of the glauconitic mineral family explains the highly variable physical and chemical properties of glaucony. Four categories, nascent, little-evolved, evolved and highly-evolved glaucony are distinguished.
Glauconitization appears to be controlled by a delicate balance between degree of physical confinement of a particle and the amount of ionic exchange between the micro-environment and ambient open marine sea water. The optimum conditions for glauconitization are those of semi-confinement. As a result the interior of a grain is more glauconitized than its less confined periphery. Similarly, for identical substrate types, large grains (500μm) provide more favourable substrates for glauconitization than lesser confined small grains.
On a larger scale the formation of glaucony is governed by the availability of iron and potassium and the balance between detrital influx and winnowing. Low accumulation rates expose grains to the open marine environment for sufficiently long times (105-106 years for highly-evolved glaucony).
566 citations
TL;DR: The hypothesis that structural design is a limiting factor for O2 flow at each level of the respiratory system is justified and the methods and results for maximal O2 consumption, pulmonary diffusing capacity, mitochondrial volume, and capillary density in muscles are presented.
368 citations
TL;DR: The purpose of this paper is to propose the necessary sampling techniques for estimating a global parameter defined in a solid opaque specimen (e.g. the total volume of mitochondria in a given liver, the total capillary surface area in agiven lung, etc.)
Abstract: SUMMARY
The purpose of this paper is to propose the necessary sampling techniques for estimating a global parameter defined in a solid opaque specimen (e.g. the total volume of mitochondria in a given liver, the total capillary surface area in a given lung, etc.). The geometry of the specimen often suggests a multi-level or cascade sampling design at different magnifications, whereby the object phase at one level becomes the reference phase in the next level. The final parameter is then estimated as the product of the intermediate ratios with the volume of the specimen, which is estimated independently. Each level can be regarded as an independent sampling design; a given stereological project may be planned in terms of one or more of these designs.
Our development is a blend of practical experience and recent theoretical advances on sampling for stereology with well-known sampling techniques previously developed with different purposes in mind.
335 citations
TL;DR: In this article, the authors define a topological number Q for spin fields on a two-dimensional lattice, which reduces to the well-known winding number in the classical continuum limit.
323 citations
TL;DR: Rapid evolutionary change involving rearrangements and the presence of repeated DNA suggests that the bulk of the sequences within introns may not have any specific function.
Abstract: Vitellogenin is synthesized under estrogen control in the liver, extensively modified, transported to the ovary, and there processed to the yolk proteins lipovitellin and phosvitin. In the frog Xenopus laevis there are at least four distinct but related vitellogenin genes. The two genes A1 and A2 have a 95 percent sequence homology in their messenger RNA coding regions, and contain 33 introns that interrupt the coding region (exons) at homologous positions. Sequences and lengths of analogous introns differ, and many introns contain repetitive DNA elements. The introns in these two genes that have apparently arisen by duplication have diverged extensively by events that include deletions, insertions, and probably duplications. Rapid evolutionary change involving rearrangements and the presence of repeated DNA suggests that the bulk of the sequences within introns may not have any specific function.
298 citations
TL;DR: It is concluded that large animals require a larger pulmonary diffusing capacity to transfer oxygen at the same rate from air to blood.
259 citations
TL;DR: Compound R 24571 is found to be a powerful inhibitor of red blood cell Ca ++ -ATPase as well as Ca ++ transport into inside-out red bloodcell vesicles with an IC 50 -value of 0.5 and 2 μM.
258 citations
TL;DR: Infrared oculographic recordings from three patients with hemianopia due to an occipital lesion showed that these patients employed a consistent set of (presumably unconscious) compensatory strategies to find and fixate objects.
Abstract: Infrared oculographic recordings from three patients with hemianopia due to an occipital lesion showed that these patients employed a consistent set of (presumably unconscious) compensatory strategies to find and fixate objects. For targets in the blind hemifield, patients at first used a staircase strategy consisting of a series of stepwise saccadic search movements. This is safe but slow. When retested later, one patient had adopted a more efficient strategy employing one large saccade calculated to overshoot the target. Other strategies for finding targets in the blind hemifield were employed in response to specific situations presented by our experiments: a predictive strategy using past experience to anticipate where the target would be found, and special strategies for recovering a lost target and for awaiting the reappearance of the target. To fixate targets in the seeing hemifield, our subjects undershot the target to prevent losing it in the blind hemifield, then held it off-fovea on the seeing side of the macula.
