Showing papers by "University of Marburg published in 1974"

Ferromagnetism near surfaces and in thin films

Abstract: The ferromagnetic order is modified near the surface of a magnetic crystal. This modification is studied most clearly in magnetic thin films consisting of only a few atomic layers. Some essential features of the theoretical description are reported as a basis for the discussion of experiments. The main experimental problem is the preparation of flat single crystal films; the real structure of the best available films is discussed. Their magnetic properties are compared with theoretical predictions. Furthermore, methods and results are reported for probing the magnetic properties of surfaces, by their interaction with low energy electrons.

Structure and function of cold receptors.

Abstract: Afferent impulses were recorded from single fibers serving cold and warm receptors in the skin of the cat's nose. The receptors were carefully tested for specificity and the receptive fields localized under the microscope with a microthermode. Each single fiber served one spot-like receptive field. The field was marked without damaging the nerve ending by inserting two thin stainless steel wires into the skin on both sides of the receptor. Investigation of semithin and ultrathin serial sections by light and electron microscopy revealed beneath each cold spot a dermal papilla which contained a single small myelinated fiber dividing into a number of unmyelinated terminals. Near the epidermis the receptor branches leave their Schwann cell envelope, penetrate the basal lamina of the epithelium, and their tips are invaginated into the cytoplasm of the basal epithelial cells. The basal lamina of the epithelium fuses with that of the receptor axon. The receptor axons contain numerous mitochondria, glycogen particles and a filamentous receptor matrix with vesicles of various sizes. The described structures were absent beneath the warm spots. In addition to the cold receptors, Merkel cell neurite complexes and lamellated encapsulated endings were found that are known to be mechanoreceptors.

Influence of emulsified fat on chlorpromazine availability in rabbit blood.

Abstract: Kaninchen uberlebten die letale Dosis von 30 mg/kg Chlorpromazin (i.v.) nur zusammen mit einer Fettinfusion (0,5 ml/kg/min Lipofundin S 10®). Es konnte in vitro gezeigt werden, dass der Zusatz einer Fettemulsion (Lipofundin S 10®) zu Kaninchenblut (25 mg Fett/ml) den Anteil an freiem Chlorpromazin (Gesamtkonzentration 10−4M) von 2,05% auf 0,87% herabsetzt.

Interaction of Ganglioside GGtet1 and Its Derivatives with Choleragen

Abstract: It was confirmed that ganglioside GGtet1, i.e. Galβ1 3GalNAcβ1 4[NeuNAcα2 3]Galβ1 4Glc-ceramide, specifically interacts with choleragen (cholera-cxoenterotoxin) as shown by precipitate formation and inhibition of the toxicity. The isolated carbohydrate moiety of ganglioside GGtet1. i.e. GGtet1 minus ceramide, neither precipitated choleragen nor interferred with the reaction between the toxin and its antibody. However, polyacrylamide gel electrophoresis revealed a specific interaction between the sialo-oligosaccharide and choleragen. Identical results were obtained with a sialo-sugar derivative prepared from the carbohydrate moiety of ganglioside GGtet1 by reductive aminatio followed by N-acetylation of its glucose unit at the reducing end. Variations in the lipohilic moiety of ganglioside GGtet1 yielded compounds (gangliosidoides) which completely retained the specific ability to precipitate choleragen, but did not interfere with its toxicity. The choleragenicity of gangliosidoide · choleragen complexes could still be abolished by ganglioside GGtet1. Polyacrylamide gel electrophoresis of galgioside · choleragen as well as gangliosidoide · choleragen complexes, in the presence of sodium dodecylsulphate, showed only the protein subunits (approx. 8000) molecular weight of the toxin to be irreversibly aggregated. When incubating canine ileal loops with ganglioside-GGtet1 · choleragen complex or with ganglioside GGtet1 in presence of sodium deoxycholate, followed by washing of the loops with buffer after a certain period of time, an inhibition of the secretory response to a subsequent challenge with choleragen was observed. Similar treatment of ileal loops with Vibrio cholerae neuraminidase dissolved in buffer without sodium deoxycholate followed by washing of the loops, caused an enhancement as well as an inhibition of the secretory response to the subsequent challenge with choleragen depending upon the time of incubation with neuraminidase.

