Showing papers by "University of Freiburg published in 1981"
TL;DR: In this paper, an SO(10) gauge theory with SU(3)c × U(1)e.m. via SU(4c × SU(2)L × SU (2)R are presented.
1,327 citations
01 Jan 1981
471 citations
TL;DR: In this paper, a systematic study of neutrino masses in models with local B -L symmetry is presented, which is necessary to explain why m e is not equal m d, is related to the scale of B-L violation.
460 citations
TL;DR: The DNA of human papilloma virus type 6 (HPV 6) has been cloned in Escherichia coli K-12 by using pBR322 as vector and the existence of at least two DNA subtypes became apparent.
Abstract: The DNA of human papilloma virus type 6 (HPV 6) has been cloned in Escherichia coli K-12 by using pBR322 as vector. The DNA was cloned at the BamHI and EcoRI cleavage sites. This DNA was mapped by employing further restriction endonucleases and by terminal labeling. No major differences were noted as compared to HPV 6 DNA originating directly from a genital wart. The existence of at least two DNA subtypes (HPV 6a and 6b) became apparent.
311 citations
TL;DR: In this article, a modified simulation model based on a two-dimensional implicit difference approximation (ADI) has been developed to describe diffusion processes at stationary unshielded (micro) disk electrodes.
198 citations
TL;DR: The crystal structure of V h -amylose has been refined by a combined analysis of stereochemical conformation and packing, and by analysis of X-ray fiber diagrams as discussed by the authors.
188 citations
TL;DR: This study strongly suggests that in cytoplasmic ribosomes the 3'-end of 5.8S rRNA is basepaired with the 5'- end of 26S r RNA, which confirms the idea that 5.4S RNA is the counterpart of the 5-terminal region of prokaryotic 23S rRNAs.
Abstract: We determined 90% of the primary structure of E.coli MRE 600 23S rRNA by applying the sequencing gel technique to products of T1, S1, A and Naja oxiana nuclease digestion. Eight cistron heterogeneities were detected, as well as 16 differences with the published sequence of a 23S rRNA gene of an E.coli K12 strain. The positions of 13 post-transcriptionally modified nucleotides and of single-stranded, double-stranded and subunit surface regions of E.coli 23S rRNA were identified. Using these experimental results and by comparing the sequences of E.coli 23S rRNA, maize chloro. 23S rRNA and mouse and human mit 16S rRNAs, we built models of secondary structure for the two 23S rRNAs and for large portions of the two mit rRNAs. The structures proposed for maize chloroplast and E.coli 23S rRNAs are very similar, consisting of 7 domains closed by long-range base-pairings. In the mitochondrial 16S rRNAs, 3 of these domains are strongly reduced in size and have a very different primary structure compared to those of the 23S rRNAs. These domains were previously found to constitute a compact area in the E.coli 50S subunits. The conserved domains do not belong to this area and contain almost all the modified nucleotides. The most highly conserved domain, 2042-2625, is probably part of the ribosomal A site. Finally, our study strongly suggests that in cytoplasmic ribosomes the 3'-end of 5.8S rRNA is basepaired with the 5'-end of 26S rRNA. This confirms the idea that 5.8S RNA is the counterpart of the 5'-terminal region of prokaryotic 23S rRNA.
181 citations
TL;DR: The NADPH:protochlorophyllide oxidoreductase of barley has been solubilized from etioplast membranes and purified to apparent homogeneity and it is proposed that each enzyme molecule contains only one polypeptide chain.
Abstract: During the illumination of etiolated barley plants a rapid decline of the NADPH: protochlorophyllide oxidoreductase is observed. Within the first 5 min of continuous light approximately 90% of the enzyme activity present in dark-grown barley plants disappears and, at the same time, the amount of enzyme protein is diminished by more than 60%. No stable polypeptide fragments have been found which might be formed during the light-induced degradation of the enzyme protein. The rate of enzyme protein synthesis is not drastically affected at the beginning of the illumination period. During the subsequent light-dependent chloroplast development a phytochrome-induced decline in the rate of protein synthesis, concomittant with a continuous light-dependent degradation of the enzyme protein, leads to a progressive decrease of the concentration of the enzyme. After 6 h of continuous light, when the rate of chlorophyll accumulation is at its greatest, only traces of the enzyme protein are visible and the enzyme activity is no longer detectable within the plants. In contrast to previous concepts of chlorophyll biosynthesis in higher plants, our results present evidence that the NADPH: protochlorophyllide oxidoreductase functions only for a short time period after the onset of light.
