Showing papers by "University of Tübingen published in 1977"
TL;DR: In this paper, it was shown that the one-dimensional classical spins with nearest neighbor Heisenberg interaction is an exactly solvable system and its dynamics describable by the nonlinear Schrodinger equation.
433 citations
TL;DR: The progress of corporatist ideas since the late nineteenth century and the advent of authoritarian "corporatist" regimes in the twentieth century have been strongly fostered by critiques of parliamentary and party government as discussed by the authors.
Abstract: The progress of corporatist ideas since the late nineteenth century and the advent of authoritarian “corporatist” regimes in the twentieth century have been strongly fostered by critiques of parliamentary and party government. To be sure, corporatist doctrines have not been unanimous in their assessment of universal suffrage, parliament, and competitive party systems. While on the one hand authors such as Spann (1934) proposed to abolish parliament, that “Schwatzbude,” and to replace it by a representation of “estates,” others merely proposed to redress the alleged shortcomings of parliamentary democracy by adding a system of corporate representation. For example, Catholic “Solidarists” (a school which has been important in the German-speaking countries), proposed a Chamber of Corporations which should supplement, but not substitute for, a parliament based on political parties (Mayer-Tasch, 1971:60). On the other hand, a socialist party leader, the “Austro-Marxist” theorist Bauer, under the influence of early Soviet experience as well as English “guild socialism,” pleaded for the improvement of merely “formal” or “political” democracy (i.e., bourgeois-dominated parliamentary government based on universal suffrage) by “functional democracy,” which demands that “the government in each single branch of its activity rests in continual understanding with the organized whole of the citizens, who, according to their profession or their plant, according to their social and economic function are immediately concerned by that particular branch of government activity” (Bauer, 1923: 187).
318 citations
TL;DR: Polynomial multiplication of degree N can be accomplished in time O (N · log N) provided the scalar field contains suitable roots of unity and the Schönhage-Strassen multiplication is employed.
Abstract: Polynomial multiplication of degree N can be accomplished in time O (N · log N) provided the scalar field contains suitable roots of unity. Otherwise at least O (N · log N · log log N) is obtained by a modified version of the Schonhage-Strassen multiplication which employs computations modulo 1 + xn (where N = 2n), if the field contains 2?1, or modulo 1 + xn + x2N, if 3?1 exists. The latter method covering all fields of characteristic 2 is presented here in detail.
224 citations
TL;DR: The experiments with rats show that, qualitatively, rats and mice do not differ in ethane production after carbon tetrachloride, but there are species variations.
153 citations
TL;DR: In this paper, the authors show that the notion of hermitian Jordan triple system cannot rely on trace forms, and prove the following main theorem: the category of simply connected, symmetric, complex Banach manifolds with base point is equivalent to the category for hermitians.
Abstract: The symmetric hermitian complex manifolds (of finite dimension) have been classi fled completely by E. Cartan [4] using the classification of simple complex Lie algebras. A Jordan theoretic approach is due to Koecher [18] and more recently to Loos [25] : The symmetric bounded domains are in a one-to-one correspondence to hermitian Jordan triple systems, for which a certain trace form is positive-definite hermitian. Bounded symmetric domains in infinite dimensions have been considered by various authors [7, 9, 11, 14-16, 28, 32]. Harris for instance proved for a big class of complex Banach spaces U (including all C*-algebras) that the open unit ball of U is homogeneous and hence symmetric. In this paper we study symmetric complex Banach manifolds. A complex Banach manifold is a complex manifold (of possibly infinite dimension) M together with a fixed norm v on the tangent bundle of M. We do not require that the restriction of v to every tangent space T~, x~M, is a Hilbert norm--otherwise we would exclude many interesting examples such as the open unit ball in the Banach space L(H) of all bounded operators on a Hilbert space H with d imH= oo. Therefore our notion of hermitian Jordan triple system cannot rely on trace forms. The major part of the paper is devoted to the proof of the following Main Theorem. The category of simply connected, symmetric, complex Banach manifolds with base point is equivalent to the category of hermitian Jordan triple systems.