Isotope shifts in the atomic spectrum of xenon and nuclear deformation effects

Abstract: Optical isotope shifts of four lines in the atomic spectrum of xenon have been measured using enriched samples of all stable xenon isotopes The spectrograms were recorded with the aid of a pressure-scanned Fabry-Perot interferometer and analysed by digital data techniques The measured isotope shifts are shown to be self-consistent by means of a King plot An estimate of the specific mass effect is given and the changesδ 〈r 2〉 of the mean square radius of the nuclear charge distribution are extracted from the measured shifts These changesδ 〈r 2〉 are discussed in terms of the nuclear deformation parameterβ 2 The results for the deformation of the stable even xenon isotopes are shown to be in good agreement with the systematic of deformation found for the neighbouring elements from Coulomb excitation experiments

Determination of empirical parameters of solvent polarity E T in binary mixtures by solvatochromic pyridinium-N-phenol betaine dyes

Abstract: Empirical parameters of solvent polarity E T of some pure solvents and their binary mixtures (especially with CCl4 and CHCl3) were determined spectrophotometrically using solvatochromic pyridinium-N-phendl betaine dyes. Calibration curves are given for 16 binary solvent mixtures. The obtained E T values show that a synergetic polarity effect appears with the organic solvents containing C=O, P=O, and S=O groups in the mixture with chloroform. With these binary mixtures the increase of E T values results from the formation of 1∶1 complexes X=O... H-CCl3 by means of hydrogen bonding. Increasing number of methylene groups in the chain increases the synergism with these type of complexes.

Darstellung einiger 4H-Pyrano[2.3-c]pyrazolderivate

Abstract: Aus 4-Aryliden-5-pyrazolonen und Malondinitril werden in Gegenwart von Natriummethylat die Titelverbindungen erhalten. Synthesis of Some 4H-Pyrano[2.3-c]pyrazoles The title compounds are prepared by reaction of 4-arylidene-5-pyrazolones with malodinitrile in presence of sodium methylate.

On the translational control of histone synthesis. Quantitation of biologically active histone mRNA from synchronized HeLa cells and its translation in different cell-free systems.

Abstract: Histone mRNA was isolated from polyribosomes and other cell fractions of synchronized HeLa cells and quantitated by its translational capacity in a rabbit reticulocyte lysate. Inhibition of DNA synthesis with hydroxyurea (5 mM) results within 30 to 60 min in a loss of 80–85% of biologically active histone mRNA from polyribosomes. In contrast, actinomycin D (5 μg/ml) during the first hour of its action, only stops further accumulation of histone mRNA on polyribosomes in early S-phase cells. Under conditions of interruption of DNA replication biologically active histone mRNA does not appear in other cell fractions suggesting that it is immediately destroyed in the cytoplasm. The possible translational control of histone synthesis in HeLa cells was investigated with special consideration of the existence of messenger-specific initiation factors. Cell-free extracts from synchronized HeLa cells in which DNA and histone synthesis were inhibited with hydroxyurea, fully retain their capacity to translate added homologous histone mRNA as compared with extracts from synchronized S-phase cells. Using a partially purified protein-synthesizing system from rat liver supplemented with initiation factors from synchronized HeLa cells differing in their histone-synthesizing capacity, it was shown that factors from hydroxyurea-treated cells are as active in stimulating the translation of histone mRNA, globin mRNA and tobacco mosaic virus RNA as are initiation factors from S-phase cells. The results suggest that messenger discriminating translation factors are not involved in the regulation of histone synthesis in HeLa cells or they are very labile and inactivated during preparation.

Evaluation of histamine elimination curves in plasma and whole blood of several circulatory regions: A method for studying kinetics of histamine release in the whole animal