235 citations
TL;DR: In this article, observations on rotatory instability of the Lateral Compartment of the Knee have been made using the Reversed Pivot Shift Sign (RSS) sign.
Abstract: (1981). Observations on Rotatory Instability of the Lateral Compartment of the Knee: Experimental Studies on the Functional Anatomy and the Pathomechanism of the True and the Reversed Pivot Shift Sign. Acta Orthopaedica Scandinavica: Vol. 52, No. sup191, pp. 1-34.
222 citations
TL;DR: Automatic image analysis and point‐counting with a 100‐point grid were the most efficient methods for reducing the relative standard errors of the Vv and Sv estimates to equivalent levels in the synthetic models.
Abstract: An evaluation is made of the relative efficiency (precision of the final estimate per unit time of measurement on a given set of sections) of different methods for planar analysis aimed at estimating aggregate, overall stereological parameters (such as VV, SV). The methods tested are point-counting with different densities of test points (4 less than or equal to PT less than 900 per picture), semiautomatic computer image analysis with MOP and automatic image analysis with Quantimet, for obtaining VV and SV estimates. One biological sample as well as three synthetic model structures with known coefficients of variation between sections are used. The standard error of an estimate is mainly determined by the coefficient of variation between sampling units (= sections in the present paper) so that measuring each sample unit with a very high precision is not necessary. Automatic image analysis and point-counting with a 100-point grid were the most efficient methods for reducing the relative standard errors of the VV and SV estimates to equivalent levels in the synthetic models. Using a 64-point grid was as precise, and about 11 times faster than using a tracing device for obtaining the estimate of VV in the biological sample.
TL;DR: The variability of structures supporting tissue oxygen transport (capillaries) and oxygen consumption (mitochondria) was analyzed in skeletal muscles of wildebeest and dik-dik and showed great variability.
TL;DR: In this article, the authors calculate the leading nonperturbative contributions to the energy levels and wavefunctions of a heavy q q pair in terms of energy and wave functions.
TL;DR: In this paper, the authors analyzed the impact of non-analytic chiral corrections to the mass spectrum of the pseudoscalar meson octet JP = 0− and the baryon octets J P = 1 2 +.
TL;DR: The accumulated evidence supports the principle of symmorphosis, i.e. of morphogenesis adapted to functional needs at all organizational levels considered, although the models used for structure-function correlation need further refinement.
TL;DR: Estimating surface and volume density of subcellular membrane systems at different magnifications yield different results, which may explain, at least in part, the large discrepancy in the estimates of the surface of cytomembranes found in the literature.
Abstract: Estimating surface and volume density of subcellular membrane systems at different magnifications yield different results. As the magnification is increased from x 18,000 to x 130,000 the estimates of surface density of endoplasmic reticulum and inner mitochondrial membranes increase by a factor of 3, whereas that for outer mitochondrial membranes increase only by 20%. The estimate of volume density of endoplasmic reticulum also increases by a factor of 3. No further increase is observed at magnifications above x 130,000 which is therefore called critical magnification. The findings are interpreted on the basis of the concept of fractals proposed by Mandelbrot, and the fractal dimensions of the membrane systems considered are estimated. This can lead to the derivation of resolution correction factors which permit measurements obtained at any magnification to be converted to estimates at critical magnification. These findings may explain, at least in part, the large discrepancy in the estimates of the surface of cytomembranes found in the literature.
TL;DR: The history of diphosphonates began with studies of inorganic pyrophosphate, which was found to occur in many biological fluids and inhibited the precipitation of calcium phosphates, and inhibited crystal aggregation and dissolution.
TL;DR: A series of pathological conditions such as angle block glaucoma, acoria, pupillary membranes and goniosynechias of various origins have been treated successfully by means of pulses emitted from a Nd: YAG Q-switched laser above optical breakdown threshold as discussed by the authors.
