Showing papers by "University of Bern published in 1976"
TL;DR: Physiological characterisation of the mutants has shown that DNA synthesis and nuclear division form a cycle of mutually dependent events which can operate in the absence of cell plate formation.
Abstract: Twenty seven recessive temperature sensitive mutants have been isolated in Schizosaccharomyces pombe which are unable to complete the cell division cycle at the restrictive temperature. These mutants define 14 unlinked genes which are involved in DNA synthesis, nuclear division and cell plate formation. The products from most of these genes complete their function just before the cell cycle event in which they are involved. Physiological characterisation of the mutants has shown that DNA synthesis and nuclear division form a cycle of mutually dependent events which can operate in the absence of cell plate formation. Cell plate formation itself is usually dependent upon the completion of nuclear division.
858 citations
TL;DR: In this paper, the adsorption of Fe(III, Cu(II), Cd(II, and Pb(II) from aqueous solutions of constant ionic strength at silica-water interfaces was investigated by potentiometric titrations at 25°.
515 citations
TL;DR: In sheep and calf ventricular bundles, increasing the internal calcium by increasing the frequency of voltage‐clamping to plateau range potentials increased the time‐independent outward current, and it is suggested that calcium at the inner side of the membrane sets the level of the background outward current.
Abstract: In sheep and calf ventricular bundles, increasing the internal calcium by increasing the frequency of voltage-clamping to plateau range potentials increased the time-independent outward current. This effect was more marked with higher [Ca]o, and was reduced if the Ca current blockers Verapamil or D 600 were used. 2. If the internal Ca was increased by the addition of cyanide and reduction of external sodium the outward current was also increased. The frequency-dependent increase in outward current also occurred in this Na-poor (12 mM) solution. 3. Tension measurement on the ventricular bundles showed that a Na-free solution with cyanide did not cause a contracture. On changing from Tyrode to a Na-free solution containing cyanide, and on changing back to Tyrode there was a potentiation of the twitch. 4. In Na-poor solution with cyanide, although no contracture was found, ECa was less positive, suggesting that under these circumstances Ca accumulates at the inner side of the membrane, but not around the myofibrils. 5. The prolongation of the action potential in Cl-free solution is frequency-dependent. A greater prolongation is seen at lower frequencies suggesting that Cl current is relatively more important for repolarization at lower frequencies of stimulation. 6. It is suggested that calcium at the inner side of the membrane sets the level of the background outward current. A feed-back mechanism on this basis is proposed for the control of the action potential duration. Various factors that could influence this basic mechanism are discussed.
240 citations
TL;DR: In this paper, a theoretical model of the laser drilling process is developed, which allows the calculation of drilling velocity and drilling efficiency as a function of the absorbed intensity, and good agreement between measurement and calculation was found in the intensity region where efficient drilling is possible, where reflection losses and vapor absorption can be neglected.
Abstract: To describe the laser drilling process, a theoretical model that includes expulsion of liquid material is developed. The model allows the calculation of drilling velocity and drilling efficiency as a function of the absorbed intensity. The same quantities were determined experimentally, using Nd‐YAG‐laser pulses of rectangular shape. Good agreement between measurement and calculation was found in the intensity region where efficient drilling is possible, i.e., where reflection losses and vapor absorption can be neglected. For most metals this region is between 1 and 100 MW/cm2.
230 citations
TL;DR: It is concluded that the aminopyrine breath test represents a simple and noninvasive procedure which quantitatively reflects the microsomal function of the cirrhotic liver.
Abstract: The method of measuring the rate of aminopyrine demethylation by breath analysis was assessed in 23 normal subjects and 20 patients with cirrhosis. Carbon 14 aminopyrine specifically labeled at the two N-methyl groups was administered by mouth in a dose of 9 mg/kg, including a total radioactivity of 2 muCi. The decay of the specific activity of 14CO2 in breath (kb) was found to correlate (r = 0.91) with the disappearance of aminopyrine from plasma (KP). In normal volunteers, kb was 22.4%/hr; in patients with alcoholic and nonalcoholic cirrhosis it was depressed to 8.4%/hr (p less than 0.001). The degree of functional impairment found with the breath test was similar to the sulfobromophthalein (BSP) disappearance curve and the galactose elimination capacity. Although many questions relating to the aminopyrine breath test remain open, our data confirm and extend previous studies of 14CO2 breath analysis after 14C-aminopyrine administration. It is concluded that it represents a simple and noninvasive procedure which quantitatively reflects the microsomal function of the cirrhotic liver.