142 citations
TL;DR: The results show that kirromycin's action appears to be directed towards a critical region of the EF-Tu molecule responsible for the regulation of the sites involved in the elongation process, and abolishing the requirement of GTP for formation of the aminoacyl-tRNA · EF- Tu complex.
Abstract: Elongation factor Tu (EF-Tu) is the target of kirromycin, an inhibitor of protein biosynthesis that enables EF-Tu to catalyze GTP hydrolysis in the absence of ribosomes and aminoacyl-tRNA. This GTPase activity conserves many of the characteristics of the physiological one, which is triggered by ribosomes plus aminoacyl-tRNA. Both activities have the same substrate specificity and are affected by aminoacyl-tRNA, but not by tRNA or N-acetylaminoacyl-tRNA. With kirromycin, aminoacyl-tRNA changes only the V of the reaction without affecting the Km for GTP, which remains the same as the one determined in the presence of aminoacyl-tRNA plus ribosomes without the antibiotic. Addition of ribosomes does not affect the course of temperature-dependence of the kirromycin-induced GTPase activity. Our results show that the catalytic center for GTP hydrolysis, associated with the enzymic binding of aminoacyl-tRNA to ribosome, is located primarily on the elongation factor and not on the ribosome.
Kirromycin binds to EF-Tu in a molar ratio of 1:1 and competes with elongation factor Ts (EF-Ts) for this binding, favoring the state of dissociation of EF-Tu and EF-Ts, probably by inhibiting their reassociation.
All the partial reactions involved in the formation of the ternary complex (aminoacyl-tRNA · EF-Tu · GTP) are affected by the antibiotic, which stimulates strongly EF-Tu affinity for GTP and consequently the GDP-GTP exchange reaction with EF-Tu · GDP. Kirromycin activates the EF-Tu site for aminoacyl-tRNA even in the presence of GDP, abolishing the requirement of GTP for formation of the aminoacyl-tRNA · EF-Tu complex.
Our results show that kirromycin does not interact directly with the EF-Tu sites for guanine nucleotides, aminoacyl-tRNA and ribosomes. Its action, which allosterically relieves tight mutual control mechanisms, appears to be directed towards a critical region of the EF-Tu molecule responsible for the regulation of the sites involved in the elongation process.
129 citations
TL;DR: In this article, the authors investigated the mechanism which allows the antibiotic kirromycin to inhibit peptide bond formation by acting on elongation factor Tu (EF-Tu) and showed that EF-Tu is not released from the ribosome, which blocks interaction of the C-C-A end of aminoacyl-tRNA bound to the acceptor site with the peptityl transferase center.
Abstract: We have investigated the mechanism which allows the antibiotic kirromycin to inhibit peptide bond formation by acting on elongation factor Tu (EF-Tu). Gel filtration experiments show that with kirromycin after enzymic binding of aminoacyl-tRNA to ribosomes and subsequent GTP hydrolysis EF-Tu is not released from the ribosome. However, ability of the ribosomal peptidyl transferase center to support puromycin reactivity of peptidyl-tRNA bound to the ribosomal donor site is still preserved. This shows that inhibition of peptide bond formation by kirromycin is the consequence of the failure of EF-Tu to leave the ribosome, which blocks interaction of the C-C-A end of aminoacyl-tRNA bound to the acceptor site with the peptityl-transferase center.
In line with these observations, kirromycin inhibits ribosome · EF-Tu GTPase activity down to one round of GTP hydrolysis when poly(U) and Phe-tRNAPhe are simultaneously present. The intrinsic inability of EF-Tu bound to ribosomes to interact in a productive way with free GTP appears to be a primary reason for inhibition of the turnover of GTPase activity in this condition.