180 citations
TL;DR: In this paper, short base-paired RNA fragments, and fragments containing intra-RNA cross-links, were isolated from E. coli 23S rRNA or 50S ribosomal subunits by two-dimensional gel electrophoresis.
Abstract: Short base-paired RNA fragments, and fragments containing intra-RNA cross-links, were isolated from E. coli 23S rRNA or 50S ribosomal subunits by two-dimensional gel electrophoresis. The interactions thus found were used as a first basis for constructing a secondary structure model of the 23S rRNA. Sequence comparison with the 23S rDNA from Z. mays chloroplasts, as well as with the 16S (large subunit) rDNA from human and mouse mitochondria, enabled the experimental model to be improved and extrapolated to give complete secondary structures of all four species. The structures are organized in well-defined domains, with over 450 compensating base changes between the two 23S species. Some ribosomal structural "'switches" were found, one involving 5S rRNA.
158 citations
01 Dec 1981
TL;DR: In this article, a quantitative model for the assessment of the thermal urban climate component in physiologically significant terms is proposed based on an adaption of Fanger's comfort (PMV) equation to outdoor conditions.
Abstract: Traditional heat island studies usually do not include bioclimatic aspects and are therefore of limited use to planners. We suggest a quantitative model for the assessment of the thermal urban climate component in physiologically significant terms. It is based on an adaption of Fanger's comfort (PMV) equation to outdoor conditions. This is achieved by parameterizing short and long wave radiative fluxes using easily obtainable meteorological data. Special emphasis is given to the change in radiation conditions within different urban structures. The spatial distribution of PMV values for a daytime and a nighttime situation in Freiburg i.Br., FRG, is presented.
158 citations
TL;DR: The nucleotide sequence of th 16S-23S spacer from a ribosomal RNA operon of Zea mays chloroplast DNA has been determined and homology between the two introns suggests that they have a common origin.
TL;DR: The results show that the prelunate cortex has access to an extraretinal signal which is activated in association with events preceding visually guided eye movements, which reflects the initiation of eye movement or the animal's interest in the stimulus.
Abstract: Single unit recording from trained rhesus monkeys demonstrate that the activity of the prelunate cortex is enhanced when a visual stimulus becomes a target of saccadic eye movement. As a rule, the enhancement is spatially selective: it does not occur if the animal makes an eye movement away from, rather than towards the stimulus. The results show that the prelunate cortex has access to an extraretinal signal which is activated in association with events preceding visually guided eye movements. Whether the signal reflects the initiation of eye movement or the animal's interest in the stimulus, which he usually selects to initiate an eye movement, remains uncertain.
TL;DR: The nucleotide sequence of 23S rDNA from Zea mays chloroplasts has been determined and reveals three small insertion sequences of 25, 65 and 78 base pairs, whereas maize 16S r DNA shows only deletions when compared with the E.coli species.
Abstract: The nucleotide sequence of 23S rDNA from Zea mays chloroplasts has been determined. Alignment with 23S rDNA from E.coli reveals 71 percent homology when maize 4.5S rDNA is included as an equivalent of the 3' end of E.coli 23S rDNA. Among the conserved sequences are sites for base modification. Chloramphenicol sensitivity and ribosomal subunit interaction. A proposal for the base pairs formed between 16S and 23S rRNAs during the 30S/50S subunit interaction is presented. The alignment of maize 23S rDNA with that of E.coli reveals three small insertion sequences of 25, 65 and 78 base pairs, whereas maize 16S rDNA shows only deletions when compared with the E.coli species.
TL;DR: Overall, the data reported in this chapter demonstrate essential similarities as well as specific differences in the responses of various members of the phototrophic bacteria toward changes in the environmental conditions.
Abstract: Publisher Summary It is generally accepted that phototrophic bacteria are recent representatives of an evolutionary ancient group of living organisms. One of the major arguments in favor of this hypothesis is the fact that all members of the phototrophic bacteria perform anoxygenic photosynthesis. It may be speculated that the acquisition of tetrapyrrole synthesis enabled original forms of these organisms to adapt to an aerobic energy metabolism employing cytochromes in a respiratory chain with oxygen as the electron acceptor. The chapter demonstrates that the photosynthetic apparatus of several species is localized in intracytoplasmic membranes, whereas the respiratory chain is contained predominantly in the cytoplasmic membrane. This cytological compartmentation of electron-transport chains cannot be generalized. Although photosynthetic bacteria exhibit considerable metabolic versatilities, all of them are largely restricted to ecological niches providing anaerobic conditions. Overall, the data reported in this chapter demonstrate essential similarities as well as specific differences in the responses of various members of the phototrophic bacteria toward changes in the environmental conditions.