Abstract: Histamine concentrations in canine whole blood and plasma were determined under several pharmacological, pathophysiological, and clinical conditions, using fluorometric methods The specificity of the assay for whole-blood histamine was investigated by comparing 3 purification procedures for the isolation of histamine from whole blood including butanol extraction (Shore), ion-exchange chromatography on Dowex 50 W-X 8, and the combination of these 2 methods (Lorenz) Histamine in whole blood was identified in analytical and preparative samples by fluorescence spectra, thin-layer chromatography, degradation by diamine oxidase from pig kidney and inactivation by histamine methyltransferase from guinea-pig brain as well as by biological tests on the isolated guinea-pig ileum Since butanol extraction resulted in significantly higher ‘histamine’ values than the other two purification procedures, ion-exchange chromatography on Dowex 50 was recommended as the method of choice for the specific determination of histamine in dog's whole blood Normal values of histamine concentrations in canine plasma were tentatively estimated They depended on the time between pretreatment of the animals (anaesthesia, operation) and the collection of blood and showed an approximately logarithmic normal distribution The median, the lower/upper quartiles and the range of the plasma histamine levels obtained 30 minutes after the end of pretreatment were 02, 0–04 and 0–12 ng/ml, respectively Nearly 50% of the values were zero (below 01 ng according to the sensitivity of the method), only 1% of them exceeded slightly 1 ng/ml Thus histamine release by drugs or by other medical treatments was only stated, when plasma histamine levels exceeded 1 ng/ml and decreased in a way to give an elimination curve of approximately first-order kinetics (Bateman function) Histamine concentrations in dog's whole blood showed approximately a logarithmic normal distribution The median, lower/upper quartiles and range were 47, 34/75 and 13–209 ng/ml respectively The histamine levels in the whole blood of four circulatory regions did not show any significant differences The plasma histamine concentrations in the portal vein were slightly higher than in the hepatic veins The injection of exogenous histamine and the concomitant determination of plasma and whole-blood histamine levels in four circulatory regions showed that the plasma histamine determination was the more sensitive method for measuring histamine elimination curves than the whole-blood histamine assay The elimination of exogenous histamine administered intravenously was influenced by several drugs including inhibitors of histamine inactivation and histamine receptor antagonists Aminoguanidine and the H2-receptor antagonist burimamide slowed down the disappearance of histamine from the plasma, the H1-receptor antagonist dimethpyrindene enhanced it, but amodiaquine had no significant effects Dimethpyrindene and burimamide were capable of releasing histamine in dogs, in some cases to a considerable extent The plasma substitute Haemaccel®, a chemically modified gelatin, released histamine in dogs Using batch 3000, from 27 animals investigated, 15 animals showed elevated plasma histamine levels and a hypotensive blood pressure response, whereas in 12 of the dogs it did not show an effect on these parameters The plasma histamine levels at the time of maximum hypotension showed an approximately logarithmic normal distribution This frequency distribution in combination with the varying incidence of anaphylactoid reactions depending on the batches used seemed very important for the interpretation of clinical reactions to Haemaccel in human test persons and patients By histamine determinations in plasma and whole blood of several circulatory regions and in various tissues before and after infusion of Haemaccel it could be demonstrated that the sites of histamine release by Haemaccel in dogs were especially the skin of the upper hemisphere of the body and the liver, whereas the gastro-intestinal tract took up histamine from the circulation These numerous results under various experimental conditions may be considered as an evidence for the high quality and reliability of the method to study histamine release in the whole animal or in human subjects by evaluating histamine elimination curves in plasma

Sjögren-Larsson syndrome. Oligophrenia--ichthyosis--di-tetraplegia.

Abstract: Since 1957 Sjogren and Larsson have published 28 cases of a new entity: ichthyosis, oligophrenia and di- or tetraspastic disorder a lot of cases have been reported from all over the world. Until now there are 111 cases, on which the diagnosis of Sjogren Larsson syndrome can be made certainly. Half the patients present speech defects, a third alterations of the fundus oculi.

Participation of two photosystems in the photo-phobotaxis of Phormidium uncinatum.

Abstract: 1. A hypothesis based on the Hill-Bendall-model of photosynthetic electron transport is proposed to explain positive and negative photo-phobotaxis inPhormidium uncinatum. In the non-cyclic electron chain a pool is located into which photosystem II (e. g. by absorption by C-phycoerythrin, 561 nm) feeds electrons while photosystem I (e.g. 723 nm) drains electrons out of it. 2. Interruption of the electron flow into the pool causes a sudden decrease of the pool size and thus a positive phobic response. This happens e.g. when an organism leaves a trap which is illuminated by a wavelength absorbed by photosystem II pigments (e. g. 561 nm). 3. A negative reaction takes place when electrons are suddenly drained out of the pool; again the pool size decreases. This is the case when an organism enters a light trap illuminated by photosystem I light (723 nm). 4. The net flow of electrons into or out of the pool—and thus the reaction sense—can be manipulated by the relative excitation of the two photosystems or by blocking the electron influx by DCMU.