In the absence of poly(U), ribosomes are very active in stimulating the kirromycin-induced EF-Tu GTPase either with or without Phe-tRNAPhe, which increases their affinity for the reaction. When Phe-tRNAPhe is present, kirromycin enables either ribosomal subunit to stimulate GTP hydrolysis of EF-Tu, showing that each subunit harbours an active site for the regulation of the catalytic center of EF-Tu. Addition of poly(U) plus Phe-tRNAPhe inhibits the turnover of the kirromycin-induced GTP hydrolysis in the presence of the 30-S subunits, but not of that in the presence of the 50-S subunit, which is inhibited when the 30-S subunit is also added. The 30-S subunit alone appears therefore to be sufficient for formation of a stable complex with EF-Tu and kirromycin. Our results show that expression of EF-Tu GTPase activity coupled with polypeptide synthesis is the result of an highly specific and coordinated mechanism, in which both ribosomal subunits participate and act on the catalytic center of the elongation factor.
No kirromycin-like activity was found in the two fragments of the antibiotic molecule, obtained by acid hydrolysis. None of the partial reactions of polypeptide synthesis tested, dependent on elongation factor G, initiation factors or aminoacyl-tRNA-synthetases, appeared to be affected by kirromycin.
128 citations
TL;DR: In this paper, the existence theorem of R. Nussbaum for periodic solutions of difference-differential equations is generalized to equations with a damping term, motivated by recent theories of neural interactions in certain compound eyes.
Abstract: The existence theorem of R. Nussbaum for periodic solutions of difference-differential equations is generalized to equations with a damping term. The study of such equations is motivated by recent theories of neural interactions in certain compound eyes.
120 citations
118 citations
TL;DR: It was of interest to examine whether or not a low molecular weight copper-rich metal-thionein was present in biological species which received no metal pretreatment at all and from bovine fetal liver an 8 Cu 2 Zn-thionin having a molecular weight of 11 500 was successfully isolated.
117 citations
TL;DR: In this paper, the authors showed that there is no certain relationship between the severity of glomerular lesions and the serum creatinine level, and that the renal interstitium was less enlarged than in 21 cases in the same stages.
Abstract: Morphometric investigations in 40 patients suffering from perimembranous glomerulonephritis at different stages showed that there is no certain relationship between the severity of glomerular lesions and the serum creatinine level. In 19 cases in stages I–III, with serum creatinine level less than 1.2 mg/100 ml on biopsy, the renal interstitium was less enlarged than in 21 cases in the same stages, but with serum creatinine level higher than 2 mg/100 ml.
TL;DR: In this paper, the authors show that spiral-type chaos is a simple type of nonperiodic oscillatory flow in 3-variable continuous systems and screw-type chaotic is a type of chaotic flow that occurs in ahysteresis oscillators between two stable limit cycles.
TL;DR: In this paper, a histopathological study was carried out on 27 patients with chronic inflammatory liver disease and clinical and biochemical evidence of cholestasis who had either mitochondrial antibodies against mitochondrial antigen fractions of 1.19 density (PBC antigen) or 1.13 density (CAH-PBC mixed-type antigen)
Abstract: A histopathological study was carried out on 27 patients with chronic inflammatory liver disease and clinical and/or biochemical evidence of cholestasis who had either mitochondrial antibodies against mitochondrial antigen fractions of 1.19 density (“PBC antigen”; 14 cases) or of 1.13 density (“CAH-PBC mixed-type antigen”; 13 cases). For comparison, the liver biopsies of 17 patients with chronic-aggressive hepatitis (CAH) and antinuclear and/or anti-smooth muscle antibodies but without cholestasis and mitochondrial antibodies, were evaluated. The 14 patients with mitochondrial antibodies against the PBC antigen showed the typical histological features of primary biliary cirrhosis (PBC). The 13 patients with mitochondrial antibodies against the CAH-PBC mixed-type antigen had heterogenous liver alterations. In 11 cases highly active CAH and/or active postnecrotic cirrhosis (AC) were found both with augmented ductular proliferation. Some of these cases showed distinct criteria of PBC as early bile duct lesions or absence of regular bile ducts. The liver histology of one case corresponded to classical PBC; another case to chronic persistent hepatitis. The CAH-patients without cholestasis and mitochondrial antibodies only occasionally showed bile duct proliferation. In conclusion, a high correlation was found between mitochondrial antibodies against the CAH-PBC mixed-type antigen and highly active CAH or early AC with augmented ductular proliferation. This represents an overlapping of CAH and PBC. In contrast, the cases with antibodies reacting to the PBC antigen showed the slowly progressive liver changes of typical PBC.
