Showing papers by "University of Göttingen published in 1974"

Isolation and characterization of a 3-chlorobenzoate degrading pseudomonad.

Abstract: A pseudomonad has been isolated from sewage, which can utilize 3-chlorobenzoic acid as a sole carbon source. In cells grown on benzoate the enzymes of the β-ketoadipic acid pathway are present. Considerable enzymic activities for chlorinated substrates were found in benzoate grown cells only for the oxygenation of 3-chlorobenzoate and the dehydrogenation of 3- and 5-chloro-3,5-cyclohexadiene-1,2-diol-1-carboxylic acid. 3-Chlorobenzoate grown cells show additional high activities for the turnover of 3- and 4-chlorocatechols and chloromuconic acids.

α-Metalated Isocyanides in Organic Synthesis. New synthetic methods (6)

Abstract: α-Alkali-metalated isocyanides, which can be obtained from isocyanides and bases, can be used for nucleophilic introduction of (masked) α-aminoalkyl groups. Intramolecular ring-closure may then follow if a nucleophile combines at the electron sextet of the isocyanide carbon. Treatment of α-alkali-metalated isocyanides with electrophilic agents permits rapid and efficient synthesis of, inter alia, 2- and 3-amino alcohols, straight-chain, branched, and β-functional α-amino acids, olefins, vinyl isocyanides, and of a large number of mainly five-, but also six- and seven-membered aza-, diaza-, oxa-aza-, and thia-aza heterocycles.

Model for mechanical to neural transduction in the auditory receptor

Abstract: We present here a model for the transduction of mechanical motion of the basilar membrane into action potentials (“spikes”) in the auditory nerve. The model, based on the generation and depletion of electrochemical quanta in a hypothetical hair cell, is more compatible with neurophysiological evidence than threshold models of mechanical-to-neural transduction. The amplitude normalization observed in auditory-nerve data is an inherent property of the model.

Geochemistry of the Rare Earth elements in spilites from the oceanic and continental crust

Abstract: Analytical data including major elements, the Rare Earths, Ni, Cu, Zn, Rb, and Sr are presented for twenty-three spilites from the Mid-Atlantic Ridge, the Hercynian part of the Variscan geosyncline in Germany, and several localities in Switzerland. Low grade metamorphism (up to approximately 400° C) and spilitization of basaltic rocks apparently do not alter the original Rare Earth element (REE) distributions. This fact permits comparison of the spilites and unaltered tholeiitic basalts from the Mid-Atlantic Ridge. The relative REE distributions thus appear suitable for delineating the original basalt types of spilites formed by metamorphism.

The Effectiveness of a Sternomastoid Muscle Flap in Preventing Post-Parotidectomy Occurrence of the Frey Syndrome

Abstract: Among over 350 parotidectomies, the effectiveness of a pedicled sternomastoid muscle flap in preventing post-parotidectomy occurrence of the Frey Syndrome was tested during the past year in a random sampling of 35 patients with such a muscle flap and 35 control patients. Results of the study indicate that the muscle flap, although improving cosmetic defects associated with surgery, is incapable of inhibiting the Frey Syndrome and that other means must yet be devised to prevent the occurrence of gustatory sweating following parotid surgery.

α-Metallierte Isocyanide in der Organischen Synthese

Abstract: α-Alkalimetallierte Isocyanide – zuganglich aus Isocyaniden und Basen — gestatten die nucleophile Einfuhrung von (maskierten) α-Aminoalkylgruppen. Ein intramolekularer Ringschlus kann folgen, wenn sich ein Nucleophil in das Elektronensextett des Isocyanid-Kohlenstoffs einlagert. Die Umsetzung der α-alkalimetallierten Isocyanide mit Elektrophilen gestattet die schnelle und ergiebige Synthese u. a. von 2- und 3-Aminoalkoholen, geradkettigen, verzweigten sowie β-funktionellen α-Aminosauren, Olefinen, Vinylisocyaniden und einer Vielzahl vorwiegend funf-, aber auch sechs- und siebengliedriger Aza-, Diaza-, Oxaza- und Thiaza-Heterocyclen.

Mechanical influence of the extrafusal muscle on the static behaviour of deefferented primary muscle spindle endings in cat.

Abstract: In 16 anesthetized cats 24 afferents of deefferented primary muscle spindle endings from the extensor digitorum longus muscle (EDL) were functionally isolated and their sensitivity to static stretches was tested. Each spindle was carefully located within the EDL using direct focal stimulation. Muscle spindle endings with “poor” static length sensitivity of stretch were always found in the most peripheral parts of the muscle fibre bundles, near to the aponeurotic and tendineous insertions. Endings having “good” static sensitivity to stretch were exclusively found in more central portions of the muscle fibre bundles. Using a photographic method, the alterations in the distance between designated points on the muscle surface ware measured during maintained muscle stretch. Only medial portions were markedly extended, whereas little or no increases in length occurred in peripheral parts of the muscle fibre bundles. Quantitatively, a direct relationship was found between the lengthening of those muscle portions, in which the muscle spindles were localized, and the receptors' sensitivity to maintained stretch.