Effects of calcium on warm and cold receptors.

Abstract: Afferent impulses were recorded from single warm and cold fibers of the cat's infraorbital nerve during thermal stimulation of the nasal area and intravenous injection of calcium ions. Doses of 2 to 8 mg Ca++/kg caused a marked increase in frequency of the warm receptor discharge, followed by a transient decrease, whereas the activity of cold receptor was depressed.

Adenine Nucleosides in Solution: Stabilisation of the anti‐Conformation by C‐5′ Substituents

Abstract: Proton magnetic resonance spectra of 30 adenine nucleosides have been obtained in dilute (0.001 to 0.05 M) aqueous or dimethyl sulfoxide solutions and have been analysed with respect to structure-dependent variations of the purine proton chemical shifts. In 2H2O the resonance signal of H-8 shows a marked dependence upon the nature of substituents linked to C-4′ of adenine ribofuranoside derivatives and upon the presence of a 2′: 3′-O-isopropylidene group while H-2 is relatively unaffected. Therefore the chemical shift difference, δH-8–δH-2 =Δδ, may serve as an indicator of intramolecular ribose-base interact ons. Δδ varies with the chemical nature of C-4′ or C-5′ substituents in the order: ammonium, sulfonium (0 ppm) < hydrogen < hydroxyl ∼ amino < thio < halogen < phosphate, carboxylate (0.4 ppm), and decreases with increasing chain length of these substituents. These results suggest the existence of electrostatic and dipolar repulsion or, in the majority of cases, attractive forces between the C-5′ and C8-H regions of adenine nucleosides which have been previously demonstrated for 5′-nucleotides only. They imply a strong preference of most adenosine derivatives with unsubstituted 2′ and 3′-hydroxyl groups for the anti-conformation range and the gauche, gauche C-5′ conformation. In dimethyl sulfoxide, basically the same situation exists but different substituents exhibit smaller individual Δδ variations than in water, indicating different solvation shells. In this solvent two additional conformation-stabilizing contributions can be recognized, viz. an interaction of the bridge oxygen (O-4′) of ribose with adenine, and a hydrogen bond between H-8 and a 5′-carboxylate anion. This energetic stabilisation of the anti and g,g-conformers by most types of adenosine C-5′ substituents supports the “rigidity” concept of nucleotides, extending it to the nucleoside level. The only exception found is 5′-nitromethyladenosine in which ultraviolet, circular dichroism and magnetic resonance spectra suggest rotation of the adenine base to a “non-classical” conformation due to base-chain π-electron interaction. The anti-conformation of the adenosine derivatives used in this study can in some cases be correlated with their enzymatic deamination by adenosine and AMP aminohydrolase.

Monosialo-lactoisohexaosyl-ceramide: a ganglioside from human spleen.

Abstract: For the monosialo-lactoisohexaosyl-ceramide, a ganglioside from human spleen, the following structure was established:

Liver growth and mixed-function oxidase activity: dose-dependent stimulatory and inhibitory effects of alpha-hexachlorocyclohexane.

Abstract: α-hexachlorocyclohexane (α-HCH) elicits liver growth and stimulation of hepatic microsomal mixed-function oxidase. In the present study the extent of these changes was determined in rats 2, 4 and 6 days after treatment with doses of α-HCH ranging from 1 to 600 mg/kg. Above the respective threshold doses liver mass, liver DNA, and the rate of aminopyrine demethylation increased in proportion to the log dose. Threshold doses were calculated to be 30 mg/kg for the increase of liver weight and DNA, and 5 mg/kg for the stimulation of aminopyrine demethylation.

Isotopieverschiebung der Bariumnuklide140Ba,138Ba,136Ba und134Ba in der Ba II-Resonanzlinie 6p 2 P 1/2-6s 2 S 1/2

Abstract: The radioactive barium nuclide140Ba (T1/2=12.8 d) has been separated chemically from fission products of uranium. The scheme of the carrier-free separation is described. The isotope shift in the barium II resonance line 6p2P1/2-6s2S1/2,λ=4934 A has been measured by means of a pressure scanned Fabry-Perot interferometer. The resultΔv(140Ba-138Ba)=−39.3 (3.2)mK has been used together with the remeasured isotope shift values of138Ba,136Ba, and134Ba to calculate the change of the mean square radius of the nuclear charge distributionδ〈r2〉. The results are compared with data for isotonic nuclides of neighbouring elements.