Abstract: A series of pathological conditions such as pupillary block glaucoma, angle block glaucoma, acoria, pupillary membranes and goniosynechias of various origins have been treated successfully by means of pulses emitted from a Nd: YAG Q-switched laser above optical breakdown threshold. Since linear absorption is not required, non-pigmented or entirely transparent structures are easily dissected by this method. We have also opened the supraciliary and suprachoroidal space in a series of cases of wide angle glaucomas. In all cases however, the clefts closed by secondary wound reactions. This method may be applied to extracapsular cataract surgery for opening the anterior capsule before lens extraction and to the hydrophthalmic eye.
TL;DR: The ratio of volume of mitochondria in these muscles toVo2max is body mass independent, and regression lines whose slopes closely parallel that obtained for Vo2max against body mass are found.
TL;DR: The relationship between capillary density and mitochondrial volume density in skeletal muscle tissue is investigated on 25 African mammals and it is found that higher capillary densities, NA (c,f) are found in muscles with higher volume densities of mitochondria, Vv(mt,f).
TL;DR: In this paper, the authors analyzed the vacuum fluctuations generated by translation-invariant gauge fields and showed that these fields are unstable unless they are (anti-)self-dual and abelian.
TL;DR: The data suggest that the GC appears very early on the membrane of the oligodendrocytes during development while cells exhibiting both GC and MBP probably represent a more differentiated oligodendedrocyte population.
TL;DR: Overall, these data lend support to the view that a structurally specific ligand-estrogen receptor complex can influence the future events within a target tissue to produce either an agonist or an antagonist response.
Abstract: The estrogenic and antiestrogenic activities of tamoxifen ICI 47,699, enclomiphene, zuclomiphene, and the geometric isomers of monohydroxytamoxifen and CI628 were determined in the 3-day immature rat uterine weight test. Tamoxifen, enclomiphene, and the releated geometric isomers of monohydroxytamoxifen and CI628 were partially estrogenic with antiestrogenic properties. ICI 47,699 and zuclomiphene were predominantly estrogenic; however, an antiestrogen effect for zuclomiphene (100 micrograms daily) was demonstrable and large doses of ICI 47,699 (1 or 10 mg daily) inhibited full estrogen action. In contrast, the geometric isomers of monohydroxytamoxifen and CI628 related to ICI 47,699 and zuclomiphene were partially estrogenic with antiestrogenic properties. The estrogenic properties of ICI 47,699 were classified in three ways: elevation of uterine wet weight, increase in whole uterine DNA, and increase in the mitotic activity of luminal epithelial cells. In general, ICI 47,699 was able to initiate estrogenic responses of DNA synthesis or mitosis by translocation of fewer cytoplasmic estrogen receptors to the nuclear compartment than tamoxifen. A model is proposed to explain antiestrogen action in terms of the geometric requirements for receptor binding. It is suggested that the position in space of the alkylaminoethoxyside chain is of fundamental importance. Overall, these data lend support to the view that a structurally specific ligand-estrogen receptor complex can influence the future events within a target tissue to produce either an agonist or an antagonist response.
TL;DR: A new face is proposed in which the face parameters of the left and the right side can be varied separately, which is more realistic, degenerates less, and avoids as much as possible mutual influences of the different face parameters.
Abstract: Proceeding from the idea of Chernoff (1971, 1973) of representing multivariate data by faces, a new face is proposed in which the face parameters of the left and the right side can be varied separately. The new face can be applied in the same way as the usual Chernoff face (with 36 instead of 18 representable variables). Special applications of the new face are the representation of multivariate paired comparison and the visual search for outliers. Several examples illustrate these applications. Compared with Chernoff's face, the new construction is more realistic, degenerates less, and avoids as much as possible mutual influences of the different face parameters.
TL;DR: Differences could be detected between Infectious bovine rhinotracheitis (IBR) and Infectious pustular vulvovaginitis (IPV) virus strains by restriction enzyme analysis of their genomes.