TL;DR: A detailed study of the hemolytic action with variations of concentration, temperature and incubation time revealed characteristic differences in the mode of hemolysis between the peptide antibiotics, which can be correlated with structural differences between these natural analogs.
Abstract: The Hemolytic Properties of the Membrane Modifying Peptide Antibiotics Alamethicin, Suzukacillin and Trichotoxin
The membrane exciting peptide antibiotics alamethicin F-50, suzukacillin A and B, and trichotoxin A-40 can be isolated from different strains of the fungus Trichoderma viride. Cultivation, isolation and purification procedures are described in detail for alamethicin F-50. At micromolar concentrations the peptide antibiotics cause hemolysis in human erythrocytes, while at nanomolar levels they induce the formation of voltage-dependent pores of multi-state properties in black lipid membranes.
A detailed study of the hemolytic action with variations of concentration, temperature and incubation time revealed characteristic differences in the mode of hemolysis between the peptide antibiotics, which can be correlated with structural differences between these natural analogs. The addition of bovine serum albumin reduces the hemolytic activity. The lytic action increases considerably from hypertonic to hypotonic media. For comparison the bee venom constituent melittin and sodium dodecylsulfate have been investigated under the same conditions. The lipophilic peptide antibiotics constitute a new class of membrane disrupting agents with particular properties not known from other lytic compounds.
Assuming that the lytic activity is proportional to the concentration of the peptide antibiotic, the temperature dependence of the concentration/activity curves allows the calculation of activation energies of 62 kJ/mol for alamethicin, 67 kJ/mol for suzukacillin A, and 79 kJ/mol for trichotoxin A-40. However, melittin revealed the very low activation energy of 49 kJ/mol. These values may be correlated with results from circular dichroism and 13C nuclear-magnetic-reonance experiments which indicate conformational changes of the peptides aggregating at the membrane/water interphase.
TL;DR: In this paper, a 25 year old man with normal hair, abundant axon swellings and spheroids were observed in the spinal cord, brain system, and cerebral cortex.
Abstract: The process of Giant Axonal Neuropathy (GAN) is not restricted to the peripheral nerves, but also involves the central nervous system. In a 25 year old man with normal hair, abundant axon swellings and spheroids were observed in the spinal cord, brain system, and cerebral cortex. The findings in the sural nerve have already been published by Boltshauser et al. (1977). Accumulations of filaments in the axons and in the perineural cells were accompanied by Rosenthal fibres. The ultrastructural pattern of GAN differs clearly from that of Neuroaxonal Dystrophies.
TL;DR: Serial blood and faecal samples were collected from patients and family contacts during an outbreak of hepatitis A in a village and tested by a solid‐phase competitive type radioimmunoassay for hepatitis A antigen and hepatitis A antibody, finding an inverse correlation between the incidence of infection and prevalence of hepatitis C antibody and age.
Abstract: Serial blood and faecal samples were collected from patients and family contacts during an outbreak of hepatitis A in a village and tested by a solid-phase competitive type radioimmunoassay for hepatitis A antigen and hepatitis A antibody. The amount and duration of excretion of hepatitis A antigen was correlated with the severity of the illness. In 2 severe clinical cases, hepatitis A antigen was demonstrated in faecal extracts 11 days before the onset of jaundice and continuing for 10 days thereafter, with maximum shedding during the late incubation period. Faecal antigen was demonstrated in low concentrations for only 2 days in a patient with mild disease and in a person with subclinical infection. There was an inverse correlation between the incidence of infection and prevalence of hepatitis A antibody and age. Of 24 infections, 19 (79%) occurred in persons in the age group 0 to 20 years, a group in which only 6% of individuals had pre-existing antibody. Hepatitis A antibody was present in the serum of 3 persons in low titres of 1:20 to 1:40 on the day jaundice developed. The antibody titres increased very rapidly during the following 2 weeks of illness and slowly during the following months, reaching titres of 1:900 to 1:3500. In a separate study, a mean antibody titre of 1:591 was found in 13 patients, 12 years after clinical hepatitis A with jaundice.