The effect of ferrous ions, tungstate and selenite on the level of formate dehydrogenase inClostridium formicoaceticum and formate synthesis from CO2 during pyruvate fermentation

Abstract: In a medium containing a trace element solution and 10-4 M ferrous ions the growth yield ofClostridium formicoaceticum on fructose was 5.5 g of weight per l; in the absence of metal ion solution it was 1 g per l. The specific activity of methyl viologen dependent formate dehydrogenase under both conditions was 0.28 and 0.03 units per mg of protein, respectively. It could be increased to 9.75 units when the growth medium contained 10-4 M tungstate and 10-5 M selenite in addition.

Effect of zero-tillage on organic carbon and total nitrogen content, and their distribution in different N-fractions in loessial soils

Abstract: In order to evaluate the effect of reduced tillage intensity on the accumulation of organic matter in Grey-brown podsolic soils near Gottingen (German Federal Republic), stratified soil analyses were made in three field trials after at least 5 years of experimenting. On old arable soil, zero-tillage increased the content of organic C of the 0–30 cm layer by mean annual rates of 0.59–1.30 tons/ha, and correspondingly the content of total N by 53.8–72.4 kg/ha. Killing a sod and cropping the former grassland with annual field crops, but without disturbing the soil, caused a mean annual loss of 2.29 tons/ha and 162.4 kg N/ha. This indicates that reduced tillage cannot preserve the original high content of soil organic matter maintained by a living sod. On arable soil, zero-tillage caused a mode of nitrogen distribution which is similar to that found in grassland soil. The N-content of fraction V (containing total amino-acid N and unknowns) increased at the expense of the ammonium-N (fraction I). The relative increase or loss of total N in the 0–5 cm layer, as caused by tillage and cropping practices, was most pronounced in fraction V, ranging between 53 and 67%.

Citrate lyase from Rhodopseudomonas gelatinosa: purification, electron microscopy and subunit structure.

Abstract: 1. Citrate lyase (EC 4.1.3.6) from Rhodopseudomonas gelatinosa has been purified to homogeneity by protamine sulfate fractionation, chromatography on DEAE-Cellulose and gel filtration. The final enzyme preparation had a specific activity of 138 units per mg of protein and was purified 43-fold over the crude extract. Analysis of citrate lyase by sedimentation equilibrium experiments and gel filtration gave molecular weights of 530000 and 560000, respectively. 2. Electron microscopic investigations of negatively stained enzyme molecules and image analysis showed that citrate lyase is composed of six large and six small subunits; they are arranged in two hexagonal rings lying face to face, each containing, in alternating sequence, three large and three small subunits. The enzyme molecule is 160 A in diameter and about 100 A thick. 3. Treatment with sodium dodecylsulfate and mercaptoethanol dissociated citrate lyase into three proteins. Protein III (small subunit) had a molecular weight of 30000 and contained the pantothenate; protein II (large subunit) had a molecular weight of 61000; protein I (Mr=97000) was probably an aggregate of II and III. 4. Based on the results obtained a model of citrate lyase was constructed. 5. Purified citrate lyase was obtained from R. gelatinosa in a deacetylated and largely oxidized form. The enzyme was activated by reduction with dithiothreitol (3 mM) and subsequent acetylation with acetic anhydride (1.75 mM). 6. The enzyme was subject to reaction inactivation, the extent of which depended on the concentration of Mg2+.

Purification and properties of acetate kinase from Clostridium thermoaceticum.

Abstract: Acetate kinase (ATP: acetate phosphotransferase EC 2.7.2.1) has been purified from Clostridium thermoaceticum. The enzyme of a specific activity of 282 μmoles min-1 mg-1 appeared homogeneous as judged from Sephadex chromatography and sedimentation velocity. Polyacrylamide gel electrophoretic patterns at pH 9.0 and 9.5 showed heterogeneity. Velocity curves obtained with varying amount of acetate were of the Michaelis-Menten type with an apparent K m of 0.135 M. With varying amounts of ATP sigmoidal kinetic was observed (S0.5=1.64 mM), suggesting cooperative binding of this substrate. The enzyme had only moderate thermal stability with a temperature optimum of about 60°C and exhibited a broken line in an Arrhenius graph. From gel filtration a molecular weight of about 60 000 daltons was estimated for the enzyme. The S20w value was 6.0 S.

From Euclidean to relativistic fields and on the notion of Markoff fields

Abstract: Recently, Nelson [2] has constructed relativistic fields from Euclidean fields which satisfy the Markoff and reflection property as well as an additional domain assumption. In this paper we replace the Markoff and reflection property by a weaker condition, a very simple positivity condition (“T-positivity”) which can be very easily expressed in terms of the expectation functionalE(f)=〈ω, exp {i φ (f)} ω〉. We show that the special role of the Markoff property in Nelson's approach is entirely due to features also shared byT-positivity. The role of Nelson's domain assumption (A′) in by-passing the difficulties with the paper of Osterwalder and Schrader [4] are made transparent, and possible ways to weaken this assumption are pointed out. If the conditions of [4] should turn out to be sufficient after all, (A′) can be replaced by a simple differentiability condition onE(τf). Our approach can also be applied to Fermi fields. The notion of Markoff and reflection property is discussed and shown to implyT-positivity.