147 citations
TL;DR: Sedimentation and electron microscopic analyses of intact rDNA † that has been neutralized from alkaline solution indicate that the entire rDNA molecule has a rotational axis of symmetry near the center.
142 citations
TL;DR: Hormone titre measurements show a drastic increase during adult life, which together with the injection experiments seems to indicate stimulating effects of low JH titre on protein synthesis and hypopharyngeal gland development during the first phase of adult life.
132 citations
TL;DR: Unlike any TTX effects reported in other tissues, the results show a voltage dependence of TTX block, which suggests possible differences in the structure of the TTX binding site or of the Na channel itself.
Abstract: TETRODOTOXIN (TTX) in many excitable membranes selectively blocks the transient change in sodium conductance which underlies the rising phase of the action potential. Electrophysiological and binding studies from nerve and skeletal muscle1–5 indicate that a one-to-one binding reaction between toxin and Na channels with a dissociation constant of about 5 × 10−9 M can adequately describe the kinetic and steady-state actions of TTX on the Na conductance. Cardiac muscle is unusual in that it shows a marked insensitivity to TTX. A substantial reduction in the rate of rise of action potentials in ventricular trabeculae and Purkinje fibres does not occur until a TTX concentration of about 10−6 M is reached6–8. We report here the results of a systematic study of the effects of TTX on mammalian cardiac muscle. The experiments were designed to determine whether the reported difference in sensitivity to TTX is an indication of basic differences in the TTX receptor of cardiac muscle as compared to nerve and skeletal muscle. Unlike any TTX effects reported in other tissues6, our results show a voltage dependence of TTX block. This suggests possible differences in the structure of the TTX binding site or of the Na channel itself.
122 citations
TL;DR: In this article, the Monte Rosa Granite has been investigated by microscopic, X-ray, wet chemical, electron microprobe, stable isotope and Rb-Sr and K-Ar methods.
Abstract: Nine samples from the Monte Rosa Granite have been investigated by microscopic, X-ray, wet chemical, electron microprobe, stable isotope and Rb-Sr and K-Ar methods. Two mineral assemblages have been distinguished by optical methods and dated as Permian and mid-Tertiary by means of Rb-Sr age determinations. The Permian assemblage comprises quartz, orthoclase, oligoclase, biotite, and muscovite whereas the Alpine assemblage comprises quartz, microcline, albite+epidote or oligoclase, biotite, and phengite.
115 citations
TL;DR: Cytological evidence supports the hypothesis that the perineural endothelium provides a relatively tight and highly selective barrier separating the peripheral nerves from surrounding tissue and its extracellular fluid spaces.
Abstract: Fine strands of motor nerves were examined with the electron microscope using thin section as well as freeze-etching techniques. The specimens were taken from frog cutaneous pectoris nerve, rat sciatic nerve, mouse and shrew phrenic nerves and from human skin nerves. The perineural sheath (Henle, Ranvier, Key and Retzius) consists of one to several concentric laminae of endothelial cells; it encases nerve fascicles and eventually individual nerve fibers and terminals. The endothelial cells are extremely thin and fitted together smoothly by overlap and dove-tailing of their border zones. The cell contacts are formed by continuous zonulae occludentes, often reinforced by maculae adhaerentes, and in depth they comprise 3–15 strands with an average of 5–6 strands per junction. The membranes of endothelial cells are studded with attachment sites and stomata of plasmalemmal vesicles suggesting a high level of pinocytotic activity. This phenomenon is by no means restricted to the external laminae of the endothelial sheath. Each endothelial lamina is vested with basement membranes on both (epineural and endoneural) sides, and the spaces between laminae contain a few collagen fibers and fibroblasts. Occasionally, punctate tight junctions are seen between laminae. Cytological evidence supports the hypothesis that the perineural endothelium provides a relatively tight and highly selective barrier separating the peripheral nerves from surrounding tissue and its extracellular fluid spaces. This effect is achieved on the one hand by the sealing of pericellular spaces and on the other hand by a membrane controlled transcellular transport mechanism (pinocytosis), both of which are enhanced by their serial arrangement.