Rückstellungsmechanismus von elastischen Hartfasern

Abstract: Elastische Hartfasern besitzen bezuglich ihrer Praparation gleiche Vorgeschichte. Das Polymere erfahrt vor einsetzender Kristallisation eine starke Orientierung in der Schmelze und ein nachfolgendes Tempern im festen Zustand. Dadurch erhalt man hochkristalline Stoffe, in denen die Kristallite in sehr gut orientierten Lamellen senkrecht zur Faserachse angcordnet sind. Solche Fasern zeigen bei Deformation ein ausgepragtes elastisches Verhalten. Analysiert wird dieses Verhalten durch die Verfolgung der thermischen Effekte bei Deformation. Das elastische Verhalten wird erklart durch Umkristallisation der lamellaren und entropicelastischen Deformation der interlamellaren Schichten.

Purification and Characteristics of Hybridase (Ribonuclease H) from Rat‐Liver Cytosol

Abstract: Ribonuclease H or hybridase, the enzyme cleaving the RNA moiety of DNA · RNA hybrids has been extensively purified from rat-liver cytosol by ammonium sulphate precipitation, DEAE-cellulose chromatography, Sephadex G-200 and G-150 superfine gel filtration, isoelectric focusing, phosphocellulose and hydroxyapatite chromatography. Neither native or denatured DNA, nor single or double-stranded natural or synthetic ribopolynucleotides are degraded by the enzyme. The pH optimum of the reaction is 7.9. Enzyme activity is totally dependent on the divalent cations Mg2+ and Mn2+, Mg2+ being optimal for the reaction. The enzyme acts on the hybrid as an endonuclease resulting in end products with a chain length less than 15, having a 5′-phosphate and a free 3′-hydroxyl end group. Synthetic homopolymer hybrids are digested only if they are composed of purine bases. The enzyme has a molecular weight of 120000–125000 and seems to be composed of two subunits with molecular weights of 85000 and 43000.

Inhibition of Rat-Liver RNA Polymerase in vitro by Aflatoxin B1 in the Presence of a Microsomal Fraction

Abstract: Aflatoxin B1 inhibits rat liver nucleoplasmic RNA polymerase B (40–50%) and cytoplasmic RNA polymerase C activities (25–35%) if applied in vivo. Nucleolar RNA polymerase A activity is not inhibited under the same conditions. Aflatoxin B1 has no effect on the activities of purified RNA polymerase enzymes A, B and C or on [3H]UTP incorporation of isolated rat liver nuclei in vitro. Aflatoxin B1, upon preincubation with a rat liver microsomal fraction, however, is apparently converted to a compound which then inhibits the activities of purified nucleoplasmic RNA polymerase (20–40%), cytoplasmic RNA polymerase (10–20%) and the incorporation of [3H]-UTP into isolated nuclei (38%). Nucleolar RNA polymerase activity is not affected under these conditions. The microsomal fraction, which most effectively converts aflatoxin B1 to an inhibitor of RNA polymerase is also the most effective cellular fraction catalysing the metabolism of aflatoxin B1.

Effects of cordycepin, hydroxyurea and cycloheximide on histone mRNA synthesis in synchronized HeLa cells.

Abstract: The effects of cordycepin, hydroxyurea and cycloheximide on the synthesis of histone mRNA in synchronized HeLa cells were studied by quantitating the RNA, using translation in a rabbit reticulocyte cell-free system. It was found that biologically active histone mRNA is synthesized in the presence of cordycepin. This result strengthens the findings by others that histone mRNA does not contain poly(A). Hydroxyurea and cycloheximide, when used at concentrations that inhibit cellular DNA synthesis, had different effects on histone messenger activity. While polyribosomal messenger activity rapidly declined after addition of hydroxyurea it was not impaired by cycloheximide. These results might help to elucidate regulatory mechanisms involved in the coupled synthesis of DNA and histones in HeLa cells.