TL;DR: In this article, the authors showed that 2,3-dihydroxybenzoate (DHB)-promoted iron uptake bypassed two functions required for the transport of ferric-enterochelin from the medium.
Abstract: The study of iron uptake promoted by 2,3-dihydroxybenzoate (DHB) into Escherichia coli K-12 aroB mutants allowed some dissection of outer and cytoplasmic membrane functions. These strains are unable to produce the iron-transporting chelate enterochelin, unless fed with a precursor such as DHB. When added to the medium, enterochelin and its natural breakdown products, the linear dimer and trimer of 2,3-dihydroxybenzoylserine (DBS), efficiently transported iron via the feuB, tonB and fep gene products. Thus mutants in these genes were defective in transport of the above chelates. However, feuB and tonB mutants were able to take up iron when DHB was added to the medium. Thus DHB-promoted iron uptake bypassed two functions required for the transport of ferric-enterochelin from the medium. One of these functions, feuB, has been shown to be an outer membrane protein. In contrast to three other iron transport systems including ferric-enterochelin uptake, DHB-promoted iron uptake was little affected by the uncoupler 2,4-dinitrophenol. Dissipation of the energized state of the cytoplasmic membrane apparently only affects those iron transport systems which require an outer membrane protein. Since DHB-promoted iron uptake bypasses the feuB outer membrane protein and the tonB function, it is concluded that, in ferricenterochelin transport, the tonB gene may function in coupling the energized state of the cytoplasmic membrane to the protein-dependent outer membrane permeability. DHB-promoted iron uptake required the synthesis and enzymatic breakdown of enterochelin as judged by the effects of the entF and fesB mutations. A fep mutant was not only deficient in the transport of the ferric chelates of enterochelin and its breakdown products, but was also deficient in DHB-promoted iron uptake. A scheme is presented in which iron diffuses as DHB-complex through the outer membrane, and is subsequently captured by enterochelin or DBS dimer or trimer and translocated across the cytoplasmic membrane.
TL;DR: The experiments support the theory that vinyl chloride metabolites react with adenosine moieties of nucleic acid under formation of 1-N(6)-etheno-adenosine and show that measurement of incorporation of radioactivity into nucleic acids after exposure of animals to radioactive vinyl chloride is not applicable.
TL;DR: The results favour the hypothesis, that one of the modes of action of anti-inflammatory drugs is the scavenging of the oxygen species responsible for the inflammatory response by their copper chelates formed in vivo.
TL;DR: This simple method for isolating large numbers of viable cells may potentially be important for use with small liver pieces, such as biopsy samples, and suitable for maintaining hepatocytes in primary monolayer cultures in order to study enzyme regulation at the cellular level in vitro.
TL;DR: The authors postulated that this cycle, which is presented schema- tically in fig.1, represents one of the systems respon- sible for reabsorption of amino acids in the kidney.
TL;DR: The conditions for deviations of thepH-absorption curve from the course predicted by the simplepH partition theory are investigated theoretically and a variable microclimatepH influenced by bulk phasepH can also produce the described deviations.
Abstract: The conditions for deviations of thepH-absorption curve from the course predicted by the simplepH partition theory are investigated theoretically. The deviations are an elevation of the asymptotic section usually approaching zero and/or a shift of the intermediate section, more exactly of the inflection point, in the direction of the abscissa and/ or the ordinate. In the absence of a specialpH at the surface of the barrier (microclimatepH), the elevation of the asymptotic section can be attributed to a permeability of the barrier to the ionized form of the permeating substance. A shift of the inflection point to the right for acids and to the left for bases can be explained by a significant unstirred layer at the surface of the barrier or-only when the concentration in the well- stirred bulk phase is decreasing with time-by a high distribution ratio of the substance between barrier and bulk phase. A variable microclimatepH influenced by bulk phasepH can also produce the described deviations.
TL;DR: Positive significant correlations (corresponding to linear and parabolic functions) between the relative interstitial volume of the renal cortex and serum creatinine concentration at the time of biopsy could be found.