105 citations
TL;DR: The results suggest that the plasma membrane acquires an increased permeability to Ca2+ only in a later phase of platelet activation, in most cases after the earlier release of Ca 2+ into the cytoplasm from Castoring organelles.
TL;DR: It is suggested that the inhibition of bone resorption by dichloromethylene diph phosphonate might be due in part to a direct effect of this diphosphonate on lysosomal hydrolases.
TL;DR: Hypertension in endstage kidney disease is often associated with resetting of the body sodium/fluid=renin feedback mechanism, and it appears evident that additional mechanisms are also operative in maintaining end-stage renal hypertension.
TL;DR: The uptake of galactose into the vesicles increased by almost 100% over the control value without galactOSE induction, which suggests that a mobile carrier for sugar transport exists in the plasma membrane.
TL;DR: The effects described might be relevant in the normal mineralization process as well as in the mechanisms leading to pathological calcification, such as urinary stone formation.
TL;DR: An economic and sensitive test system for measuring random and directional migration of human neutrophils is described and standardized procedures for measuring and reporting neutrophil chemotaxis are proposed.
Abstract: An economic and sensitive test system for measuring random and directional migration of human neutrophils is described The technique, based on a modified Boyden chamber equipped with a two-filter system, permits a substantial reduction of both incubation time and sample volume The influence of various technical factors such as the neutrophil concentration in the cell suspension, the incubation time of the chambers, the test concentration of activated plasma or serum, the presence of heparin, and the procedure for separating neutrophils from human peripheral blood, was investigated Standardized procedures for measuring and reporting neutrophil chemotaxis are proposed The method has been used to study the significance of factors regulating neutrophil migration such as cytotaxin inactivators and neutrophil immobilizing factors (NIF) Activity of cytotaxin inactivators as assessed in undiluted serum or plasma at pH 74, 60 or 40 was very low In contrast, potent neutrophil immobilizing activity was found in human serum or diluted plasma These factors which inhibit migration were accordingly termed neutrophil immobilizing factors of plasma (NIF-P) and neutrophil immobilizing factor of serum (NIF-S) These factors are heat-stable, non-dialysable and of high molecular weight
TL;DR: Some points of the past Big Bang in the closed fourdimensional Friedman-model are found to be identical with points ofThe future collapse according to the bundle-boundary definition.
Abstract: Some points of the past Big Bang in the closed fourdimensional Friedman-model are found to be identical with points of the future collapse according to the bundle-boundary definition.
TL;DR: In this article, statistical analyses of the carbohydrate compositions of eleven IgA1 and six IgA2 meyloma proteins revealed that in addition to the known difference in the content of galactosamine, which is present only in proteins of the IgA 1 subclass, there are further quantitative differences in the carbohydrate composition of both subclasses.
TL;DR: The uptake of bilirubin was studied in the perfused rat liver by a multiple-indicator dilution technique employing the three-compartment model of Goresky, indicating that the hepatic uptake system for bilirubs under normal conditions is operating far below saturation.
Abstract: 1. The uptake of bilirubin was studied in the perfused rat liver by a multiple-indicator dilution technique employing the three-compartment model of Goresky. 2. The kinetics of hepatic bilirubin uptake could be described by the Michaelis—Menten equation. 3. The maximal uptake velocity ( V max .) and the apparent half-saturation constant ( K m ) were 4·4 ± 0·5 nmol s −1 g −1 of liver and 58 ±16 nmol/g of liver respectively, indicating that the hepatic uptake system for bilirubin under normal conditions is operating far below saturation. 4. Sodium taurocholate did not compete with bilirubin for hepatic uptake. 5. These findings are consistent with the concept that carrier-mediated transport is responsible for hepatocellular uptake of bilirubin and that bilirubin and bile acids enter the hepatocyte via separate pathways.