Abstract: Differences could be detected between Infections bovine rhinotracheitis (IBR) and Infectious pustular vulvovaginitis (IPV) virus strains by restriction enzyme analysis of their genomes.
TL;DR: It is demonstrated that acute hypercalcemic hypertension is mediated by an increase in peripheral vascular resistance, and calcium-mediated increase in adrenal epinephrine release may play a mild contributory role, and plasma volume contraction, an inhibitory role.
TL;DR: In this article, strong coupling expansions for the mass gap in euclidean lattice gauge theories in any space-time dimension were derived for gauge groups SU(2), SU(3), Z2 and Z3 up to order g−16.
TL;DR: It is concluded that specifically labelled caffeine is a suitable and promising substrate for studying demethylation by breath analysis, Presumably, caffeine represents a safe and sensitive indicator of the activity of the cytochrome P-448 system.
Abstract: [1-Methyl-14C], [3-Methyl-14C] and [7-Methyl-14C] caffeine were used to investigate demethylation in control rats, and in rats pretreated with phenobarbital or 3-methylcholanthrene, by a14CO2-exhalation test. Compared to controls, pretreatment with phenobarbital did not enhance demethylation of any of the labelled caffeines. In contrast, induction by 3-methylcholanthrene, presumably of cytochrome P-448, resulted in highly significant increases in peak14CO2 exhalation rates,14CO2 disappearance constants and areas under the exhalation rate — time curves. Based on these results, [7-methyl-14C] and [3-methyl-14C] caffeine were chosen for assessing the feasibility of a caffeine breath test in man, using 5 normal volunteers and 2 patients with compensated liver cirrhosis.14CO2 exhalation curves in cirrhotics were clearly different from those in normal volunteers, being characterised by a slower rise and a lower specific activity of exhaled14CO2. Since the variability of the levels of the specific activity in subjects with normal livers suggested the influence of extraneous factors, a second group of normal volunteers, smokers and nonsmokers, was investigated. With either labels, the average14CO2 exhalation rate was doubled in smokers. From these studies in rats and preliminary results in man it is concluded that specifically labelled caffeine is a suitable and promising substrate for studying demethylation by breath analysis. Presumably, caffeine represents a safe and sensitive indicator of the activity of the cytochrome P-448 system.
TL;DR: The purpose of the present investigation was to study the topographical distribution of plaque formation using chlorhexidine digluconate (CH) as a mouthrinse and in oral irrigators during experimental gingivitis.
Abstract: The purpose of the present investigation was to study the topographical distribution of plaque formation using chlorhexidine digluconate (CH) as a mouthrinse and in oral irrigators during experimental gingivitis. Forty dental students (aged 22--26) with clean teeth and healthy gingivae abolished oral hygiene for a period of 3 weeks (Loe et al. 1965). During this period the participants were randomly assigned to one of five groups. Group A rinsed daily with 30 ml of a placebo and Group B with 30 ml 0.1% chlorhexidine digluconate. In Groups C and E a fractionated jet irrigator was used for the daily application of 600 ml placebo (C) or 0.05% CH (E); 600 ml of 0.05% CH was also used in a monojet irrigator (Group D). At the start, after 1, 2 and 3 weeks of no oral hygiene and 1 week following reinstituted oral hygiene, plaque was assessed using the Plaque Index (Silness & Loe 1964) and gingival health was scored according to the criteria of the Gingival Index (Loe & Silness 1963). The discoloration of the teeth was determined using a set of color photos. During the experiment all groups reached plaque levels that were significantly different from each other. The highest PlI were seen in the placebo rinsing group (A) following by placebo irrigation (C). Plaque was significantly reduced in the CH groups. However, rinsing group (A) followed by placebo irrigation (C). Plaque was significantly reduced in the CH groups. However, rinsing (B) formed significantly more plaque than using the oral irrigator (D, E). Group E showed the least amount of plaque. In addition, the interproximal PlI were equally low as the buccal and lingual. With CH (B, D, E), gingivitis did not develop except for some interproximals in Group B. A fractionated jet irrigator was more effective for the application of CH than rinsing.