TL;DR: In this article, the experimental observation of free negatively charged water clusters in the gas phase was reported, i.e., the same species have been postulated to occur in irradiated liquids or high-density vapors, the so-called hydrated electrons.
Abstract: We report the experimental observation of free negatively charged water clusters, i.e., ${{({\mathrm{H}}_{2}\mathrm{O})}_{n}}^{\ensuremath{-}}$ with $ng~8$. These species have been postulated to occur in irradiated liquids or high-density vapors---the so-called hydrated electrons---but have never been observed so far in the gas phase.
TL;DR: Pronounced differences in substrate specificities between the enzymes from spruce and soybean were found, which reflect the different lignin composition of gymnosperm and dicotyledenous angiosperms, and under physiological conditions feruloyl-CoA is the preferred substrate for the reductase from both sources.
Abstract: Cambial sap of spruce (Picea abies) proved to be a good source for isolation of cinnamoyl-CoA reductase and cinnamyl alcohol:NADP+ dehydrogenase. Apparently homogeneous enzymes were obtained by a multistep procedure including dye-ligand chromatography and for the reductase also affinity chromatography on (coenzyme A)-agarose. An improved purification procedure for the reductase from soybean cell cultures is also reported. Molecular weights and subunit composition of reductase and dehydrogenase from spruce are very similar to those of the corresponding enzymes from soybean. Reduction of feruloyl-CoA to coniferaldehyde catalysed by the reductase is a freely reversible reaction with an equilibrium constant of 5.6 x 10(-4) M at pH 6.25. A strong dependence of the Michaelis constants on the type of buffer was found. For reductase the Km-value of feruloyl-CoA in phosphate buffer (5.2 microM) is about 14-times similar than in citrate buffer (73 microM). Pronounced differences in substrate specificities between the enzymes from spruce and soybean were found, which reflect the different lignin composition of gymnosperms and dicotyledenous angiosperms. From the kinetic constants of the enzymes it can be concluded that under physiological conditions feruloyl-CoA is the preferred substrate for the reductase from both sources whereas sinapoyl-CoA is a substrate only for the soybean reductase and sinapyldehyde a substrate only for the soybean dehydrogenase. 4-Coumaroyl-CoA is a poor substrate for the reductase from both spruce and soybean. This result is consistent with the low content of 4-coumaryl alcohol units in gymnosperm and angiosperm lignin.
TL;DR: Investigations on a possible role of human genital wart virus in genital cancer were initiated after a number of unsuccessful attempts to demonstrate herpes simplex type II DNA in biopsies of such tumors by nucleic acid hybridization.
TL;DR: Measurements of zymosan induced chemiluminescence in freshly drawn unfractionated and fractionated blood seem to be especially suited to monitor and analyze deviations and defects of the cellular and humoral defence mechanisms.
Abstract: The present investigations were undertaken to find out whether chemiluminescence measurements of stimulated granulocytes can be carried out in freshly drawn blood and — because of the ease of the method — be introduced into routine diagnostics. Blood was drawn from the cubital vein of healthy volunteers at various times and under various conditions. Subsequently the zymosan induced and luminol amplified chemiluminescence was recorded and analyzed. It could be demonstrated that variations existed between individuals which can, however, be minimized when photon counts obtained under standard conditions were related to the number of granulocytes present in the blood samples. It could be further demonstrated that also platelets are activated by zymosan as well and that they, contribute to the total chemiluminescence by a share of about 5%. Platelet chemiluminescence can effectively be suppressed by aspirin. Opsonising factors in plasma (presumably antibodies and/or complement) play a decisive role in the intensity and kinetics of blood chemiluminescence. Measurements of zymosan induced chemiluminescence in freshly drawn unfractionated and fractionated blood seem to be especially suited to monitor and analyze deviations and defects of the cellular and humoral defence mechanisms.
TL;DR: The solubilization and partial purification of a plant microsomal ATPase by CaMSepharose affinity chromatography and on the CaMdependence of the partially purified enzyme are reported on.
TL;DR: The IC50 values obtained for different standard acidic NSAID's varied within 4 orders of magnitude They correspond favorably to their clinical potency and their potency in a variety of standard tests for antiinflammatory drugs as mentioned in this paper.