TL;DR: In this article, a new species of poly (A)-containing RNA in Xenopus males was found to have a molecular weight of 2.34 X 10(6) compared to the mouse 28-S rRNA.
Abstract: Estrogen treatment of Xenopus males leads to the appearance of a new species of poly (A)-containing RNA in the liver, at a stage when large amounts of the estrogen-induced yolk precursor protein, vitellogenin, is produced. This estrogen-induced RNA sediments at 28 S and migrates on gels in aqueous solution with an apparent molecular weight of 2.0 X 10(6). Contour length measurements under denaturing conditions in the electron microscope reveal a molecular weight of 2.34 X 10(6) compared to the mouse 28-S rRNA. Labeling experiments show that the estrogen-induced RNA has a stability than the average liver poly(A)-containing RNA and represents 10-20% of the poly(a)-containing RNA in the cytoplasm after 24 h of labeling. Hybridization of complementary DNA, synthesized on the isolated estrogen-induced RNA, with its template suggests a complexity corresponding to a single species of poly(A)-containing RNA of such a high molecular weight. Hybridization of the complementary DNA with cytoplasmic poly (A)-containing RNA from estrogen-treated Xenopus males and control toads show that the estrogen-induced RNA constitutes 12-15% of all cytoplasmic poly(A)-containing RNA, and is at least 2000-fold less abundant in untreated males. Size, complexity and abundance of the estrogen-induced RNA are characteristics expected for a mRNA coding for vitellogenin.
TL;DR: Fractionation of erythrocytes according to density and age shows that most of the residual catalase activity is localized in juvenile acatalasemic cells, whereas in normal and heterozygous individuals the catal enzyme activity level does not alter significantly during the life span of the red cells.
Abstract: The unstable catalase variant found in the blood of individuals homozygous for Swiss-type acatalasemia and the enzyme species present in heterozygous carriers of this rare defect have been further characterized. The mutant enzyme isolated from acatalasemic red cells is considerably more heat labile and differs in electrophoretic mobility from the normal enzyme. Catalase preparations obtained from heterozygotes consist of an apparently uniform enzyme species, probably representing a molecular hybrid, with properties intermediate to those of the normal and the variant enzyme. However, antigenic identity of catalase from all three sources is observed. Model experiments indicate that hybrid catalase molecules can be produced by recombining normal and variant dimer subunits. Fractionation of erythrocytes according to density and age shows that most of the residual catalase activity is localized in juvenile acatalasemic cells, whereas in normal and heterozygous individuals the catalase activity level does not alter significantly during the life span of the red cells. These findings agree with the observation that there is no gene dosage in heterozygotes, their catalase activity values falling within the normal range.
TL;DR: It is concluded that a poly(A) on a nuclear RNA does not ensure the transport of the adjacent sequence to the cytoplasm, as shown by the fact that 30% of the nuclear cDNA fails to hybridize with cy toplasmic poly( A)-containing RNA.
Abstract: Poly(A)-containing RNAs from cytoplasm and nuclei of adult Xenopus liver cells are compared. After denaturation of the RNA by dimethysulfoxide the average molecule of nuclear poly(A)-containing RNA has a sedimentation value of 28 S whereas the cytoplasmic poly(A)-containing RNA sediments slightly ahead of 18 S. To compare the complexity of cytoplasmic and nuclear poly(A)-containing RNA, complementary DNA (cDNA) transcribed on either cytoplasmic or nuclear RNA is hybridized to the RNA used as a template. The hybridization kinetics suggest a higher complexity of the nuclear RNA compared to the cytoplasmic fraction. Direct evidence of a higher complexity of nuclear poly(A)-containing RNA is shown by the fact that 30% of the nuclear cDNA fails to hybridize with cytoplasmic poly(A)-containing RNA. An attempt to isolate a specific probe for this nucleus-restricted poly(A)-containing RNA reveals that more than 10(4) different nuclear RNA sequences adjacent to the poly(A) do not get into the cytoplasm. We conclude that a poly(A) on a nuclear RNA does not ensure the transport of the adjacent sequence to the cytoplasm.