Production, modification, and consumption of atmospheric trace gases by microorganisms

Abstract: Some trace gases are contained in the atmosphere in appreciable amounts: methane, carbon monoxide, hydrogen, nitrous oxide. The bulk of these gases is of biological origin. Hydrogen is a primary product of microbial metabolism under anaerobic conditions. However, before reaching the atmosphere, it is converted by methane bacteria to methane, by nitrate reducing bacteria to nitrogen and to nitrous oxide and by sulfate reducing bacteria to hydrogen sulfide. Carbon monoxide is produced from certain organic compounds. Hydrogen, methane, and carbon monoxide are quickly oxidized by microorganisms under aerobic conditions. However, especially methane and carbon monoxide reach the atmosphere. The literature dealing with the microorganisms and biochemical reactions involved in the production and conversion of trace gases is reviewed. DOI: 10.1111/j.2153-3490.1974.tb01947.x

Studies on the mechanism of L-leucine-and alpha-ketoisocaproic acid-induced insulin release from perifused isolated pancreatic islets.

Abstract: The insulinotropic effects of L-leucine and α-ketoisocaproic acid have been compared in perifused isolated pancreatic islets. In contrast to α-ketoisocaproic acid (10 mM), L-leucine (10 mM) released less insulin in the presence than in the absence of glucose (5 mM). Changes of islet cell metabolism accompanying insulin release were studied by recording the fluorescence of reduced pyridine nucleotides. The traces of L-leucine-or α-ketoisocaproic acid-induced fluorescence increase differed both in the absence and in the presence of glucose (5 mM). When the medium perif using the islets contained 30 mM L-leucine, α-ketoisocaproic acid (10 mM) still triggered a significant insulin release. These results argue against an indirect action of α-ketoisocaproic acid via transformation to L-leucine. Isocaproic acid (10 mM), L-α-hydroxyisocaproic acid (10 mM) or α-ketoisovaleric acid stimulated no remarkable insulin release, demonstrating that the strong insulinotropic effect of α-ketoisocaproic acid is coupled both to its α-ketogroup and to the length of its carbon chain.

The pancreatic secretion of enzymes in rats treated with soybean diet.

Abstract: Folsch, U. R. & Wormsley. K. G. The pancreatic secretion of enzymes in rats treated with soybean diet. Scand. J. Gastroent. 1974, 9, 679–683.The secretory response to CCK-PZ and secretin has been s...

N2-fixation by chemoautotrophic hydrogen bacteria.

Abstract: The Gram-positive coryneform bacteria strains 14g and 7C were found to be able to grow with N2 as sole nitrogen source when incubated under microaerobic conditions. Nitrogenase activity in whole cells was assayed by acetylene reduction. High rates of ethylene production (50–120 nmole/hxmg cell protein) were observed in N2 or glutamate grown cell suspensions shaken in an atmosphere of 2.5% O2, 10% acetylene and 87.5% argon.

Taxonomic studies on some gram-positive coryneform hydrogen bacteria

Abstract: Recently isolated coryneform hydrogen bacteria were investigated under taxonomical aspects. Strains 7 C, RH 10, and 14 g are characterized by the snapping type of cell division, 68.5 to 69.7% GC content, dl-diaminopimelic acid in the cell wall, content of metachromatic granules, weak utilization of sugars and inhibitory effect of citrate. The strains are placed to the group 1—genus Corynebacterium—of the classification of coryneform bacteria of Yamada and Komagata (1972) and the name Corynebacterium autotrophicum sp.nov. is proposed. Strains 11 X and RH 12 are characterized by the bending type of cell division, a GC content of 70.2 and 70.5%, ll-diaminopimelic acid in the cell wall, absence of metachromatic granules, utilization of several sugars and no changes in cell morphology by citrate. The strains have to be placed to group 6 of coryneform bacteria.

The Circadian Rhythm of Free Cortisol Determined by Urine Sampling at Two-Hour Intervals in Normal Subjects and in Patients with Severe Obesity or Cushing's Syndrome

Abstract: A method for the investigation of the cortisol rhythm, estimating the free cortisol in 2-hr urine samples, is described. In each of 7 normal individuals highly reproducible curves with circadian rhythm could be found. Due to differences in the time of the morning peak the mean curve of the normal individuals resembles the individual curves only after synchronizing them according to the morning peak. In this peak sample the cortisol excretion rate is 2½ times higher than during the remainder of the day. Eight severely obese patients did not differ from the control subjects in their circadian rhythm: the difference in the absolute daily cortisol excretion (obese patients: 29.1 normal subjects: 46.3 μg/24 hr) probably represents the difference between hospitalized and nonhospitalized persons. Six patients with Cushing's syndrome due to bilateral adrenal hyperplasia exhibited a great heterogeneity with the following observations in different patients: very uneven curves without a distinct pattern, di...