Abstract: 1
A sensitive, simple, reproducible, and economical assay for structure-activity investigations of non-steroidal anti-inflammatory drugs (NSAID) is lacking This has promted us to investigate the advantages and limitations of defining for that purpose the potency of NSAID's as inhibitors of tumour promoter-induced prostaglandin (PG) release from mouse peritoneal macrophages in culture
2
These cells release mainly PGE2 and PGI2 (measured as its stable hydrolysis product 6-keto-PGF1α) upon stimulation with the tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA)
3
The PG release was dose-dependently inhibited by a variety of NSAID's Their inhibitory potency was dependent on the culture conditions employed The widely used acidic NSAID's were more potent when assayed under serum free culture conditions at low pH
4
Dose response curves for acidic NSAID tested under serum free conditions allowed for the definition of IC50 values being reproducible within their 95% confidence limits
5
The IC50 values obtained for different standard acidic NSAID's varied within 4 orders of magnitude They corresponded favourably to their clinical potency and their potency in a variety of standard tests for antiinflammatory drugs
6
IC50 values of five congeners of indomethacin differed up to 2 orders of magnitude in agreement with in vivo observations indicating the applicability of this assay for structure-activity investigations
TL;DR: In this paper, a method to recover Wightman fields from a Haag-Kastler theory of local observables is presented, which may provide a basis for the comparison of different theories and for an algebraic description of high energy behaviour.
Abstract: We present a method to recover Wightman fields from a Haag-Kastler theory of local observables. This may provide a basis for the comparison of different theories and for an algebraic description of high energy behaviour.
TL;DR: Kupffer cells were isolated from pronase-perfused rat livers and were maintained as a monolayer culture in a state of high purity and viability, and chemiluminescence and O2- production were almost completely inhibited by superoxide dismutase and iodoacetate.
Abstract: Kupffer cells were isolated from pronase-perfused rat livers and were maintained as a monolayer culture in a state of high purity and viability. Immediately after contact with zymosan particles, O2 uptake of the Kupffer cells increased fivefold; about 50% of the net oxygen consumed was accounted for as superoxide released into the medium. Concomitantly, a transient burst of luminol-dependent chemiluminescence, an increased activity of NAD(P)H oxidase and a stimulation of the flow of glucose through the hexose monophophate shunt were observed. Chemiluminescence and O2 production were almost completely inhibited by superoxide dismutase and iodoacetate. Zymosan-induced chmiluminesceance was not inhibited in the presence of the non-penetrating thiol reagents, 5,5′-dithio-bis-2-nitrobenzoate and iodoacetyl-sepharose. Iodoacetate acted on the cytosolic glucose-6-phosphate dehydrogenase rather than on NAD(P)H oxidase of the cell membrane.
TL;DR: Four compounds are added to the list of drugs with α-adrenoceptor affinity which inhibit (agonists) or facilitate (antagonists) action-potential-evoked release of noradrenaline in rat brain cortex.
TL;DR: A computer simulation was used to quantify the effects of fluctuation, mutation, and package death by accident and it is suggested that life started out with compartments containing not more than 3 different genes.
Abstract: The “package model” discussed here is concerned with the preservation of genetic information by primordial compartments. Each viable “package” encloses a complete set of unlinked genes in varying numbers of copies. Due to stochastic distribution and error-prone replication two potent perils endanger the informational integrity of packages: fluctuation and mutation.
TL;DR: It appears that the strength training in group A involved the fast fibers of both muscles, whereas in group B the training influence was less marked, and affected both fast and slow fiber types.
Abstract: Thirty young male adults matched in two experimental groups (n=12) and a control group (n=6) were investigated before and after an 8-week strength training period. Group A trained with few repetitions and maximal loads, whereas group B had more repetitions with smaller loads. Both groups lifted the same total load during each training period, four times a week. Maximal voluntary strength (MVS) of a shot-put arm movement, muscular excitability and contractile properties (time to peak of contraction with threshold stimuli, half relaxation time) were measured in M. deltoideus and M. triceps brachii, C. longum, for two durations of stimulation. Increases of 14.8% (group A) and 12.2% (group B) in MVS were observed. Muscle excitability significantly increased in all types of training and both muscles. Significant shortening of the contraction time, dependent on the type of training, was observed in both studied muscles. It appears that the strength training in group A involved the fast fibers of both muscles, whereas in group B the training influence was less marked, and affected both fast and slow fiber types.
TL;DR: For the classical two-dimensional nonlinear σ-model on a Riemannian symmetric space of dimensionm and rankp, there exist p independent series of higher local conservation laws, and the field equations of the model to a system of nonlinear partial differential equations possessing an associated Lax pair and involving m+p independent variables as discussed by the authors.