01 Jan 1976
TL;DR: A hitherto unknown defect in the maturation of B-cells leading to an abnormal ratio of kappa- and lambda-type immunoglobulin-secreting cells is suggested in young male adults suffering from primary hypogammaglobulinemia and intrinsic factor-deficient pernicious anemia.
TL;DR: Individual memory for the distance between the foraging hole and feeding place has been demonstrated in homing termites and it is shown that termites going out from the nest tend to use pheromonal orientation more readily than those returning.
Abstract: 1.
Hodotermes workers conduct both day and night harvesting expeditions in the open air.
2.
The harvesting direction taken from the foraging hole is determined at the beginning of the foraging period.
3.
Two systems of aboveground orientation can be employed: optical menotaxis and pheromonal (chemical) orientation.
4.
Optical orientation is more precise than pheromonal orientation. If both parameters are experimentally set in competition, optical cues dominate over pheromonal cues when ever they can be utilized.
5.
Pheromonal orientation is crucial in “diffuse-light” or “no-light” conditions. It is always essential in the close vicinity of the foraging hole.
6.
The pheromonal source is the sternal gland. A field of pheromonal marks is built up along the main foraging direction. Pheromonal orientation is performed by klinotactic motion along the chemical field.
7.
Termites going out from the nest tend to use pheromonal orientation more readily than those returning.
8.
In addition to directional orientation, individual memory for the distance between the foraging hole and feeding place has been demonstrated in homing termites.
TL;DR: In this article, the angle between the temperature and the pressure gradients and the magnitude of the temperature gradient must be considered when isograd patterns are used to determine the distribution of pressure and temperature in the rocks when the isograds formed.
Abstract: In rocks undergoing regional metamorphism, pressure and temperature gradients are not everywhere parallel, that is, isotherms are not everywhere parallel to isobars. Temperature gradients vary across the metamorphic terrain and decrease with increasing temperature. The angle between the temperature and the pressure gradients and the magnitude of the temperature gradient must be considered when isograd patterns are used to determine the distribution of pressure and temperature in the rocks when the isograds formed. In Val Mesolcina, southeastern Switzerland, post-tectonic isograds corresponding to mineral dehydration reactions dip steeply northward intersecting the more gently dipping isograd corresponding to the kyanite-andalusite transition. Distributions of pressure and temperature compatible with the isograd pattern have values of α (the angle between the pressure and the temperature gradients) of 50–70° and temperature gradients of 12–15 °C/km. These results indicate that at or near the peak of the Tertiary (Lepontine) phase of Alpine metamorphism isothermal surfaces in these rocks dipped steeply northward and isobaric surfaces were horizontal. The westward divergence of Lepontine mineral zone boundaries can be explained by decreasing values of α; that is, the flattening toward the west of a steep-sided thermal dome present in the eastern part of the Lepontine terrain at the time of metamorphism.
01 Sep 1976
TL;DR: The Ion Composition Experiment (ICE) on GEOS represents the first comprehensive attempt to measure the positive ion composition at high altitudes in the magnetosphere as discussed by the authors, which consists primarily of a cylindrical electrostatic analyzer followed by a curved analyzer incorporating crossed magnetic and electric fields.
Abstract: The Ion Composition Experiment (ICE) on GEOS represents the first comprehensive attempt to measure the positive ion composition at high altitudes in the magnetosphere. Due to the heterogeneous nature of the magnetospheric plasma a novel mass spectrometer has been developed to cover the mass per charge range from H-1(+) to beyond Ba-138(+) and the energy per charge range from 0 to 16 keV/e. The ICE consists primarily of a cylindrical electrostatic analyzer followed by a curved analyzer incorporating crossed magnetic and electric fields. This combination has limited angular and energy focusing properties, but it maintains a mass resolution of about 4 over a wide range in energy and mass, sufficient for the objectives of measuring plasmas of both solar and terrestrial origin. High sensitivity and low background should allow measurements of rarer ion constituents down to flux levels of 0.01 ions/sq cm sec ster eV. A sophisticated electronics combined with powerful ground computer and telecommand systems allow for very efficient scanning of the mass-energy space.