Abstract: Morphometric investigations were performed in 33 biopsies with minimal proliferative intercapillary glomerulonephritis with nephrotic syndrome (MPI with NS, minimal changes with nephrotic syndrome) and in 65 biopsies with focal sclerosing glomerulonephritis (FGS). Both diseases are, in our opinion, variants of a single entity. Positive significant correlations (corresponding to linear and parabolic functions) between the relative interstitial volume of the renal cortex and serum creatinine concentration at the time of biopsy could be found. No correlations were observed between percentage of glomeruli affected by segmental and focal sclerosis in FGS and relative interstitial volume, or the percentage of involved glomeruli and serum creatinine concentration. The enlargement of the cortical interstitium by fibrosis may lead to a narrowing of the postglomerular vessels, to an elevation of the postglomerular flow resistance and to a slowing of the glomerular blood flow. In this way the filtrate of the glomerulus could be reduced and lead to a elevation of the serum creatinine concentration. Alternatively the observed tubular atrophy in fibrotic areas — caused by malnutrition or inactivity — could impair the tubular capacity of resorption. This may lead to a reduction of the glomerular filtrate by the so called Thurau mechanism in the case of interstitial fibrosis.
TL;DR: In this paper, a point-counting-method, tubulometry-based approach was used to investigate the relationship between relative interstitial volume and the concentration of serum creatinine at the time of biopsy.
Abstract: Renal biopsies of 44 patients with endocapillary acute glomerulonephritis (gn) and 64 patients with moderately severe mesangioproliferative gn were investigated morphometrically (point-counting-method, tubulometry). In both gn's statistically significant positive correlations between relative interstitial volume and the concentration of serum creatinine at the time of biopsy were found. Despite severe glomerular lesions the serum creatinine concentration is not increased in most cases of endocapillary acute gn, providing the relative interstitial volume is not increased by more than 15%. Increased serum creatinine concentration without a markedly enlarged interstitium was found in 11 cases of endocapillary acute gn with clinically and morphologically proven acute renal failure. In these cases the glomerular function is probably impaired by the Thurau-mechanism. In all other patients, especially in those with moderately severe mesangioproliferative gn, the serum creatinine concentration rises with an enlargement of relative interstitial volume. This reduction of renal function may be explained by a decrease to the total cross-sectional area of postglomerular vessels, caused by interstitial fibrosis. That may possibly lead to diminished renal blood flow and glomerular filtration with an increase of the serum creatinine concentration.
TL;DR: The chemical and physico-chemical data allow the conclusion that homologous Cu(I)-(thiolate) 2 -chromophores are present in these microbial Cu-thioneins.
TL;DR: In this article, azo compounds including heteroaromatics with a NN bond of strong double-bond character can eliminate molecular nitrogen on addition of sufficient thermal energy or on electronic excitation.
Abstract: Cyclic azo compounds including heteroaromatics with a NN bond of strong double-bond character can eliminate molecular nitrogen on addition of sufficient thermal energy or on electronic excitation. Some substrates decompose spontaneously, others are moderately or even extremely resistant to N2-elimination. From a preparative point of view this type of reaction opens a variety of interesting possibilities, e.g. the synthesis of small carbocycles or heterocycles, strained bi- and polycycles, as well as cage compounds. From a theoretical mechanistic viewpoint, current importance attaches to the primary fragments such as carbenes, diradicals, trimethylene, trimethylenemethane, dipoles, ylides, antiaromatic 4π-systems, unstable cycloalkynes, and arynes.
TL;DR: In this article, the molecular geometries of Me 3 COOCMe 3 and Me 3 SiOOSiMe 3, in the gas phase were determined by electron diffraction.
TL;DR: The corresponding enzyme from Aspergillus fumigatus revealed low reduction of coprogen and high reduction of ferrichrome, indicating genusdependent specificities of sideramine reduction enzymes in fungi.
TL;DR: Lipoprotein, from the outer membrane of E. coli, and several derivatives were investigated for lymphocyte stimulating activity in different species to show that lipoprotein exhibits activity towards mouse and rat splenocytes and rabbit and bovine lymph node cells.