Abstract: We show that for the classical two-dimensional nonlinear σ-model on a Riemannian symmetric space of dimensionm and rankp, there existp independent series of higher local conservation laws, and we reduce the field equations of the model to a system of nonlinear partial differential equations possessing an associated Lax pair and involvingm+p independent variables
TL;DR: The structure of the hydrated amylose-iodine complex has been determined by combined methods of X-ray diffraction and stereochemical packing analysis as discussed by the authors, and the unit cell was identified as orthorhombic with a
TL;DR: A combinatorial lemma is proved and used here to derive new results on ω -automata and to give simpler proofs of known ones and new normal form theorems and also decidability results are proved for the first-order and the monadic second-order theory of certain structures over the ordering of natural numbers.
Abstract: A combinatorial lemma is proved and used here to derive new results on ω -automata and to give simpler proofs of known ones. In particular, we reprove McNaughton's fundamental theorem (characterizing the ω -regular sequence-sets), without having to construct a sophisticated ω -automaton. The theorem is obtained by coding the behaviour of automata in a second-order language and a simple application of the lemma. In close analogy (now referring to a first-order language) a theory of counter-free ω-automata is developed; it is shown that these automata are appropriate for characterizing the ω -star-free sequence-sets. Finally, the lemma is applied in mathematical logic: Here new normal form theorems and also decidability results are proved for the first-order and the monadic second-order theory of certain structures over the ordering of natural numbers.
TL;DR: Fu “excretion rate — response” curves showed diminished tubular sensitivity to Fu in cirrhosis, and there was a significant reduction in urine sodium and volume, whereas potassium excretion remained unchanged.
Abstract: After rapid intravenous injection of furosemide 40 mg (Fu), plasma levels were determined in 7 healthy volunteers, 8 patients with liver cirrhosis with ascites and 7 patients with end-stage renal disease (ESRD). The diuretic response was evaluated by measuring the urinary excretion of sodium and potassium and the urine volume. The mean elimination half life (tF1/2+) of Fu averaged 51±7.7 (±SD) min in healthy subjects, 52±7.7 min in cirrhosis and 200±57 min in ESRD. The non-renal clearance (Clnr) in healthy subjects (56±28 ml/min) corresponds to the total plasma clearance in functionally anephric patients (54±18 ml/min). In cirrhosis there was no significant change in the disposition parameters of Fu in comparison to the healthy volunteers, but there was a significant reduction in urine sodium and volume, whereas potassium excretion remained unchanged. Fu “excretion rate — response” curves showed diminished tubular sensitivity to Fu in cirrhosis.
TL;DR: Electroantennogram (EAG) studies correlated well with the behavioural studies and revealed both sexes to have a lower threshold for the pheromone, (S)‐(‐)‐cis‐verbenol, than its host terpene precursor, (‐]‐alpha‐pinene, in both sexes.
Abstract: . Field tests showed (S)-(-)-cis-verbenol and (R)-(+)-trans-verbenol in combination with a second pheromonal component, 2-methyl-3-buten-2-ol, more attractive than the combination with their optical antipodes. Inhibition of response to the attractant component, (S)-(-)-cis-verbenol, by high concentrations of its optical antipode did not occur. No significant differences were noted for response to the attractant, (S)-(-)-cis-verbenol and 2-methyl-3-buten-2-ol, with the addition of either ipsdienol enantiomer or a racemic mixture of ipsdienol enantiomers. Electroantennogram (EAG) studies correlated well with the behavioural studies. EAGs recorded from male and female beetles revealed both sexes to have a lower threshold for the pheromone, (S)-(-)-cis-verbenol, than its host terpene precursor, (-)-alpha-pinene. EAGs showed a greater number of acceptors for (-)-alpha-pinene in males than in females. EAGs at acceptor saturation to the enantiomers of alpha-pinene and the verbenol isomers showed males more responsive to (-)-alpha-pinene, (±)-cis-verbenol, and (R)-(+)-trans-verbenol. Significantly greater EAGs were elicited in females than in males to (-)-alpha-pinene, and (±)- and (S)-(-)-cis-verbenol. No significant differences in EAGs of females to the enantiomers of trans-verbenol were noted. EAGs showed similar thresholds in males and females to the pheromone component, 2-methyl-3-buten-2-ol; however, female response at threshold was significantly greater than male response. The results are discussed with regard to olfactory acceptor evolution.